Effects of pheromones on neuroendocrine regulation of reproductive behavior in male rats,/

Abstract

Neural regulation of male reproductive behavior has been studied extensively through the use of a variety of techniques. Studies have indicated that several brain areas are involved in the regulation of sexual behavior, including the amygdala, hypothalamus, nucleus accumbens, and the corpus striatum. The amygdala and limbic forebrain structures, along with their connections to the hypothalamus and medial preoptic area, are important for the motivational processes that lead to the initiation of actions. The nucleus accumbens functions as the neural interface between areas of the brain processing the motivational state and those controlling the motor systems. Research has also suggested that dopamine (DA) and norepinephrine (NE) in these brain areas may be involved in the regulation of copulatory activity, but the precise role of these catecholamines has yet to be elucidated. iii The present study analyzed the effects of sexual - behavior and pheromone exposure on various behavioral parameters as well as on the catecholamine levels in the anterior amygdaloid area (AAA), anterior hypothalamic area (AHA), preoptic area (POA) , nucleus accumbens (ACB) , and caudate putamen (CPU). Sexually naive male rats were exposed to pheromones for three consecutive days, and then monitored for changes in various parameters of reproductive behavior when placed in an observation chamber with a receptive female. The effects of pheromone exposure were also studied through measurement of catecholamine concentrations (NE and DA) and some of their major metabolites (DOPAC and HVA) in homogenated isolates from discrete brain areas (AAA, AHA, POA, ACB, CPU) by HPLC-ED. Results suggest that pheromonal exposure has minimal effect on sexual behavior in naive male rats. However, the increased levels of DOPAC found in the CPU and ACB suggest that exposure to pheromones may cause an increase in dopaminergic nerve activity in these brain areas. Determining the precise role of dopamine in the regulation of pheromonal cues will require further investigation.