Marsal J, Egea G, Solsona C, Rabasseda X, Blasi J
Departament de Biologia Cellular i Anatomia Patològica, Facultat de Medicina, Hospital de Bellvitge, Universitat de Barcelona, Spain.
Proc Natl Acad Sci U S A. 1989 Jan;86(1):372-6. doi: 10.1073/pnas.86.1.372.
The action of botulinum neurotoxin on acetylcholine release, and on the structural changes at the presynaptic membrane associated with the transmitter release, was studied by using a subcellular fraction of cholinergic nerve terminals (synaptosomes) isolated from the Torpedo electric organ. Acetylcholine and ATP release were continuously monitored by chemiluminescent methods. To catch the membrane morphological changes, the quick-freezing method was applied. Our results show that botulinum neurotoxin inhibits the release of acetylcholine from these isolated nerve terminals in a dose-dependent manner, whereas ATP release is not affected. The maximal inhibition (70%) is achieved at neurotoxin concentrations as low as 125 pM with an incubation time of 6 min. This effect is not linked to an alteration of the integrity of the synaptosomes since, after poisoning by botulinum neurotoxin type A, they show a nonmodified occluded lactate dehydrogenase activity. Moreover, membrane potential is not altered by the toxin with respect to the control, either in resting condition or after potassium depolarization. In addition to acetylcholine release inhibition, botulinum neurotoxin blocks the rearrangement of the presynaptic intramembrane particles induced by potassium stimulation. The action of botulinum neurotoxin suggests that the intramembrane particle rearrangement is related to the acetylcholine secretion induced by potassium stimulation in synaptosomes isolated from the electric organ of Torpedo marmorata.
利用从电鳐电器官分离得到的胆碱能神经末梢亚细胞组分（突触体），研究了肉毒杆菌神经毒素对乙酰胆碱释放以及与递质释放相关的突触前膜结构变化的作用。采用化学发光法连续监测乙酰胆碱和ATP的释放。为捕捉膜形态变化，应用了快速冷冻法。我们的结果表明，肉毒杆菌神经毒素以剂量依赖方式抑制这些分离神经末梢释放乙酰胆碱，而ATP释放不受影响。在神经毒素浓度低至125 pM且孵育时间为6分钟时，可实现最大抑制（70%）。这种效应与突触体完整性的改变无关，因为在A型肉毒杆菌神经毒素中毒后，它们显示出未改变的封闭乳酸脱氢酶活性。此外，无论是在静息状态还是钾去极化后，毒素对膜电位的影响与对照相比均未改变。除抑制乙酰胆碱释放外，肉毒杆菌神经毒素还阻断了钾刺激诱导的突触前膜内颗粒重排。肉毒杆菌神经毒素的作用表明，膜内颗粒重排与从斑纹电鳐电器官分离的突触体中钾刺激诱导的乙酰胆碱分泌有关。
