Testing the hypothesis that locus coeruleus hyperactivity produces depression-related changes via galanin.

This paper reviews progress made in testing the idea that depression-related behavioral changes can arise from hyperactivity of locus coeruleus (LC) neurons which consequently inhibits activity of mesocorticolimbic dopamine neurons in the ventral tegmentum (VTA) via release of galanin from terminals on LC axons in VTA. Results from pre-clinical testing are described, including the most recent findings indicating that, in an animal model that shows long-lasting symptoms of depression, recovery to normal activity in the home cage is accelerated by infusion of a galanin receptor antagonist, galantide (M15), into VTA. Data are also described suggesting that all effective antidepressant treatments decrease activity of LC neurons.