Received February 20, 2007
Revised March 21, 2007
Accepted after revision June 14, 2007

¹ Universidade Federal Rural do Rio de Janeiro
² University of Iowa
³ Faculdade de Medicina de Ribeirão Preto, USP

^* To whom correspondence should be addressed. E-mail: daniel-passosjunior{at}uiowa.edu.

	Abstract

We investigated the effects of chronic administration of sertraline (~20 mg\kg\day on drinking water), a selective serotonin re-uptake inhibitor (SSRI), on water and sodium intake, and on oxytocin (OT) and vasopressin (AVP) plasma levels in basal and stimulated conditions. Basal water intake was reduced in SERT-treated rats. After 24 h of water deprivation, 21 day-SERT-treated rats ingested less water than the control rats (9.7 ± 0.5 mL vs 20.0 ± 0.9 mL, at 300 min, after water presentation, P < 0.0001). Subcutaneous injection of 2 M NaCl or isoproterenol evoked a lower dipsogenic response in 21 day-SERT-treated rats. Fluid and food deprivation also induced a weaker dipsogenic response in SERT treated-rats (1.6 ± 0.5 mL vs 10.2 ± 1.2 mL, at 300 min, P < 0.0001) but had no effect on saline intake. Sodium depletion induced a higher natriorexigenic response in SERT (1.2 ± 0.3 mL vs 5.6 ± 1.3 mL, at the 300 min, P < 0.0002) group. Higher urinary density and lower plasma sodium levels were observed after SERT treatment. SERT also increased vasopressin and oxytocin plasma levels (AVP, 2.65 ± 0.36 pg/mL vs 1.31 ± 0.16 pg/mL, P < 0.005; OT, 17.16 ± 1.06 pg/mL vs 11.3 ± 1.03 pg/mL, P < 0.0009, at the 3rd week post-treatment). These data constitute the first evidence that chronic SERT treatment affect water and sodium intake in rats. These effects seem to be related to the hyponatremia caused by the higher AVP and OT plasma levels.

Key Words: Oxytocin, Serotonin, Vasopressin