Ishizuki Masafumi, Yanagisawa Mitsuhiko
Department of Orthopaedic Surgery, Faculty of Medicine, Tokyo Medical and Dental University, Bunkyo-ku, Tokyo 113 Japan Department of Pharmacology, Faculty of Medicine, Tokyo Medical and Dental University, Bunkyo-ku, Tokyo 113 Japan.
Pain. 1992 Jan;48(1):101-106. doi: 10.1016/0304-3959(92)90136-Y.
Antinociceptive effects of three centrally acting muscle relaxants, tizanidine, diazepam and eperisone, were studied using an isolated newborn rat spinal cord-tail preparation. Potentials were recorded from a lumbar ventral root (L3-L5) extracellularly using a suction electrode. Pinch stimulation applied to the tail elicited a depolarizing response in the ventral root lasting 15-30 sec, referred to as the tail-pinch potential. Electrical stimulation of the ipsilateral dorsal root of the same segment with a single shock induced depolarizing responses in the ventral root. The responses consisted of monosynaptic and polysynaptic reflexes with a fast time course, followed by a slow depolarizing response lasting about 20 sec. The latter slow response was designated the ipsilateral slow ventral root potential (VRP). Both the tail-pinch potential and the ipsilateral slow VRP were depressed by application to the spinal cord of tizanidine (2-3 microM), diazepam (2 microM) and eperisone (100-200 microM). The effect of tizanidine was reversed by alpha 2-adrenoreceptor antagonists, yohimbine and idazoxan, but not by an alpha 1-antagonist, prazosin. The effect of diazepam was reversed by the benzodiazepine antagonist, flumazenil.
使用新生大鼠脊髓 - 尾巴离体标本研究了三种中枢性肌肉松弛剂替扎尼定、地西泮和乙哌立松的镇痛作用。使用吸引电极在细胞外记录腰段腹根（L3 - L5）的电位。对尾巴施加捏夹刺激可在腹根诱发持续15 - 30秒的去极化反应，称为捏尾电位。用单次电击刺激同侧同一节段的背根可在腹根诱发去极化反应。这些反应包括具有快速时间进程的单突触和多突触反射，随后是持续约20秒的缓慢去极化反应。后一种缓慢反应被称为同侧缓慢腹根电位（VRP）。将替扎尼定（2 - 3 microM）、地西泮（2 microM）和乙哌立松（100 - 200 microM）应用于脊髓会抑制捏尾电位和同侧缓慢VRP。替扎尼定的作用可被α2 - 肾上腺素能受体拮抗剂育亨宾和伊达唑新逆转，但不能被α1 - 拮抗剂哌唑嗪逆转。地西泮的作用可被苯二氮䓬拮抗剂氟马西尼逆转。
