The distribution of monoaminergic cells and fibers in a periventricular preoptic nucleus involved in the control of gonadotropin release: Immunohistochemical evidence for a dopaminergic sexual dimorphism
There is no author summary for this article yet. Authors can add summaries to their articles on ScienceOpen to make them more accessible to a non-specialist audience.
Abstract
A small, discrete nucleus at the rostral end of the third ventricle, the anteroventral
periventricular nucleus (AVPv), has been reported to be involved in the control of
gonadotropin release. Since monoaminergic neurotransmitter systems have also been
implicated in this function we used an indirect immunohistochemical approach to examine
the distribution of 3 monoaminergic neurotransmitter systems in this nucleus. Sections
through the AVPv of both colchicine and non-colchicine-treated adult male and female
Sprague-Dawley rats were processed for immunohistofluorescence with antisera directed
against tyrosine hydroxylase (TH), dopamine beta-hydroxylase (DBH), or serotonin (5-HT),
and were subsequently counterstained with the fluorescent Nissl stain ethidium bromide.
The distributions of TH-, DBH- and 5-HT-immunoreactive neural elements within the
AVPv were evaluated and a comparison was made between males and females. In both sexes,
few 5-HT-stained fibers were seen within the borders of the AVPv, in contrast to the
relatively high 5-HT-stained fiber density of the surrounding region. A dramatic sexual
dimorphism was found in the distribution of TH-immunoreactive fibers and cell bodies.
Compared to males, the AVPv in the female contained 3-4 times as many TH-stained perikarya,
and a 2- to 3-fold greater density of TH-stained fibers. A low to moderate density
of DBH-immunoreactive fibers, and no DBH-stained cell bodies, were seen in the nucleus.
A clear sex difference was not found in the density of DBH-stained fibers in the AVPv,
indicating that the sexual dimorphism in TH-immunoreactive neural elements in this
nucleus is due to a greater density of dopaminergic fibers and a greater number of
dopaminergic cell bodies in the female. These results suggest that dopamine may participate
in the control of gonadotropin secretion at the level of the AVPv.