Many factors other than epinephrine are involved in the lipolytic response to stress, exercise, and fasting. Calcitonin gene-related peptide (CGRP) is the most potent among the vasodilatory neuropeptides that might mimic epinephrine's vasodilatory and lipolytic effects on adipose tissue. In the present study, we have identified CGRP in rat periepididymal adipose nerve fibers by immunohistochemistry and demonstrated its lipolytic actions in adipocytes isolated from periepididymal fat. To verify CGRP's effect and to begin studies of the underlying mechanism, we chose a convenient cell culture model, 3T3-L1 adipocytes. In these cells CGRP exhibits a half-maximal effect (EC50) for lipolysis at approximately 10-11 M (about 10-fold lower than epinephrine's EC50, 10-10 M). The EC50 for CGRP-induced stimulation of intracellular cAMP is approximately 0.5 x 10-10 M and for epinephrine, 3 x 10-13 M. CGRP actions appear to be mediated by a specific CGRP receptor and not through the calcitonin receptor, because calcitonin did not stimulate lipolysis under similar conditions. Moreover, CGRP-induced lipolysis proceeds in the presence of propranolol but can be blocked by low doses of CGRP8-37, a competitive inhibitor that binds to the CGRP receptor(s). These results indicate a role for CGRP in fat metabolism.
|Original language||English (US)|
|Number of pages||8|
|Journal||Endocrinology and Metabolism, Supplement|
|State||Published - Jan 1 1996|
ASJC Scopus subject areas
- Endocrinology, Diabetes and Metabolism