Effects in vivo of neurohypophysial hormones on the contractile activity of accessory sex organs in male rabbits.

Abstract

The effects of single intravenous injections of synthetic oxytocin and lysine-vasopressin on the contractile activity of the distal part of the ductus epididymidis, the proximal and distal parts of the vas deferens and the vesicula seminalis were studied in seventy-two anaesthetized rabbits. The muscular contractions were registered as changes in the intraluminal pressure of the organs, and the amplitude, frequency, duration and tonus were measured. An injection of 20 m-i.u. of oxytocin/kg body weight caused a small but significant increase of the amplitude of the contractions in the ductus epididymidis and the proximal part of the vas deferens. An injection of 100 m-i.u. of oxytocin increased the tone in the proximal part of the vas deferens but decreased this parameter in the distal part of the organ. The infusion of 20 m-i.u. of vasopressin enhanced the frequency, decreased the duration and elevated the muscular tone in the ductus epididymidis and increased the frequency and the tone in the proximal part of the vas deferens. The infusion of 100 m-i.u. of vasopressin resulted in increased amplitudes in both these regions. A gradual increase in the effects of oxytocin and vasopressin towards the testis was observed, indicating a polarity in response to the hormones of the male reproductive ducts. The results support the theory that neurohypophysial hormones may regulate sperm transport in the male through their effects on the contractile elements of the genital organs, possibly being complementary in their actions.