Role of Lower Brain Stem in Regulating Sexual Behaviors in Male and Female Rats.

研究了中缝髓核在大鼠雌雄性行为调节中的作用。切除卵巢的大鼠中缝隐核（ROBN）和中缝大核（RMGN）被射频损伤发生器破坏。术后4 -5周，所有女性均植入含有雌二醇（E_2）的硅胶管。植入E_<>后第2天开始性行为测试，每天进行5天。与非颅脑手术和假手术的女性相比，ROBN病变女性在第一次测试中显示出高水平的前凸商（LQ）。RMGN病变组的平均LQ与对照组相当。此外，ROBN病变组的扭耳发生率高于其他组。提示中缝隐核在调节雌性大鼠性行为中起抑制作用。在阉割的雄性大鼠中，ROBN或RMGN被破坏。术后4 -5周，所有雄性小鼠均植入含有睾酮的硅胶管。给药后1周开始性行为测试，每隔1周进行3次测试。与RMBN病变组、非颅脑手术组和假手术组相比，ROBN病变组的勃起、射精和射精频率较低。这些结果表明，与雌性不同，中缝隐核在调节雄性大鼠性行为中起促进作用。此外，在接受对氯苯丙氨酸（一种血清素合成抑制剂）治疗后，ROBN病变男性的性行为频率高于未接受PCPA治疗的ROBN病变男性，但低于接受PCPA治疗的非脑外科对照男性。因此，PCPA可能作用于除ROBN外的5 -羟色胺能神经元，促进雄性大鼠的雄性性行为。

Roles of the medullary raphe nuclei in regulating female and male sexual behaviors were investigated in rats.In ovariectomized rats, the raphe obscurus nucleus (ROBN) or the raphe magnus nucleus (RMGN) was destroyed by radio frequency lesion generator. Four-5 weeks after operations, all females were implanted with a Silastic tubing containing estradiol (E_2). Sexual behavioral tests were started 2 days after E_<> implantations and carried out daily for 5 days. ROBN lesion-females showed high levels of lordosis quotient (LQ) in the first test, when compared with those of non-brain surgery and sham operated females. The mean LQ of RMGN lesion group was comparable to those of control groups. In addition, incidence of ear-wiggling in ROBN lesion group was higher than those in other groups. These results suggest that the raphe obscurus nucleus play an inhibitory role in regulating female rat sexual behaviors.In castrated male rats, ROBN or RMGN was destroyed. Four-5 weeks after operation, all males were implanted Silastic tubings containing testosterone. Sexual behavior tests were started 1 week after testosterone administration and 3 tests were carried out 1 week intervals. In ROBN lesion group, frequencies of mounting, intromission and ejaculation were lower than those in RMBN lesion, non-brain surgery and sham operated groups. These results suggest that in contrast to the female case, the raphe obscurus nucleus play a facilitatory role in regulating male rat sexual behaviors. Furthermore, after treatment with p-chlorophenylalanine (PCPA, an inhibitor for serotonin synthesis), ROBN lesion-males showed higher frequencies of sexual behaviors than those in non-PCPA treated ROBN lesion males, but the frequencies were lower than those in PCPA treated non-brain surgery control males. Thus, PCPA may act on serotonergic neurons other than those in the ROBN and facilitate male sexual behaviors in male rats.