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In several species, including humans, circulating insulin-like growth factor I (IGF-I) levels increase during the onset of puberty, suggesting that this peptide contributes to attaining sexual maturity. Because IGF-I elicits LHRH release from the median eminence (ME) of immature female rats in vitro, we hypothesized that it may represent one of the(More)
Manganese (Mn), an essential element considered important for normal growth and reproduction, has been shown in adults to be detrimental to reproductive function when elevated. Because Mn can cross the blood-brain barrier and accumulate in the hypothalamus, and because it has been suggested that infants and children are potentially more sensitive to Mn than(More)
Nitric oxide (NO) synthase, the enzyme which converts arginine into citrulline plus NO, a highly active free radical, has been found in many neurons in the brain, including neurons in the hypothalamus. Our previous experiments showed that norepinephrine-induced prostaglandin E2 release from hypothalamic explants incubated in vitro is mediated by NO. Since(More)
The ovary of humans and nonhuman primates is innervated by sympathetic and sensory neurons of the peripheral nervous system. Recent studies demonstrated that the density of the sympathetic innervation to the rhesus monkey ovary is developmentally regulated, with adult density being attained around the time of puberty. In the present study, we used an(More)
Fractionation of hypothalamic extracts on a Sephadex G-25 column separates follicle-stimulating hormone-releasing factor (FSHRF) from luteinizing hormone-releasing hormone (LHRH). The FSH-releasing peak contained immunoreactive lamprey gonadotropin-releasing hormone (lGnRH) by radioimmunoassay, and its activity was inactivated by an antiserum specific to(More)
Conscious ovariectomized rats were administered either saline or an ethanol (ETOH)-saline solution via a permanent intragastric cannula, and plasma LH, FSH and PRL were measured by RIA of jugular blood samples drawn every 10 min through an indwelling silastic catheter. Control injections of saline into the gastric cannula did not modify any of the plasma(More)
Insulin-like growth factor-1 (IGF-1) is emerging as a signal of peripheral origin capable of acting centrally to induce luteinizing hormone (LH) secretion and accelerate the initiation of female puberty. Since we have shown previously that ethanol (ETOH) can suppress prepubertal LH release and delay female puberty, we hypothesized that these detrimental(More)
We studied the effect of intravenous injection of lipopolysaccharide (LPS) (30-250 micrograms) on the release of several anterior pituitary hormones as indicated by changes in their concentrations in plasma. Within 30 min after intravenous injection of LPS there was a dose-related stimulation of ACTH release; prolactin (PRL) release was induced only by the(More)
In both rats and primates, including humans, serum levels of insulin-like growth factor I (IGF-I) increase during the onset of puberty, suggesting a role for IGF-I in this process. We examined the ability of IGF-I to affect the release of hypothalamic luteinizing hormone releasing hormone (LHRH) in prepubertal female rats. Our results indicate that IGF-I(More)
Manganese (Mn) is an important element for normal growth and reproduction. Because Mn accumulates in the hypothalamus and is capable of stimulating puberty-related hormones in female rats, we assessed whether this metal could cause similar effects in male rats. We have demonstrated that MnCl2, when administered acutely into the third ventricle of the brain,(More)