Increase in reactive cholesterol in the presynaptic membrane of depolarized Torpedo synaptosomes: blockade by botulinum toxin type A.
We have investigated the redistribution of filipin-cholesterol complexes at freeze-fractured presynaptic membrane of pure cholinergic synaptosomes isolated from Torpedo electric organ during acetylcholine release. After chemical depolarization, filipin-induced lesions increase at the presynaptic membrane. These changes do not take place when synaptosomes are stimulated in a calcium-free medium. Botulinum neurotoxin type A blocks both acetylcholine release and the rearrangement of filipin-induced lesions induced by depolarization. Since botulinum neurotoxin type A does not block either membrane depolarization or calcium entry into the nerve terminal, our results suggest that the redistribution of filipin-cholesterol complexes is linked to the acetylcholine release process.
Egea
G
G
Departament de Biologia Cellular i Anatomia Patològica, Facultat de Medicina, Hospital de Bellvitge, Universitat de Barcelona, Barcelona, Spain.
Marsal
J
J
Solsona
C
C
Rabasseda
X
X
Blasi
J
J
D000109:Acetylcholine / Q000378:metabolism; D000818:Animals; D001905:Botulinum Toxins / Q000494:pharmacology*; D002784:Cholesterol / Q000378:metabolism*; D004557:Electric Organ / Q000378:metabolism* / Q000648:ultrastructure; D005614:Freeze Fracturing; D013574:Synaptosomes / Q000378:metabolism* / Q000648:ultrastructure; D014101:Torpedo / Q000378:metabolism / Q000502:physiology*
D002784:Cholesterol; D001905:Botulinum Toxins; D000109:Acetylcholine