Neuropeptide Y release by pumiliotoxin-B in the electrically-stimulated mouse vas deferens: an immunohistochemical study

Morphologic and immunohistochemical studies were conducted to ascertain whe ther pumiliotoxin-B (PTX-B), an indolizine alkaloid from the skin of the Ne otropical dendrobatid frog, Dendrobates pumilio, affects the anatomic and i mmunohistochemical features of the electrically stimulated mouse vas defere ns preparations. PTX-B, at a concentration of I mu M, consistently decrease d the density pattern of neuropeptide Y (NPY)-immunoreactive nerve fibers c ontained within the circular muscular layer. The alkaloid also induced stri king morphologic changes. It enlarged the lumen of the vasa and relaxed the muscular wall. Pretreatment with prazosin or haloperidol affected neither the release of NPY nor the morphologic changes; pretreatment with tetrodoto xin and guanethidine abolished NPY release and prevented the PTX-B-induced morphologic changes. PTX-B had no appreciable effect on the density and dis tribution pattern of nerve fibers immunostained for vasoactive intestinal p olypeptide, substance P, calcitonin gene-related peptide, enkephalin, pancr eatic polypeptide, 5-hydroxy-tryptamine and tyrosine hydroxylase. (C) 1999 Elsevier Science Inc. All rights reserved.