Intracerebroventricular administration of galanin or galanin receptor subtype 1 agonist M617 induces c-Fos activation in central amygdala and dorsomedial hypothalamus

The neuropeptide galanin and galanin receptors are widespread throughout cortical, limbic and midbrain areas implicated in reward, learning/memory, pain, drinking and feeding. While many studies have shown that galanin produces a variety of presynaptic and post-synaptic responses, work studying the effects of galanin on neural activation is limited. The present study examined patterns of c-Fos immunoreactivity resulting from intracerebroventricular administration of galanin versus saline injection in awake rats. An initial comprehensive qualitative survey was conducted to identify regions of high c-Fos expression followed up with quantitative analysis. Galanin induced a significant increase in c-Fos levels relative to saline-treated controls in dorsomedial hypothalamus and in the central nucleus of the amygdala. This pattern of activation was also produced by galanin receptor type 1 agonist M617. The present findings confirm that galanin upregulates c-Fos activation in hypothalamic nuclei, and supports roles for galanin in central amygdala-mediated regulation of stress-responses, food intake, and Pavlovian conditioning.