Margaret F Menadue

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In unanaesthetized rats chronically prepared with venous and intracerebral cannulae, noradrenaline injected into the region of the supraoptic nuclei caused a dose-dependent increase in plasma vasopressin, measured by radioimmunoassay. A similar response was obtained with phenylephrine, but not with either clonidine or isoprenaline. The secretion of(More)
Prolactin concentrations were measured in plasma in unanaesthetized male rats chronically prepared with venous and intracerebral cannulae, before and after treatment with bilateral intracerebral injections of serotonin and fenfluramine. Serotonin 1, 5, and 10 nmol injected in the medial basal hypothalamus caused dose-related rises in prolactin(More)
Localized intracerebral microinjections of GABA, muscimol, picrotoxin and bicuculline were made in the anterior and basal hypothalamus to determine possible sites of action of GABA in the regulation of prolactin and growth hormone (GH) secretion. Studies were carried out in unanesthetized male rats with chronic indwelling atrial cannulae and intracerebral(More)
In conscious rats, serotonin microinjected into the basal hypothalamus caused secretion of GH maximal within 10-25 min. The effects of serotonin on GH were blocked by the non-selective serotonin receptor blocker, metergoline 2.5 mg/kg, but not by the serotonin type 2 receptor blocker, ketanserine 0.2 mg/kg. Injections of serotonin in the preoptic/anterior(More)
Growth hormone (GH) and prolactin secretory patterns in male rats chronically implanted with venous cannulae were studied in response to treatments known to acutely or chronically deplete central serotonin (5-HT) or to permanently destroy a high proportion of 5-HT neural structures. Spontaneous prolactin secretion was little affected by chronic 5-HT(More)
GH and PRL levels were measured by RIA in plasma samples taken from genetically obese and nonobese rats over a 6-h period at consecutive 15-min intervals. The mean GH level was 204 ng/ml for lean animals and 48 ng/ml for obese rats; the difference is significant (t = 5.8; P less than 0.01). For the group of 5 lean rats, there were 10 GH peaks that exceeded(More)
Medio-basal hypothalamic (MBH) catecholamine mechanisms in the regulation of prolactin and growth hormone (GH) secretion were investigated in unanesthetized rats with chronic indwelling venous cannulae and bilateral MBH directed intracerebral guide cannulae. MBH injections of the catecholamine-specific neurotoxin 6-hydroxydopamine (6-OHDA; 2 micrograms base(More)
Human growth hormone (hGH) was administered to chronically cannulated male rats and its effect upon the physiological secretory patterns of rat growth hormone (rGH) and prolactin were observed. In comparison with injected control animals, a reduction in the size of spontaneous secretory bursts of rGH was apparent when hormone concentrations were compared(More)
Plasma growth hormone (GH) and prolactin concentrations were measured by radioimmunoassay in unanesthetized male rats after stereotaxic microinjection of adrenergic agents and 6-hydroxydopamine into the preoptic-anterior hypothalamic area (PO/AHA). Norepinephrine, epinephrine, isoprenaline and clonidine failed to stimulate GH, moreover, 16 nanomoles(More)
OBJECTIVE The aim was to investigate (1) the relationship between atrial natriuretic factor (ANF) release and the extent of ischaemia-hypoxia, and (2) the potential role of eicosanoids in ANF release during global ischaemia, particularly the cyclo-oxygenase derivatives (prostaglandins) and the lipoxygenase derivatives (leukotrienes). METHODS Using an(More)