Effects of galanin n-terminal fragment (1-15) in sac- charin self-administration and sucrose preference test in rats.

Abstract

The Galanin N-terminal fragment (1-15) [GAL(1-15)] induces depressant- and anxiogenic- like actions in several behavioral tests, and these effects were significantly stronger than the ones induced by Galanin (1-29). Since, anhedonia is a core feature of major depressive disor- der, we have analyzed GAL(1-15) actions in two anhedonic-like behaviour tests: saccharin Self-administration and Sucrose Preference test. Three sets of experimemts were conducted in the saccharin Self-administration test. In the first, a dose-response curve of GAL(1-15) 1nmol, 3nmol or vehicle was performed. We have also compared the effects in the number of saccharine reinforcements of Galanin (1-29) 3nmol and GAL(1-15) 3nmol. In the last experiments, rats received i.c.v. GAL(1-15) 3nmol and the GALR2 antagonist M871 3nmol. In Sucrose Preference test, we have analyzed the effects of GAL(1-15) 3nmol in the sucrose intake and preference after 2, 8 and 24 h. GAL(1-15) 3nmol significantly decreased the number of reinforcement of saccharin self- administer (p<0.01), while 1nmol lacked effect. GAL(1-15) also significantly reduced the number of reinforcement (p<0.01) compared with Galanin (1-29). The GALR2 antagonist M871 significantly blocked (p<0.05) the decrease in the number of saccharin reinforcements administration induced by GAL(1-15). In the Sucrose Preference test, GAL(1-15) decreased the sucrose intake 8 (p<0.05) and 24 hours (p<0.01) after administration. In the current study, we described for the first time that GAL(1-15) induced a strong anhe- donia-like phenotype in the saccharin self-administration and Sucrose Preference test, con- firming an important role of this neuropeptide in anhedonia, a core feature of major depres- sive disorders.