Estrogen receptors and emotional behavior in a seminatural environment (continuation)

There are important sex differences with regard to the incidence of several psychiatric disorders. One important endocrine sex difference is the higher concentration of circulating ovarian hormones in women. In rodents, estrogens have multiple behavioral effects. However, essentially all the existing knowledge of the behavioral actions of estrogens stems from short observations in highly simplified contexts. The purpose of the present project is to analyze the effects of estrogens on sociosexual behaviors and on responses to stressful and pleasurable stimuli (short exposure to noise and predator odor and lavender odor, music and chocolate, respectively) in groups of rats living in a seminatural environment for an extended period. Each group (the observation group) consists of 4 females and 3 males. Emotional behavior in each individual as well as interactions between individuals will be carefully described. This environment has been used in several earlier studies (FOTS id 3700, 3878, 5441 and 7102). The present project is a continuation of FOTS id 7102, which had to be interrupted because of a lack of the viral vector. When we finally received the vector, the authorization for that study has expired. There are still three observation groups missing for obtaining the required number of animals in each treatment group. We will determine the role of the estrogen receptors alpha and beta at different brain sites. In this part of the study, we will use 14 females (of which 2 are replacement females) and 9 male rats. Females will be given intracerebral infusions of an iRNA directed against the estrogen receptors alpha or beta, and subcutaneous injections with estradiol and progesterone shortly before behavioral observation. The target structures are the ventromedial nucleus of the hypothalamus, and the central amygdala, all implicated in sociosexual and emotional behaviors. The females will receive analgesic treatment for 48 h after surgery (ovariectomy and intracerebral infusion). Extensive experience with these procedures show that they are not deleterious to animal health, and they produce only moderate, short-lasting discomfort. These studies will give entirely new data concerning behavioral actions of estrogens, and may contribute to an understanding of the etiology of some psychiatric disorders.