Studies On Relationship Between Estrogen, Androgen, And Their Receptor Distribution, FOS Expression And Social Behaviors Of The Mandarin Voles (Microtus Mandarinus) And The Reed Voles (M.fostis)

Social behaviors of rodent are not only related with existence environment, mating system, heredity et al., but also are regulated by neuroendocrine, particularly by androgen and estrogen. Therefore, studies the relation between hormone and social behaviors of different species with different mating system, can not only explore the neuroendocrinical mechanism of social behaviors, but also can reveal the intrinsic mechanism, evolution mechanism and adaptation function.The microtine rodents show profound differences in reproductive biology and social organization in spite of their taxonomic relationship. In order to explore the relation between androgen, estrogen, androgen receptor, estrogen receptor, expression of Fos protein and social behaviors, using monogamous mandarin voles (Microtus mandarinus) and reed voles (Microtus fortis) with promiscuous reproductive characteristics as two study objects, the neurobiological basis of social organization, memory, mating, aggressive behavior of two species are studied through two olfactory systems, and explore evolution mechanism and adaptation function of two species voles. The study is divided in five parts.1. In order to investigate the neurobiological mechanism of the social behavior difference in the adult male mandarin voles (Microtus mandarinus) and reed voles(M.fostis), the behavior focal sampling method and immunohistochemistry method were used to investigate these differences in the behaviors of intraspecies male-male interactions and the expressions of estrogen receptor P (ER0) and androgen receptor (AR) between two species, respectively (n=15). During the two hour interaction of male-male individuals, the mandarin voles spent significantly more time on the aggressive and defensive behavior to homosexual invaders in the first one hour than in the last hour, while the reed voles didn't have significantly behavioral difference between the first and the last one hour (p>0.05); During the whole two-hour interaction of male-male individuals, the mandarin voles spent significantly more time on theaggressive and defensive behaviors to homosexual invaders and less time on the nonsocial behaviors than the reed voles. Before the two-hour interaction of male-male individuals , we found there were obviously fewer and lighter stained ERp immunoreactive neurons (ER|3-IRs) in both main olfactory bulb system project regions and vomeronasal system project regions in the mandarin voles than in the reed voles, but no significant difference in numbers of AR immunoreactive neurons (AR-IRs) between the two species through the examining of immunoreactive neurons, moreover, there were significantly fewer AR-IRs than ERp-IRs in two species of vole before the two-hour interactions. There were significantly fewer ER-IRs in both the main olfactory bulb project regions and the vomeronasal system project regions in the mandarin voles after interactions than before interactions, but there were significantly more AR-IRs after interactions than before interactions in the mandarin voles; There were not significant difference in both numbers of ER|3-IRs and AR-IRs between before and after interactions in the reed voles, and there were greatly significantly more ERp-IRs neurons in the reed voles than in the mandarin voles which had gone through interactions, there were significantly fewer AR-IRs in the reed voles than in the mandarin voles which had gone through interactions. The results indicate that mandarin voles and reed voles had different social behaviors in social interactions. The result suggest that the decrease of ERp-IRs and increase of AR-IRs might affect social recognition and aggressive behavior, and this might also be one of reasons of social behaviors difference in two vole species.2. Aggressive behavior of the adult male mandarin was conducted on 7,14 and 30 days after castration, respectively, the aggressive behavior was not decreased on 7 and 14 days after castration, however, the aggressive behavior was significantly decreased on 30 days after castration. 7 days after cast...