Journal of Neuroscience, Vol 14, 3643-3654, Copyright © 1994 by Society for Neuroscience
c-fos expression in vomeronasal pathways of mated or pheromone- stimulated male golden hamsters: contributions from vomeronasal sensory input and expression related to mating performance
GD Fernandez-Fewell and M Meredith
Department of Biological Science, Florida State University, Tallahassee 32306.
The vomeronasal system projects to the accessory olfactory bulb (AOB), to
the medial (Me) and posterior medial cortical nuclei (PMCN) of the
amygdala, to the bed nucleus of the stria terminalis (BNST), and to other
central structures shown to be important in mating behavior, including the
medial preoptic area (MPOA). In these experiments c-fos expression was used
as a marker of neural activity to identify the contribution of vomeronasal
sensory input during mating behavior in male golden hamsters, either intact
or with vomeronasal organs removed (VNX). Inexperienced hamsters were
either stimulated with a receptive female and allowed to mate, exposed to
female hamster vaginal fluid (HVF), which contains stimuli known to act
through the VN system, or placed in a clean cage alone. Densely stained
Fos-positive nuclei were evident in mated animals in the central VN pathway
[AOB, Me, posterior medial BNST (pmBNST)] and a VN target area (MPOA).
HVF-exposed animals showed Fos expression in the AOB, Me, and BNST but not
MPOA. Unstimulated animals showed almost no activation. Most VNX animals
exposed to females did not mate, but performed intense chemoinvestigation.
They had few Fos-positive nuclei in any of these areas except the caudal
pmBNST. A few VNX animals that did mate had patterns of Fos activation that
were similar but less intense than those of intact mating animals,
suggesting a selective activation of VN central pathways during mating
regardless of VN sensory input. The main olfactory system showed low levels
of Fos expression in all animals (stimulated and unstimulated). Fos
expression in the MPOA and rostral pmBNST was seen only in mated animals,
suggesting that these regions are concerned with mating performance or its
consequences, rather than the chemosensory input that triggers it. Fos
expression in the caudal encapsulated pmBNST was evident in all groups of
animals that performed chemosensory investigation, regardless of VN status
or mating, suggesting that this region either directs or responds to
chemosensory investigation.
Previous Article | Next Article
