NEUROPEPTIDE-Y INNERVATION OF ESTROGEN-INDUCED PROGESTERONE RECEPTOR-CONTAINING DOPAMINE CELLS IN THE MONKEY HYPOTHALAMUS - A TRIPLE LABELING LIGHT AND ELECTRON-MICROSCOPIC STUDY
Tl. Horvath et al., NEUROPEPTIDE-Y INNERVATION OF ESTROGEN-INDUCED PROGESTERONE RECEPTOR-CONTAINING DOPAMINE CELLS IN THE MONKEY HYPOTHALAMUS - A TRIPLE LABELING LIGHT AND ELECTRON-MICROSCOPIC STUDY, Endocrinology, 133(1), 1993, pp. 405-414
Light and electron microscopic triple immunostaining was performed on
coronal vibratome sections prepared from the hypothalamus of ovariecto
mized (OVX) and OVX plus estrogen-treated African green monkeys (Cerco
pithecus aethiops). Immunoreactivity for progesterone receptors (PRs)
and neuropeptide-Y (NPY) was visualized by a dark blue to black nickel
diaminobenzidine reaction, while the tyrosine hydroxylase-containing
perikarya were labeled with a light brown diaminobenzidine reaction. I
n the OVX plus estrogen-treated material, 30% of the tyrosine hydroxyl
ase-immunoreactive neurons contained PR-immunopositive nuclei. The maj
ority of these cells were found in the central portion of the perivent
ricular area, and a few could be observed in the anterior hypothalamus
and the arcuate and dorsomedial hypothalamic nuclei. These tyrosine h
ydroxylase-immunoreactive PR-containing cells were surrounded with NPY
-immunoreactive axon terminals. A correlated electron microscopic anal
ysis of the same sections revealed synaptic contacts between these NPY
-immunoreactive boutons and the PR-containing tyrosine hydroxylase-imm
unoreactive neurons. In contrast, in the OVX animals, no PR-containing
tyrosine hydroxylase-immunoreactive neurons could be detected. In the
se monkeys, the frequency of synaptic contacts between the NPY-immunor
eactive axon terminals and tyrosine hydroxylase-immunopositive cells w
as similar to that in the OVX plus estrogen-treated monkeys. These obs
ervations indicate that in a population of hypothalamic dopamine cells
, the presence of nuclear PRs is estrogen dependent, show that these c
ells are innervated by NPY axons, and suggest that these estrogen-indu
ced PR-containing dopamine neurons are involved in mediation of the ef
fect of NPY on hypophyseal hormone secretion, including ovarian steroi
d hormone-dependent LH and PRL release.