Neuropeptide Y, produced in the arcuate nucleus of the hypothalamus, plays a key role in the central regulation of anterior pituitary and appetitive functions. The pleiotropic nature of neuropeptide Y in these mechanisms indicates the existence of heterogeneity in the hypothalamic neuronal population producing neuropeptide Y. In this study, we report the… (More)
The study reported here examined the effects of a phytoestrogen diet on progestin receptor induction, vaginal opening, and the onset and maintenance of vaginal cycles in developing female rats. A natural dietary concentration (0.01%) of the isoflavonoid coumestrol was incorporated into the AIN semipurified diet and fed from 21 to 24 days (acute treatment)… (More)
CONTEXT Preclinical studies suggest that estrogen affects neural structure and function in mature animals; clinical studies are less conclusive with many, but not all, studies showing a positive influence of estrogen on verbal memory in postmenopausal women. OBJECTIVE To investigate the effects of estrogen on brain activation patterns in postmenopausal… (More)
A double-label electron microscopic immunostaining procedure was employed to examine the interconnections of glutamic acid decarboxylase(GAD)- and LHRH-immunoreactive neurons in the medial preoptic area of the rat. The results provide ultrastructural evidence that GABA-ergic neurons establish symmetric (Gray II) synapses on LHRH neurons.
During the estrous cycle there is a phasic synaptic remodelling in the hypothalamic arcuate nucleus, consisting in a loss and regain of axo-somatic synapses during the 48 h period between the morning of proestrus and the morning of metestrus. Synaptic changes are accompanied by cyclic modifications in the number of intramembrane particles in the plasma… (More)
Sexual differentiation of reproductive and behavior patterns is largely effected by hormones produced by the gonads. In many higher vertebrates, an integral part of this process is the induction of permanent and essentially irreversible sex differences in central nervous function, in response to gonadal hormones secreted early in development.
It is now obvious that the CNS is capable of undergoing a variety of plastic changes at all stages of development. Although the magnitude and distribution of these changes may be more dramatic in the immature animal, the adult brain retains a remarkable capacity for undergoing morphological and functional modifications. Throughout development, as well as in… (More)
Bcl-2, a protein which negatively modulates apoptosis, is up-regulated by estrogen in several tissues. To determine the effect of estradiol on Bcl-2 in the adult brain, its immunoreactive distribution was examined in the hypothalamic arcuate nucleus of female rats under different endocrine conditions. The number of Bcl-2-immunoreactive neurons was… (More)
Central administration of neuropeptide-Y (NPY) inhibits pituitary LH release in ovariectomized rats and stimulates LH release in intact and ovariectomized rats pretreated with ovarian steroids. Although the precise neural mechanism of this dual effect of NPY is not known, experimental evidence suggests an underlying interaction between hypothalamic NPY and… (More)
Intraneuronal production of estradiol from testosterone has been shown to play a pivotal role in gender-specific brain development of most vertebrates, and to participate in numerous functions of the adult central nervous system. Previous biochemical and morphological approaches demonstrated that estrogen synthetase (aromatase) is present in specific limbic… (More)