3 research outputs found
Prenatal uterine environment and sexual differentiation of rats
prenatal factors relevant to hormonal environment on the sexual differentiation of
behavior, morphology and central nervous system in rats. The effects of such
factors as prenatal sex composition of the litter and position in utero on the sexual
differentiation of normally developed (i.e. untreated) male and female rats was
examined. In addition, the effects of experimentally induced changes in the
perinatal hormonal milieu on the central nervous system and behavior of male rats
were assessed.
This general introduction provides an overview of the effects of hormones on
reproductive morphology and behavior, and function and morphology of the central
nervous system of mammals, with emphasis on rats. Current questions and
hypotheses that led to the experiments presented in this thesis will be outlined
Plasma testosterone in fetal rats and their mothers on day 19 of gestation
Plasma testosterone levels were higher in pooled samples from male fetuses than from female fetuses on day 19 of pregnancy. Plasma testosterone from female fetuses with males located caudally in the uterus was higher than from females that lacked such males. Testosterone level of both male and female fetuses was correlated with maternal testosterone. No correlation was found between maternal testosterone and number of males in the litter, male-to-female ratio, or litter size. These results corroborate earlier findings of a sex difference in plasma testosterone levels on fetal day 19 in rats, and provide support for the hypothesis that female rats receive androgens from males located caudally in the uterus. No evidence was found that testosterone of pregnant females is affected by the sex ratio or size of her litter
SDN-POA volume, sexual behavior, and partner preference of male rats affected by perinatal treatment with ATD
The present study investigated 1) the importance of the aromatization process during the perinatal period for the development of the sexually dimorphic nucleus in the preoptic area of the hypothalamus (SDN-POA) of male rats, and 2) the relationship between SDN-POA volume and parameters of masculinization in male rats that were treated perinatally with the aromatase-inhibitor ATD. Males were treated with ATD either prenatally or pre- and neonatally, or with the vehicle. Masculine sexual behavior and partner preference were investigated in adulthood. Thereafter, animals were sacrificed and SDN-POA volume was measured. The SDN-POA volume was reduced in both the prenatally and the pre- and neonatally treated group, with a larger reduction in the latter than in the former group. Combined pre- and neonatal ATD treatment resulted in reduced frequency of mounts, intromissions, and ejaculations, as well as a reduced preference for a female over a male. The SDN-POA size was significantly and positively correlated with frequency of masculine sexual behavior, as well as preference for a female over a male