|
(M40) PHEROMONE DETECTION BY THE MAIN OLFACTORY SYSTEM AND MAMMALIAN GENDER RECOGNITION. Baum, Michael1, 1 Dept. of Biology, Boston, MA ABSTRACT- The vomeronasal organ-accessory olfactory bulb has recently received much attention as the primary sensory system responsible for the detection and processing of pheromonal signals in mice and other rodents that lead to gender recognition and the selection of opposite-sex mating partners. Data will be presented for a higher mammalian species, the ferret, which instead points to the main olfactory epithelium and its associated main olfactory bulb (MOB) as the olfactory system that is primarily responsible for mate recognition in this carnivore. When gonadectomized ferrets were treated with either estradiol or testosterone, they showed a significant preference to sniff wood blocks previously soiled by opposite-sex ferrets. Likewise, gonadectomized male (testosterone-treated) as well as female (estradiol-treated) ferrets preferred to approach volatile body odors from opposite-sex ferrets in Y-maze tests. Occlusion of the main olfactory epithelium eliminated these preferences in ferrets of both sexes, and providing visual plus auditory signals or the opportunity for physical interaction with conspecifics after each Y-maze operant trial failed to compensate for these disruptive effects of peripheral anosmia. Even without sex steroid priming, gonadectomized ferrets of both sexes were able to distinguish between anal scent gland secretions from male vs female conspecifics in home-cage habituation/dishabituation tests. Prior to steroid priming, gonadectomized ferrets did not respond to a range of increasing dilutions of anal scents; however, after estadiol treatment subjects of both sexes investigated even the most dilute anal scents that were presented. Gonadectomized male and female ferrets showed equivalent levels of Fos immunoreactivity (IR) in granule cells of the main olfactory bulb, but not in the accessory olfactory bulb, 90 min. after exposure to soiled estrous bedding, and administration of a sex steroid (testosterone) significantly augmented granule cell Fos responses to estrous odors. Exposure to peppermint odor also stimulated Fos-IR in these same regions of the MOB; however, testosterone failed to enhance Fos responses to this non-social odorant. These data in ferrets complement previous studies in the pig implicating the main as opposed to the accessory olfactory system in the detection of pheromonal cues leading to mate recognition. The main olfactory system may also mediate some behavioral responses to pheromonal signals derived from urine (mice) as well as scent gland/vaginal secretions (hamsters) of same versus opposite-sex conspecifics, suggesting that this system may contribute to gender recognition and mating partner selection in rodents as in higher mammals (Supported by HD21094 and by MH59200). KEY WORDS: pheromones , mate recognition , main olfactory system , vomeronasal |
