Aggression is a normal component of the social behaviors of female mammals, including women. Despite the occurrence of aggression among females, relatively little research has focused on biological mechanisms regulating female aggression. To the contrary, most models of aggression in both animals and humans focus on a context in which males are aggressive, but females are not. This has lead to several critical errors in our understanding of aggression in females. The first error has been the perpetuation of the myth that there is a sex difference in aggression. This “sex difference” is more appropriately described in differences in the form in which aggression occurs and in the context in which individuals will express aggression. Following from this has been the focus on biological processes controlling aggression. Again, this has typically been a biology of male aggression. For example, we found that a member of a group of drugs called “serenics” (reducing aggression by making people serene) was very effective in reducing aggression in male hamsters, but was ineffective in altering aggression in female hamsters.
We determined that progesterone and related hormones do indeed act in the brain to inhibit aggression.
So what would regulate aggression in females? In rodents, it is clear that the release of hormones from the ovary (i.e., estrogen and progesterone) eliminates female aggression. In contrast, during the phases of the reproductive cycle when hormone levels are low, or following surgical removal of the ovaries, aggression is markedly elevated. We focused on the role of progesterone in the inhibition of aggression in female hamsters, because this hormone suggests possibilities for basic research that may lead to therapeutic treatments for anxiety and aggression in women. In recent years it has become clear that hormones like progesterone when produced in the brain act in a similar fashion to a class of minor tranquilizers, the benzodiazepines (e.g., valium). The goal of this research project was to examine conditions in which progesterone and related hormones would inhibit aggression using female hamsters as the model system. In fact, we determined that progesterone and related hormones do indeed act in the brain to inhibit aggression. The advantage of using these hormones as a basis for developing drug therapies for aggression and anxiety in females is that these naturally occurring substances could prove to be effective in women with fewer side effects than would traditional drug therapies.
Kohlert, J.G. and Meisel, R.L. Inhibition of aggression by progesterone and its metabolites in female Syrian hamsters. Aggressive Behavior, 27, 372-381, 2001.