The role of galanin in cholinergically-mediated memory processes.

1. Galanin, a 29 amino-acid neuroactive peptide, has been shown to affect diverse processes throughout the nervous system and to coexist with several "classical" neurotransmitters, including norepinephrine, serotonin, and acetylcholine. 2. Galanin coexists with acetylcholine in neurons of the medial septum, diagonal band, and nucleus basalis of Meynert, cells which degenerate during the course of Alzheimer's disease. 3. In the ventral hippocampus, galanin inhibits the release of acetylcholine and inhibits carbachol stimulated phosphatidyl inositol hydrolysis. 4. Galanin impairs choice accuracy in learning and memory paradigms in rats, and is therefore hypothesized to be a contributory factor in the memory and cognitive disabilities found in Alzheimer's patients. 5. Newly developed galanin antagonists, by eliminating putative inhibitory effects of endogenous galanin on cholinergic function, may serve as useful therapies for memory disorders.