ROLE OF THE CYTOSKELETON IN THE SECRETORY RESPONSE OF THE FROG ADRENAL-GLAND TO CALCITONIN-GENE-RELATED PEPTIDE

We have previously shown that calcitonin gene-related peptide (CGRP) s timulates the secretion of corticosterone and aldosterone from the fro g adrenal gland in vitro. The aim of the present study was to investig ate the role of cytoskeletal elements in the stimulatory effect of CGR P on corticosteroid production. Perifusion of adrenal explants with th e microfilament-disrupting agent cytochalasin B (5 x 10(-5) M) induced a reversible inhibition of the spontaneous secretion of corticosteron e and aldosterone, and markedly reduced the stimulatory effect of frog CGRP (3 x 10(-7) M) on corticosteroid release. In contrast, administr ation of the antimicrotubular agent vinblastine (10(-5) M) and the int ermediate filament inhibitor beta-beta' iminodipropionitrile (10(-3) M ) had no significant effect on either spontaneous or CGRP-evoked stero id secretion. Taken together, these data provide the first evidence fo r the involvement of microfilaments in CGRP-induced corticosteroid sec retion. In contrast, microtubules and intermediate filaments are not i mplicated in the mechanism of action of CGRP. (C) 1997 Elsevier Scienc e Ltd. All rights reserved.