González-Forero D, De La Cruz R R, Delgado-García J M, Pastor A M
Laboratorio de Neurociencia, Facultad de Biología, Universidad de Sevilla, Spain.
Neuroreport. 2001 Mar 26;12(4):753-6. doi: 10.1097/00001756-200103260-00028.
Tetanus neurotoxin (TeNT) is a blocker of synaptic vesicle exocytosis in central synapses with preferential affinity for inhibitory neurotransmission. Following its intramuscular injection, TeNT is retrogradely and trans-synaptically transported towards the premotor terminals. Therefore, we have used TeNT as a tool to study the consequences of functional deafferentation on motoneurons following its peripheral administration. For this, we injected the toxin into the lateral rectus muscle at doses of 5 or 0.5 ng/kg and recorded the discharge activity of abducens motoneurons and internuclear neurons in the alert cat. Our results showed that: (i) TeNT blocked selectively the afferent inhibitory signals on abducens neurons only when used at a low dose, whereas both excitatory and inhibitory synaptic drive was lost after the high dose treatment; (ii) all effects were reversible within one month; and (iii) strikingly, the internuclear neurons of the abducens nucleus showed similar discharge alterations to the motoneurons, suggesting a TeNT action on shared common afferences.
破伤风神经毒素（TeNT）是中枢突触中突触小泡胞吐作用的阻滞剂，对抑制性神经传递具有优先亲和力。肌肉注射后，TeNT逆行并跨突触向运动前终末运输。因此，我们使用TeNT作为工具，研究其外周给药后功能去传入对运动神经元的影响。为此，我们以5或0.5 ng/kg的剂量将毒素注射到外直肌中，并记录清醒猫外展运动神经元和核间神经元的放电活动。我们的结果表明：（i）仅在低剂量使用时，TeNT才选择性地阻断外展神经元上的传入抑制信号，而高剂量治疗后兴奋性和抑制性突触驱动均丧失；（ii）所有效应在一个月内均可逆转；（iii）引人注目的是，外展神经核的核间神经元表现出与运动神经元相似的放电变化，表明TeNT对共同的传入神经有作用。
