鞘内注射MRS2211对糖尿病神经痛大鼠脊髓炎症因子和JAK2/STAT3表达及NR2B磷酸化的影响

The effect of intrathecally injected MRS2211 on the expression of spinal inflammatory factors,JAK2/STAT3 and NR2B in diabetic rats

目的:观察鞘内注射MRS2211对糖尿病神经痛(diabetic neuropathic pain,DNP)大鼠脊髓背角IL-1β、IL-6及JAK2/STAT3和NR2B(p Tyr1336,p Tyr1472)表达的影响。方法:成年SD大鼠随机分为5组(n=8):(1)对照组(鞘内注射生理盐水)、(2)糖尿病组(糖尿病+鞘内注射生理盐水)、(3)^(5)DNP+MRS2211组(糖尿病+鞘内分别注射10、50、100 pmol/L MRS2211)。大鼠腹腔注射链脲菌素50 mg/kg,2周后热痛阈明显下降认为造模成功。随后鞘内给药2次/日,4周。STZ注射前1 d、注射后第2、4和6周末测定给药后热缩足潜伏期(thermal withdrawal latency,TWL);酶联免疫吸附试验测定背角IL-1β和IL-6表达,免疫印迹检测背角JAK2/STAT3和NR2B表达。结果:与对照组相比,糖尿病组TWL明显降低(P<0.01);鞘内分别给予10、50、100pmol/L MRS2211可明显缓解STZ注射4周时的TWL(P<0.05),但STZ注射6周时,抑制TWL效果不明显。与对照组相比,在STZ注射2、4和6周后糖尿病大鼠脊髓背角IL-1β、IL-6和STAT3以及p Tyr1336NR2B、p Tyr1472NR2B表达明显上调(P<0.01);在STZ注射4和6周后脊髓背角JAK2表达明显上调(P<0.01)。在STZ注射4周时,MRS2211(100 pmol/L)处理组脊髓背角IL-1β、IL-6、JAK2/STAT3表达下调(P<0.05),同时Tyr1336NR2B磷酸化减弱(P<0.05),但在STZ注射6周时抑制效果不明显。鞘内注射MRS2211(100 pmol/L)不影响糖尿病大鼠脊髓背角p Tyr1472NR2B磷酸化。结论:鞘内注射MRS2211可明显缓解DNP大鼠热痛敏症状,其机制可能与抑制脊髓背角IL-1β和IL-6表达,进一步下调JAK2/STAT3表达,间接抑制背角神经元p Tyr1336NR2B磷酸化有关。

Objective： The aim of this study is to investigate the effect of intrathecal injection of MRS2211 on the expression of IL-1β,IL-6,JAK2,STAT3,p Tyr1336 NR2 B and p Tyr1472 NR2 B in spinal dorsal horn of rat with diabetic neuropathic pain（ DNP）. Methods： All rats were randomized into five groups（ n = 8） ：（ 1） normal group（ intrathecal saline）,（ 2） diabetic neuropathic pain（ DNP,intrathecal saline）,（ 3） ^（ 5） DNP ＋ MRS2211 group（ intrathecal injection of MRS2211,10,50 and 100 pmol/L）. Diabetic neuropathic pain model was induced by a single intraperitoneal injection of STZ（ 50 mg/kg）. After two weeks,DNP model was confirmed when thermal pain thresh-old decreased significantly. Then,MRS2211 or saline were administered twice per day for 4 weeks. All rats were tested for thermal withdrawal latency（ TWL） 1 day before and 2 th,4 th and 6 th week after STZ injection. The expression of IL-1β and IL-6 in dorsal horn was examined by ELISA. The expression of JAK2/STAT3 and NR2 B（ p Tyr1336,p Tyr1472） were examined by Western Blot. Results： TWL in DNP group were significantly lower than that in normal group（ P〈0. 01）. Compared with DNP group,the TWL were significantly increased after MRS2211（ 10,50 and 100 pmol/L） administration on 4 th weekend（ P〈0. 05） but not on 6 th weekend. The ELISA and WB results indicated that compared with control group,the expression of IL-1β,IL-6 and JAK2 and NR2 B（ p Tyr1336,p Tyr1472） was significantly increased in dorsal horn on 2 th,4 th and 6 th weekend after STZ injection（ P〈0. 05）. The expression of STAT3 in the dorsal spinal cord was significantly increased at 4 and 6 weeks after STZ injection（ P〈0. 01）. Intrathecal administration of MRS2211（ 100 pmol/L） suppressed the increased level of IL-1β,IL-6,JAK2,STAT3 and p Tyr1336 NR2 B mainly at the end of 4 th week（ P〈0. 05） but not at the end of 6 th week. However,the expression of p Tyr1472 NR2 B was not impaired by MRS2211 in diabetic rats. Conclusion： These results suggest that intrathecal MRS2211 produces antinociceptive effect in the early stage of DNP. MRS2211 inhibits the levels of IL-6,which subsequently inhibits the expression of the JAK2/STAT3 and NR2 B-containing NMDAR phosphorylation in dorsal horn neurons, thereby attenuating the development of DNP.