丹参酮ⅡA对糖尿病大鼠神经病理性疼痛的影响

Effect of tashinone IIA on diabetic neuropathic pain in rats

目的研究丹参酮IIA对糖尿病大鼠神经病理性疼痛的影响及其机制。方法18只成年雄性SD大鼠,随机分为3组：正常对照组(C组)、糖尿病组(B组)、糖尿病+IIA组(A组)(n=6)。以佐脲霉菌素(STZ)75mg·kg^(-1)一次性经腹腔注射建立糖尿病模型,分别于注射STZ前、注射后7、14、27d测定机械性痛阈。于A组机械性痛阈小于8g开始腹腔注射丹参酮IIA 25 mg·kg^(-1),每日1次,持续2周。于注射STZ后27d处死大鼠,取I_(?)脊髓,采用尼氏体染色法光镜下观察脊髓组织的形态学变化,应用免疫组化法测脊髓神经元降钙素基因相关肽(CGRP)表达。结果与C组比较,A组、B组机械性痛阈降低(P＜0．05)；与B组比较．A组在注射STZ后27 d机械性痛阈升高(P＜0．05)。B组脊髓背角萎缩．冲经元变性坏死,数量减少．背角神经元内尼氏体减少,溶解消失；与B组比较,A组脊髓背角萎缩减轻,神经元数量增多．可见少量尼氏体。C组脊髓背角神经元有较多CGRP表达；B组背角神经元有少量或者无CGRP表达；与B组比较,A组脊髓背角神经元有大量CGRP表达。结论丹参酮IIA减轻糖尿病大鼠神经病理性疼痛,对脊髓背角神经元有保护作用,其机制可能与丹参酮IIA上调脊髓背角神经元CGRP的表达有关。

Objective To investigate the effect of tanshinone Ⅱ A on diabetic neuropathic pain and the mechanism. Methods Eighteen male SD rats weighing 180-220 g were randomly divided into 3 groups （ n = 6 each） ： group Ⅰ normal control; group Ⅱ diabetes mellitus and group Ⅲ diabetes mellitus ＋ treatment . Diabetes mellitus （DM） was induced according to Aubel B, et al. Streptozotocin （STZ） 75 mg. kg^-1 was injected intraperitoneally （IP）. Three days later DM was confirmed by blood glucose （13.3 mmol.L^-1）. In group Ⅲ 1 week after STZ IP injection tanshinone Ⅱ A 25 mg. kg^-1 was given IP q.d. for 2 weeks. Mechanical allodynia was measured with yon Frey filaments before and at 7, 14 and 27 d after STZ injection. All rats were sacrificed at 27 d after STZ injection by transcardiae perfusion with 200 ml of 4% paraformaldehyde in 0, 1 mmol. L^-1 phosphate buffer. Lumbar segment of spinal cord was removed and fixed for 10h in 4% parafonnaldehyde. Paraffin slides of the spinal cord were prepared with Nissl＇s staining for detection of pathologic changes. The level of calcitonin gene- related peptide （CGRP） was determined by immuno-histochemistry. Results Pain threshold to mechanical stimuli in group Ⅱ and Ⅲ was significantly decreased as compared with group Ⅰ （ P 〈 0.05） ; while animals in group Ⅲ had a higher threshold to noxious mechanical stimuli than animals in group Ⅱ （P 〈 0,05 ） . Microscopic examination showed that in group Ⅱ dorsal horn of the spinal cord was atrophic; the number of neurons were decreased and the Nissl＇ s bodies in spinal dorsal horn neurons were diminished or vanished; while in group Ⅲ these DM-induced changes were significantly attenuated. The level of CGRP in the spinal dorsal horn was significantly lower in group Ⅱ than in group Ⅲ . Conclusion Tanshinone Ⅱ A an attenuate diabetic neuropathic pain and the mechanism may partly be explained by increasing the CGRP expression in spinal dorsal horn.