Bernard B Brodie Department of Neuroscience, University of Cagliari, Cagliari Section, Cittadella Universitaria, SS 554, km 4.500, 09042 Monserrato, Cagliari, Italy.
Neuropharmacology. 2010 Jun;58(7):1153-60. doi: 10.1016/j.neuropharm.2010.02.008. Epub 2010 Feb 13.
Oxytocin (100 ng) induces penile erection when injected unilaterally into the ventral subiculum of the hippocampus of male rats. The pro-erectile effect started mostly 30 min after treatment and occurred 15 min after an increase in both nitric oxide (NO) production, measured by the concentration of NO(2)(-) and NO(3)(-), the main metabolites of newly formed NO, and extra-cellular glutamic acid concentration in the dialysate obtained from the ventral subiculum by intracerebral microdialysis. These responses were abolished by d(CH(2))(5)Tyr(Me)(2)-Orn(8)-vasotocin (2 microg), an oxytocin receptor antagonist, S-methyl-L-thiocitrulline (SMTC), a selective inhibitor of neuronal NO-synthase (25 microg), and haemoglobin, a NO scavenger (25 microg), given into the ventral subiculum before oxytocin. Unlike d(CH(2))(5)Tyr(Me)(2)-Orn(8)-vasotocin, SMTC and haemoglobin, (+)MK-801 (5 microg), a noncompetitive antagonist of NMDA receptors abolished oxytocin-induced penile erection, but reduced only partially the increase in NO production and extra-cellular glutamic acid. As NMDA (0.25-1 microg) injected into the ventral subiculum induces penile erection episodes, which also occurred with an increase of NO production and extra-cellular glutamic acid, and NMDA responses were abolished by (+)MK-801 (5 microg), but not by SMTC (25 microg) or haemoglobin (25 microg), injected into the ventral subiculum, these results show that oxytocin injected into the ventral subiculum increases NO production by activating its own receptors. NO in turn increases glutamic acid neurotransmission, leading to penile erection, possibly through neural (glutamatergic) efferent projections from the ventral subiculum to extra-hippocampal brain areas (e.g., prefrontal cortex) modulating the activity of mesolimbic dopaminergic neurons.
当催产素（100ng）被单侧注射到雄性大鼠海马腹侧下托时，会引起阴茎勃起。这种促勃起作用大多在治疗后 30 分钟开始，并在一氧化氮（NO）产生增加 15 分钟后出现，这可以通过腹侧下托内的脑室内微透析获得的透析液中 NO（2）（-）和 NO（3）（-）（新形成的 NO 的主要代谢物）浓度以及细胞外谷氨酸浓度来测量。这些反应被催产素受体拮抗剂 d(CH(2))(5)Tyr(Me)(2)-Orn(8)-vasotocin（2μg）、神经元型一氧化氮合酶的选择性抑制剂 S-甲基-L-硫代瓜氨酸（SMTC）（25μg）和一氧化氮清除剂血红蛋白（25μg）消除，这些物质都被预先注射到腹侧下托中。与 d(CH(2))(5)Tyr(Me)(2)-Orn(8)-vasotocin 不同，SMTC 和血红蛋白，而非 NMDA 受体非竞争性拮抗剂 (+)MK-801（5μg）消除了催产素引起的阴茎勃起，但仅部分减少了 NO 产生和细胞外谷氨酸的增加。由于 NMDA（0.25-1μg）注射到腹侧下托中会引起阴茎勃起，同时也会增加 NO 产生和细胞外谷氨酸，并且 (+)MK-801（5μg）消除了 NMDA 反应，但 SMTC（25μg）或血红蛋白（25μg）没有，这些结果表明，催产素注射到腹侧下托中会通过激活自身受体来增加 NO 的产生。NO 反过来又增加谷氨酸神经传递，导致阴茎勃起，可能是通过腹侧下托向调节中脑边缘多巴胺神经元活动的海马外脑区（例如前额叶皮层）的神经（谷氨酸能）传出投射。
