Oxytocin is normally produced by the paraventricular nucleus of the hypothalamus and released by the posterior pituitary. Estrogen has been found to increase the secretion of oxytocin and to increase the expression of its Cocaine dilated cervix orgasmthe oxytocin receptorin the brain. The oxytocin peptide is synthesized as an inactive precursor protein from the OXT gene.
The last hydrolysis that releases the active oxytocin nonapeptide is Cocaine dilated cervix orgasm by peptidylglycine alpha-amidating monooxygenase PAM. The activity of the PAM enzyme system is dependent upon vitamin C ascorbatewhich 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.
In the hypothalamusoxytocin 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 Cocaine dilated cervix orgasm neurons in the nucleus accumbensa brain structure where oxytocin receptors are expressed.
In the pituitary glandoxytocin 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 "Cocaine dilated cervix orgasm." These cells generate action potentials that propagate down axons to the nerve endings in the pituitary; the "Cocaine dilated cervix orgasm" contain large numbers of oxytocin-containing vesicles, which are released by exocytosis when the nerve terminals are depolarised.
Endogenous Cocaine dilated cervix orgasm concentrations in the brain have been found to be as much as fold higher Cocaine dilated cervix orgasm 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 Leydig cells in some species have been shown to possess
Cocaine dilated cervix orgasm biosynthetic machinery to manufacture testicular oxytocin de novoto be specific, in rats which can synthesize vitamin C endogenouslyand in guinea pigs, which, like humans, require an exogenous source of vitamin C ascorbate in their diets.
Oxytocin is synthesized by corpora lutea of several species, including ruminants and primates. 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, bases apart on Cocaine dilated cervix orgasm same chromosomeand are transcribed in opposite directions however, in fugu the homologs are further apart and transcribed in the same direction. The Cocaine dilated cervix orgasm genes are believed to result from a gene duplication event; the ancestral gene is estimated to be about million years old and is found in cyclostomata modern members of the Agnatha.
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 that requires magnesium and cholesterol. It Cocaine dilated cervix orgasm to the rhodopsin -type class I group of G-protein-coupled receptors. Studies have looked at oxytocin's role in various behaviors, including orgasmsocial recognitionpair bondinganxietyand maternal behaviors.
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 glandor that are collaterals from them.
In the prairie voleoxytocin released Cocaine dilated cervix orgasm 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. In a 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.
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. 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. 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.
Oxytocin is typically remembered for the effect it has on prosocial behaviorssuch as its role in facilitating trust and attachment between individuals. There is consensus that oxytocin modulates fear and anxiety ; that is, it does not directly elicit fear or anxiety. Nasally administered oxytocin has been reported to reduce fearpossibly by inhibiting the amygdala which is thought to be responsible for fear responses. Thus, oxytocin increases the salience of cues that imply contamination, which leads to a faster response because these cues are especially relevant Cocaine dilated cervix orgasm 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. 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.
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. Sildenafil has been found to enhance electrically evoked oxytocin release from the pituitary gland. It has been shown that oxytocin differentially affects males Cocaine dilated cervix orgasm females. Females who are administered oxytocin are overall faster in responding to socially relevant stimuli than males who received oxytocin.
This phenomenon can be explained by looking at the role of gonadal hormonesspecifically estrogenCocaine dilated cervix orgasm 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 directly suppresses oxytocin in mice. With
Cocaine dilated cervix orgasm suppressed, activities such as hunting and attacking invaders would be less mentally difficult as oxytocin is strongly associated with empathy.
While the structure of oxytocin is highly conserved in mammals, a novel structure of oxytocin was recently reported in marmosetstamarinsand 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.
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: Oxytocin and vasopressin
Cocaine dilated cervix orgasm isolated and their total synthesis reported in work for which Vincent du Vigneaud was awarded the Nobel Prize in Chemistry with the citation: Oxytocin and vasopressin are the only known hormones released by the human posterior Cocaine dilated cervix orgasm gland to act at a distance.
However, oxytocin neurons make other peptides, including corticotropin-releasing hormone and dynorphinfor example, that act locally. The magnocellular neurosecretory cells that make oxytocin are adjacent to Cocaine dilated cervix orgasm neurosecretory cells that make vasopressin. These are large neuroendocrine neurons which are excitable and can generate action potentials.
The uterine-contracting properties of the principle that would later be named oxytocin were discovered by British pharmacologist Sir Henry Hallett Dale in  and its milk ejection property was described by Ott and Scott in  and by Schafer and Mackenzie in Oxytocin became the first polypeptide hormone to be sequenced  or synthesized.
From Wikipedia, the free encyclopedia. This article is the hormone. For its use as a medication, see Oxytocin medication. Not to be confused with Oxycontin. Anatomical Basis of Clinical Practice 41 ed.
Human Biology 7th ed. The Journal of Physiology. International Union of Basic and Clinical Pharmacology. Retrieved 14 December "Cocaine dilated cervix orgasm" Endogenous oxytocin is a hormone and neuropeptide, which plays a role in social bonding, sexual reproduction and is required during and after childbirth. Purified oxytocin is used clinically. Retrieved 1 June Women's Sexual Function and Dysfunction: Study, Diagnosis and Treatment.
The Journal of Biological Chemistry. The Journal of Clinical Endocrinology and Metabolism. The Journal of Endocrinology. Annals of the New York Academy of Sciences.
Biochimica et Biophysica Acta. Cell and Tissue Research. The American Journal of the Medical Sciences. Retrieved March 29, American Journal of Medical Genetics. Part B, Neuropsychiatric Genetics. What can voles teach us about monogamy?
Archived from the original on October 15, Veterinary Journal London, England: British Society for Neuroendocrinology. Archived from the original on Frontiers in Behavioral Neuroscience. Role for the endogenous oxytocin system". Pharmacology Biochemistry and Behavior. The Journal of Neuroscience. The Journal of Physiological Sciences. Neuroscience and Biobehavioral Reviews. Social Hormones and Human Behavior: of the cervix”, an effect Cocaine dilated cervix orgasm was apparently independent of the anti-anxiety and reduced increased power of orgasm .
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