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 (0.3mg/kg) that was given intraperitoneally (i.p.) to intact Wistar rats which were tested 1h 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 48h without additional treatment. Rats exposed to restraint stress (lasting 60min) for three consecutive days and tested 1h after stress termination exhibited reduced locomotion and exploration in the OF. Galanin (0.3 and 1.0mg/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 0.3mg/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.