COMPARATIVE EFFECTS OF HYPOPHYSECTOMY AND ADRENALECTOMY UPON PLASMA AND ADRENAL MONOAMINES IN PREGNANT AND NON‐PREGNANT RATS

Abstract

1 The influence of hypophysectomy and adrenalectomy upon release and storage of adrenaline and noradrenaline during rat oestrous cycle and pregnancy has been studied.2 Hypophysectomy during the pro‐oestrous phase of the oestrous cycle increased plasma noradrenaline concentration which was unchanged, however, by similar treatment in pregnant females. After adrenalectomy during dioestrous and pro‐oestrous phases, as well as on day 15 post‐coitum, plasma noradrenaline showed an increase, although the increase in pregnant females was greater.3 Adrenocorticotrophic hormone (ACTH) administration to non‐pregnant and pregnant females increased plasma adrenaline values significantly, compared with control values. Treatment of adrenalectomized rats with hydrocortisone lowered plasma noradrenaline to control values in both non‐pregnant and pregnant females.4 Hypophysectomy produced a decrease in plasma adrenaline content, whilst ACTH treatment increased it. Plasma adrenaline disappeared completely after adrenalectomy, during the pro‐oestrous phase and pregnancy, but extirpation of adrenals during the dioestrous phase still left appreciable amounts of adrenaline in plasma. Hydrocortisone treatment of both non‐pregnant and pregnant adrenalectomized females resulted in the reappearance of plasma adrenaline5 Adrenal stores of adrenaline and noradrenaline declined after hypophysectomy but the decreases were greater in pregnant females.6 Compensatory administration of ACTH to hypophysectomized females increased adrenaline and noradrenaline content of adrenals to control non‐pregnant female values during the pro‐oestrous phase of the oestrous cycle but similar treatment in pregnant females resulted in an increase in adrenaline.7 Although ACTH administration increased adrenal noradrenaline levels in pregnant hypophysectomized females, the mean value remained below that of non‐operated pregnant females.8 The results suggest that, during oestrous cycle and pregnancy the effects of pituitary and adrenal hormonal deficiency upon storage and release of monoamines differ quantitatively.