S A Whitehead

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1. Electrophysiological experiments have been performed on intact cycling female rats to investigate the neural connexions that exist between the medial forebrain bundle, the anterior hypothalamic region, which included the preoptic area, and the basal hypothalamus. Recordings have been made from a total of 351 neurones in the anterior hypothalamus of which(More)
Histological studies have demonstrated that polycystic ovaries (PCO) contain increased numbers of preantral follicles with a specific increase in primary follicles. Polycystic ovary syndrome is associated with hyperandrogenism and pre- and postnatal androgenization of primates increases the pool of growing follicles producing changes resembling PCO. In(More)
Pituitary glands of pro-oestrous and oestrous rats were perifused in series with isolated ovarian follicles and the luteinizing hormone (LH) and follicle-stimulating hormone (FSH) responses to gonadotropin-releasing hormone (GnRH) were measured. Pituitary glands from pro-oestrous rats, perifused with the effluent medium from isolated preovulatory follicles,(More)
Assessment of occlusal fissure systems and restorations of amalgam in 100 extracted teeth were carried out by four examiners. An initial assessment, made with the naked eye, was repeated with binocular magnification (x 3). The data indicated that restorative decision-making behavior was modified when magnification was used, with an increase in the number of(More)
Abstract Several second messenger systems have been implicated in mediating the action of gonadotrophin-releasing hormone on the pituitary gonadotrophs and numerous studies have shown that activation of these systems induces luteinizing hormone (LH) secretion. However, it is not known how gonadotrophin-releasing hormone or the second messenger systems(More)
Chronic ovariectomized rats treated neonatally with MSG showed reduced circulating concentrations of LH coupled with elevated hypothalamic LHRH stores. Despite the apparent loss of LHRH secretion, the small pituitary glands showed an increased density of LHRH receptors and normal responsiveness to the releasing hormone. The positive feedback effects of(More)
The effects of the opiate antagonist naloxone on serum LH concentrations was investigated in gonadectomized rats given different regimes of steroid pretreatment. Two injections of testosterone given 48 and 24 h before naloxone treatment failed to reinstate LH responses to this drug in castrated rats while subcutaneous testosterone-filled silicone elastomer(More)
The effects of acute and sub-chronic hyperprolactinaemia on the positive feedback action of progesterone in oestrogen-primed ovariectomized rats have been compared. A single injection of ovine prolactin administered with progesterone had no effect on the LH surge measured 5 h later although hyperprolactinaemia induced by 5-day treatment with the dopamine(More)
Injection of 150 micrograms 6-hydroxydopamine (6-OHDA) into the third ventricle of rats depleted the mean hypothalamic concentration of noradrenaline by 71% whereas the mean dopamine concentration was only reduced by an insignificant 7%. Isolated perfused pituitary glands taken from intact 6-OHDA-treated rats showed a markedly increased LH response to(More)
Although neuroleptic-induced hyperprolactinaemia is a common cause of amenorrhoea in women, the mechanism by which ovarian function is disturbed is unknown. Previous studies on both hyperprolactinaemic women and rats have indicated that an impairment of the pituitary response to LH-RH may be involved. We have investigated this possibility in female(More)