The effects of orchidectomy and testosterone replacement therapy on plasma and brain oxytocin in normal rats

In male rats, two-week orchidectomy induced a significant increase in the pituitary content of oxytocin-immunoreactivity and a significant fall in its hypothalamic concentration, without detectable changes in plasma. Testosterone replacement therapy in castrated animals abolished the stimulant effect of orchidectomy on pituitary accumulation of oxytocin. The present study demonstrates an inhibitory effect of testicular androgens on oxytocin release. These results and previous observations suggest that the neurohypophysial hormone oxytocin may play a role in male reproductive system.