Investigation of mechanism of pain generation focusing on the relationship between muscle adipose tissue and inflammatory cytokines

2020 Fiscal Year Final Research Report

• Project/Area Number: 18K16667
• Research Category: Grant-in-Aid for Early-Career Scientists
• Allocation Type: Multi-year Fund
• Review Section: Basic Section 56020:Orthopedics-related
• Research Institution: Sapporo Medical University
• Principal Investigator: Takashima Hiroyuki 札幌医科大学, 医学部, 研究員 (90608738)
• Project Period (FY): 2018-04-01 – 2021-03-31
• Keywords: chronic low back pain / fat degeneration / intra-myocellular lipid / animal model

Outline of Final Research Achievements

Previous studies have reported the relationship between low back pain (LBP) and fat degeneration or atrophy in the paraspinal muscles. We applied MR spectroscopy to the investigation of LBP. We compared intra-myocellular lipid (IMCL) and extra-myocellular lipid (EMCL) in paraspinal muscles between asymptomatic volunteers and LBP patients and reported that IMCL in Mm of patients with LBP was higher than that in Mm of asymptomatic volunteers. However, there were no fundamental studies investigating relationship between IMCL and pain. To investigate the relationship between pain and IMCL, we considered that it was essential to develop animal model indicating increasing IMCL. This study results that there was significant decrease of IMCL using tail-suspended combined with hind-limbs-casted rat model. Tail-suspended combined with casted rat model enables to use as rat model showing decrease of IMCL.

Free Research Field

脊椎脊髄病学

Academic Significance and Societal Importance of the Research Achievements

IMCLの上昇に伴う遊離脂肪酸の蓄積により脂肪組織特異的なホルモンが分泌され、炎症促進因子（TNFα、IL-6など）の産生が惹起されることで腰痛が発生することが示唆されている。しかし、ヒトでは筋の採取などを含め、これらの仮説を立証することは困難であることから、IMCLの変化を反映する動物モデルの開発はこれらのメカニズムを解明するために必要不可欠である。本研究では、IMCLが低下するモデルを確立することができたが、今後はIMCLが上昇するモデルを開発し、慢性疼痛の病態解明および治療法の開発につながる基礎研究を行うことが可能となる。