Effect of vasopressin antagonist on antidiuresis by oxotremorine microinjected into the hypothalamic supraoptic and paraventricular nuclei in a water-loaded and ethanol-anesthetized rat.
Microinjection of the muscarinic agonist oxotremorine into the hypothalamic supraoptic (SON) and paraventricular (PVN) nuclei which contain cell bodies of vasopressinergic neurons induced potent antidiuretic effects in water-loaded and ethanol-anesthetized rats. The effects included both decreases in urine outflow and increases in urine osmotic pressure. However, no significant changes in various visceral functions other than antidiuresis such as mean blood pressure, heart rate, respiration rate and rectal temperature were observed when oxotremorine was microinjected into the SON. Only a slight change in mean blood pressure (approx. 10 mmHg decrease) was observed by the microinjection into the PVN. Intravenous preinjection of a vasopressin (AVP) V1 V2 antagonist that has one of the most potent V2 (antidiuretic)-antagonist activities, d(CH2)5-D-Tyr(Et)VAVP, inhibited nearly completely the antidiuretic effects induced by the microinjection of oxotremorine. The results demonstrated that oxotremorine stimulated muscarinic receptors in the hypothalamic SON and PVN, released AVP and induced an antidiuretic effect through AVP-receptors in the kidney.
Mori
M
M
Department of Pharmacology, Nagoya City University Medical School, Japan.
Tsushima
H
H
Matsuda
T
T
D000758:Anesthesia; D000818:Animals; D001794:Blood Pressure / Q000187:drug effects; D001831:Body Temperature / Q000187:drug effects; D004231:Diuresis / Q000187:drug effects*; D000431:Ethanol; D006339:Heart Rate / Q000187:drug effects; D007032:Hypothalamus, Anterior; D008297:Male; D008845:Microinjections; D009997:Osmotic Pressure; D010095:Oxotremorine / Q000008:administration & dosage / Q000494:pharmacology*; D010286:Paraventricular Hypothalamic Nucleus; D051381:Rats; D011919:Rats, Inbred Strains; D012119:Respiration / Q000187:drug effects; D014667:Vasopressins / Q000037:antagonists & inhibitors*; D014867:Water / Q000494:pharmacology
D014867:Water; D014667:Vasopressins; D000431:Ethanol; D010095:Oxotremorine