Effect of L-5-Hydroxytryptophan on drinking behavior in Coturnix japonica (Temminck and Schlegel, 1849) (Galliformes: Aves): involvement of renin-angiotensin system.

Departamento de Ciências Fisiológicas, Instituto de Biologia, Universidade Federal Rural do Rio de Janeiro, Seropédica, RJ, 23890-000, Brazil.
Brazilian Journal of Biology (Impact Factor: 0.68). 12/2007; 67(4):771-6. DOI: 10.1590/S1519-69842007000400027
Source: PubMed

ABSTRACT The purpose of this study was to explore the role of L-5-hydroxytryptophan (L-HTP) and its relationship with the renin-angiotensin system (RAS) on the drinking behavior in Japanese quails. Normally-hydrated quails that received injections of L-HTP (12.5; 25 and 50 by the intracoelomic route (ic) expressed an increase in water intake, which was inhibited by captopril, an angiotensin converting enzyme (ACE) inhibitor. In addition, captopril also induced such a response in birds under previous fluid deprivation. High doses of captopril (35-70, sc) in normally-hydrated quails decreased the spontaneous water intake while low doses of captopril (2-5, sc) did not prompt water intake after L-HTP administration. Losartan, an AT1 receptor antagonist in mammals, did not change the water intake levels in normally-hydrated or water-deprivated birds. Serotonin (5-HT) injections did not provoke its known dipsogenic response.

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