Objective:Injury can lead to long-term changes that increase the sensitivity of afferent nerve endings to subsequent stimulation and pain can transition from acute to chronic.This phenomenon is known as hyperalgesic p...Objective:Injury can lead to long-term changes that increase the sensitivity of afferent nerve endings to subsequent stimulation and pain can transition from acute to chronic.This phenomenon is known as hyperalgesic priming(HP).This study aimed to understand the mechanisms underlying the effect of electroacupuncture(EA)on HP and optimize acupoint selection for EA to prevent pain transition.Methods:A rat HP model was established using sequential intraplantar injections of carrageenan(Cg)and prostaglandin E2(PGE2).The pain thresholds were measured using von Frey filaments.EA on bilateral Zusanli(ST36)and Kunlun(BL60)was used to prevent pain transition.The number of mast cells in the ipsilateral hindpaw skin was determined using toluidine blue or fluorescencelabeled avidin staining.The protein expression levels of protein kinase C epsilon(PKCε)in the lumbar dorsal root ganglions(DRGs)were detected by western blotting 24 h after PGE2 injection.Serial pharmacological experiments were conducted to evaluate the relationship between mast cells and pain transition.Finally,EA on the bilateral ST36 and Chongyang(ST42)or a novel combination(ST36 and ST42 on the ipsilateral side,and ST36 and BL60 on the contralateral side)was used to prevent pain transition.Results:Although EA applied to ST36 and BL60 alleviated acute pain induced by Cg injection,it failed to prevent the pain transition caused by PGE2 injection.Mast cell accumulation in the ipsilateral hind paw was observed 7 days after Cg injection.Furthermore,mast cell degranulation may be responsible for PKCεactivation in the DRG,a marker of pain transition.EA significantly decreased the number of mast cells in the skin of the ipsilateral hind paw when applied at ST36 and ST42,but not when applied at ST36 and BL60.Furthermore,EA employed to ST36 and ST42 significantly reversed long-term hyperalgesia induced by PGE2 injection,even when administered before injection.However,EA did not alleviate acute pain caused by Cg injection.By using a novel acupoint combination,EA simultaneously alleviated acute pain and prevented pain transition.Conclusions:Our study suggests that mast cells play a critical role in both HP and the transition from acute to chronic pain,whereas EA can prevent pain transition by decreasing the number of mast cells in the local tissue.展开更多
Objective:Preventing the transition from acute to chronic pain(pain transition)is a new strategy for treating chronic pain.The present study aimed to investigate the role of K+-Cl−Cotransporter Isoform 2(KCC2)andγ-am...Objective:Preventing the transition from acute to chronic pain(pain transition)is a new strategy for treating chronic pain.The present study aimed to investigate the role of K+-Cl−Cotransporter Isoform 2(KCC2)andγ-aminobutyric acid receptor type A(GABAAR)in the spinal cord dorsal horn(SCDH)in pain transition and the intervention effect of electroacupuncture(EA),and to understand the mechanism of EA in preventing acute and chronic pain transition in the spinal center.Methods:A rat model of hyperalgesic priming(HP)was established by injecting carrageenan(Car)into the plantar area of rats,followed by the injection of prostaglandin E2(PGE2)into the dorsal foot 7 days later.The GABAAR agonist(muscimol)and KCC2 activator(CLP257)were intrathecally injected for three consecutive days after PGE2 injection.EA was applied at a frequency of 2/100 Hz to the bilateral foot Zusanli(ST36)and Kunlun(BL60).A von Frey filament was used to detect the pain threshold in each group of rats.Western blotting(WB)and immunofluorescence(IF)were used to detect GABAAR and KCC2 expression in each rats group.By combining EA intervention with a KCC2 inhibitor(VU0240551),we explored the mechanism of pain transition of EA regulation of GABAAR and KCC2 expression in SCDH.Results:The HP model was established by injecting mice with Car/PGE2.Compared to the normal saline(NS)+NS and NS+PGE2 groups,the pain threshold of the Car+PGE2 group decreased significantly 48 hours after PGE2 injection(P<0.01).The WB results indicated that intrathecal injection of a GABAAR agonist upregulated GABAAR expression in the SCDH of HP model rats(P<0.05).WB and IF results revealed that intrathecal injection of the KCC2 activator significantly increased GABAAR and KCC2 expression in the SCDH of HP model rats(P<0.01)and that GABAAR and KCC2 were co-expressed in the same SCDH cells.Compared to the Car+PGE2 group,EA intervention significantly increased MWTs from 48 to 72 hours after the first injection and 4,24,and 48 hours after the second injection(P<0.01).EA upregulated GABAAR and KCC2 expression in the SCDH of rats with HP(P<0.05).Intrathecal injection of the KCC2 inhibitor blocked the analgesic effect of EA in HP model rats(P<0.01).Conclusions:In SCDH,KCC2 expression was downregulated,causing downregulation of GABAAR expression and resulting in pain transition.EA upregulates KCC2 and GABAAR expression and prevents pain transition.展开更多
基金the Zhejiang Provincial Natural Science Fund of China(LY24H270003)the National Natural Science Fund of China(82174490,82374561)+1 种基金the Zhejiang Medical and Health Science and Technology Program(2021RC098)the Research Project of Zhejiang Chinese Medical University(2022JKZKTS44).
文摘Objective:Injury can lead to long-term changes that increase the sensitivity of afferent nerve endings to subsequent stimulation and pain can transition from acute to chronic.This phenomenon is known as hyperalgesic priming(HP).This study aimed to understand the mechanisms underlying the effect of electroacupuncture(EA)on HP and optimize acupoint selection for EA to prevent pain transition.Methods:A rat HP model was established using sequential intraplantar injections of carrageenan(Cg)and prostaglandin E2(PGE2).The pain thresholds were measured using von Frey filaments.EA on bilateral Zusanli(ST36)and Kunlun(BL60)was used to prevent pain transition.The number of mast cells in the ipsilateral hindpaw skin was determined using toluidine blue or fluorescencelabeled avidin staining.The protein expression levels of protein kinase C epsilon(PKCε)in the lumbar dorsal root ganglions(DRGs)were detected by western blotting 24 h after PGE2 injection.Serial pharmacological experiments were conducted to evaluate the relationship between mast cells and pain transition.Finally,EA on the bilateral ST36 and Chongyang(ST42)or a novel combination(ST36 and ST42 on the ipsilateral side,and ST36 and BL60 on the contralateral side)was used to prevent pain transition.Results:Although EA applied to ST36 and BL60 alleviated acute pain induced by Cg injection,it failed to prevent the pain transition caused by PGE2 injection.Mast cell accumulation in the ipsilateral hind paw was observed 7 days after Cg injection.Furthermore,mast cell degranulation may be responsible for PKCεactivation in the DRG,a marker of pain transition.EA significantly decreased the number of mast cells in the skin of the ipsilateral hind paw when applied at ST36 and ST42,but not when applied at ST36 and BL60.Furthermore,EA employed to ST36 and ST42 significantly reversed long-term hyperalgesia induced by PGE2 injection,even when administered before injection.However,EA did not alleviate acute pain caused by Cg injection.By using a novel acupoint combination,EA simultaneously alleviated acute pain and prevented pain transition.Conclusions:Our study suggests that mast cells play a critical role in both HP and the transition from acute to chronic pain,whereas EA can prevent pain transition by decreasing the number of mast cells in the local tissue.
基金supported by the Natural Science Foundation of Zhejiang Province(No.LY23H270007)。
文摘Objective:Preventing the transition from acute to chronic pain(pain transition)is a new strategy for treating chronic pain.The present study aimed to investigate the role of K+-Cl−Cotransporter Isoform 2(KCC2)andγ-aminobutyric acid receptor type A(GABAAR)in the spinal cord dorsal horn(SCDH)in pain transition and the intervention effect of electroacupuncture(EA),and to understand the mechanism of EA in preventing acute and chronic pain transition in the spinal center.Methods:A rat model of hyperalgesic priming(HP)was established by injecting carrageenan(Car)into the plantar area of rats,followed by the injection of prostaglandin E2(PGE2)into the dorsal foot 7 days later.The GABAAR agonist(muscimol)and KCC2 activator(CLP257)were intrathecally injected for three consecutive days after PGE2 injection.EA was applied at a frequency of 2/100 Hz to the bilateral foot Zusanli(ST36)and Kunlun(BL60).A von Frey filament was used to detect the pain threshold in each group of rats.Western blotting(WB)and immunofluorescence(IF)were used to detect GABAAR and KCC2 expression in each rats group.By combining EA intervention with a KCC2 inhibitor(VU0240551),we explored the mechanism of pain transition of EA regulation of GABAAR and KCC2 expression in SCDH.Results:The HP model was established by injecting mice with Car/PGE2.Compared to the normal saline(NS)+NS and NS+PGE2 groups,the pain threshold of the Car+PGE2 group decreased significantly 48 hours after PGE2 injection(P<0.01).The WB results indicated that intrathecal injection of a GABAAR agonist upregulated GABAAR expression in the SCDH of HP model rats(P<0.05).WB and IF results revealed that intrathecal injection of the KCC2 activator significantly increased GABAAR and KCC2 expression in the SCDH of HP model rats(P<0.01)and that GABAAR and KCC2 were co-expressed in the same SCDH cells.Compared to the Car+PGE2 group,EA intervention significantly increased MWTs from 48 to 72 hours after the first injection and 4,24,and 48 hours after the second injection(P<0.01).EA upregulated GABAAR and KCC2 expression in the SCDH of rats with HP(P<0.05).Intrathecal injection of the KCC2 inhibitor blocked the analgesic effect of EA in HP model rats(P<0.01).Conclusions:In SCDH,KCC2 expression was downregulated,causing downregulation of GABAAR expression and resulting in pain transition.EA upregulates KCC2 and GABAAR expression and prevents pain transition.
