González-Darder J M, Ortega-Alvaro A, Ruz-Franzi I, Segura-Pastor D
Department of Neurosurgery, Faculty of Medicine, University of Càdiz, Spain.
Anesth Analg. 1992 Jul;75(1):81-6.
Deafferentation pain has been related to abnormal electrical hyperactivity in the neurons of the sensory relays in the central nervous system. This electrical activity resembles the epileptoid pattern observed in experimental epileptoid foci. With the aim of preventing this hyperactivity, rats were given long-term treatment with phenobarbital after sciatic transection and dorsal cervical rhizotomy. Daily intramuscular injections of saline solution or 5 and 10 mg/kg of phenobarbital were administered for 20 days, starting 10 days before surgery. Larger doses of phenobarbital delayed the onset and reduced the severity of autotomy. In a test of acute pain, the effect of intraperitoneal (1-16 mg) and intrathecal (100-500 micrograms) phenobarbital was studied by measuring the "tail-flick" response latency. Intraperitoneal phenobarbital did not modify acute pain, but 500 micrograms of intrathecal phenobarbital increased the threshold of pain. These results indicate that (a) phenobarbital, a drug with anticonvulsant activity, reduces deafferentation behavior in rats, and (b) intrathecal phenobarbital has an antinociceptive action in acute experimental pain.
去传入性疼痛与中枢神经系统感觉传导通路神经元的异常电活动增强有关。这种电活动类似于在实验性癫痫病灶中观察到的癫痫样模式。为了预防这种活动增强，在坐骨神经横断和颈背神经根切断术后，给大鼠长期使用苯巴比妥治疗。从手术前10天开始，每天肌肉注射生理盐水或5毫克/千克和10毫克/千克的苯巴比妥，持续20天。较大剂量的苯巴比妥延迟了自残行为的发作并减轻了其严重程度。在急性疼痛测试中，通过测量“甩尾”反应潜伏期，研究了腹腔注射（1 - 16毫克）和鞘内注射（100 - 500微克）苯巴比妥的效果。腹腔注射苯巴比妥未改变急性疼痛，但500微克鞘内注射苯巴比妥提高了疼痛阈值。这些结果表明：（a）具有抗惊厥活性的药物苯巴比妥可减少大鼠的去传入性行为；（b）鞘内注射苯巴比妥在急性实验性疼痛中具有抗伤害感受作用。
