Receptor-mediated effects of clonidine on need-induced 3% NaCl and water intake.
Clonidine combined with adrenergic antagonists were injected in the medial septal area in order to characterize the type of receptors involved with its inhibitory effect on 3% NaCl and water intake of sodium-depleted (furosemide + 24 h of removal of ambient sodium) and 30-h water-deprived rats, respectively. The inhibitory effect of clonidine (20 nmol) on need-induced water intake was reduced 50% by an 80-nmol dose of either idazoxan, yohimbine or prazosin. The inhibitory effect of clonidine (30 nmol) on need-induced 3% NaCl intake was completely antagonized by idazoxan (80, 160 nmol), not altered by yohimbine (40-160 nmol), and partially potentiated (40 nmol) or inhibited (160 nmol) by prazosin. Propranolol did not alter the effects of clonidine on either water (80 nmol) or 3% NaCl (40-160 nmol) intake. The results suggest that the inhibitory effects of clonidine on 3% NaCl and water intake are mediated by different types of alpha2-adrenergic receptors.
Yada
M M
MM
Department of Physiological Sciences, School of Dentistry, Paulista State University-UNESP, Araraquara, São Paulo, Brazil.
de Paula
P M
PM
Menani
J V
JV
Renzi
A
A
Camargo
L A
LA
Saad
W A
WA
De Luca
L A
LA
D000818:Animals; D003000:Clonidine / Q000494:pharmacology*; D004305:Dose-Response Relationship, Drug; D004326:Drinking / Q000187:drug effects*; D019329:Idazoxan / Q000494:pharmacology; D008297:Male; D051381:Rats; D011941:Receptors, Adrenergic / Q000187:drug effects*; D012965:Sodium Chloride / Q000494:pharmacology*
D011941:Receptors, Adrenergic; D012965:Sodium Chloride; D003000:Clonidine; D019329:Idazoxan