雄激素对大鼠视前内侧区一氧化氮合酶阳性神经元的影响

Effect of androgen on nitric oxide synthase positive neurons in the medial preoptic area

目的 探讨雄激素对大鼠下丘脑一氧化氮合酶 (NOS)阳性神经元的影响。方法 2个月龄雄性大鼠分成A组 (去势组 )、B组 (假手术组 )、C组 (去势 +睾酮替代组 )以及D组 (保列治喂饲组 ) ,分别于处理前、处理后 2周和 2个月观察大鼠 3 0min非接触性阴茎勃起 (NCE)的次数 ,对视前内侧区 (MPOA)、视上核 (SON)、室旁核 (PVN)以及终纹床核行尼克酰胺腺嘌呤二核苷酸黄递酶 (NADPH d)组织化学染色。结果 A组和D组大鼠 3 0minNCE次数明显少于B组和C组。在NADPH组织化学染色中 ,术后 2周各组大鼠脑组织阳性着色差异无显著性 ,术后 2个月 ,A组与D组MPOA阳性着色明显少于B组和C组 ,而其他脑区阳性着色在各组间差异仍无显著性。结论 大鼠阴茎勃起功能对雄激素具有依赖性 ,而雄激素对性反应调节中枢的影响可能与调节MPOANOS阳性神经元有关 ;其中 5α 双氢睾酮可能是主要的雄激素活性成分。

Objective To investigate the effect of androgen on the erectile function and nitric oxide synthase (NOS) positive neurons in the medial preoptic area (MPOA).Methods Male Sprague-Dawley rats were divided into 4 groups:A (castration),B (sham operation),C (castration+testosterone replenishment) and D (sham operation with finasteride administration).Penis erection times in the presence of inaccessible estrous females in 30 min were measured before and 2 weeks and 2 months after the operation.Brain tissues were collected for coronal sections.The NOS positive neurons in MPOA,supraoptic nucleus (SON),paraventricular nucleus (PVN) and bed nucleus of stria terminalis (BNST) were determined by NADPH-d histochemical staining.Results The times of the non-contact erection during 30 min observation in groups A and D 2 weeks/2 months after operation were 2.18±0.15/0 and 3.22± 0.21/0 respectively,significantly less than in group B (27.82±6.35/23.71±6.25) and group C (26.90± 5.88/23.28±3.84) (P<0.01).Two months but not two weeks after castration and 5alpha-reductase inhibitor finasteride administration the NOS positive neurons in MPOA were significantly reduced.There was no significant difference in the NOS positive neurons in SON,PVN and BNST among all groups.Conclusion The erectile function of rat penis is dependent on androgen.Androgen may promote copulation in part through actions on NOS positive neurons in MPOA;DHT seems to be the major androgen responsible for the effects.