Peptidyl amidating enzyme
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.
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.
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.
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.
Oxytocin enhances the aversive social memory, leading the rat to display a greater fear response when the aversive stimulus is encountered again.
It has been shown that oxytocin differentially affects males and females.
The last hydrolysis that releases the active oxytocin nonapeptide is catalyzed by peptidylglycine alpha-amidating monooxygenase (PAM).
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.
Oxytocin has peripheral (hormonal) actions, and also has actions in the brain.
Its actions are mediated by specific, oxytocin receptors.