INTRAVENTRICULAR ADMINISTRATION OF GALANIN DOES NOT AFFECT BEHAVIORS ASSOCIATED WITH LOCUS-COERULEUS ACTIVATION IN RATS

The 29 amino acid peptide galanin (GAL) coexists with norepinephrine i n rat locus coeruleus (LC) neurons to a remarkably high degree. The ef fects of central administration of GAL were examined in three behavior al paradigms that putatively involve increases in the activity of LC n eurons. GAL did not affect behavioral signs associated with naloxone-p recipitated withdrawal in rats treated chronically with morphine, a co ndition in which the firing rate of LC neurons is dramatically increas ed, although the behavioral signs of withdrawal were abolished by clon idine. Foot shock induced freezing behavior was similarly unaffected b y either dose of GAL but was significantly diminished by clonidine and the corticotropin-releasing factor (CRF) antagonist alpha-helical CRF . GAL did not influence the decrease in exploratory activity in a nove l open field induced by idazoxan. The behavioral activity of the pepti de and route of administration were confirmed in a feeding paradigm. D oses of GAL that were inactive in the three paradigms were active in s timulating intake of a palatable food to a similar degree as clonidine -stimulated intake. These results suggest that intraventricularly admi nistered GAL may not influence behaviors thought to be mediated by act ivation of neurons in the LC.