Objective To evaluate the effect of neuropathic pain on the expression of GABAB receptor subtypes in spinal cord of rats with chronic constriction injury.Methods 36 rats were divided into Sham group and CCI group respectively.In CCI group,the left common sciatic nerve of anesthetized rats was exposed,four silk ligatures（30） were tied loosely proximal to the sciatica’s trifurcation.In Sham group,Sham surgery was undergone by exposing the left sciatic nerve without ligation.Hind paw thermal withdrawl latency（TWL） to thermal stimulus and mechanical withdrawl threshold（MWT） of mechanical stimulus were recorded before ligation or on 1 d,3 d,5 d,7 d,10 d,14 d,21 d,28 d after ligation respectively（n=8）.Expression of GABAB receptor subtypes were detected before ligation and 1 d,3 d,7 d,14 d,28 d after ligation respectively using bothe immunohistochemical assay（n=6） and Western blot technique（n=4）.Results There were no significant differences on the values of MWT and TWL before ligation between Sham group and CCI group.Compared with Sham group,the MWT and TWL of rats in CCI group significantly decreased after ligation（P<0.01,P<0.05） and continued to be decreased until 28 d after ligation.Both immunoreactive neurons and protein content of GABAB1a or GABAB2 subtypes increased on the 3rd day after ligation,then both decreased on the 7th day after ligation,and lasted for 28 dafter ligation.（P<0.01,P<0.05）.There were no changes of GABAB1b after ligation（P>0.05）.Conclusion There existed differences among expression of spinal GABAB receptor subtypes on rats with chronic constriction injury induced neuropathic pain.The expression of spinal GABAB1a and GABAB2 decreased while there were no changes of GABAB1b on neuropathic rats.
目的观察丙泊酚在vlPAG对大鼠伤害性感受的影响及GABAA受体在其中可能的作用。方法Sprague-Daw ley(SD)♀大鼠随机分组,丙泊酚(Propofol,Pro)和荷包牡丹碱(B icucu lline,B ic)采用中脑导水管周围灰质腹外侧区(ven-trolateral portion of the PAG,vlPAG)注射。行为学实验采用热板法和福尔马林实验,分别以舔后爪潜伏时间(Hot-p latelatency,HPL)和疼痛(累计)评分为指标。免疫组化方法观察丙泊酚在vlPAG对福尔马林单侧足底皮下注射诱发的脊髓背角Fos蛋白表达的影响。结果行为学部分:两种疼痛模型中丙泊酚(10 g.L-1)vlPAG注射引起痛敏(P<0.01)。热板法实验中,丙泊酚vlPAG微量注射的痛敏作用可被相同部位预先注射25 mg.L-1B ic在10和20 m in时间点分别拮抗70%和71%(均P<0.01),在30和40 m in完全拮抗。在福尔马林实验中,丙泊酚vlPAG微量注射使福尔马林疼痛评分增加,此作用可被B ic(25 mg.L-1)在60 m in拮抗57%(P<0.05)。免疫组化部分中,丙泊酚vlPAG微量注射使福尔马林引起的脊髓背角各层FLI阳性细胞数明显增多(P<0.01),B ic vlPAG微量注射(25 mg.L-1)可部分拮抗丙泊酚vlPAG微量注射的作用(P<0.01)。结论在大鼠vlPAG微量注射丙泊酚能产生痛敏作用;GABAA受体部分介导了丙泊酚的以上作用。
