选择性磷酸二酯酶-2A抑制剂Bay 60-7550对脊髓损伤大鼠机械痛阈及小胶质细胞/巨噬细胞极化状态的影响

The effects of Bay 60-7550, a selective phosphodiesterase-2A inhibitor, on mechanical pain threshold and microglia/macrophages polarization in the rats after spinal cord injury

摘要:

目的：探讨选择性磷酸二酯酶-2A（PDE2A）抑制剂Bay 60-7550对脊髓损伤后神经病理性疼痛(spinal cord injury-neuropathic pain, SCI-NP)模型大鼠机械痛阈的影响及其可能机制。方法：雄性SPF级SD大鼠随机分为4组:假手术组（sham组）、模型组（SCI组）、溶媒组（vehicle组）和给药组（Bay 60-7550组）。术前1 d至术后21 d采用von Frey纤维丝间断测试大鼠后爪机械痛阈值。免疫组化检测大鼠脊髓组织中PDE2A表达。流式细胞术和qRT-PCR检测M1/M2型小胶质细胞/巨噬细胞极化比例；qRT-PCR检测小胶质细胞/巨噬细胞及其下游生物标志物(CD86、CD163、IL-6、IL-1β、IL-10、TGF-β)的表达。结果：鞘内注射Bay 60-7550可显著降低脊髓损伤大鼠的机械痛阈值。与sham组相比，SCI组大鼠脊髓背角PDE2A表达显著增加（P＜0.01），而Bay60-7550组PDE2A的过表达被抑制。与vehicle组相比，Bay60-7550组脊髓促炎因子IL-6、IL-1β mRNA表达显著降低（P＜0.01, P＜0.05）、抗炎因子IL-10、TGF-β mRNA的表达显著增加（P＜0.05）。鞘内注射Bay60-7550可使SCI后小胶质细胞/巨噬细胞M2型比例增加，而M1型细胞比例降低。结论:抑制PDE2A的过表达能有效缓解大鼠脊髓损伤后神经病理性疼痛，其机制可能与其调节小胶质细胞/巨噬细胞的极化状态有关。

Abstract:

Background:The present study aimed to investigate the effects of Bay 60-7550, a selective phosphodiesterase-2A(PDE2A) inhibitor, on mechanical pain threshold and its potential mechanism in the neuropathic pain(spinal cord injury-neuropathic pain, SCI-NP) models of rats after spinal cord injury (SCI).Methods: Male SD rats were randomly divided into four groups: the Sham group, SCI group, SCI+Vehicle group and SCI+Bay 60-7550 group. The mechanical pain thresholds were evaluated by the von Frey test from the day before surgery until the 21th postoperative day. PDE2A expression levels in spinal cord were measured by immunohistochemistry. The proportions of M1/M2 microglia/macrophages polarization were assessed by flow cytometry and qRT-PCR. The expressions of microglia/macrophages and their downstream biomarkers (CD86、CD163、IL-6、IL-1β、IL-10、TGF-β) were measured by qRT-PCR. Results: Intrathecal administration of Bay 60-7550, significantly attenuated mechanical allodynia in rats after SCI. Compared with the sham group, PDE2A expression was dramatically elevated in the spinal dorsal horn of rats after SCI（P＜0.01）. Furthermore, the overexpression of PDE2A was inhibited by Bay 60-7550 treatment. Bay60-7550 delivery reduced pro-inflammatory factors (IL-6, IL-1β) expression（P＜0.01, P＜0.05）, increased anti-inflammatory factors (IL-10, TGF-β) expression in the spinal cord significantly（P＜0.05）. Consistently, Bay60-7550 treatment promoted the proportion of M2-type microglia/macrophages while decreased the proportion of M1-type microglia/macrophages in rats after SCI. Conclusion: Inhibiting the overexpression of PDE2A might attenuate the development of NP in rats after SCI, and the mechanism might be related to the regulation of microglia/macrophages polarization.