Marson L, McKenna K E
Department of Physiology M211, Northwestern University Medical School, Chicago, IL 60611.
Brain Res. 1994 Feb 28;638(1-2):103-8. doi: 10.1016/0006-8993(94)90638-6.
The urethrogenital (UG) reflex is a spinal sexual reflex which is tonically inhibited in the intact male rat by neurons in the nucleus paragigantocellularis (nPGi). The medial preoptic area of the hypothalamus (MPOA) is involved in the activation of male sexual behavior. The present study examines the effect of hypothalamic stimulation on the UG reflex in the intact male rat. Areas of the hypothalamus were stimulated bilaterally with either electrical stimulation or D,L-homocysteic acid (DLH) and the presence of the UG reflex examined. Stimulation of discrete aras of the hypothalamus evoked the UG reflex. The UG reflex could be initiated in the absence of genital stimulation. Microinjections of DLH into the MPOA also initiate the UG reflex. These data suggest that stimulation of neurons in the MPOA overcome the inhibition by the nPGi and facilitate spinal genital reflexes leading to ejaculation.
尿道生殖（UG）反射是一种脊髓性反射，在完整的雄性大鼠中，它受到巨细胞旁核（nPGi）中神经元的紧张性抑制。下丘脑的内侧视前区（MPOA）参与雄性性行为的激活。本研究考察了下丘脑刺激对完整雄性大鼠UG反射的影响。采用电刺激或D，L-高胱氨酸（DLH）双侧刺激下丘脑各区域，并检测UG反射的存在情况。刺激下丘脑的离散区域可诱发UG反射。UG反射可在无生殖器刺激的情况下启动。向MPOA微量注射DLH也可启动UG反射。这些数据表明，刺激MPOA中的神经元可克服nPGi的抑制作用，并促进脊髓生殖器反射从而导致射精。
