Endocrine
Insulin directly affects many aspects of cellular metabolism. An additional, poorly studied effect of insulin is the regulation of multiple genes whose products are important in many cellular functions. Using differential screening techniques, we identified insulin-regulated genes induced in insulin-treated rat H4IIE (H4) hepatoma cells. Two of the mRNAs identified were homologous to the previously...
Interactions between testosterone, estradiol, and inhibin in the control of gonadotrophin secretion in males are poorly understood. Castrated rams were treated with steroid-free bovine follicular fluid (bFF), testosterone, or estradiol and for 7 d(2×2×2 factorial design). Given independently, none of the exogenous hormones affected follicle-stimulating hormone (FSH) concentrations, but the combination...
The estrogenic activity of sulfonated estrogens results from the release of active estrogens via desulfonation (hydrolysis) catalyzed by estrogen sulfatase. In this study, the relative importance of uterine or hepatic estrone (E1)-3-sulfatase in mediating the uterotropic action of E1-3-sulfate is evaluated by comparing its hormonal potency in animals that have comparable uterine E1-3-sulfatase activity...
We have investigated at the single-cell level how the human LH receptor mediates a dose-responsive increase in intracellular free calcium-ion concentrations ([Ca2+]i). In human embryonic kidney cells (293 cells) stably transfected with the full-length human LH receptor cDNA. Intact dimeric LH, but not LH β- or α-subunits, evoked specific [Ca2+]i signals. High-resolution fluorescence (fura-2) video-microscopy...
A total of seven experiments were conducted to investigate the potential facilitative interaction of growth hormone (GH) and insulin-like growth factor II (IGF-II) in stimulating steroidogenesis by cultured porcine granulosa cells and to examine the possible nature of this action. Porcine granulosa cells were cultured in serum-free medium in the presence or absence of GH or prolactin, with or without...
Nicotine is known to have multiple effects on neuroendocrine, autonomic, and behavioral responses. Its neuroendocrine effect on the stress-responsive hormone, ACTH, depends on central pathways that act on corticotropin-releasing hormone (CRH) neurons in the paraventricular nucleus of the hypothalamus (PVN). Other CRH neurons throughout the brain also are involved in coordinating aspects of the stress...
Luteinizing hormone-releasing hormone (LHRH release, which serves as the primary drive to the hypothalamic-pituitary gonaldal axis, is controlled by many neuro-mediators. Serotonin has been implicated in this regulation. However, it is unclear whether the central effect of serotonin on LHRH secretion is exerted directly on LHRH neurosecretory neurons or indirectly via multisynaptic pathways. The present...
Suuccinic acid esters are currently under investigation as possible insulinotropic tools in the treatment of noninsulin-dependent diabetes mellitus. The present article introduces three novel nutrient esters and aims mainly to explore, in both normal and GK rats, the secretory response to such esters when tested alone or in combination. It documents that in pancreatic islets from normal rats, methyl...
Diabetes in both humans and rats is accompanied by low bone formation, which is presumably caused by serum-borne factors. To explore its pathogenesis, we carried out experiments in diabetic and nondiabetic BB rats, using plasma osteocalcin concentrations (OC) as a marker for osteoblast activity. In nondiabetic rats, the iv infusion of glucose (30%, 4 d) did not change OC; sc insulin infusion (4 U/d,...
Dopamine is considered to be the major physiological tonic inhibitor of prolactin release, yet there is increasing evidence showing that it can also stimulate prolactin release from lactotrophs. In primary cultured lactotrophs, the major dopamine receptors responsible for inhibiting prolactin release are dopamine D2 receptors. A dopamine receptor subtype may be responsible for the stimulatory action,...
Leptin, the product of the obese gene first identified in mice, restores fertility in obese mice, and accelerates puberty in mice. We hypothesized that leptin’s putative role in reproduction may extend to pregnancy and lactation. Leptin levels were determined inMyotis lucifugus, the little brown bat, a free-ranging mammal with a seasonal breeding cycle. The present study shows that plasma levels of...
We have previously shown that the major correlates of growth following growth hormone (GH) therapy in growth hormone-deficient (GHD) children are changes in circulating insulin-like growth factor-I (IGF-I) and IGF binding protein-3 (IGFBP-3), suggesting a synergistic interaction between IGF-I and IGFBP-3 (1). The first aim of this project was to examine the molecular forms of IGFBP-3 and the acid-labile...
Immune-endocrine interactions are important to the regulation of Leydig cell steroidogenesis. We have shown previously that both tumor necrosis factor-α (TNF-α) and interleukin-1β (IL-1-β) inhibit 8-bromo-cAMP-(8-Br-cAMP)-stimulated steroidogenesis in mouse Leydig cells. TNF and IL-1 both inhibit cAMP-stimulated testosterone production as well as mRNA and protein levels of cholesterol side chain cleavage...
We studied the pulsatile luteinizing hormone (LH) and follicle-stimulating hormone (FSH) secretory patterns, at early or intermediate years of menopause in seven normal women with different degrees of obesity, taking blood samples every minute for 40 min to 2 h. The hormones were assayed with an immunoradiometric assay (IRMA) system, analyzing with the cluster pulse algorithm. All women showed hormone...
This study was undertaken to investigate the relationship between dopamine (DA) induced changes in the cytosolic calcium concentration ([Ca2+]i) and the rate of prolactin secretion using GH4ZR7, a rat pituitary cell line, which express only one subtype of D2 receptor. GH4ZR7 cells were loaded with Fluo-3, a fluorescent Ca2+ indicator, and then perifused with two different doses of DA (10−7 mol/L and...
The hypothesis that cytosolic calcium concentration ([Ca2+ cyt]) is the primary regulator of parathyroid hormone (PTH) secretion is supported by a number of studies that show an inverse relationship between them. One agent shown to inhibit PTH secretion is thapsigargin, a sesquiterpene lactone that raises [Ca2+ cyt] by inhibiting the Ca-ATPase that pumps Ca2+ from the cytosol into the lumen of the...
The objective of this study was to determine the effects of neonatal exposure to phytoestrogens on male reproductive function as adults. Male rats were injected either with 100 μg coumestrol or DMSO (controls) daily during their first 5 d of life. Pituitary gland, testes, sex accessory organs, and blood were collected on d 60 of life. Serum testosterone, LH, and FSH levels were determined by RIA....
Patients with ectopic ACTH syndrome often develop hypertension and hypokalemic alkalosis with an abnormal increase in the ratio of plasma cortisol to cortisone, indicating that 11β-hydroxysteroid dehydrogenase (11βHSD) activity is inhibited. Inhibition of 11βHSD allows access of cortisol or corticosterone to the mineralocorticoid receptor where it act as a mineralocorticoid. Two isozymes, 11βHSD-1...
Endothelin (ET) and its G-protein-coupled receptors are distributed in a wide variety of tissues, including the brain. In this study, we have identified and characterized the endothelin receptor subtypes in sheep choroid plexus. Competitive binding experiments using [125I]ET-1 and the receptor subtype-selective ligands, ET-1, ET-3, BQ-123, Sarafotoxin 6c, and [Ala1,3,11,15]ET-1 demonstrated the presence...