NEURAL REGULATION OF THE VAS-DEFERENS IN THE RAT - AN ELECTROPHYSIOLOGICAL ANALYSIS

Electrophysiological analysis of the neural control of the vas deferens was performed in urethan-anesthetized rats. Intraluminal distension (0.2 ml/min) or electrical stimulation of hypogastric (threshold 1-5 V, 20 Hz) and pelvic nerves (2-5 V, 20 Hz) produced contractions of the vas deferens. Distension-evoked contractile activity was not abolished by nicotinic ganglionic blockade or ipsilateral hypogastric and pelvic nerve transection. Contractions following hypogastric nerve stimulation were abolished by prazosin, while pelvic nerve-evoked responses were partially blocked by atropine. Hypogastric nerve, pelvic nerve, and sympathetic chain stimulation evoked volleys with latencies of 10-30 ms in vasal nerves. Crude estimates for conduction velocities for these responses (<0.5 m/s) corresponded to activation of unmyelinated C-fibers. Stimulation of the dorsal nerve of the penis (DNP) (10-16 V, 10-40 Hz) or administration of 5-methoxy-N,N-dimethyltryptamine, both of which produce seminal emission, elicited reflex discharges in nerves to the vas deferens. Hypogastric nerve but not pelvic nerve transection abolished both spontaneous and evoked (105- to 380-ms latency) reflex activity. These experiments provide insight into the organization of afferents in the DNP and efferents conveyed by autonomic pathways that regulate male reproduction.