Xueqi Tang1, Haiyun Wu1, Xiaofang Mao1, Xinyan Li1, Yongxiang Wang2. 1. King's Lab, Shanghai Jiao Tong University School of Pharmacy, Shanghai, 200240, China. 2. King's Lab, Shanghai Jiao Tong University School of Pharmacy, Shanghai, 200240, China. Electronic address: yxwang@sjtu.edu.cn.
Abstract
OBJECTIVES: To assess the protective effect of the glucagon-like peptide-1 receptor (GLP-1R) agonist morroniside against neuropathic pain and its downstream mechanisms of activating microglial GLP-1R/interleukin-10 (IL-10)/β-endorphin antinociceptive pathway. METHODS: Spinal nerve ligation-induced neuropathic pain rats were intrathecally injected with morroniside, with mechanical paw withdrawal threshold being assessed. The expression of spinal and cultured microglia IL-10 and β-endorphin were detected with qRT-PCR. KEY FINDINGS: Morroniside alleviated mechanical allodynia in neuropathic rats, which was blocked by inhibiting or depleting microglia. In addition, neutralizing spinal IL-10 or β-endorphin with specialized antibodies or blocking the μ-opioid receptor was able to fully reverse the morroniside-induced mechanical antiallodynia. Morroniside treatment stimulated the gene expression of IL-10 and β-endorphin in the spinal lumbar enlargements of neuropathic rats as well as in primary cultured microglia. Furthermore, pretreatment with the IL-10 antibody blocked morroniside-stimulated β-endorphin expression in the spinal cords of neuropathic rats and cultured primary microglia, whereas the β-endorphin antibody failed to affect morroniside-stimulated gene expression of IL-10. CONCLUSIONS: These results reveal that morroniside produces therapeutic effects in neuropathy through spinal microglial expression of IL-10 and subsequent β-endorphin after activation of GLP-1R.
OBJECTIVES: To assess the protective effect of the glucagon-like peptide-1 receptor (GLP-1R) agonist morroniside against neuropathic pain and its downstream mechanisms of activating microglial GLP-1R/interleukin-10 (IL-10)/β-endorphin antinociceptive pathway. METHODS: Spinal nerve ligation-induced neuropathic painrats were intrathecally injected with morroniside, with mechanical paw withdrawal threshold being assessed. The expression of spinal and cultured microglia IL-10 and β-endorphin were detected with qRT-PCR. KEY FINDINGS:Morroniside alleviated mechanical allodynia in neuropathicrats, which was blocked by inhibiting or depleting microglia. In addition, neutralizing spinal IL-10 or β-endorphin with specialized antibodies or blocking the μ-opioid receptor was able to fully reverse the morroniside-induced mechanical antiallodynia. Morroniside treatment stimulated the gene expression of IL-10 and β-endorphin in the spinal lumbar enlargements of neuropathicrats as well as in primary cultured microglia. Furthermore, pretreatment with the IL-10 antibody blocked morroniside-stimulated β-endorphin expression in the spinal cords of neuropathicrats and cultured primary microglia, whereas the β-endorphin antibody failed to affect morroniside-stimulated gene expression of IL-10. CONCLUSIONS: These results reveal that morroniside produces therapeutic effects in neuropathy through spinal microglial expression of IL-10 and subsequent β-endorphin after activation of GLP-1R.