| Abstract No.: | A-G1196 |
| Country: | Canada |
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| Title: | MATERNAL CARE, THE ENDOCRINE SYSTEM DEVELOPMENT AND MOUNTING BEHAVIOR IN THE FEMALE RAT |
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| Authors/Affiliations: | 1 Adina Del Corpo*; 1 Nicole M. Cameron; 1 Andre K. Portella; 1 Shakti Sharma; 1 Michael J. Meaney;
1 McGill University Douglas Hospital, Montreal, QC, Canada.
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| Content: | Background: Lactating rats exhibit individual differences in the frequency of pup licking/grooming (LG) that are transmitted across generations. Compared to the offspring of high LG dams (high), the female offspring of low LG mothers (low), show earlier vaginal opening and in adulthood display significantly more receptive and proceptive behaviors towards the male during mating. Maternal care also has important effects on endocrine regulation of the estrous cycle in the female rat. At proestrus, the low females have higher levels of leutinizing hormone, estrogen and progesterone compared to the high females. A cross-fostering study showed that part of the sexual behavior (lordosis) is directly dependent on maternal care, whereas other behaviors (pacing) are not. We propose that these effects are associated with alterations in the development of neuroendocrine systems that mediate reproductive behavior and that the highs are masculinized. We hypothesize that the differences in reproductive function between the highs and lows are mediated by differences in androgen exposure during fetal development.
Objectives: Through two studies we aimed to reveal the association between differences in endocrine development in utero and reproductive behavior in high and low females.
Materials and Methods: In the first study, male-typical mounting behaviors were observed in ovariectomized females injected with either oil (O) or testosterone (T). Females were then perfused 1 h after testing and immunohistochemistry was performed for cfos, phospho androgen receptor (pAR) and phospho estrogen receptor alpha (pERα). In the second study, pre-characterized females were mated and sacrificed on gestational day 20. The fetuses were sexed and amniotic fluid was collected. T in the amniotic fluid was analyzed using radioimmunoassay.
Results: In the first study, high T injected females displayed significantly more male-typical mounting behaviors than lows and oil injected females. There was no difference in latency to mount and anogenital investigation between groups. The high females had significantly more cfos labeled cells in the medial preoptic area (MPOA) than the lows. Females injected with T had significantly more pAR in the MPOA than oil injected animals and there was a trend for an increase in staining of pERα in high T injected females. In the second study, the female fetuses of pre-characterized high LG dams had significantly more T levels in the amniotic fluid than the fetuses of low LG dams at gestational day 20.
Conclusion: These results suggest that the differences in reproductive behavior between high and low females may in part be mediated by differences in androgen exposure during fetal development and that the high females are potentially masculinized.
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