Houtsmuller E J, Slob A K
Department of Endocrinology, Growth and Reproduction, Faculty of Medicine and Health Sciences, Erasmus University, Rotterdam, The Netherlands.
Physiol Behav. 1990 Oct;48(4):555-60. doi: 10.1016/0031-9384(90)90299-j.
It is assumed that female rats are masculinized by the presence of males in the same uterine horn. Two hypotheses regarding the mechanism have been proposed: 1) interamniotic diffusion of androgens (contiguity hypothesis) and 2) transport of androgens via the bloodflow (caudal male hypothesis). This study was designed to test these hypotheses while taking into account two previously uncontrolled factors: hemihysterectomy of the mother during pregnancy and birth by caesarean section. Pregnant females were hemihysterectomized during pregnancy or left intact; pups were born naturally or through caesarean section. Position in utero was determined. In adulthood all females were ovariectomized and tested for mounting behavior before and during testosterone treatment and lordosis behavior during estradiol treatment. It was found that females with males located caudally in the same uterine horn were more masculinized and defeminized than females without such males. Adjacent males had no influence on the behavioral sexual differentiation of females. These results confirm the "caudal male hypothesis" rather than the "contiguity hypothesis." Hemihysterectomy during pregnancy prevented the "caudal male effect." Birth through caesarean section did not interfere with the caudal male effect.
一般认为，雌性大鼠会因同一子宫角内存在雄性大鼠而发生雄性化。关于其机制，已提出两种假说：1）雄激素的羊膜间扩散（相邻假说）和2）雄激素通过血流的转运（尾侧雄性假说）。本研究旨在检验这些假说，同时考虑两个先前未得到控制的因素：孕期对母体进行半子宫切除术以及通过剖宫产分娩。将怀孕的雌性大鼠在孕期进行半子宫切除术或保持完整；幼崽通过自然分娩或剖宫产出生。确定其在子宫内的位置。成年后，所有雌性大鼠均接受卵巢切除术，并在睾酮治疗前和治疗期间测试其爬跨行为，在雌二醇治疗期间测试其脊柱前凸行为。结果发现，与同一子宫角内尾侧无雄性大鼠的雌性相比，尾侧有雄性大鼠的雌性大鼠雄性化程度更高且雌性化程度更低。相邻的雄性大鼠对雌性大鼠的行为性分化没有影响。这些结果证实了“尾侧雄性假说”而非“相邻假说”。孕期进行半子宫切除术可阻止“尾侧雄性效应”。剖宫产分娩并未干扰尾侧雄性效应。
