Chemosensory communication plays a major role in the reproductive physiology and behavior of several species. The vomeronasal organ, an "accessory olfactory" chemoreceptive structure, is thought to detect pheromonal signals from conspecifics. This system projects directly to central brain regions important in reproductive behavior. Removal of the vomeronasal organ, in sexually inexperienced male hamsters results in severe impairments of mating behavior and most animals do not mate. After sexual experience however, main olfactory pathways can sustain mating behavior in the absence of vomeronasal input. / The expression of an immediate early gene, c-fos was used as a marker of neuronal activation to distinguish the roles of chemosensory input in activating brain regions, important for mating. Activated brain and bulb regions were analyzed following mating or pheromonal stimulation in inexperienced and experienced male hamsters, both intact and those with vomeronasal organs removed. / Central vomeronasal pathways of inexperienced animals were activated above control levels after mating or pheromonal stimulation, while main olfactory pathways were not. Fos expression in the accessory olfactory bulb, posteromedial cortical amygdala and part of the medial nucleus, reflects activation by vomeronasal sensory input while activation in the caudal posteromedial bed nucleus of the stria terminalis (pmBNST) reflects chemoinvestigatory behavior. In inexperienced animals, the medial preoptic area (MPOA) and rostral pmBNST were activated only during copulatory performance but in sexually experienced males these regions were activated by both copulation and pheromonal stimulation. Fos expression patterns in experienced VNX animals may reflect rerouting of chemosensory information via main olfactory pathways and point to the anterior cortical nucleus, as an important region for this rerouting. / Behavioral data show that intracerebroventricular Luteinizing hormone releasing hormone (LHRH) injections can substantially restore mating behavior in inexperienced animals with vomeronasal organs removed. This action may be independent of the effects of LHRH on the pituitary. Fos and LHRH immunocytochemistry revealed an intermingling of LHRH cells and fibers with Fos activated neurons, consistent with the working hypothesis that intracerebral LHRH release may be involved in the mechanisms underlying vomeronasal chemoreception during mating behavior. / Source: Dissertation Abstracts International, Volume: 56-02, Section: B, page: 0669. / Major Professor: Michael Meredith. / Thesis (Ph.D.)--The Florida State University, 1994.
| Identifer | oai:union.ndltd.org:fsu.edu/oai:fsu.digital.flvc.org:fsu_77361 |
| Contributors | Fernandez, Gwendolyn Diedre., Florida State University |
| Source Sets | Florida State University |
| Language | English |
| Detected Language | English |
| Type | Text |
| Format | 288 p. |
| Rights | On campus use only. |
| Relation | Dissertation Abstracts International |
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