Effect of sulpiride-induced hyperprolactinaemia on catecholamine turnover and LRH concentration in the medial basal hypothalamus of rats

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Abstract
To clarify the mechanism of hyperprolactinemic anovulation, the medial basal hypothalamic (MBH) catecholamine (CA) turnover and LHRH concentration, and the serum levels and pituitary contents of gonadotropins and prolactin (Prl) in hyperprolactinemic female rats were examined. Hyperprolactinemia (HPrl) was produced by oral administration of sulpiride for 10 consecutive days; each measurement made on the sulpiride-treated rats was compared with that of control diestrus rats. Prl, LH [lutropin], FSH and LHRH were determined by radioimmunoassay; CA turnover, as assessed by the accumulation of CA following monoamine oxidase inhibition, was assayed by high performance liquid chromatography with electrochemical detection. Sulpiride treatment induced an increase in the serum Prl and a decrease in the serum LH, an increase in the pituitary FSH and LH contents, an increase in the MBH LHRH concentration, and an increase in the MBH dopamine (DA) turnover. HPrl may induce anovulation by impaired LH secretion which was caused by the suppression of LHRH release due to an increase in DA turnover in the MBH.