Fregly M J, Rowland N E, Greenleaf J E
Brain Res Bull. 1983 Jan;10(1):121-6. doi: 10.1016/0361-9230(83)90083-7.
Subcutaneous administration of the alpha 2-adrenoreceptor antagonists, yohimbine and tolazoline, at doses up to 1000 micrograms/kg, had no effect on water intake of female rats. However, when these compounds were administered SC in combination with either the beta-adrenoreceptor agonist, isoproterenol (10 to 25 micrograms/kg, SC), or with angiotensin II (200 micrograms/kg, SC), water intake was enhanced. In contrast, intraventricular administration of either tolazoline (10 and 20 micrograms/kg) or yohimbine (300 micrograms/kg) failed to augment the dipsogenic response to angiotensin II (150 micrograms/kg, SC). Thus, the enhancing effect of these alpha 2-adrenoreceptor antagonists on isoproterenol- and angiotensin II-induced water intakes appears to be manifested peripherally, rather than centrally. In view of the fact that clonidine, an alpha 2-adrenoreceptor agonist, has been shown to inhibit water intake induced by both isoproterenol and angiotensin II, the results suggest that the alpha 2-adrenoreceptor may play a role in modulating water intake induced by these two dipsogenic agents.
