Effect of the intracerebroventricular administration of GR 113808, a selective 5-HT4 antagonist, on water intake during hyperosmolarity and hypovolemia.
We demonstrate here that acute third ventricle injections of GR 113808, a highly selective 5-HT4 antagonist, decrease water intake induced by a previous salt load while potentiating drinking elicited by hypovolemia induced by previous subcutaneous administration of polyethylene glycol in male Wistar rats (200 +/- 20 g). At the dose of 160 nmol/rat, third ventricle injections of GR 113808 induced a significant reduction of water intake in salt-loaded animals after 120 min as compared to salt-loaded animals receiving third ventricle injections of saline (salt load + GR = 3.44 +/- 0.41 ml, N = 12; salt load + saline = 5.74 +/- 0.40 ml, N = 9). At the dose of 80 nmol/rat, GR 113808 significantly enhanced water intake in hypovolemic animals after 120 min as compared to hypovolemic animals receiving third ventricle injections of saline (hypovol + GR = 4.01 +/- 0.27 ml, N = 8; hypovol + saline = 2.41 +/- 0.23 ml, N = 12). We suggest that central 5-HT4 receptors may exert a positive drive on water intake due to hyperosmolarity and a negative input on drinking provoked by hypovolemia.
Castro
L
L
Departamento de Fisiologia, Instituto de Ciências da Saúde, Universidade Federal da Bahia, 40110-100 Salvador, BA, Brazil.
Varjão
B
B
Silva
I
I
Duque
B
B
Batista
A
A
Santana
R
R
Luz
P
P
Rocha
M A
MA
Fregoneze
J B
JB
De Castro-e-Silva
E
E
D000818:Animals; D004326:Drinking / Q000187:drug effects*; D020896:Hypovolemia / Q000378:metabolism* / Q000503:physiopathology; D007211:Indoles / Q000008:administration & dosage / Q000494:pharmacology*; D007276:Injections, Intraventricular; D008297:Male; D009994:Osmolar Concentration; D051381:Rats; D017208:Rats, Wistar; D012702:Serotonin Antagonists / Q000008:administration & dosage / Q000494:pharmacology*; D013449:Sulfonamides / Q000008:administration & dosage / Q000494:pharmacology*; D020542:Third Ventricle
D007211:Indoles; D012702:Serotonin Antagonists; D013449:Sulfonamides; C082871:GR 113808