Participation of periventricular dopamine receptors in vasopressin secretion elicited by hypertonicity of systemic blood in rats.
The aim of this study was to examine in conscious rats the role of periventricular dopamine receptors in vasopressin secretion caused by hypertonicity of the systemic blood. Intracerebroventricular injections of dopamine (0.15 or 0.75 mumol) produced dose-related increases in plasma AVP 90 sec or 5 min later, without affecting plasma osmolality, concentrations of electrolytes, hematocrit, arterial pressure or heart rate. The AVP response to 0.75 mumol dopamine was blocked by its antagonists, SCH 23390, sulpiride and haloperidol, given intracerebroventricularly at a dose of 0.15 mumol 10 or 40 min before the injection of dopamine. The ip injections (2 ml/100 g) of 600 mmol/l NaCl produced, 15 or 30 min later, augmentations in plasma AVP accompanied by elevations in plasma osmolality, sodium and chloride. At a dose of 0.15 mumol given intracerebroventricularly 10 min before the injection of 600 mmol/l NaCl, SCH 23390 or sulpiride inhibited the AVP response at 15 min, and sulpiride or haloperidol inhibited that at 30 min. The increases in plasma osmolality and the electrolytes owing to hypertonic saline were not reduced by these dopamine antagonists. The intracerebroventricular applications of the antagonists followed by those of vehicles for dopamine or by ip injections of 150 mmol/l NaCl were without any effect on plasma AVP or the other plasma variables. On the basis of these results, we concluded that dopamine receptors in the periventricular regions may contribute to AVP secretion in response to hypertonicity of the systemic blood.
Yamaguchi
K
K
Department of Physiology, Niigata University School of Medicine, Japan.
Hama
H
H
D000818:Animals; D001552:Benzazepines / Q000494:pharmacology; D002712:Chlorides / Q000097:blood; D004298:Dopamine / Q000494:pharmacology; D004305:Dose-Response Relationship, Drug; D006220:Haloperidol / Q000494:pharmacology; D007031:Hypothalamus / Q000502:physiology / Q000648:ultrastructure*; D007276:Injections, Intraventricular; D008297:Male; D009994:Osmolar Concentration; D051381:Rats; D011919:Rats, Inbred Strains; D011954:Receptors, Dopamine / Q000502:physiology*; D012462:Saline Solution, Hypertonic / Q000494:pharmacology; D012964:Sodium / Q000097:blood; D013469:Sulpiride / Q000494:pharmacology; D014667:Vasopressins / Q000097:blood*
D001552:Benzazepines; D002712:Chlorides; D011954:Receptors, Dopamine; D012462:Saline Solution, Hypertonic; D014667:Vasopressins; D013469:Sulpiride; D012964:Sodium; D006220:Haloperidol; D004298:Dopamine