Differential effect of alpha-latrotoxin on exocytosis from small synaptic vesicles and from large dense-core vesicles containing calcitonin gene-related peptide at the frog neuromuscular junction

Proc Natl Acad Sci U S A. 1988 Oct;85(19):7366-70. doi: 10.1073/pnas.85.19.7366.

Abstract

The regulatory peptide called calcitonin gene-related peptide (CGRP) was detected by immunofluorescence in frog motor neurons and motor nerve terminals. In motor nerve terminals, CGRP-like immunoreactivity was found to be segregated within large dense-core vesicles. To determine whether exocytosis from acetylcholine-containing small synaptic vesicles and from CGRP-containing large dense-core vesicles can be independently stimulated, nerve-muscle preparations were exposed to alpha-latrotoxin. This toxin induced complete depletion of acetylcholine-containing small synaptic vesicles but did not induce a parallel depletion of CGRP-like immunoreactivity and of large dense-core vesicles. These effects were independent of the presence of extracellular Ca2+ and occurred both at room temperature and at low temperature (1-3 degrees C). These findings suggest that exocytosis from the two vesicle populations is mediated by distinct biochemical mechanisms, which might be differentially regulated by physiological stimuli.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Animals
  • Arthropod Venoms / pharmacology*
  • Calcitonin Gene-Related Peptide
  • Exocytosis / drug effects*
  • Fluorescent Antibody Technique
  • Immunohistochemistry
  • Microscopy, Electron
  • Neuromuscular Junction / analysis*
  • Neuropeptides / analysis*
  • Rana pipiens
  • Spider Venoms / pharmacology*
  • Synaptic Vesicles / cytology*

Substances

  • Arthropod Venoms
  • Neuropeptides
  • Spider Venoms
  • alpha-latrotoxin
  • Calcitonin Gene-Related Peptide