Induction of c-fos in hamster accessory olfactory bulbs by natural and cloned aphrodisin.

Male hamsters were exposed to the female pheromone, aphrodisin (APH), its cloned protein backbone (rAPH), and the homologous lipocalin, beta-lactoglobulin (beta-LG). Of these, only APH elicited mating behavior. Enhanced c-fos protein was found in the nuclei of neurons in the accessory olfactory bulb (AOB) after exposure to these stimuli. Relative to beta-LG, both rAPH and APH produced significant increases in AOB labeling. The modest labeling elicited by rAPH was evenly distributed, but the heavier staining elicited by APH was concentrated in the caudal region of the AOB. Thus, pheromone receptor neurons in the basal compartment of the vomeronasal epithelium, which project to the caudal region of the AOB, may respond to APH and provide the input which drives mating behavior.