Effects of intrathecal neostigmine on excitatory amino-acid contents in spinal cord in a rat model of incisional pain / 中华麻醉学杂志

ABSTRACT

Objective To investigate the effects of intrathecal (IT) neostigmine on the excitatory amino-acid content in the L4-5 segment of spinal cord in a rat model of incisional pain. Methods Thirty-two male SD rats weighing 250-270 g were anesthetized with intraperitoneal pentobarbital 40 mg ? kg-1 . Intrathecal catheter was placed with the tip reaching the lumbar region according to the method of Yaksh. Five days later an 1 cm long incision was made in the plantar region of the right hind paw under isoflurane anesthesia according to the method of Brennan. Pain behavior was assessed at 1h after incision by cumulative pain score. The animals were randomly divided into four groups with 8 animals in each group Ⅰsham operation group received IT artificial cerebro-spinal fluid (ACSF) 20 ?l but no incision was made in the hind paw; Ⅱ control group received ACSF 20 ?1 30 min before incision was made; Ⅲ postoperative neostigmine group received IT neostigmine 10 ?g 30 min after incision; Ⅳ preoperative neostigmine group received IT neostigmine 10 ?g before incision. 2h after incision the animals were decapitated and lumbar segment of spinal cord was removed for determination of aspartate and glutamate contents by high performance liquid chromatography (HPLC) with fluorescence detection. Results The cumulative pain scores in group Ⅱ were significantly higher than those in group Ⅰ (P 0.05) . Conclusion The decline in the increased excitatory amino-acid contents in spinal cord induced by incisional pain is involved in the mechanisms of analgesia provided by IT neostigmine.