The relationship between social behavior and the expression of estrogen receptor β and androgen receptor in olfactory-related brain regions of the male mandarin vole Microtus mandarinus and reed vole M. fostis

摘要

In order to investigate the neurobiological mechanism of the social behavior difference in adult male mandarin voles Microtus mandarinus and reed voles M. fostis , the behavior focal sampling method and immunohistochemistry method were used to investigate differences in intraspecies male-male interactions and the expressions of estrogen receptor β(ERβ) and androgen receptor (AR) between two species , respectively (n=15). During the two-hour interaction of male individuals, mandarin voles spent significantly more time on aggressive and defensive behavior to homosexual invaders in the first one hour than in the last hour, whereas the reed voles did not have significantly behavioral difference between the first and last hour. During the whole two-hour interaction of male individuals, mandarin voles spent significantly more time engaged in aggressive and defensive behaviors to homosexual invaders and less time on the nonsocial behaviors than the reed voles. Before the two-hour interaction of male individuals ， we found obviously fewer and lighter-stained ERβ immunoreactive neurons （ ERβ-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 ERβ-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. Differences in both numbers of ERβ-IRs and AR-IRs between before and after interactions in the reed voles were not significant. There were greatly significantly more ERβ-IRs neurons in reed voles than in mandarin voles which had gone through interactions and 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 results suggest that the decrease of ERβ-IRs and increase of AR-IRs might affect social recognition and aggressive behavior ， and this might explain differences in social behaviors between the two vole species [ Acta Zoologica Sinica 50 (2): 165 -175 , 2004].