Antidipsogenic effects of central adenosine-5'-triphosphate

Author(s)

D.R.G. de Faria ^[1] ; J.S. Santana ^[2] ; J.V. Menani ^[3] ; P.M. de Paula ^[4]

Affiliation

^[1] Universidade Estadual Paulista. Faculdade de Odontologia de Araraquara. Departamento de Fisiologia e Patologia - Brasil

^[2] Universidade Estadual Paulista. Faculdade de Odontologia de Araraquara. Departamento de Fisiologia e Patologia - Brasil

^[3] Universidade Estadual Paulista. Faculdade de Odontologia de Araraquara. Departamento de Fisiologia e Patologia - Brasil

^[4] Universidade Estadual Paulista. Faculdade de Odontologia de Araraquara. Departamento de Fisiologia e Patologia - Brasil

• Document type: Journal article
• Source: Brazilian Journal of Medical and Biological Research; v. 42, n. 1, p. 105-113, 2009-01-00.

Abstract

Besides other physiological functions, adenosine-5'-triphosphate (ATP) is also a neurotransmitter that acts on purinergic receptors. In spite of the presence of purinergic receptors in forebrain areas involved with fluid-electrolyte balance, the effect of ATP on water intake has not been investigated. Therefore, we studied the effects of intracerebroventricular (icv) injections of ATP (100, 200 and 300 nmol/µL) alone or combined with DPCPX or PPADS (P1 and P2 purinergic antagonists, respectively, 25 nmol/µL) on water intake induced by water deprivation. In addition, the effect of icv ATP was also tested on water intake induced by intragastric load of 12% NaCl (2 mL/rat), acute treatment with the diuretic/natriuretic furosemide (20 mg/kg), icv angiotensin II (50 ng/µL) or icv carbachol (a cholinergic agonist, 4 nmol/µL), on sodium depletion-induced 1.8% NaCl intake, and on food intake induced by food deprivation. Male Holtzman rats (280-320 g, N = 7-11) had cannulas implanted into the lateral ventricle. Icv ATP (300 nmol/µL) reduced water intake induced by water deprivation (13.1 ± 1.9 vs saline: 19.0 ± 1.4 mL/2 h; P < 0.05), an effect blocked by pre-treatment with PPADS, but not DPCPX. Icv ATP also reduced water intake induced by NaCl intragastric load (5.6 ± 0.9 vs saline: 10.3 ± 1.4 mL/2 h; P < 0.05), acute furosemide treatment (0.5 ± 0.2 vs saline: 2.3 ± 0.6 mL/15 min; P < 0.05), and icv angiotensin II (2.2 ± 0.8 vs saline: 10.4 ± 2.0 mL/2 h; P < 0.05), without changing icv carbachol-induced water intake, sodium depletion-induced 1.8% NaCl intake and food deprivation-induced food intake. These data suggest that central ATP, acting on purinergic P2 receptors, reduces water intake induced by intracellular and extracellular dehydration. (AU)