The in vitro perifused rat ovary: II. Role of oxygen tension in the whole and quartered ovary.

In vitro perifusion of whole ovaries raises questions about tissue viability and its effects on the observed ovarian steroid secretion. To assess effects of tissue degeneration, whole and quartered ovaries from pregnant mare serum gonadotropin (PMSG-) treated immature rats were perifused for 8 h, employing various levels of pO2. Histological examination of both the whole and quartered ovary showed signs of degeneration in centrally located follicles but not in follicles located near the surface.

The in vitro perifused rat ovary: I. Steroid secretion in response to ramp and pulsatile stimulation with luteinizing hormone and follicle stimulating hormone.

A computer-controlled perifusion apparatus has been used to investigate the effects of different patterns of hormonal stimulation on secretion of steroids by ovaries from untreated, or pregnant mare serum gonadotropin (PMSG)-pretreated, immature rats. With ovaries from untreated rats, a low rate of increasing concentration of gonadotropins (luteinizing hormone (LH) plus follicle stimulating hormone (FSH)) induced a maximum secretion of estradiol within 60 min (22.6 +/- 1.

Unilateral transplantation of human fetal mesencephalic tissue into the caudate nucleus of patients with Parkinson's disease.

Background: Parkinson's disease is characterized by the loss of midbrain dopamine neurons that innervate the caudate and the putamen. Studies in animals suggest that fetal dopaminergic neurons can survive transplantation and restore neurologic function. This report compares the clinical results in four case patients with severe Parkinson's disease who underwent stereotaxic implantation of human fetal ventral mesencephalic tissue in one caudate nucleus with the results in a control group of similar subjects assigned at random to a one-year delay in surgery.

Neuropeptide-Y innervation of beta-endorphin-containing cells in the rat mediobasal hypothalamus: a light and electron microscopic double immunostaining analysis.

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 the inhibitory beta-endorphin (beta END) systems in the neuroendocrine regulation of pituitary LH release in the rat. The present study was undertaken to examine the morphological basis of the interaction between these two peptidergic systems in the hypothalamus.

Steroid hormones and CNS sexual dimorphisms modulate symptom expression in Tourette's syndrome.

We present our hypothesis that various steroid hormones play an important role in the symptom expression of Gilles de la Tourette's syndrome (TS) and that androgenic hormones, in particular, are likely to exacerbate symptoms of the disorder. We review the clinical evidence supporting our hypothesis. Sex steroids establish brain sexual dimorphisms early in CNS development, and we suggest mechanisms whereby androgenic and other hormonal changes later in human development might act at dimorphic brain regions to influence the natural history of TS.

GABAergic and catecholaminergic innervation of mediobasal hypothalamic beta-endorphin cells projecting to the medial preoptic area.

In the absence of cellular estrogen receptors or proven direct estrogen action in the rat, it is assumed that estrogen indirectly regulates the secretory activity of the preoptic area luteinizing hormone-releasing hormone-producing cells. We have previously shown that pro-opiomelanocortin neurons in the arcuate nucleus of the rat send axons rostrally to connect with luteinizing hormone-releasing hormone neurons of the preoptic area. An experiment combining retrograde tracing and double-immunostaining was used to test the hypothesis that rat GABAergic and/or catecholaminergic neurons can influence luteinizing hormone-releasing hormone-producing cells via mediobasal hypothalamic beta-endorphin neurons.

Involvement of protein kinase-C in the mitogenic effect of insulin-like growth factor-I on rat astrocytes.

Insulin-like growth factor-I (IGF-I) stimulates the proliferation of many cell types, including astrocytes. Astrocytes are a population of brain cells highly enriched in IGF-I receptors, which unlike neurons, retain the ability to proliferate in the adult brain. Although astrocyte proliferation in response to IGF-I is well documented, the intracellular mechanisms that mediate this phenomenon are poorly defined.

Presence of calbindin and lack of parvalbumin in progesterone receptor-containing neurons of the monkey mediobasal hypothalamus.

All of the progesterone receptor-containing cells of the monkey hypothalamus are GABAergic. The aim of this study was to further characterize these GABAergic progesterone receptor-containing neurons based on their calbindin or parvalbumin content. These calcium-binding proteins are characteristic markers of different populations of GABAergic neurons in the central nervous system.

Beta-endorphin innervation of dopamine neurons in the rat hypothalamus: a light and electron microscopic double immunostaining study.

Pharmacological data suggest that opiates, acting indirectly via the catecholaminergic system, are involved in the inhibition of LH release and the stimulation of PRL secretion. The aim of this study was to demonstrate on the ultrastructural level whether beta-endorphin-immunoreactive fibers form synaptic contacts with hypothalamic dopaminergic neurons. Light and electron microscopic double immunostaining experiments were performed on vibratome sections prepared from the hypothalamus of acrolein-fixed female rat brains.

Transmitter content and afferent connections of estrogen-sensitive progestin receptor-containing neurons in the primate hypothalamus.

Progestin receptor-containing cells in the hypothalamus of the adult female green monkey (Cercopithecus aethiops) were examined by double-label immunocytochemical methods to determine their anatomical location, neurotransmitter content and afferent connections. Animals were ovariectomized and administered either estradiol valerate or the oil injection vehicle, and were sacrificed after 10 days of treatment. Using a monoclonal antibody raised against rabbit uterine progestin receptor (PR), the distribution of PR-immunoreactive cells in the mediobasal hypothalamus and the effect of estrogen treatment on this distribution was determined.

Sex differences in estrogen receptor binding in the rat hypothalamus: effects of subsaturating pulses of estradiol.

The effects of subsaturating pulses of estradiol on cell nuclear retention of estrogen receptors in brain regions of male and female rats were determined. In the first experiment, age-matched adrenalectomized/gonadectomized (ADX/GDX) rats were killed 1 h after i.v.

Estrogen-like effects of the mammary carcinogen 7,12-dimethylbenz(alpha)anthracene on hypothalamic neuronal membranes.

Previous studies have shown that in Sprague-Dawley female rats, but not in Wistar females, the mammary carcinogen dimethylbenz(alpha)anthracene (DMBA) results in extended preovulatory prolactin and estradiol surges, associated with inhibition of preovulatory gonadotropin surges, and in the induction of mammary tumors. Because earlier studies of similar endocrine states have shown this to be linked to hypothalamic arcuate nucleus neuronal membrane organization, in this study freeze-fracture methodology was used to determine whether DMBA may affect the ultrastructure of the neuronal membrane in the arcuate nucleus. The effects of estradiol valerate and DMBA were studied on 55- to 60-day-old cycling females, in Sprague-Dawley and Wistar rats, 8 weeks after the treatment.

Neuroanatomical specificity in the autoregulation of aromatase-immunoreactive neurons by androgens and estrogens: an immunocytochemical study.

Testosterone (T) increases brain aromatase activity (AA) in quail and other avian and mammalian species. It was shown both in quail and in rat that this enzymatic induction results from a synergistic action of androgens and estrogens. These studies provide little information on possible anatomical or cellular specificity of the effect.

Effects of a normal, human-concentration, phytoestrogen diet on rat uterine growth.

The estrogenic action of the prototype natural phytoestrogen coumestrol was examined in rats in in vitro and in vivo tests. To establish the binding specificity of coumestrol and its relation to biological activities, saturation analyses and uterine weight assays were performed. These assays indicated that coumestrol competitively inhibited binding to the estrogen receptor and induced increases in uterine weight in keeping with its estrogen receptor affinity constant.

Effects of a phytoestrogen diet on estrogen-dependent reproductive processes in immature female rats.

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) or from 22 to 60 days (chronic treatment).

Regulation of plasminogen activators and type-1 plasminogen activator inhibitor by cyclic AMP and phorbol ester in rat astrocytes.

Two plasminogen activators (PAs): tissue-type plasminogen activator (t-PA) and urokinase-type plasminogen activator (u-PA), as well as the type-1 plasminogen activator inhibitor (PAI-1) are synthesized and secreted by rat astrocytes. Preliminary studies suggest that PA activity plays a role in astrocyte development and differentiation. We have examined the regulation of the PA system by the cAMP-dependent protein kinase (PKA) and protein kinase C (PKC) in purified rat astrocyte cultures.

Estrogen induces ultrastructural changes in progesterone receptor-containing GABA neurons of the primate hypothalamus.

Estrogen affects gonadotrophin levels and sex behavior in monkeys. This action could be via inhibitory GABA-ergic neurons in the hypothalamus. We tested for direct estrogen actions on such neurons.

Loss of sexual dimorphism in rat arcuate nucleus neuronal membranes with reproductive aging.

Arcuate neurons of the rat hypothalamus have a sexual dimorphic membrane phenotype: quantitative analysis of freeze-fracture replicas has revealed that a population of intramembrane protein particles (IMP) of small size (less than 10 nm) is enriched in the plasma membrane of perikarya and dendritic shafts of cycling females compared to males, whereas a population of large IMPs (greater than 10 nm) is enriched in the membrane of dendritic shafts of males. This different membrane organization is associated with a sex dimorphic synaptic connectivity. To determine whether sex differences in neuronal membrane are affected by reproductive senescence, IMPs were assessed in freeze-fracture replicas of arcuate neuronal plasma membranes of male and female Sprague-Dawley rats aged 3, 15, and 18 months.

Astrocytes within the hypothalamic arcuate nucleus contain estrogen-sensitive peroxidase, bind fluorescein-conjugated estradiol, and may mediate synaptic plasticity in the rat.

Estrogen treatment induces synaptic plasticity accompanied by damaged structures and aggregates of peroxidase in astrocytes in the hypothalamic arcuate nucleus of the rat. Synaptic plasticity also occurs within the arcuate nucleus after physiologic surges of estrogen. Although the function of estrogen-induced peroxidase is unclear at present, in other systems peroxidase can generate free radicals by catalyzing the oxidation of some molecules, including estrogen.

Convergent vasopressinergic and hippocampal input onto somatospiny neurons of the rat lateral septal area.

Electron microscopic immunocytochemistry, was combined with acute anterograde axon degeneration, following transection of the fimbria-fornix, to describe the innervation of somatospiny neurons by vasopressin-immunoreactive and degenerated hippocamposeptal axon terminals in the rat lateral septal area. Vasopressin-immunopositive boutons characterized by symmetric synaptic membrane specializations, and the degenerated hippocamposeptal axon terminals which form asymmetric synaptic contacts, frequently terminate on the same dendritic and somatic profiles, and particularly on the somata of somatospiny neurons. Although hippocamposeptal fibers predominantly form axospinous synapses in the lateral septal area, they terminate mainly on the dendritic shafts and soma of the vasopressin-receptive neurons.

African green monkeys have sexually dimorphic and estrogen-sensitive hypothalamic neuronal membranes.

Previous studies have shown sex differences in intramembrane particle content in the arcuate neurons of the rat hypothalamus. In this study, freeze-fracture replicas were prepared from the infundibular hypothalamus of adult African green monkeys (Cercopithecus aethiops) in order to determine whether primates also have sexual dimorphism in neuronal membranes. Intramembrane particles (IMP) were quantitatively assessed in the perikaryal plasma membranes of infundibular neurons.

Sexual differentiation of synaptic connectivity and neuronal plasma membrane in the arcuate nucleus of the rat hypothalamus.

Plasma membranes of the hypothalamic arcuate neurons of the rat show a sexually dimorphic phenotype: the numerical density of intramembrane protein particles is greater in females. Male and female Sprague-Dawley rats, 10, 20 and 100 days old, were studied in order to determine whether sexual differentiation of the neuronal plasma membrane in the soma of arcuate neurons is associated with the establishment of sex differences in the pattern of axo-somatic synaptic contacts. Axo-somatic synapses were counted in thin sections of the arcuate nucleus and intramembrane particles were assessed in freeze-fracture replicas of the neuronal membrane.