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Thursday, April 29, 2021

Ethnocentrism

From Wikipedia, the free encyclopedia
 
Polish sociologist Ludwig Gumplowicz is believed to have coined the term "ethnocentrism" in the 19th century, although he may have merely popularized it.

Ethnocentrism in social science and anthropology—as well as in colloquial English discourse—means to apply one's own culture or ethnicity as a frame of reference to judge other cultures, practices, behaviors, beliefs, and people, instead of using the standards of the particular culture involved. Since this judgement is often negative, some people also use the term to refer to the belief that one's culture is superior to, or more correct or normal than, all others—especially regarding the distinctions that define each ethnicity's cultural identity, such as language, behavior, customs, and religion. In common usage, it can also simply mean any culturally biased judgment. For example, ethnocentrism can be seen in the common portrayals of the Global South and the Global North.

Ethnocentrism is sometimes related to racism, stereotyping, discrimination, or xenophobia. However, the term "ethnocentrism" does not necessarily involve a negative view of the others' race or indicate a negative connotation. The opposite of ethnocentrism is cultural relativism, which means to understand a different culture in its own terms without subjective judgments.

The term "ethnocentrism" was first applied in the social sciences by American sociologist William G. Sumner. In his 1906 book, Folkways, Sumner describes ethnocentrism as "the technical name for the view of things in which one's own group is the center of everything, and all others are scaled and rated with reference to it." He further characterized ethnocentrism as often leading to pride, vanity, the belief in one's own group's superiority, and contempt for outsiders.

Over time, ethnocentrism developed alongside the progression of social understandings by people such as social theorist, Theodore W. Adorno. In Adorno's The Authoritarian Personality, he and his colleagues of the Frankfurt School established a broader definition of the term as a result of "in group-out group differentiation," stating that ethnocentrism "combines a positive attitude toward one's own ethnic/cultural group (the in-group) with a negative attitude toward the other ethnic/cultural group (the out-group)." Both of these juxtaposing attitudes are also a result of a process known as social identification and social counter-identification.

Origins and development

The term ethnocentrism derives from two Greek words: "ethnos," meaning nation, and "kentron," meaning center. Scholars believe this term was coined by Polish sociologist Ludwig Gumplowicz in the 19th century, although alternate theories suggest that he only popularized the concept as opposed to inventing it. He saw ethnocentrism as a phenomenon similar to the delusions of geocentrism and anthropocentrism, defining Ethnocentrism as "the reasons by virtue of which each group of people believed it had always occupied the highest point, not only among contemporaneous peoples and nations, but also in relation to all peoples of the historical past."

Subsequently, in the 20th century, American social scientist William G. Sumner proposed two different definitions in his 1906 book Folkways. Sumner stated that "Ethnocentrism is the technical name for this view of things in which one's own group is the center of everything, and all others are scaled and rated with reference to it." In the War and Other Essays (1911), he wrote that "the sentiment of cohesion, internal comradeship, and devotion to the in-group, which carries with it a sense of superiority to any out-group and readiness to defend the interests of the in-group against the out-group, is technically known as ethnocentrism." According to Boris Bizumic it is a popular misunderstanding that Sumner originated the term ethnocentrism, stating that in actuality he brought ethnocentrism into the mainstreams of anthropology, social science, and psychology through his English publications.

Several theories have been reinforced through the social and psychological understandings of ethnocentrism including T.W Adorno's Authoritarian Personality Theory (1950), Donald T. Campbell's Realistic Group Conflict Theory (1972), and Henri Tajfel's Social identity theory (1986). These theories have helped to distinguish ethnocentrism as a means to better understand the behaviors caused by in-group and out-group differentiation throughout history and society.

Ethnocentrism in social sciences

William Graham Sumner

In social sciences, ethnocentrism means to judge another culture based on the standard of one's own culture instead of the standard of the other particular culture. When people use their own culture as a parameter to measure other cultures, they often tend to think that their culture is superior and see other cultures as inferior and bizarre. Ethnocentrism can be explained at different levels of analysis. For example, at an intergroup level, this term is seen as a consequence of a conflict between groups; while at the individual level, in-group cohesion and out-group hostility can explain personality traits. Also, ethnocentrism can helps us to explain the construction of identity. Ethnocentrism can explain the basis of one's identity by excluding the outgroup that is the target of ethnocentric sentiments and used as a way of distinguishing oneself from other groups that can be more or less tolerant. This practice in social interactions creates social boundaries, such boundaries define and draw symbolic boundaries of the group that one wants to be associated with or belong to. In this way, ethnocentrism is a term not only limited to anthropology but also can be applied to other fields of social sciences like sociology or psychology.   

Anthropology

The classifications of ethnocentrism originate from the studies of anthropology. With its omnipresence throughout history, ethnocentrism has always been a factor in how different cultures and groups related to one another. Examples including how historically, foreigners would be characterized as "Barbarians," or how China believed their nation to be the "Empire of the Center" and viewed foreigners as privileged subordinates. However, the anthropocentric interpretations initially took place most notably in the 19th century when anthropologists began to describe and rank various cultures according to the degree to which they had developed significant milestones, such as monotheistic religions, technological advancements, and other historical progressions.

Most rankings were strongly influenced by colonization and the belief to improve societies they colonized, ranking the cultures based on the progression of their western societies and what they classified as milestones. Comparisons were mostly based on what the colonists believed as superior and what their western societies have accomplished. Thomas Macaulay, an English politician in the 19th Century, attempted to validate the opinion that "one shelf of a Western library" had more knowledge then the years of text and literature developed by the Eastern societies. Ideas developed by Charles Darwin has ethnocentric ideals where societies who believed they were superior were most likely to survive and prosper. Edward Said's orientalist concept represented how Western reactions to non-Western societies were based on an "unequal power relationship" that Western peoples developed due to colonization and the influence it held over non-Western societies.

The ethnocentric classification of "primitive" were also used by 19th and 20th century anthropologists and represented how unawareness in cultural and religious understanding changed overall reactions to non-Western societies. Modern anthropologist Sir Edward Burnett Tylor wrote about "primitive" societies in Primitive Culture (1871) creating a "civilization" scale where it was implied that ethnic cultures preceded civilized societies. The use of "savage" as a classification is modernly known as "tribal" or "pre-literate" where it was usually referred as a derogatory term as the "civilization" scale became more common. Examples that demonstrate a lack of understanding include when European travelers judged different languages based on that fact that they could not understand it and displayed a negative reaction, or the intolerance displayed by Westerners when exposed to unknown religions and symbolisms. Georg Wilhelm Friedrich Hegel, a German philosopher, justified Western colonization by reasoning that since the non-Western societies were "primitive" and "uncivilized," their culture and history was not worth conserving and should allow Westernization.

Anthropologist Franz Boas saw the flaws in this formulaic approach to ranking and interpreting cultural development and committed himself to overthrowing this inaccurate reasoning due to many factors involving their individual characteristics. With his methodological innovations, Boas sought to show the error of the proposition that race determined cultural capacity. In his 1911 book The Mind of Primitive Man, Boas wrote that:

It is somewhat difficult for us to recognize that the value which we attribute to our own civilization is due to the fact that we participate in this civilization, and that it has been controlling all our actions from the time of our birth; but it is certainly conceivable that there may be other civilizations, based perhaps on different traditions and on a different equilibrium of emotion and reason, which are of no less value than ours, although it may be impossible for us to appreciate their values without having grown up under their influence.

Together, Boas and his colleagues propagated the certainty that there are no inferior races or cultures. This egalitarian approach introduced the concept of cultural relativism to anthropology, a methodological principle for investigating and comparing societies in as unprejudiced as possible and without using a developmental scale as anthropologists at the time were implementing. Boas and anthropologist Bronisław Malinowski argued that any human science had to transcend the ethnocentric views that could blind any scientist's ultimate conclusions.

Both had also urged anthropologists to conduct ethnographic fieldwork to overcome their ethnocentrism. To help, Malinowski would develop the theory of functionalism as guides for producing non-ethnocentric studies of different cultures. Classic examples of anti-ethnocentric anthropology include Margaret Mead's Coming of Age in Samoa (1928), which in time has met with severe criticism for its incorrect data and generalisations, Malinowski's The Sexual Life of Savages in North-Western Melanesia (1929), and Ruth Benedict's Patterns of Culture (1934). Mead and Benedict were two of Boas's students.

Scholars generally agree that Boas developed his ideas under the influence of the German philosopher Immanuel Kant. Legend has it that, on a field trip to the Baffin Islands in 1883, Boas would pass the frigid nights reading Kant's Critique of Pure Reason. In that work, Kant argued that human understanding could not be described according to the laws that applied to the operations of nature, and that its operations were therefore free, not determined, and that ideas regulated human action, sometimes independent of material interests. Following Kant, Boas pointed out the starving Eskimos who, because of their religious beliefs, would not hunt seals to feed themselves, thus showing that no pragmatic or material calculus determined their values.

Causes

Ethnocentrism is believed to be a learned behavior embedded into a variety of beliefs and values of an individual or group.

Due to enculturation, individuals in in-groups have a deeper sense of loyalty and are more likely to following the norms and develop relationships with associated members. Within relation to enculturation, ethnocentrism is said to be a transgenerational problem since stereotypes and similar perspectives can be enforced and encouraged as time progresses. Although loyalty can increase better in-grouper approval, limited interactions with other cultures can prevent individuals to have an understanding and appreciation towards cultural differences resulting in greater ethnocentrism.

The social identity approach suggests that ethnocentric beliefs are caused by a strong identification with one's own culture that directly creates a positive view of that culture. It is theorized by Henri Tajfel and John C. Turner that to maintain that positive view, people make social comparisons that cast competing cultural groups in an unfavorable light.

Alternative or opposite perspectives could cause individuals to develop naïve realism and be subject to limitations in understandings. These characteristics can also lead to individuals to become subject to ethnocentrism, when referencing out-groups, and black sheep effect, where personal perspectives contradict those from fellow in-groupers.

Realistic conflict theory assumes that ethnocentrism happens due to "real or perceived conflict" between groups. This also happens when a dominant group may perceive the new members as a threat. Scholars have recently demonstrated that individuals are more likely to develop in-group identification and out-group negatively in response to intergroup competition, conflict, or threat.

Although the causes of ethnocentric beliefs and actions can have varying roots of context and reason, the effects of ethnocentrism has had both negative and positive effects throughout history. The most detrimental effects of ethnocentrism resulting into genocide, apartheid, slavery, and many violent conflicts. Historical examples of these negative effects of ethnocentrism are The Holocaust, the Crusades, the Trail of Tears, and the internment of Japanese Americans. These events were a result of cultural differences reinforced inhumanely by a superior, majority group. In his 1976 book on evolution, The Selfish Gene, evolutionary biologist Richard Dawkins writes that "blood-feuds and inter-clan warfare are easily interpretative in terms of Hamilton's genetic theory." Simulation-based experiments in evolutionary game theory have attempted to provide an explanation for the selection of ethnocentric-strategy phenotypes.

The positive examples of ethnocentrism throughout history have aimed to prohibit the callousness of ethnocentrism and reverse the perspectives of living in a single culture. These organizations can include the formation of the United Nations; aimed to maintain international relations, and the Olympic Games; a celebration of sports and friendly competition between cultures.

Effects

A study in New Zealand was used to compare how individuals associate with in-groups and out-groupers and has a connotation to discrimination. Strong in-group favoritism benefits the dominant groups and is different from out-group hostility and/or punishment. A suggested solution is to limit the perceived threat from the out-group that also decreases the likeliness for those supporting the in-groups to negatively react.

Ethnocentrism also influences consumer preference over which goods they purchase. A study that used several in-group and out-group orientations have shown a correlation between national identity, consumer cosmopolitanism, consumer ethnocentrism, and the methods consumer choose their products, whether imported or domestic.

Ethnocentrism and racism

Ethnocentrism is usually associated with racism. However, as mentioned before, ethnocentrism does not necessarily implicate a negative connotation. In European research the term racism is not linked to ethnocentrism because Europeans avoid applying the concept of race to humans; meanwhile, using this term is not a problem for American researchers. Since ethnocentrism implicated a strong identification with one's in-group, it mostly automatically leads to negative feelings and stereotyping to the members of the outgroup, which can be confused with racism. Finally, scholars agree that avoiding stereotypes is an indispensable prerequisite to overcome ethnocentrism; and mass media play a key role regarding this issue.

Effects of ethnocentrism in the media

Ethnocentrism in Western films

Mass media plays an important role in our current society. We are constantly exposed to media content every day. Researchers had found that ethnocentrism is dysfunctional in communication and similar fields because the lack of acceptance of other cultures leads to the creation of barriers for people of different backgrounds to interact with each other. The presence of ethnocentrism in media content creates an issue in the exchange of messages in the communication process. The media industry is dominated by the Global North, so Western ethnocentrism tends to be exposed in the media. This can be seen in the predominance of Westerner content in TV shows, film, and other forms of mass media. Some Western shows tend to depict foreign cultures as inferior or strange in contrast to their own culture.

Film

Aladdin from Disney as an example of ethnocentrism

Cinema has been around our society since the beginning of the 20th century, and it is an important tool that allow to entertain and/or educate the viewer. Western companies are usually the leaders of the film industry. Thus, it is common to be exposed to content based on Westerners' point of view. Examples of ethnocentrism are constantly seen in films whether intentionally or unintentionally. A clear example of this can be seen on the American animated film Aladdin by Disney in 1992; the opening song of the movie is "Arabian Nights," it is mentioned on the lyrics that that land "it's barbaric, hey, but it's home," which had caused debates among the audience because it could lead to thinking that the Arabic culture is barbaric. Examples like this abound on many Hollywood films. Experts on the field propose that a way of overcoming ethnocentrism is to avoid the use of stereotypes in films. Therefore, the presence of ethnocentrism in cinema leads to stereotypical images of cultures that differ from ours.

Social media

A considerable number of people are exposed to social media, whose purpose is to encourage interaction among users. However, that exchange of information can be hindered by ethnocentrism because it can diminish the interest of interacting with people from other cultures.

Oxytocin

From Wikipedia, the free encyclopedia

Oxytocin
Oxytocin with labels.png
OxitocinaCPK3D.png
Clinical data
Pronunciation/ˌɒksɪˈtsɪn/
Physiological data
Source tissuespituitary gland
Target tissueswide spread
Receptorsoxytocin receptor
Antagonistsatosiban
Precursoroxytocin/neurophysin I prepropeptide
Metabolismliver and other oxytocinases
Pharmacokinetic data
Protein binding30%
Metabolismliver and other oxytocinases
Elimination half-life1–6 min (IV)
~2 h (intranasal)
ExcretionBiliary and kidney
Identifiers

CAS Number
PubChem CID
IUPHAR/BPS
DrugBank
ChemSpider
UNII
KEGG
ChEBI
ChEMBL
CompTox Dashboard (EPA)
ECHA InfoCard100.000.045 Edit this at Wikidata
Chemical and physical data
FormulaC43H66N12O12S2
Molar mass1007.19 g·mol−1
3D model (JSmol)

Oxytocin (Oxt) is a peptide hormone and neuropeptide. It is normally produced in the hypothalamus and released by the posterior pituitary. It plays a role in social bonding, reproduction, childbirth, and the period after childbirth. Oxytocin is released into the bloodstream as a hormone in response to love and in labor. This helps with birth, bonding with the baby, and milk production.

Oxytocin is derived by enzymatic splitting from the peptide precursor encoded by the human OXT gene. The deduced structure of the active nonapeptide is:

·Cys – Tyr – Ile – Gln – Asn – Cys – Pro – Leu – Gly – NH2, or CYIQNCPLG-NH2.

Discovery

Oxytocin was discovered by Henry Dale in 1906. Its molecular structure was determined in 1952. It is also used as a medication to facilitate childbirth (see oxytocin (medication) for more information). In the early 1950s, American biochemist Vincent du Vigneaud found that oxytocin is made up of nine amino acids, and he identified its amino acid sequence. In 1953 du Vigneaud carried out the synthesis of oxytocin, making it the first polypeptide hormone to be synthesized.

Biochemistry

Estrogen has been found to increase the secretion of oxytocin and to increase the expression of its receptor, the oxytocin receptor, in the brain. In women, a single dose of estradiol has been found to be sufficient to increase circulating oxytocin concentrations.

Biosynthesis

The biosynthesis of the different forms of OT
The biosynthesis of the different forms of OT

The oxytocin peptide is synthesized as an inactive precursor protein from the OXT gene. This precursor protein also includes the oxytocin carrier protein neurophysin I. The inactive precursor protein is progressively hydrolyzed into smaller fragments (one of which is neurophysin I) via a series of enzymes. The last hydrolysis that releases the active oxytocin nonapeptide is catalyzed by peptidylglycine alpha-amidating monooxygenase (PAM).

The activity of the PAM enzyme system is dependent upon vitamin C (ascorbate), which is a necessary vitamin cofactor. By chance, sodium ascorbate by itself was found to stimulate the production of oxytocin from ovarian tissue over a range of concentrations in a dose-dependent manner. Many of the same tissues (e.g. ovaries, testes, eyes, adrenals, placenta, thymus, pancreas) where PAM (and oxytocin by default) is found are also known to store higher concentrations of vitamin C.

Oxytocin is known to be metabolized by the oxytocinase, leucyl/cystinyl aminopeptidase. Other oxytocinases are also known to exist. Amastatin, bestatin (ubenimex), leupeptin, and puromycin have been found to inhibit the enzymatic degradation of oxytocin, though they also inhibit the degradation of various other peptides, such as vasopressin, met-enkephalin, and dynorphin A.

Neural sources

In the hypothalamus, oxytocin is made in magnocellular neurosecretory cells of the supraoptic and paraventricular nuclei, and is stored in Herring bodies at the axon terminals in the posterior pituitary. It is then released into the blood from the posterior lobe (neurohypophysis) of the pituitary gland. These axons (likely, but dendrites have not been ruled out) have collaterals that innervate neurons in the nucleus accumbens, a brain structure where oxytocin receptors are expressed. The endocrine effects of hormonal oxytocin and the cognitive or behavioral effects of oxytocin neuropeptides are thought to be coordinated through its common release through these collaterals. Oxytocin is also produced by some neurons in the paraventricular nucleus that project to other parts of the brain and to the spinal cord. Depending on the species, oxytocin receptor-expressing cells are located in other areas, including the amygdala and bed nucleus of the stria terminalis.

In the pituitary gland, oxytocin is packaged in large, dense-core vesicles, where it is bound to neurophysin I as shown in the inset of the figure; neurophysin is a large peptide fragment of the larger precursor protein molecule from which oxytocin is derived by enzymatic cleavage.

Secretion of oxytocin from the neurosecretory nerve endings is regulated by the electrical activity of the oxytocin cells in the hypothalamus. These cells generate action potentials that propagate down axons to the nerve endings in the pituitary; the endings contain large numbers of oxytocin-containing vesicles, which are released by exocytosis when the nerve terminals are depolarised.

Non-neural sources

Endogenous oxytocin concentrations in the brain have been found to be as much as 1000-fold higher than peripheral levels.

Outside the brain, oxytocin-containing cells have been identified in several diverse tissues, including in females in the corpus luteum and the placenta; in males in the testicles' interstitial cells of Leydig; and in both sexes in the retina, the adrenal medulla, the thymus and the pancreas. The finding of significant amounts of this classically "neurohypophysial" hormone outside the central nervous system raises many questions regarding its possible importance in these diverse tissues.

Male

The Leydig cells in some species have been shown to possess the biosynthetic machinery to manufacture testicular oxytocin de novo, to be specific, in rats (which can synthesize vitamin C endogenously), and in guinea pigs, which, like humans, require an exogenous source of vitamin C (ascorbate) in their diets.

Female

Oxytocin is synthesized by corpora lutea of several species, including ruminants and primates. Along with estrogen, it is involved in inducing the endometrial synthesis of prostaglandin F to cause regression of the corpus luteum.

Evolution

Virtually all vertebrates have an oxytocin-like nonapeptide hormone that supports reproductive functions and a vasopressin-like nonapeptide hormone involved in water regulation. The two genes are usually located close to each other (less than 15,000 bases apart) on the same chromosome, and are transcribed in opposite directions (however, in fugu, the homologs are further apart and transcribed in the same direction).

The two genes are believed to result from a gene duplication event; the ancestral gene is estimated to be about 500 million years old and is found in cyclostomata (modern members of the Agnatha).

Biological function

Oxytocin has peripheral (hormonal) actions, and also has actions in the brain. Its actions are mediated by specific oxytocin receptors. The oxytocin receptor is a G-protein-coupled receptor, OT-R, which requires magnesium and cholesterol and is expressed in myometrial cells. It belongs to the rhodopsin-type (class I) group of G-protein-coupled receptors.

Studies have looked at oxytocin's role in various behaviors, including orgasm, social recognition, pair bonding, anxiety, in-group bias, situational lack of honesty, autism, and maternal behaviors.

Physiological

The peripheral actions of oxytocin mainly reflect secretion from the pituitary gland. The behavioral effects of oxytocin are thought to reflect release from centrally projecting oxytocin neurons, different from those that project to the pituitary gland, or that are collaterals from them. Oxytocin receptors are expressed by neurons in many parts of the brain and spinal cord, including the amygdala, ventromedial hypothalamus, septum, nucleus accumbens, and brainstem, although the distribution differs markedly between species. Furthermore, the distribution of these receptors changes during development and has been observed to change after parturition in the montane vole.

  • Milk ejection reflex/Letdown reflex: in lactating (breastfeeding) mothers, oxytocin acts at the mammary glands, causing milk to be 'let down' into lactiferous ducts, from where it can be excreted via the nipple. Suckling by the infant at the nipple is relayed by spinal nerves to the hypothalamus. The stimulation causes neurons that make oxytocin to fire action potentials in intermittent bursts; these bursts result in the secretion of pulses of oxytocin from the neurosecretory nerve terminals of the pituitary gland.
  • Uterine contraction: important for cervical dilation before birth, oxytocin causes contractions during the second and third stages of labor. Oxytocin release during breastfeeding causes mild but often painful contractions during the first few weeks of lactation. This also serves to assist the uterus in clotting the placental attachment point postpartum. However, in knockout mice lacking the oxytocin receptor, reproductive behavior and parturition are normal.
  • In male rats, oxytocin may induce erections. A burst of oxytocin is released during ejaculation in several species, including human males; its suggested function is to stimulate contractions of the reproductive tract, aiding sperm release.
  • Human sexual response: Oxytocin levels in plasma rise during sexual stimulation and orgasm. At least two uncontrolled studies have found increases in plasma oxytocin at orgasm – in both men and women. Plasma oxytocin levels are increased around the time of self-stimulated orgasm and are still higher than baseline when measured five minutes after self arousal. The authors of one of these studies speculated that oxytocin's effects on muscle contractibility may facilitate sperm and egg transport.
In a study measuring oxytocin serum levels in women before and after sexual stimulation, the author suggests it serves an important role in sexual arousal. This study found genital tract stimulation resulted in increased oxytocin immediately after orgasm. Another study reported increases of oxytocin during sexual arousal could be in response to nipple/areola, genital, and/or genital tract stimulation as confirmed in other mammals. Murphy et al. (1987), studying men, found that plasma oxytocin levels remain unchanged during sexual arousal, but that levels increase sharply after ejaculation, returning to baseline levels within 30 minutes. In contrast, vasopressin was increased during arousal but returned to baseline at the time of ejaculation. The study concludes that (in males) vasopressin is secreted during arousal, while oxytocin is only secreted after ejaculation. A more recent study of men found an increase in plasma oxytocin immediately after orgasm, but only in a portion of their sample that did not reach statistical significance. The authors noted these changes "may simply reflect contractile properties on reproductive tissue".
  • Due to its similarity to vasopressin, it can reduce the excretion of urine slightly, and so it can be classified as an antidiuretic. In several species, oxytocin can stimulate sodium excretion from the kidneys (natriuresis), and, in humans, high doses can result in low sodium levels (hyponatremia).
  • Cardiac effects: oxytocin and oxytocin receptors are also found in the heart in some rodents, and the hormone may play a role in the embryonal development of the heart by promoting cardiomyocyte differentiation. However, the absence of either oxytocin or its receptor in knockout mice has not been reported to produce cardiac insufficiencies.
  • Modulation of hypothalamic-pituitary-adrenal axis activity: oxytocin, under certain circumstances, indirectly inhibits release of adrenocorticotropic hormone and cortisol and, in those situations, may be considered an antagonist of vasopressin.
  • Preparing fetal neurons for delivery (in rats): crossing the placenta, maternal oxytocin reaches the fetal brain and induces a switch in the action of neurotransmitter GABA from excitatory to inhibitory on fetal cortical neurons. This silences the fetal brain for the period of delivery and reduces its vulnerability to hypoxic damage.
  • Feeding: a 2012 paper suggested that oxytocin neurons in the para-ventricular hypothalamus in the brain may play a key role in suppressing appetite under normal conditions and that other hypothalamic neurons may trigger eating via inhibition of these oxytocin neurons. This population of oxytocin neurons is absent in Prader-Willi syndrome, a genetic disorder that leads to uncontrollable feeding and obesity, and may play a key role in its pathophysiology. Research on the oxytocin-related neuropeptide asterotocin in starfish also showed that in echinoderms, the chemical induces muscle relaxation, and in starfish specifically caused the organisms to evert their stomach and react as though feeding on prey, even when none were present.

Psychological

  • Autism: Oxytocin has been implicated in the etiology of autism, with one report suggesting autism is correlated to a mutation on the oxytocin receptor gene (OXTR). Studies involving Caucasian, Finnish and Chinese Han families provide support for the relationship of OXTR with autism. Autism may also be associated with an aberrant methylation of OXTR.

Bonding

In the prairie vole, oxytocin released into the brain of the female during sexual activity is important for forming a pair bond with her sexual partner. Vasopressin appears to have a similar effect in males. Oxytocin has a role in social behaviors in many species, so it likely also does in humans. In a 2003 study, both humans and dog oxytocin levels in the blood rose after five to 24 minutes of a petting session. This possibly plays a role in the emotional bonding between humans and dogs.

  • Maternal behavior: Female rats given oxytocin antagonists after giving birth do not exhibit typical maternal behavior. By contrast, virgin female sheep show maternal behavior toward foreign lambs upon cerebrospinal fluid infusion of oxytocin, which they would not do otherwise. Oxytocin is involved in the initiation of human maternal behavior, not its maintenance; for example, it is higher in mothers after they interact with unfamiliar children rather than their own.
  • Human ingroup bonding: Oxytocin can increase positive attitudes, such as bonding, toward individuals with similar characteristics, who then become classified as "in-group" members, whereas individuals who are dissimilar become classified as "out-group" members. Race can be used as an example of in-group and out-group tendencies because society often categorizes individuals into groups based on race (Caucasian, African American, Latino, etc.). One study that examined race and empathy found that participants receiving nasally administered oxytocin had stronger reactions to pictures of in-group members making pained faces than to pictures of out-group members with the same expression. Moreover, individuals of one race may be more inclined to help individuals of the same race than individuals of another race when they are experiencing pain. Oxytocin has also been implicated in lying when lying would prove beneficial to other in-group members. In a study where such a relationship was examined, it was found that when individuals were administered oxytocin, rates of dishonesty in the participants' responses increased for their in-group members when a beneficial outcome for their group was expected. Both of these examples show the tendency of individuals to act in ways that benefit those considered to be members of their social group, or in-group.

Oxytocin is not only correlated with the preferences of individuals to associate with members of their own group, but it is also evident during conflicts between members of different groups. During conflict, individuals receiving nasally administered oxytocin demonstrate more frequent defense-motivated responses toward in-group members than out-group members. Further, oxytocin was correlated with participant desire to protect vulnerable in-group members, despite that individual's attachment to the conflict. Similarly, it has been demonstrated that when oxytocin is administered, individuals alter their subjective preferences in order to align with in-group ideals over out-group ideals. These studies demonstrate that oxytocin is associated with intergroup dynamics. Further, oxytocin influences the responses of individuals in a particular group to those of another group. The in-group bias is evident in smaller groups; however, it can also be extended to groups as large as one's entire country leading toward a tendency of strong national zeal. A study done in the Netherlands showed that oxytocin increased the in-group favoritism of their nation while decreasing acceptance of members of other ethnicities and foreigners. People also show more affection for their country's flag while remaining indifferent to other cultural objects when exposed to oxytocin. It has thus been hypothesized that this hormone may be a factor in xenophobic tendencies secondary to this effect. Thus, oxytocin appears to affect individuals at an international level where the in-group becomes a specific "home" country and the out-group grows to include all other countries.

Drugs

Fear and anxiety

Oxytocin is typically remembered for the effect it has on prosocial behaviors, such as its role in facilitating trust and attachment between individuals. However, oxytocin has a more complex role than solely enhancing prosocial behaviors. There is consensus that oxytocin modulates fear and anxiety; that is, it does not directly elicit fear or anxiety. Two dominant theories explain the role of oxytocin in fear and anxiety. One theory states that oxytocin increases approach/avoidance to certain social stimuli and the second theory states that oxytocin increases the salience of certain social stimuli, causing the animal or human to pay closer attention to socially relevant stimuli.

Nasally administered oxytocin has been reported to reduce fear, possibly by inhibiting the amygdala (which is thought to be responsible for fear responses). Indeed, studies in rodents have shown oxytocin can efficiently inhibit fear responses by activating an inhibitory circuit within the amygdala. Some researchers have argued oxytocin has a general enhancing effect on all social emotions, since intranasal administration of oxytocin also increases envy and Schadenfreude. Individuals who receive an intranasal dose of oxytocin identify facial expressions of disgust more quickly than individuals who do not receive oxytocin. Facial expressions of disgust are evolutionarily linked to the idea of contagion. Thus, oxytocin increases the salience of cues that imply contamination, which leads to a faster response because these cues are especially relevant for survival. In another study, after administration of oxytocin, individuals displayed an enhanced ability to recognize expressions of fear compared to the individuals who received the placebo. Oxytocin modulates fear responses by enhancing the maintenance of social memories. Rats that are genetically modified to have a surplus of oxytocin receptors display a greater fear response to a previously conditioned stressor. Oxytocin enhances the aversive social memory, leading the rat to display a greater fear response when the aversive stimulus is encountered again.

Mood and depression

Oxytocin produces antidepressant-like effects in animal models of depression, and a deficit of it may be involved in the pathophysiology of depression in humans. The antidepressant-like effects of oxytocin are not blocked by a selective antagonist of the oxytocin receptor, suggesting that these effects are not mediated by the oxytocin receptor. In accordance, unlike oxytocin, the selective non-peptide oxytocin receptor agonist WAY-267,464 does not produce antidepressant-like effects, at least in the tail suspension test. In contrast to WAY-267,464, carbetocin, a close analogue of oxytocin and peptide oxytocin receptor agonist, notably does produce antidepressant-like effects in animals. As such, the antidepressant-like effects of oxytocin may be mediated by modulation of a different target, perhaps the vasopressin V1A receptor where oxytocin is known to weakly bind as an agonist.

Sildenafil enhances electrically evoked oxytocin release from the pituitary gland. In accordance, it may have promise as an antidepressant.

Sex differences

It has been shown that oxytocin differentially affects males and females. Females who are administered oxytocin are overall faster in responding to socially relevant stimuli than males who received oxytocin. Additionally, after the administration of oxytocin, females show increased amygdala activity in response to threatening scenes; however, males do not show increased amygdala activation. This phenomenon can be explained by looking at the role of gonadal hormones, specifically estrogen, which modulate the enhanced threat processing seen in females. Estrogen has been shown to stimulate the release of oxytocin from the hypothalamus and promote receptor binding in the amygdala.

It has also been shown that testosterone directly suppresses oxytocin in mice. This has been hypothesized to have evolutionary significance. With oxytocin suppressed, activities such as hunting and attacking invaders would be less mentally difficult as oxytocin is strongly associated with empathy.

Social

  • Affecting generosity by increasing empathy during perspective taking: In a neuroeconomics experiment, intranasal oxytocin increased generosity in the Ultimatum Game by 80%, but had no effect in the Dictator Game that measures altruism. Perspective-taking is not required in the Dictator Game, but the researchers in this experiment explicitly induced perspective-taking in the Ultimatum Game by not identifying to participants into which role they would be placed. Serious methodological questions have arisen, however, with regard to the role of oxytocin in trust and generosity. Empathy in healthy males has been shown to be increased after intranasal oxytocin. This is most likely due to the effect of oxytocin in enhancing eye gaze. There is some discussion about which aspect of empathy oxytocin might alter – for example, cognitive vs. emotional empathy. While studying wild chimpanzees, it was noted that after a chimpanzee shared food with a non-kin related chimpanzee, the subjects' levels of oxytocin increased, as measured through their urine. In comparison to other cooperative activities between chimpanzees that were monitored including grooming, food sharing generated higher levels of oxytocin. This comparatively higher level of oxytocin after food sharing parallels the increased level of oxytocin in nursing mothers, sharing nutrients with their kin.
  • Trust is increased by oxytocin. Disclosure of emotional events is a sign of trust in humans. When recounting a negative event, humans who receive intranasal oxytocin share more emotional details and stories with more emotional significance. Humans also find faces more trustworthy after receiving intranasal oxytocin. In a study, participants who received intranasal oxytocin viewed photographs of human faces with neutral expressions and found them to be more trustworthy than those who did not receive oxytocin. This may be because oxytocin reduces the fear of social betrayal in humans. Even after experiencing social alienation by being excluded from a conversation, humans who received oxytocin scored higher in trust on the Revised NEO Personality Inventory. Moreover, in a risky investment game, experimental subjects given nasally administered oxytocin displayed "the highest level of trust" twice as often as the control group. Subjects who were told they were interacting with a computer showed no such reaction, leading to the conclusion that oxytocin was not merely affecting risk aversion. When there is a reason to be distrustful, such as experiencing betrayal, differing reactions are associated with oxytocin receptor gene (OXTR) differences. Those with the CT haplotype experience a stronger reaction, in the form of anger, to betrayal.
  • Romantic attachment: In some studies, high levels of plasma oxytocin have been correlated with romantic attachment. For example, if a couple is separated for a long period of time, anxiety can increase due to the lack of physical affection. Oxytocin may aid romantically attached couples by decreasing their feelings of anxiety when they are separated.
  • Group-serving dishonesty/deception: In a carefully controlled study exploring the biological roots of immoral behavior, oxytocin was shown to promote dishonesty when the outcome favored the group to which an individual belonged instead of just the individual.
  • Oxytocin affects social distance between adult males and females, and may be responsible at least in part for romantic attraction and subsequent monogamous pair bonding. An oxytocin nasal spray caused men in a monogamous relationship, but not single men, to increase the distance between themselves and an attractive woman during a first encounter by 10 to 15 centimeters. The researchers suggested that oxytocin may help promote fidelity within monogamous relationships. For this reason, it is sometimes referred to as the "bonding hormone". There is some evidence that oxytocin promotes ethnocentric behavior, incorporating the trust and empathy of in-groups with their suspicion and rejection of outsiders. Furthermore, genetic differences in the oxytocin receptor gene (OXTR) have been associated with maladaptive social traits such as aggressive behavior.
  • Social behavior and wound healing: Oxytocin is also thought to modulate inflammation by decreasing certain cytokines. Thus, the increased release in oxytocin following positive social interactions has the potential to improve wound healing. A study by Marazziti and colleagues used heterosexual couples to investigate this possibility. They found increases in plasma oxytocin following a social interaction were correlated with faster wound healing. They hypothesized this was due to oxytocin reducing inflammation, thus allowing the wound to heal more quickly. This study provides preliminary evidence that positive social interactions may directly influence aspects of health. According to a study published in 2014, silencing of oxytocin receptor interneurons in the medial prefrontal cortex (mPFC) of female mice resulted in loss of social interest in male mice during the sexually receptive phase of the estrous cycle. Oxytocin evokes feelings of contentment, reductions in anxiety, and feelings of calmness and security when in the company of the mate. This suggests oxytocin may be important for the inhibition of the brain regions associated with behavioral control, fear, and anxiety, thus allowing orgasm to occur. Research has also demonstrated that oxytocin can decrease anxiety and protect against stress, particularly in combination with social support. It is found, that endocannabinoid signaling mediates oxytocin-driven social reward.

Chemistry

Oxytocin (ball-and-stick) bound to its carrier protein neurophysin (ribbons)

Oxytocin is a peptide of nine amino acids (a nonapeptide) in the sequence cysteine-tyrosine-isoleucine-glutamine-asparagine-cysteine-proline-leucine-glycine-amide (Cys – Tyr – Ile – Gln – Asn – Cys – Pro – Leu – Gly – NH2, or CYIQNCPLG-NH2); its C-terminus has been converted to a primary amide and a disulfide bridge joins the cysteine moieties. Oxytocin has a molecular mass of 1007 Da, and one international unit (IU) of oxytocin is the equivalent of 1.68 μg of pure peptide.

While the structure of oxytocin is highly conserved in placental mammals, a novel structure of oxytocin was recently reported in marmosets, tamarins, and other new world primates. Genomic sequencing of the gene for oxytocin revealed a single in-frame mutation (thymine for cytosine) which results in a single amino acid substitution at the 8-position (proline for leucine). Since this original Lee et al. paper, two other laboratories have confirmed Pro8-OT and documented additional oxytocin structural variants in this primate taxon. Vargas-Pinilla et al. sequenced the coding regions of the OXT gene in other genera in new world primates and identified the following variants in addition to Leu8- and Pro8-OT: Ala8-OT, Thr8-OT, and Val3/Pro8-OT. Ren et al. identified a variant further, Phe2-OT in howler monkeys.

The biologically active form of oxytocin, commonly measured by RIA and/or HPLC techniques, is the oxidized octapeptide oxytocin disulfide, but oxytocin also exists as a reduced straight-chain (non-cyclic) dithiol nonapeptide called oxytoceine. It has been theorized that oxytoceine may act as a free radical scavenger, as donating an electron to a free radical allows oxytoceine to be re-oxidized to oxytocin via the dehydroascorbate / ascorbate redox couple.

Recent advances in analytical instrumental techniques highlighted the importance of liquid chromatography (LC) coupled with mass spectrometry (MS) for measuring oxytocin levels in various samples derived from biological sources. Most of these studies optimized the oxytocin quantification in electrospray ionization (ESI) positive mode, using [M+H]+ as the parent ion at mass-to-charge ratio (m/z) 1007.4 and the fragment ions as diagnostic peaks at m/z 991.0, m/z 723.2 and m/z 504.2. These important ion selections paved the way for the development of current methods of oxytocin quantification using MS instrumentation.

The structure of oxytocin is very similar to that of vasopressin. Both are nonapeptides with a single disulfide bridge, differing only by two substitutions in the amino acid sequence (differences from oxytocin bolded for clarity): Cys – Tyr – Phe – Gln – Asn – Cys – Pro – Arg – Gly – NH2. Oxytocin and vasopressin were isolated and their total synthesis reported in 1954, work for which Vincent du Vigneaud was awarded the 1955 Nobel Prize in Chemistry with the citation: "for his work on biochemically important sulphur compounds, especially for the first synthesis of a polypeptide hormone."

Oxytocin and vasopressin are the only known hormones released by the human posterior pituitary gland to act at a distance. However, oxytocin neurons make other peptides, including corticotropin-releasing hormone and dynorphin, for example, that act locally. The magnocellular neurosecretory cells that make oxytocin are adjacent to magnocellular neurosecretory cells that make vasopressin. These are large neuroendocrine neurons which are excitable and can generate action potentials.

History

The uterine-contracting properties of the principle that would later be named oxytocin were discovered by British pharmacologist Sir Henry Hallett Dale in 1906, and its milk ejection property was described by Ott and Scott in 1910 and by Schafer and Mackenzie in 1911. In the 1920s, oxytocin and vasopressin were isolated from pituitary tissue and given their current names. The word oxytocin was coined from the term oxytocic, Greek ὀξύς, oxys, meaning "sharp" or "swift", and τόκος, toκos, meaning "childbirth".

Oxytocin became the first polypeptide hormone to be sequenced or synthesized. Du Vigneaud was awarded the Nobel Prize in 1955 for his work.

Further work on different synthetic routes for oxytocin, as well as the preparation of analogues of the hormone (e.g. 4-deamido-oxytocin) was performed in the following decade by Iphigenia Photaki.

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