||Neuroendocrine Responses to Social Regulation of Puberty in the Female House Mouse.
Darney, K. J. ;
Goldman, J. M. ;
Vandenbergh., J. G. ;
||NSI Technology Services Corp., Research Triangle Park, NC. ;North Carolina State Univ. at Raleigh. Dept. of Zoology.;Health Effects Research Lab., Research Triangle Park, NC.
Animal sex behavior ;
Brain chemistry ;
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First estrus is advanced in female house mice exposed to an adult male and delayed in those housed in groups. Experiments were conducted to explore possible mechanisms by which the hypothalamus integrates these puberty regulating social signals. Female mice weaned at 21 d of age were placed in: groups of 8 (G8JF) a juvenile female with a juvenile male (JFJM) or juvenile female with an adult male (JFAM). All females were ovariectomized on d 28 and sacrificed on d 29. Two way ANOVA (social treatment x estradiol treatment) revealed no differences or interactions in brain catecholamines as a result of estradiol injection. The G8JF treatment significantly increased NE, DA and DOPAC in the mediobasal hypothalamus (MBH), and the MHPG/NE ratio in the preoptic area (POA). In the final experiments, isolate prepubertal female mice were treated with either water or male urine (MU) on the oronasal groove. Eight d of MU treatment resulted in significant uterine growth, however there were no differences in serum LH, POA or MBH catecholamines or POA and median eminence LHRH. The results suggest that the mechanism by which male and grouped female exposure alters first estrus may not involve changes in sensitivity to estradiol negative feedback.