Effect of galanin and enterostatin on sympathetic nerve activity to interscapular brown adipose tissue

The effects of galanin and enterostatin on sympathetic activity have been examined in rats using electrophysiological techniques. Galanin, in doses of 25-300 pmol, and enterostatin, in doses of 0.5-10 nmol, were injected into the third ventricle of anesthetized male Sprague-Dawley rats in 1-mu l volumes. Galanin produced a dose-dependent suppression (ranging between 20 and 80%) of sympathetic firing rate of nerves innervating interscapular brown adipose tissue. In rats fed a chow diet, injection of enterostatin produced only a transient 10% rise in firing rate which returned to baseline within 10-15 min. In contrast, animals fed a high-fat diet showed a dose-dependent increase in firing rate lasting for 60 min. The results of this experiment are consistent with the hypothesis that food intake and sympathetic nervous system activity have a reciprocal relationship. The implications of this relationship are discussed.