VAGOTOMY BLOCKS RESPONSES TO VAGINOCERVICAL STIMULATION AFTER GENITOSPINAL NEURECTOMY IN RATS

To ascertain whether any effects of vaginocervical stimulation (VS) ar e mediated by the vagus nerve, all known afferent nerves from the repr oductive tract to the spinal cord were transected and the rats were te sted for residual responses to VS. After combined bilateral transectio n of the pelvic, hypogastric, and pudendal nerves (NX), the following responses to VS were greatly reduced or abolished: lordosis to flank-p erineum palpation, leg extension, immobilization, and blockage of both tail withdrawal to radiant heat and leg withdrawal to foot pinch. How ever, after these nerve cuts, the following persisted as significant r esidual responses to VS: 1) analgesia [measured as increase in vocaliz ation threshold (VOCT) to tailshock], 2) pupil dilatation (PD), and 3) increase in heart rate (HR). Subsequent bilateral subdiaphragmatic va gotomy (VX) significantly reduced the magnitude of PD and abolished th e analgesia. By contrast, VX produced no significant effect on the HR increase to VS. The above findings provide evidence that brain-mediate d responses to vaginocervical stimulation can be elicited via the vagu s nerves.