Department of Veterinary Physiology, BK21 PLUS Program for Creative Veterinary Science Research, Research Institute for Veterinary Science and College of Veterinary Medicine, Seoul National University, Seoul, 08826, Republic of Korea.
Department of Veterinary and Biomedical Sciences, College of Veterinary Medicine, University of Minnesota, St Paul, MN, 55108, USA.
Biomed Pharmacother. 2019 Oct;118:109299. doi: 10.1016/j.biopha.2019.109299. Epub 2019 Aug 4.
We have recently demonstrated that the neurosteroid-metabolizing enzyme, cytochrome P450c17 is increased in spinal astrocytes contributing to the development of mechanical allodynia in chronic constriction injury (CCI)-induced neuropathic mice. However, the mechanisms by which spinal P450c17 modulates pathological changes in astrocytes remain unclear. In this study we investigated whether P450c17 modulates astrocyte activation and whether this process is mediated by spinal p38 mitogen-activated protein kinase phosphorylation ultimately leading to the development of mechanical allodynia in CCI mice. Sciatic nerve injury induced a significant increase in glial fibrillary acidic protein (GFAP) expression in the superficial dorsal horn (SDH, laminae I-II) and nucleus proprius (NP, laminae III-IV) regions of the spinal cord dorsal horn. Repeated daily (from days 0-3 post-surgery) intrathecal administration of the P450c17 inhibitor, ketoconazole (10 nmol) significantly inhibited the CCI-induced increase in GFAP-immunoreactivity, but had no effect on the CCI-induced increase in Iba-1-immunoreactivity. In addition, intrathecal administration of ketoconazole significantly inhibited the CCI-induced increase in p38 phosphorylation, while the levels of ERK and JNK phosphorylation remained unchanged. The CCI-induced development of mechanical allodynia was attenuated by administration of either ketoconazole (10 nmol) or the p38 MAPK inhibitor, SB203580 (5 nmol). Administration of a sub-effective dose of SB203580 (0.5 nmol) potentiated the pharmacological effect of ketoconazole (1 nmol) on spinal GFAP-immunostaining, as well as, the development of mechanical allodynia following CCI. Collectively these data suggest that spinal P450c17 activates astrocytes via p38 phosphorylation, ultimately leading to the development of mechanical allodynia in a model of peripheral neuropathy.
我们最近的研究表明，神经甾体代谢酶细胞色素 P450c17 在脊髓星形胶质细胞中增加，导致慢性缩窄性损伤（CCI）诱导的神经病理性小鼠机械性痛觉过敏的发展。然而，脊髓 P450c17 调节星形胶质细胞病理变化的机制尚不清楚。在这项研究中，我们研究了 P450c17 是否调节星形胶质细胞的激活，以及这一过程是否通过脊髓 p38 丝裂原活化蛋白激酶磷酸化介导，最终导致 CCI 小鼠机械性痛觉过敏的发展。坐骨神经损伤导致脊髓背角浅层（SDH，I-II 层）和固有核（NP，III-IV 层）中神经胶质纤维酸性蛋白（GFAP）表达显著增加。重复每日（术后 0-3 天）鞘内给予 P450c17 抑制剂酮康唑（10nmol）可显著抑制 CCI 诱导的 GFAP-免疫反应增加，但对 CCI 诱导的 Iba-1-免疫反应增加无影响。此外，鞘内给予酮康唑可显著抑制 CCI 诱导的 p38 磷酸化增加，而 ERK 和 JNK 磷酸化水平保持不变。CCI 诱导的机械性痛觉过敏的发展通过给予酮康唑（10nmol）或 p38 MAPK 抑制剂 SB203580（5nmol）而减轻。给予低有效剂量的 SB203580（0.5nmol）增强了酮康唑（1nmol）对脊髓 GFAP 免疫染色以及 CCI 后机械性痛觉过敏发展的药理学作用。总之，这些数据表明，脊髓 P450c17 通过 p38 磷酸化激活星形胶质细胞，最终导致周围神经病变模型中机械性痛觉过敏的发展。
