Open AccessAntidiuretic Effects of Alpha- and Beta-Adrenoceptor Agonists Microinjected into the Hypothalamic Paraventricular Nucleus in a Water-Loaded and Ethanol-Anesthetized Rat
Author(s) -
Hiromi Tsushima,
Mayumi Mori,
Tomohiro Matsuda
Publication year - 1986
Publication title -
japanese journal of pharmacology/japanese journal of pharmacology
Language(s) - English
Resource type - Journals
eISSN - 1347-3506
pISSN - 0021-5198
DOI - 10.1254/jjp.40.319
Subject(s) - endocrinology , medicine , chemistry , norepinephrine , phenoxybenzamine , stimulation , antidiuretic , hypothalamus , antagonist , atropine , epinephrine , propranolol , vasopressin , receptor , dopamine
Effects of catecholamines microinjected into the paraventricular nucleus in the hypothalamus on urine outflow in a rat which was loaded with water and anesthetized with ethanol were studied. L-Norepinephrine, L-epinephrine and L-isoproterenol induced potent antidiuresis with similar time courses to each other. The ED50 values for L-norepinephrine, L-epinephrine and L-isoproterenol were approximately 5, 10 and 5 nmol, respectively. The D-isomer of isoproterenol demonstrated no significant antidiuretic activity. The effect of L-norepinephrine was inhibited strongly by premicroinjection of alpha- and beta-adrenoceptor antagonists. The effect of DL-isoproterenol was inhibited strongly by beta-adrenoceptor antagonists, but not affected by alpha-adrenoceptor antagonist. Premicroinjection of a muscarinic antagonist, atropine, partially inhibited anti-diuretic effects induced by L-norepinephrine and DL-isoproterenol. Visceral functions other than urine outflow such as mean blood pressure, respiration rate, heart rate and rectal temperature were not significantly altered when the urine outflow decreased down to 20-30% of the control by microinjection of L-norepinephrine and DL-isoproterenol. The results demonstrated that stimulation of alpha- and beta-adrenoceptor in the paraventricular nucleus induced potent antidiuretic effects, partial inhibition of which by atropine suggested a possible presynaptic facilitation of the release of ACh by the stimulation of the adrenoceptors.