Role of corticotrophin-releasing factor in effects of leptin on sympathetic nerve activity and arterial pressure.

Leptin and corticotrophin-releasing factor increase sympathetic nervous activity to interscapular brown adipose tissue, kidneys, and adrenal glands. Leptin is known to increase hypothalamic corticotrophin-releasing factor. In this study, we tested the hypothesis that leptin-dependent increases in sympathetic nervous activity are mediated through increases in central nervous system corticotrophin-releasing factor activity. We examined the effects of intracerebroventricular administration of corticotrophin-releasing factor and intravenous leptin on sympathetic nervous activity to interscapular brown adipose tissue through multifiber neurography in anesthetized Sprague-Dawley rats pretreated with intracerebroventricular alpha-helical corticotrophin-releasing factor(9-41) (corticotrophin-releasing factor receptor antagonist) or vehicle. Centrally administered corticotrophin-releasing factor substantially increased interscapular brown adipose tissue sympathetic nervous activity. The responses to corticotrophin-releasing factor were substantially attenuated in animals pretreated with alpha-helical corticotrophin-releasing factor(9-41). Leptin-dependent increases in interscapular brown adipose tissue sympathetic nervous activity were significantly inhibited by pretreatment with alpha-helical corticotrophin-releasing factor(9-41). Interestingly, leptin also significantly increased arterial pressure over 6 hours, but this pressor action was not attenuated by the corticotrophin-releasing factor receptor antagonist. These results suggest that corticotrophin-releasing factor may mediate the sympathoexcitatory effect of leptin on thermogenic tissue without altering its cardiovascular actions.