Differential inhibition by botulinum neurotoxin A of cotransmitters released from autonomic vasodilator neurons.
The role of the soluble NSF attachment protein receptor (SNARE) protein complex in release of multiple cotransmitters from autonomic vasodilator neurons was examined in isolated segments of guinea pig uterine arteries treated with botulinum neurotoxin A (BoNTA; 50 nM). Western blotting of protein extracts from uterine arteries demonstrated partial cleavage of synaptosomal-associated protein of 25 kDa (SNAP-25) to a NH2-terminal fragment of approximately 24 kDa by BoNTA. BoNTA reduced the amplitude (by 70-80%) of isometric contractions of arteries in response to repeated electrical stimulation of sympathetic axons at 1 or 10 Hz. The amplitude of neurogenic relaxations mediated by neuronal nitric oxide (NO) was not affected by BoNTA, whereas the duration of peptide-mediated neurogenic relaxations to stimulation at 10 Hz was reduced (67% reduction in integrated responses). In contrast, presynaptic cholinergic inhibition of neurogenic relaxations was abolished by BoNTA. These results demonstrate that the SNARE complex has differential involvement in release of cotransmitters from the same autonomic neurons: NO release is not dependent on synaptic vesicle exocytosis, acetylcholine release from small vesicles is highly dependent on the SNARE complex, and neuropeptide release from large vesicles involves SNARE proteins that may interact differently with regulatory factors such as calcium.
Morris
J L
JL
Department of Anatomy and Histology, Centre for Neuroscience, Flinders University, Adelaide SA 5001, Australia. Judy.Morris@flinders.edu.au
Jobling
P
P
Gibbins
I L
IL
D000109:Acetylcholine / Q000494:pharmacology; D000818:Animals; D001158:Arteries / Q000294:innervation; D019274:Botulinum Toxins, Type A / Q000494:pharmacology*; D002217:Carbachol / Q000494:pharmacology; D018679:Cholinergic Agonists / Q000494:pharmacology; D004791:Enzyme Inhibitors / Q000494:pharmacology; D005260:Female; D006168:Guinea Pigs; D008565:Membrane Proteins / Q000032:analysis / Q000378:metabolism; D019331:NG-Nitroarginine Methyl Ester / Q000494:pharmacology; D009419:Nerve Tissue Proteins / Q000032:analysis / Q000378:metabolism; D009465:Neuromuscular Agents / Q000494:pharmacology*; D009474:Neurons / Q000502:physiology; D009569:Nitric Oxide / Q000378:metabolism; D009599:Nitroprusside / Q000494:pharmacology; D011189:Potassium Chloride / Q000494:pharmacology; D017729:Presynaptic Terminals / Q000737:chemistry / Q000378:metabolism; D011460:Prostaglandins F / Q000494:pharmacology; D050600:SNARE Proteins; D013564:Sympathetic Nervous System / Q000166:cytology / Q000187:drug effects / Q000502:physiology*; D009435:Synaptic Transmission / Q000187:drug effects*; D050825:Synaptosomal-Associated Protein 25; D014599:Uterus / Q000098:blood supply; D014660:Vasoactive Intestinal Peptide / Q000494:pharmacology; D014661:Vasoconstriction / Q000502:physiology; D014664:Vasodilation / Q000502:physiology*; D014665:Vasodilator Agents / Q000494:pharmacology; D033921:Vesicular Transport Proteins
D018679:Cholinergic Agonists; D004791:Enzyme Inhibitors; D008565:Membrane Proteins; D009419:Nerve Tissue Proteins; D009465:Neuromuscular Agents; D011460:Prostaglandins F; D050600:SNARE Proteins; D050825:Synaptosomal-Associated Protein 25; D014665:Vasodilator Agents; D033921:Vesicular Transport Proteins; D009599:Nitroprusside; D009569:Nitric Oxide; D014660:Vasoactive Intestinal Peptide; D011189:Potassium Chloride; D002217:Carbachol; D019274:Botulinum Toxins, Type A; D000109:Acetylcholine; D019331:NG-Nitroarginine Methyl Ester