Effects of galanin n-terminal fragment (1-15) in the light/dark and tail suspension tests

Abstract

Galanin N-terminal fragment (1-15) [Gal(1-15)] is involved in mood regulation. The intracerebroventricular (icv) administration of Gal(1-15) produces a depressive-like behaviour in the forced swim test (FST) and an anxiety-like behaviour in the open field test (OF) in rats. In this work we analyze the effect of Gal(1-15) in two more behavioural tests, the tail suspension test (TLT) and the light/dark test.

Gal(1-15) (3nmol), effective dose in FST and OF, or artificial cerebrospinal were injected in animals (n=5-8) 15 minutes before the test. Behavioural assessment were conducted with at least one week between tests. Student’s t-test was used for comparision between experimental groups.

In the light/dark test we analyzed during 5 min three parametres as indicators of anxiety-like behaviour. Gal(1-15) significantly reduced the time spent in the light compartiment by 52% (p<0.05) and the latency time for entering the dark box by 65% (p<0.05). An increased in the latency time for re-entering the light box was also observed (p<0.05). In the TST, total immobility time was analyzed during 6 min test as parameter indicator of depressive-like behaviour. Gal(1-15) significantly increased rat immobility by 16% (p<0.05).

Our results describe that Gal(1-15) exerts strong depressive- and anxiety-like effects in these tests, indicating a potential role of Gal(1-15) in mood disorders. These results may give the basis for the development of novel therapeutic drugs targeting Gal(1-15) for depression and anxiety.