Estrogen-responsive neural circuits governing male and female mating behavior in mice

Estrogen Receptor Alpha-Expressing Neurons in Bed Nucleus of the Stria Terminalis and Hypothalamus Encoding Aggression and Mating

Aggression and mating of male mice are strongly associated with Esr1-expressing neurons in the bed nucleus of the stria terminalis (BNSTpr) and hypothalamus in the vomeronasal pathway. By projecting to the downstream hypothalamus, the upstream BNSTprEsr1 gates mating and aggression of male mice and maternal behavior of female mice. The medial preoptic area (MPOA) and ventrolateral subdivision of the ventromedial hypothalamus (VMHvl) are two subdivisions of the hypothalamus downstream. In addition to receiving projections from upstream BNSTpr, there is also a mutual projection between MPOA and VMHvl. In the process of transforming sex information into mating and aggression, Esr1-expressing neurons in BNSTpr, MPOA, and VMHvl act as messengers of information, finally producing inhibitory or excitatory projection. These projections are different in direction, but they all work together to control the behavior selection that is most conducive to defense and reproduction when male mice encounter female or male mice. Here, we summarized the property and the function of connections between these Esr1-expressing neurons in BNSTpr, MPOA, and VMHvl that encode mating and aggression and highlight the importance and benefits of inhibitory projection of Esr1-expressing cells in mating and aggression.

Androgen receptors and sociosexual behaviors in mammals: The limits of generalization

Circulating testosterone is easily aromatized to estradiol and reduced to dihydrotestosterone in target tissues and elsewhere in the body. Thus, the actions of testosterone can be mediated either by the estrogen receptors, the androgen receptor or by simultaneous action at both receptors. To determine the role of androgens acting at the androgen receptor, we need to eliminate actions at the estrogen receptors. Alternatively, actions at the androgen receptor itself can be eliminated. In the present review, I will analyze the specific role of androgen receptors in male and female sexual behavior as well as in aggression. Some comments about androgen receptors and social recognition are also made. It will be shown that there are important differences between species, even between strains within a species, concerning the actions of the androgen receptor on the behaviors mentioned. This fact makes generalizations from one species to another or from one strain to another very risky. The existence of important species differences is often ignored, leading to many misunderstandings and much confusion.

Rodent models for mood disorders - understanding molecular changes by investigating social behavior

Mood disorders, including depressive and bipolar disorders, are the group of psychiatric disorders with the highest prevalence and disease burden. However, their pathophysiology remains poorly understood. Animal models are an extremely useful tool for the investigation of molecular mechanisms underlying these disorders. For psychiatric symptom assessment in animals, a meaningful behavioral phenotype is needed. Social behaviors constitute naturally occurring complex behaviors in rodents and can therefore serve as such a phenotype, contributing to insights into disorder related molecular changes. In this narrative review, we give a fundamental overview of social behaviors in laboratory rodents, as well as their underlying neuronal mechanisms and their assessment. Relevant behavioral and molecular changes in models for mood disorders are presented and an outlook on promising future directions is given.