Expression of mRNA for isoforms of GABA_B receptor in the spinal cord in a rat model of chronic neuropathic pain / 中华麻醉学杂志

ABSTRACT

Objective To investigate the effect of GABAB receptor in spinal cord by detecting semi-quantitatively the mRNA for isoforms of GABAB receptor in a chronic neuropathic pain model. Methods Twenty-four male SD rats weighing 200-250g were anesthetized with intraperitoneal pentobarbital. Lamina of L5 vertebra and superior articular process of L6 were removed and posterior root of left L5 spinal nerve was exposed and tightly ligated with 7/0 atraumatic suture. The animals were randomly divided into 4 groups of 6 animals in each group group A in which animals were observed for 7 days after sham operation; group B in which animals were observed for 7 days after ligation of posterior root of L5 spinal nerve; in group C animals were observed for 14 days after sham operation and in group D animals were observed for 14 days after ligation. Pain threshold was measured by heat stimulation of bilateral hindlimbs before and on the 1st , 3rd , 7th , 10th and 14th day after operation. Lumbar spinal cord was removed on the 7th or 14th day after operation and mRNA for isoforms of GABAB receptor in the spinal cord was detected semi-quantitatively by digoxin hybridization in situ.Results Pain threshold of left hindlimb (ligated side) was significantly lower than that of right hindlimb on the 7th, 10th and 14th day after operation as measured by heat stimulation. There were less mRNA for three isoforms of GABAB receptor in group B and D as compared with group A and C respectively. Conclusion The gene expression of three isoforms of GABAB receptor in the spinal cord has plasticity and is reduced during chronic neuropathic pain.