The infraspinal neural pathway of apomorphine-induced erection : an experimental study by the comparison with electrostimulation-induced erection on the rat model

Lee, Sung Won; Paick, Jae Seung; Park, Kwan Hyun; Oh, Seung Joon; Choo, Myung Soo; Jo, Hyung Kee

Abstract

The erectile response is peripherally mediated by cavernous nerve that contains thoracolubar sympathetic nerve and sacral parasympathetic nerve. It is known that thoracolubar sympathetic nerve involves in detumescence and sacral parasympathetic nerve in tumescence, however there are some opinions that rhoracolubar sympathetic nerve participates in psychogenic erectile mechanism. We previously reported that by the comparison with electrostimulation-induced erection, apomor- phine-induced erection was a vascular event. The aim of our study was to determine the infraspinal neural pathway of APO-induced erection. The sham operated rats remained normal in all measured respects. All rats having undergone neurotomy ot the hypogastric nerves showed APO-induced erection except one. The only 5 rats having undergone neurotomy of the pelvic nerves showed APO-induced erection. Erections could be elicited upon cavernous or pelvic nerves stimulation in all rats having undergone neurolomy of the hypogastric nerves. Among 17 rats having undergone neurotomy of the pelvic nerve erection could be elicited upon cavernous nerves slimulation in 14 rats, however. the intracavernous pressure (47.9+/-16.5 mmHg) was lower than that found in sham-operated rats. Erectile response in these 14 rats appeared to result from stimulation of penile neurons coming from the major pelvic ganglion. In contrast to no response in sham-operated rats, stimulation of the hypogastric nerves also resulted in erections in 7 out of 17 rats. In conclusion, this present study suggests that APO-induced ereclion is primarily mediated via the sacral parasympathetic nerve system and may be mediated by the thoracolumbar sympathetic pathway following injury to the parasympathetic nerve system. Furthermore we can guess the possibility that the neural pathway of psychogenic erection is same that of AP0- induced erection.