Hermans R H, McGivern R F, Chen W, Longo L D
Department of Physiology, Loma Linda University, School of Medicine, CA 92350.
Neurotoxicol Teratol. 1993 Nov-Dec;15(6):353-63. doi: 10.1016/0892-0362(93)90051-o.
The last week of gestation is a critical period for the sexual differentiation of the brain in the rat. Exposure to prenatal stress during this period has been shown to demasculinize and/or feminize adult male sexual behavior. Many of the neurochemical and endocrine responses to hypoxia are similar to that observed under stressful conditions such as restraint stress. Therefore, we examined the postnatal consequences on reproductive and nonreproductive sexually dimorphic behaviors in male offspring of dams exposed to chronic hypoxia during the last week of gestation. In addition, we examined sensorimotor development in offspring of both sexes. Pregnant Sprague-Dawley dams were exposed to continuous hypoxia (10.5% O2 from gestational day 15 to 21). Offspring were weaned at 22 days of age and group housed. Behavioral tests were conducted with littermate representatives. In adulthood, male rats prenatally exposed to hypoxia had significantly delayed initiation latencies of masculine sexual behavior and decreased number of ejaculations, but did not display a significant increase in feminine sex behavior potentials. Developmentally, animals exposed to prenatal hypoxia did not differ significantly from controls with respect to day of eye or ear opening, or the in times of righting reflex, negative geotaxis or cliff avoidance. Wire hanging latencies in hypoxic exposed animals were significantly greater than controls around the time of eye opening, but did not differ at earlier or later ages. A significant effect of hypoxia was detected on stride length at 95 days of age, but other aspects of gait patterns were similar to controls. No group differences in gait patterns were observed at 17 or 45 days of age. In addition, no significant differences were observed in open field activity, circadian locomotor activity, saccharin preference, or Morris water maze test. This hypoxia regimen did not influence the occurrence of the prenatal or postnatal surge of plasma testosterone. Overall, these results provide some evidence that, in males, mild, chronic prenatal hypoxia may result in incomplete masculinization of adult reproductive behavior in the absence of overt changes in perinatal testosterone surges.
妊娠的最后一周是大鼠大脑性别分化的关键时期。研究表明，在此期间暴露于产前应激会使成年雄性性行为去雄化和/或雌性化。许多对缺氧的神经化学和内分泌反应与在诸如束缚应激等应激条件下观察到的反应相似。因此，我们研究了在妊娠最后一周暴露于慢性缺氧的母鼠所生雄性后代在生殖和非生殖性二态性行为方面的产后后果。此外，我们还研究了两性后代的感觉运动发育情况。将怀孕的斯普拉格-道利母鼠暴露于持续缺氧环境（从妊娠第15天至21天，氧气含量为10.5%）。幼崽在22日龄时断奶并群居。对同窝代表进行行为测试。成年后，产前暴露于缺氧环境的雄性大鼠的雄性性行为起始潜伏期显著延迟，射精次数减少，但雌性性行为潜能未显著增加。在发育方面，暴露于产前缺氧环境的动物在睁眼或开耳日、翻正反射、负趋地性或避崖时间方面与对照组无显著差异。在睁眼前后，暴露于缺氧环境的动物的悬线潜伏期显著长于对照组，但在更早或更晚的年龄则无差异。在95日龄时检测到缺氧对步幅有显著影响，但步态模式的其他方面与对照组相似。在17日龄或45日龄时未观察到步态模式的组间差异。此外，在旷场活动、昼夜运动活动、糖精偏好或莫里斯水迷宫测试中也未观察到显著差异。这种缺氧方案并未影响产前或产后血浆睾酮高峰的出现。总体而言，这些结果提供了一些证据，表明在雄性中，轻度慢性产前缺氧可能导致成年生殖行为的雄性化不完全，而围产期睾酮高峰无明显变化。
