硫化氢诱发疼痛大鼠脊髓背角N-甲基-D-天冬氨酸受体2B亚基的表达变化

Expression of N-methyl-D-aspartate receptor subunit 2B containing N-methyl-D-aspartate receptorsin the spinal dorsal horn of rats with hydrogen sulfide-induced pain

目的观察足底注射NariS诱发疼痛大鼠脊髓背角N-甲基一D一天冬氨酸（NMDA）受体2B亚基（NR2B）的表达变化，探讨其疼痛形成的机制。方法雄性sD大鼠30只，体质量180—200g，随机分为3组：对照组（C组）、H2s组（s组）和氯胺酮组（K组），S组和K组每天经足底给予NariS1nmol（0．1m1），C组给予等体积生理盐水，持续5d（1次／天），然后K组每天肌肉注射盐酸氯胺酮注射液10mg／kg（0．2m1），s组和c组则给予同体积生理盐水，连续7d（1次／天）。分别于足底给药前1d（Tc）、第1次足底给药后20rain（T1）、第5次足底给药后20min（2）、第7天肌肉注射给药后20min（T3）测定机械缩足阈值（PwT），并于最后1次PwT测定完成后取脊髓组织，分别采用逆转录一聚合酶链反应（1iT—PCR）法和Westernblot法测定脊髓背角NR2BmRNA及蛋白表达水平。结果s组Tl、T2、T3PwT分别为（2．72±1．17）、（1．48±0．57）、（2．40±0．89）g，与C组比较明显降低（P〈0．05），s组NR2BmRNA及NR2B蛋白表达分别为0．75±0．07、1．36±0．08，与c组比较明显增多（P〈0．05）；K组在乃时PWT为（8．89±1．09）g，与s组比较显著升高（P〈0．05），NR2B受体mRNA及NR2B受体蛋白表达分别为0．55±0．05、1．024-0．06，与s组比较显著减少（P〈0．05）。结论脊髓背角NR2B的表达上调可能是H：s诱发的持续性疼痛的机制之一，而氯胺酮则可抑制其表达而发挥一定镇痛作用。

Objective To investigate the role of N-methyl-D-aspartate receptor subunit 2B （NR2B） containing N-methyl-D-aspartate （NMDA） receptors in the spinal dorsal horn of rats with hydro- gen sulfide-induced pain. Methods Thirty male SD rats aged 7 weeks were randomly divided into 3 groups （n = 10 each）： control group （group C）, H2S group （group S）, and ketamine group （group K）. Intra- plantar administration of NariS （ H2S donor） 1 nmol （ 100 p3） for 5 days in group S and group K, and the equal volum （ 100 p^l） of normal saline （NS） in group C （ once each day） was done. Then rats in group K were injected with ketamine 10 mg/kg （0. 2 ml） intramuscularly for 7 days, and the equal volum of NS was injected in group C and group S （once each day）. The paw withdrawal threshold （PWT） to mechanical stimulation was measured at first day before the first administration of NaHS/NS （Tc）, 20 rain after the first administration of NaHS/NS （T1）, 20 rain after the fifth administration of NaHS/NS （ T2）, and 20 min after the seventh administration of ketamine/NS （T3）. Tile rats were sacrificed after the last PWT measurement. The lumber segment of the spinal cord was removed for determination of the expressions of NR2B subunit by using RT-PCR and Western blotting. Results The PWT at T1, T2 and T3 was （2. 72±1.17 ）, （ 1.48±0. 57 ） and （2.40±0. 89 ） g respectively in group S, which was significantly lower than in group C, and the expressions of NR2B mRNA and protein in spinal dorsal horn was （0. 75 ＋ O. 07） and （ 1.36 ±0. 08） respectively, which was significantly higher than in group C. The PWT at T3 was （8. 89±1.09）g in group K, which was higher than in group S, and the expression of NR2B mRNA and protein in spinal dorsal horn was （0. 55± 0.05） and （ 1.02±0.06） respectively, which was lower than in group S. Conclusion The upregnlation of NR2B subunit in spinal dorsal horn was one of meachanisms in hydrogen sulfide-induced pain and inhibition of NR2B expression may contribute to the antinociceptive effects of ket- amine.