Erskine M S, Tobet S A, Baum M J
Department of Biology, Boston University, Massachusetts 02215.
Endocrinology. 1988 Feb;122(2):524-30. doi: 10.1210/endo-122-2-524.
The present studies examined the patterns of circulating testosterone (T) within 0-24 h after birth in male and female ferrets along with concomitant changes in neural aromatase activity and hypothalamic concentrations of estradiol (E2). Plasma and brain samples were obtained 0 and 2 h (cesarean delivery) or 0, 2, 12, and 24 h (natural delivery) after birth. Plasma T levels were significantly higher in male neonates 2 h after birth than at 0 h in both cesarean-delivered (9.48 +/- 1.25 vs. 3.37 +/- 0.60 ng/ml) and naturally delivered (19.28 +/- 2.94 vs. 5.13 +/- 1.93 ng/ml) ferrets, while female neonates showed no significant changes in T over these sampling times. T levels had returned to 0 h levels by 12 h in naturally delivered males. T was significantly lower in females than in males 0, 2, and 24 h after natural delivery, whereas T levels were equivalent in males and females immediately after cesarean delivery. Male kits kept on a heating pad for 2 h after natural delivery had lower plasma T levels than males that were left with their mothers over this same period. Brain aromatase activity in anterior hypothalamus-preoptic area, medial basal hypothalamus (MBH), temporal lobe, and cerebral cortex was equivalent in males and females at all postpartum ages, regardless of whether delivery occurred by cesarean section or naturally. However, in naturally delivered kits of both sexes significant elevations in aromatase activity occurred in MBH and temporal lobe 24 h postpartum. Finally, E2 concentrations in anterior hypothalamus-preoptic area and MBH were equivalent 0 and 2 h postpartum in males and females, regardless of whether they were delivered naturally or by cesarean section. The observed postnatal elevation in T may contribute to brain and behavioral sexual differentiation of male ferrets. It is unclear, however, whether such an effect of T depends on its neural aromatization to E2.
本研究检测了雄性和雌性雪貂出生后0至24小时内循环睾酮（T）的模式，以及神经芳香化酶活性和下丘脑雌二醇（E2）浓度的相应变化。在出生后0小时和2小时（剖宫产）或0、2、12和24小时（自然分娩）采集血浆和脑样本。剖宫产出生的雄性新生儿出生后2小时的血浆T水平显著高于0小时（9.48±1.25对3.37±0.60 ng/ml），自然分娩的雄性新生儿也是如此（19.28±2.94对5.13±1.93 ng/ml），而雌性新生儿在这些采样时间内T无显著变化。自然分娩的雄性新生儿在12小时时T水平已恢复到0小时水平。自然分娩后0、2和24小时，雌性的T水平显著低于雄性，而剖宫产后立即，雄性和雌性的T水平相当。自然分娩后在加热垫上放置2小时的雄性幼崽的血浆T水平低于同期与母亲在一起的雄性。无论分娩是剖宫产还是自然分娩，产后各年龄段雄性和雌性下丘脑前视前区、内侧基底下丘脑（MBH）、颞叶和大脑皮层的脑芳香化酶活性均相当。然而，在自然分娩的两性幼崽中，产后24小时MBH和颞叶的芳香化酶活性显著升高。最后，无论雄性和雌性是自然分娩还是剖宫产，产后0和2小时下丘脑前视前区和MBH中的E2浓度相当。观察到的出生后T升高可能有助于雄性雪貂的脑和行为性别分化。然而，尚不清楚T的这种作用是否依赖于其向E2的神经芳香化。
