A Study On The Analgesic Mechanism Of Acupuncture Stimulation In Knee Osteoarthritis Based On MRS And FMRI

Knee Osteoarthritis(KOA)is common in middle-aged and elderly people,and its main symptom is long-term chronic pain.Acupuncture is an effective method to relieve chronic pain in KOA.Chronic pain and acupuncture analgesia are closely related to nociceptive signal transmission and neurometabolism in the central nervous system,but the exact mechanism remains unclear.As the main inhibitory neurotransmitter in the central nervous system,gamma-aminobutyric acid(GABA)is directly involved in the transmission of pain signals.Therefore,this study used GABA as a biomarker to investigate the mechanism of chronic pain and acupuncture analgesia from the perspective of neurotransmitter metabolism.A total of 31 KOA patients with chronic pain and 33 healthy controls were recruited in this study,and 1H MRS experiment and fMRI experiment were performed respectively.Right thalamic magnetic resonance spectroscopy(MRS)data,whole-brain functional magnetic resonance imaging(fMRI)data,and pain assessment scale were acquired before and after acupuncture stimulation.Since GABA has problems such as low absolute content and overlapping spectral peaks,it is difficult to detect.In this study,MEGA-PRESS sequence was independently designed and developed to collect MRS data and quantitatively detect and evaluate GABA+level.In addition,to further analyze the effect of changes in GABA+levels on brain functional activity,the functional connectivity of the right thalamus to the whole brain was assessed using whole-brain fMRI data.In this study,the subjects were divided into four groups according to gender for data analysis.The 1H MRS experiment found that the GABA+level in the right thalamus of KOA chronic pain patients before acupuncture stimulation was significantly different from that of healthy controls,and the GABA+level in the right thalamus of KOA chronic pain patients before and after acupuncture stimulation showed a significant trend of change.Specifically,for male patients with KOA chronic pain,the GABA+level in the right thalamus was significantly higher than that of healthy controls before acupuncture stimulation,and decreased and tended to the level of healthy controls after acupuncture stimulation;for female patients with KOA chronic pain,the level of GABA+in the right thalamus was significantly lower than that of healthy controls,and increased and tended to the level of healthy controls after acupuncture stimulation,indicating that there are significant gender differences in GABA metabolism in chronic pain and acupuncture analgesia.However,fMRI experiments did not find significant differences between KOA chronic pain patients and healthy controls before acupuncture stimulation,and between KOA chronic pain patients before acupuncture stimulation and after acupuncture stimulation.This study found for the first time that the GABA+levels in the right thalamus of male and female KOA chronic pain patients were significantly different from those of healthy controls before acupuncture stimulation,and the change trend after acupuncture stimulation was opposite,but both tended to the GABA+levels of healthy controls.The results of GABA+levels in the right thalamus indicates that chronic pain of KOA leads to abnormal neurometabolism in patients,and acupuncture promotes the restoration of balance of abnormal neurometabolism.Furthermore,this study revealed significant gender differences in mechanisms of KOA chronic pain and acupuncture analgesia,suggesting that gender factors should be considered in future research on acupuncture analgesia for KOA chronic pain.The above findings help people to understand the mechanisms of chronic pain and acupuncture analgesia with important clinical significance.