Galanin modulating effect on restraint stress-induced short- and long-term behavioral changes in Wistar rats

The neuropeptide galanin has been recognized as a possible neurotransmitter/neuromodulator, and in addition has been implicated in anxiety- and depression-related behaviors. The present study demonstrates increased locomotion and rearing after galanin (0.3 mg/kg) that was given intraperitoneally (i.p.) to intact Wistar rats which were tested 1 h later in the open field (OF). These effects, which suggest an anxiolytic-like action, were blocked by i.p. administered peptidic galanin antagonist M40. Further, the locomotion increase caused by galanin and the inhibitory effect of M40 persisted for 48 h without additional treatment. Rats exposed to restraint stress (lasting 60 min) for three consecutive days and tested 1 h after stress termination exhibited reduced locomotion and exploration in the OF. Galanin (0.3 and 1.0 mg/kg) given immediately after each stress exposure prevented the decrease of locomotion and exploration induced by stress in all trials. When the test was repeated 6 days later without stress and galanin treatment the reduction of locomotion produced by stress persisted; the anti-stress behavioral effects of both galanin doses were also present. Testing performed on the 12th day after the last stress and galanin treatment with 0.3 mg/kg revealed an increased locomotion compared with unstressed and stress-exposed rats. Our results demonstrate that behavioral effects of the peptide galanin are evident even after i.p. administration. These results also suggest that galanin elicits stress-modulatory action, and support the notion that the galaninergic system may serve as a drug target in stress-related conditions. (C) 2011 Published by Elsevier Ireland Ltd.