关键词: α雌激素受体, 田鼠属, 单配制, 催产素, 社会性行为, 加压素

Abstract: In mammals monogamy occurs in a form known as social monogamy,which is defined not by sexual exclusivity, but by a suite of characteristics including the formation of long-term pair bonds，biparental care offspring, incest avoidance, and a lack of sexual dimorphism. In this review we examine the contribution that comparative studies using rodents of the genus Microtus (voles) have made to understanding the evolution of social monogamy and the underlying mechanisms，including the neural circuitry, that regulate the expression of monogamy. Studies with Microtus species support the hypothesis that monogamy may evolve under harsh conditions, while also suggesting that female sexual selection may help to maintain monogamy. The evolution of monogamy in mammals requires an increase in the expression of male prosocial behaviors,such ills as affiliation, which facilitate pair bond formation and male parental care. The increased expression of prosocial behaviors associated with monogamy are the product of the interaction of neuropeptides, oxytocin (OT) and vasopressin(AVP), and steroids. OT and AVP regulate the expression of pair bonds and parental care and polygynous and monogamous voles express significantly different patterns of OT and Vla (AVP) receptors. While comparative studies have provided insight into the reguation of social monogamy in microtines, the occurrence of intraspecific variation and behavioral plasticity has provided even greater understanding of its regulation. For example, under some conditions polygynous meadow vole (Microtus pennsylvanicus) males display paternal behavior. Despite the fact that they display the Vla receptor pattern associated with polygyny, central adminislration of vasopressin stimulates the expression of paternal behavior. In the monogamous prairie vole (Microtus ochrogaster)，voles
from lllinois display high levels of prosocial behavior,while prairie voles from Kansas are much less social and are sexually dimorphic. While the expression of OT or Vla receptor patterns does not differ between the two populations there is a significant difference, especially in males, in the expression of estrogen receptors (ER). Illinois males express significantly lower levels of ER in the bed nucleus of the stria terminalis and the medial amygdala，two regions of the brain that regulate the expression of affiliation and aggression,than males from Kansas. This suggests that a lack of sensitivity to estrogen may permit the expression of high levels of prosocial behavior and a reduction in certain types of aggression.

Key words: Estrogen receptor alpha, Microtus, Monogamy, Oxytocin, Social behavior, Vasopressin