Barbeau H, Julien C, Rossignol S
Département de Physiologie, Faculté de Médecine, Université de Montréal, Que., Canada.
Brain Res. 1987 Dec 22;437(1):83-96. doi: 10.1016/0006-8993(87)91529-0.
The effects on the locomotor pattern of a noradrenergic agonist (clonidine) and an antagonist (yohimbine) were studied in 3 adult chronic spinal cats walking on a treadmill. In the early post-transection period, when the cat walked mainly on the tip of its feet, without supporting its own weight, it was observed that clonidine (150 micrograms/kg) could induce a good bilateral foot placement and intermittent complete weight support. When clonidine was given 1-3 months following the transection, at a time when the spinal cats had a stable and regular locomotor performance, the step length increased markedly, especially at low speeds. This was associated with an increase in the duration of the flexor and extensor bursts, as well as an increase of the angular excursion of all joints. These effects, seen during forward locomotion, were also observed during backward locomotion. In addition, the latter was more easily elicited after clonidine. Yohimbine (1.5-3 mg/kg) partially antagonized these effects. The threshold current needed to elicit a small flexion reflex through wires implanted in the dorsum of the paw was 2-3 times higher after clonidine. Trains of shocks in the animal, standing quietly, did not induce the prolonged late discharges normally found in acute spinal cats. Fast paw shaking, elicited by dipping one paw in water, was abolished by clonidine and reappeared after yohimbine. These results indicate that noradrenergic drugs may influence both spinal locomotion and the excitability of cutaneous reflexes. This class of substances could thus play a useful role in the recovery and/or maintenance of locomotor functions after spinal trauma.
在3只在跑步机上行走的成年慢性脊髓猫中，研究了去甲肾上腺素能激动剂（可乐定）和拮抗剂（育亨宾）对运动模式的影响。在横断后的早期，当猫主要用脚尖行走，不支撑自身重量时，观察到可乐定（150微克/千克）可诱导良好的双侧足部放置和间歇性完全负重支撑。在横断后1 - 3个月给予可乐定，此时脊髓猫的运动表现稳定且规律，步长显著增加，尤其是在低速时。这与屈肌和伸肌爆发持续时间的增加以及所有关节角位移的增加有关。这些在前向运动中观察到的效应，在向后运动中也被观察到。此外，在可乐定作用后，向后运动更容易引发。育亨宾（1.5 - 3毫克/千克）部分拮抗了这些效应。通过植入爪背的电线引发小的屈曲反射所需的阈值电流在给予可乐定后提高了2 - 3倍。在安静站立的动物中施加一连串电击，不会诱发急性脊髓猫中通常出现的延长的晚期放电。将一只爪子浸入水中引发的快速爪子抖动，在给予可乐定后被消除，在给予育亨宾后重新出现。这些结果表明，去甲肾上腺素能药物可能影响脊髓运动和皮肤反射的兴奋性。因此，这类物质可能在脊髓损伤后运动功能的恢复和/或维持中发挥有益作用。
