Effects of individual or combined administration of reserpine and niamide on plasmatic release and adrenal storage of catecholamines in pregnant rats

Abstract

Summary Plasmatic adrenaline and noradrenaline in 20 days pregnant rats were markedly lower than the controls. Adrenal stores of noradrenaline during pregnancy were higher than controls but adrenal adrenaline in pregnant rats was lower. The effects of reserpine and niamide administration in control and pregnant rats differed in the intensities of their actions and showed high statistical significances. 24 hours after a single injection of reserpine, adrenaline in plasma and adrenals of control rats declined. Similar treatment to pregnant rats declined plasmatic adrenaline but both adrenal and plasmatic noradrenaline increased. Niamide administration reduced adrenal and plasmatic adrenaline in controls but in pregnants adrenaline in plasma increased and decreased in adrenals. Adrenal stores of noradrenaline in both cases were augmented after niamide administration. There was a high rise in plasmatic noradrenaline in pregnant rats after niamide injection but in controls it declined. The combined administration of reserpine and niamide depressed plasmatic adrenaline in control as well as pregnant rats. Plasmatic noradrenaline in controls reduced with rise in adrenal stores but the pregnant rats demonstrated increased plasmatic noradrenaline and decreased adrenal noradrenaline after combined administration. The differences in intensities and modes of actions of both drugs in control and pregnant rats appear to be the consequence of hormonal state of rats and suggest that variable concentrations of different hormones in pregnancy counteract the effects of reserpine and niamide.