Attenuation of thirst in estrogen-treated rats
Fregly, M.J.
Federation Proceedings 37(13): 2694-2698
1978
ISSN/ISBN: 0014-9446 PMID: 710590 Document Number: 137156
Chronic administration of ethynyl oestradiol or oestradiol benzoate to female rats was accompanied by attenuation of the drinking response to the beta -adrenergic agonist, isoproterenol. Attenuation was observed after 2 weeks of continuous treatment with ethynyl oestradiol. As isoproterenol may induce a drinking response in rats by stimulating release of renin from juxtaglomerular cells, renin was given exogenously to bypass a possible block by oestrogens at this level. Rats treated chronically with ethynyl oestradiol had an attenuated drinking response to renin, 2 or 4 Goldblatt units, compared with untreated controls. As oestrogens might interfere at the level of the formation of angiotensin II from the combination of renin and renin substrate, angiotensin II was given exogenously. Rats treated chronically with ethynyl oestradiol or oestradiol benzoate had an attenuated drinking response to angiotensin II given at 100 or 200 mu g/bodyweight intraperitoneally. The results do not rule out the possibility that attenuation of the isoproterenol-induced drink in oestrogen-treated rats may be associated with reduced responsiveness of beta -adrenergic receptors at the level of the juxtaglomerular cells and with reduction in the formation of angiotensin II from the combination of renin and renin substrate in blood; they suggest that attenuation is apparently associated with reduced responsiveness to angiotensin II at the level of the central nervous system. Chronic administration of the progestational agent, norethynodrel had no effect on water intake stimulated by isoproterenol or renin.