Centro de Investigaciones Cerebrales, Universidad Veracruzana, Mexico; Doctorado en Investigaciones Cerebrales, Universidad Veracruzana, Mexico.
Centro de Investigaciones Cerebrales, Universidad Veracruzana, Mexico.
Behav Brain Res. 2019 Nov 18;374:112117. doi: 10.1016/j.bbr.2019.112117. Epub 2019 Jul 27.
According to the organizational-activational hypothesis, testosterone or its metabolite estradiol, can organize the brain in a male direction (permanently or for long periods) if exposure occurs during a critical (sensitive) time of brain development like the prenatal period. Male rodents with insufficient levels of testosterone during such critical period would irreversibly fail to display sexual partner preference for receptive females in adulthood. However, exposure to testosterone during puberty is believed to function as a second critical period for organization of brain and behavior. Thus, in the present study we explored the effects of neonatal gonadectomy at postnatal day 1 (GNX) on the partner preference of adult males and the size of some sexually dimorphic regions in the brain like the SDN-MPOA, SCN, MeApd and VMH; and challenged its irreversibility by providing exogenous testosterone during puberty. Our results indicated that neonatal GNX impaired partner preference for females and reduced the size of SDN-MPOA, MeApd and VMH, but not SCN. GNX males restored with testosterone in PD30-PD59 (GNX + T) expressed partner preference for sexually receptive females and increased the size of SDN-MPOA and VMH, but not MeApd in adulthood. We conclude that neonatal castration and the lack of testosterone during the first month of life alters sexual behavior and brain dimorphism in adult male rats, but pubertal testosterone reverses the effects on behavior and brain dimorphism to some extent.
根据组织激活假说，如果睾酮或其代谢物雌二醇在大脑发育的关键（敏感）时期（如产前）暴露，它可以使大脑向男性方向发育（永久性或长期）。在关键时期雄性啮齿动物如果睾酮水平不足，成年后将不可逆转地无法表现出对接受雌性的性伴侣偏好。然而，青春期暴露于睾酮被认为是大脑和行为组织的第二个关键时期。因此，在本研究中，我们探讨了新生期睾丸切除术（GNX）对成年雄性大鼠的性伴侣偏好和大脑中一些性别二态区域（如 SDN-MPOA、SCN、MeApd 和 VMH）大小的影响，并通过在青春期提供外源性睾酮来挑战其不可逆性。我们的结果表明，新生期 GNX 损害了雄性大鼠对雌性的性伴侣偏好，并减少了 SDN-MPOA、MeApd 和 VMH 的大小，但 SCN 没有。在 PD30-PD59 期间用睾酮恢复的 GNX 雄性（GNX+T）对性接受雌性表现出性伴侣偏好，并增加了 SDN-MPOA 和 VMH 的大小，但 MeApd 没有。我们得出结论，新生期去势和生命的第一个月缺乏睾酮改变了成年雄性大鼠的性行为和大脑二态性，但青春期的睾酮在某种程度上逆转了对行为和大脑二态性的影响。
