The Role Of MGluR3 And MGluR 5 Regulating Spinal Astrocytes Activation During The Development Of Bone Cancer Pain And Treating Bone Cancer Pain With Traditional Chinese Medicine In A Mouse Modle

Objective:To investigate the role of spinal metabotropic glutamate receptor subtypes 3 and 5 regulating astrocytes activation during the development of bone cancer pain and the analgesic effects of Shentong Zhuyu Decoction(SZD) and Tanshinone IIA and their possible mechanisms.Methods:The femur marrow cavity of C3H/HeNCrlVr male mice were injected with NCTC 2472 fibrosarcoma cells to make bone cancer pain model and NCTC 2472 fibrosarcoma cells were replaced by the equal volum of a-MEM in the sham model.The number of spontaneous foot lifting/2 min, paw withdrawal mechanical threshold (PWMT) and paw withdrawal thermal latency (PWTL) were used to assess pain behaviours performance.The level of spinal glial fibrillary acidic protein(GFAP) and tumor necrosis factor-a(TNF-a) mRNA and protein expression to reflect astrocytes activation level.To treat bone cancer pain with mGluR3 agonist (2R,4R)-4-Aminop-yrrolidine-2,4-dicarboxylate (APDC),mGluR3 receptor antagonist (2S)-2-Amino-2-[(1S,2S)-2-carbo-xycycloprop-1-yl]-3-(xan th-9-yl) propanoic acid (LY341495), mGluR5 agonist (RS)-2-Chloro-5-hydroxyphenylglycine (CHPG),mGluR5 receptor antagonist 3-((2-Methyl-1,3-thiazol-4-yl) e-thynyl) pyridine hydrochloride (MTEP) and Tanshinone IIA by intrathecal catheter. Shentong Zhuyu Decoction was given by intragastric administration. To observe pain behaviors changes at different time points and the L3-L5 spinal cord segments of sacrificed mice were dissected to detect glial fibrillary acidic protein and tumor necrosis factor-a mRNA and protein expression by Real-time quantitative RT-PCR and western blot respectively.Results:(1) NCTC 2472 fibrosarcoma cells inoculation of the left femur of the male C3H/HeNCrlVr mice produced progressive spontaneous flinches, mechanical hyperalgesia and thermal hyperalgesia(P<0.05);(2)NCTC 2472 fibrosarcoma cells inoculation of the left femur of the male C3H/HeNCrlVr mice induces spinal astrocytes activation, characterized by up-regulation of GFAP and TNF-a mRNA and protein expression(P<0.05);(3) The level of spinal mGluR3, mGluR5 mRNA and protein expression progressively increased during the development of bone cancer pain(P<0.05); (4) Intrathecal administration of APDC and MTEP could improve bone cancer pain behaviors performance and inhibit the expression of spinal GFAP and TNF-a, but LY341495 and CHPG could promote the expression of spinal GFAP and TNF-a in the sham groups(P<0.05);(5) Intrathecal injection of tanshinone IIA could improve the bone cancer pain behaviors performance and inhibit the expression of spinal GFAP and TNF-a dose-dependently(P<0.05); (6) Given SZD orally could dose-dependently improve the bone cancer pain behaviors performance, and could suppress the expression of spinal GFAP and TNF-a (P<0.05).Conclusion:The spinal metabotropic glutamate receptor subtypes 3 and 5 play important roles in the development of bone cancer pain by regulating the activation of spinal astrocytes.Tanshinone IIA and SZD could improve bone cancer pain behaviors performance, and the inhibition of activation of spinal astrocytes may be one of their mechanisms.