Lordosis inhibiting systems in the septum and dorsal raphe nucle-us

外侧隔（LS）在雌性和雄性大鼠的雌性特征性性行为（如脊柱前凸和引诱行为）的调节中发挥抑制作用。中缝背核（DRN）内的多巴胺能神经元也存在抑制机制。在雄性大鼠中，这些雌性性行为模式是非常罕见的，即使用大剂量的雌激素治疗。女性性行为在男性中的低发生率被认为是由LS和DRN的强烈抑制作用引起的，本实验用神经内分泌学方法分析了这些抑制机制，并得到以下结果。一曰：由于腹侧切断DRN前部增强了雄性和雌性大鼠的脊柱前凸行为，因此该核的前腹侧投射参与了脊柱前凸抑制机制。图2：通过切断雄性大鼠内侧前脑束诱导雌性大鼠脊柱前凸活动水平。这表明束作为前凸抑制影响的途径的重要性。第三章：为了阐明雌激素在LS和DRN的抑制系统中的作用，将雌二醇直接植入这些区域，在阈下剂量的苯甲酸雌二醇注射去势雌性和雄性大鼠中观察到脊柱前凸。结果，雌激素植入LS而非DRN促进了雌性大鼠的脊柱前凸。这一结果表明雌激素对LS前凸的抑制作用是由雌激素直接释放的，而不是在DRN中。此外，在男性LS中植入雌激素对前凸没有影响。因此，雌性大鼠性行为发生率低的原因是雌激素不能直接释放LS的强烈抑制。

The lateral septum (LS) exerts an inhibitory influence in regulation of female characteristic sexual behavior, such as lordosis and soliciting behavior in both female and male rats. The inhibitory mechanism also exist in the serotonergic neurons in the dorsal raphe nucleus (DRN). In male rats, these female sexual behavioral patterns are very rare, even when treated with large doses of estrogen. The low incidence of female sexual behavior in males is thought to be cased by strong inhibitory influences in the LS and DRN.In this experiment, these inhibitory mechanisms have been analyzed by neuroendocrinological methods and following results were obtained. 1 : Since the ventral cut of the anterior part of the DRN enhanced lordotic behavior in both male and female rats, anteroventral projections of this nucleus are involved in lordosis inhibitory mechanisms. 2 : Female levels of lordotic activity was induced by transection of the medial forebrain bundle in male rats. This suggests an importance of the bundle as a pathway for lordosis inhibiting influence. 3 : To clarify the role of estrogen in the inhibitory systems of the LS and DRN, estradiol was implanted directly in these areas and lordosis was observed in subthreshold doses of estradiol benzoate-injected castrated female and male rats. As a result, estrogen implanted in the LS butnot in the DRN facilitated lordosis in female rats. This result indicates that the inhibition for lordosis in the LS is released directly by estrogen but not in the DRN.Furthermore, implantation of estrogen into the LS in males had no effect on lordosis. Thus, the reason of low incidence of female sexual behavior in male rats is the development of strong inhibition in the LS which can not be released directly by estrogen.