摘要
通过对犬胸腰段内脏神经的电刺激来验证射精时交感神经信号的传导径路。该信号在射精时，使精液从射精管道泄出并使膀胱颈关闭。在大的胸腰段内脏神经中有两组神经纤维，一组从胸段和腰１的交感神经干发出，下行到主动脉前壁上的肠系膜尾丛（相当于人类的肠系膜下神经丛和腹下丛的上部）；另一组从腰段（腰１～腰５）的交感神经干发出，延伸到主动脉前壁，但不覆盖精索动脉，称为腰部内脏神经。用电刺激第１组神经，既不引起泄精，也不引起膀胱颈关闭；而刺激第２组神经（腰部内脏神经）的每一分支，都可引起泄精和膀胱颈关闭，当腹下神经被切断后，上述两种现象就不再发生。经过一段时间后，由于腰骶交感神经干和精索神经的代偿作用可恢复泄精，但膀胱颈关闭得不到代偿。因此，切断腹下神经可导致大的逆行射精。
Canine thoracolumbar splanchnic nerves were electrically stimulated to identify the rout of sympathetic signals which generate seminal emission from ejaculatory ducts and bladder neck closure at ejaculation. There were two groups of nerve fibers in thoracolumbar splanchnic nerves. One branched from thoracic and L1 levels of sympathetic trunks, going down to caudal mesenteric plexus (inferior mesenteric and superior hypogastric plexuses in humans) on the anterior wall of the aorta. The other branched from the lumbar sympathetic trunk at levels of L1～L5 ganglia and reached to the anterior wall of the aorta not overlying spermatic arteries, which was designated as thelumbar splanchnic nerve. The electrical stimulation of the former group caused neither seminal emission nor bladder neck closure. In contrast, each of lumbar splanchnic nerves generated both seminal emission and bladder neck closure. Both phenomena by the electric stimultion were lost by hypogastric nerve transections. Seminal emission was compensated by signals through the lumbosacral sympathetic trunk and spermatic nerve after a while. However, no obvious compensation was observed in bladder neck closure, resulting in the retrograde ejaculation in dogs whose hypogastric nerves were previously transected. in dogs and from the superior hypogastric plexus in the human. The present results indicate that not intermesenteric splanchnic nerves but lateral splanchnic nerves control seminal emission and bladder neck closure at ejaculation. Therefore, it appears very likely that lateral splanchnic nerves branching from sympathetic trunks at levels from L1 to L5 form the superior hypogastric plexus and control both seminal emission and bladder neck closure at ejaculation in the human. The assumption is supported by such clinical experiences that no serious ejaculatory disorders have been observed after unilateral para-aortic lymph node dissection and/or damage of intermesenteric plexus while loss of emission has occurred after classic bilateral para-aortic lymph node dissection.The present results also suggest the mechanism of retrograde ejaculation after the damage of hypogastric and/or lateral splanchnic nerves at lymph node dissection of the retroperitoneal and/or pelvic area, namely presence of compensatory pathway of sympathetic signals to generate seminal emission from ejaculatory ducts and lack of such compensation to generate bladder neck closure at ejaculation.
关键词
射精
泄精
膀胱颈关闭
seminal emission
bladder neck closure
retrograde ejaculation
