Modulatory effects of galanin in the lateral bed nucleus of the stria terminalis on behavioral and neuroendocrine responses to acute stress.

The neuropeptide galanin has been identified as a possible neurotransmitter/neuromodulator within the central nervous system. In the present study, a potential role for galanin in the lateral bed nucleus of the stria terminalis (BSTL) in modulating behavioral and neuroendocrine responses to an acute stress was investigated. In the first experiment, acute immobilization stress induced anxiety-like behavioral responses in rats, measured on the social interaction and elevated plus-maze tests. Immobilization stress decreased both social interaction time and open arm exploratory behavior on the elevated plus-maze. Bilateral administration of the galanin antagonist M40 (1.0 nmole/0.2 microl) into BSTL immediately prior to stress exposure attenuated the anxiogenic-like effects of immobilization stress, restoring both social interaction time and exploration of open arms to control levels. Administration of the antagonist alone had no effect on baseline behavior of unstressed control rats in either test, suggesting that the modulatory effect of galanin elicited during stress is not exerted tonically in unstressed animals. In the second experiment, immobilization stress produced an increase in plasma adrenocorticotropic hormone (ACTH) that was also attenuated by bilateral administration of M40 into BSTL prior to stress. These results suggest that during stress, the neuropeptide galanin exerts a modulatory effect in the BSTL, facilitating behavioral and neuroendocrine components of the acute stress response.