Sodium-potassium-chloride cotransporter 1 (NKCC1) and potassium-chloride cotransporter 2 (KCC2) are associated with the transmission of peripheral pain.We investigated whether the increase of NKCC1 and KCC2 is associa...Sodium-potassium-chloride cotransporter 1 (NKCC1) and potassium-chloride cotransporter 2 (KCC2) are associated with the transmission of peripheral pain.We investigated whether the increase of NKCC1 and KCC2 is associated with peripheral pain transmission in dorsal root ganglion neurons.To this aim,rats with persistent hyperalgesia were randomly divided into four groups.Rats in the control group received no treatment,and the rat sciatic nerve was only exposed in the sham group.Rats in the chronic constriction injury group were established into chronic constriction injury models by ligating sciatic nerve and rats were given bumetanide,an inhibitor of NKCC1,based on chronic constriction injury modeling in the chronic constriction injury + bumetanide group.In the experiment measuring thermal withdrawal latency,bumetanide (15 mg/kg) was intravenously administered.In the patch clamp experiment,bumetanide (10 μg/μL) and acutely isolated dorsal root ganglion neurons (on day 14) were incubated for 1 hour,or bumetanide (5 μg/μL) was intrathecally injected.The Hargreaves test was conducted to detect changes in thermal hyperalgesia in rats.We found that the thermal withdrawal latency of rats was significantly decreased on days 7,14,and 21 after model establishment.After intravenous injection of bumetanide,the reduction in thermal retraction latency caused by model establishment was significantly inhibited.Immunohistochemistry and western blot assay results revealed that the immune response and protein expression of NKCC1 in dorsal root ganglion neurons of the chronic constriction injury group increased significantly on days 7,14,and 21 after model establishment.No immune response or protein expression of KCC2 was observed in dorsal root ganglion neurons before and after model establishment.The Cl^– (chloride ion) fluorescent probe technique was used to evaluate the change of Cl^– concentration in dorsal root ganglion neurons of chronic constriction injury model rats.We found that the relative optical density of N-(ethoxycarbonylmethyl)-6-methoxyquinolinium bromide (a Cl^– fluorescent probe whose fluorescence Cenintensity decreases as Cl– concentration increases) in the dorsal root ganglion neurons of the chronic constriction injury group was significantly decreased on days 7 and 14 after model establishment.The whole-cell patch clamp technique revealed that the resting potential and action potential frequency of dorsal root ganglion neurons increased,and the threshold and rheobase of action potentials decreased in the chronic constriction injury group on day 14 after model establishment.After bumetanide administration,the above indicators were significantly suppressed.These results confirm that CCI can induce abnormal overexpression of NKCC1,thereby increasing the Cl^– concentration in dorsal root ganglion neurons;this then enhances the excitability of dorsal root ganglion neurons and ultimately promotes hyperalgesia and allodynia.In addition,bumetanide can achieve analgesic effects.All experiments were approved by the Institutional Ethics Review Board at the First Affiliated Hospital,College of Medicine,Shihezi University,China on February 22,2017 (approval No.A2017-169-01).展开更多
The circadian system plays an immense role in controlling physiological processes in our body.The suprachiasmatic nucleus (SCN) supervises this system,regulating and harmonising the circadian rhythms in our body.Most ...The circadian system plays an immense role in controlling physiological processes in our body.The suprachiasmatic nucleus (SCN) supervises this system,regulating and harmonising the circadian rhythms in our body.Most neurons present in the SCN are GABAergic neurons.Although GABA is considered the main inhibitory neurotransmitter of the CNS,recent studies have shown that excitatory responses were recorded in this area.These responses are enabled by an increase in intracellular chloride ions[Cl;];levels.The chloride (Cl;) levels in GABAergic neurons are controlled by two solute carrier 12 (SLC12)cation-chloride-cotransporters (CCCs):Na^(+)/K^(+)/Cl^(-)co-transporter (NKCC1) and K^(+)/Cl^(-)cotransporter (KCC2),that respectively cause an influx and efflux of Cl^(-).Recent works have found altered expression and/or activity of either of these co-transporters in SCN neurons and have been associated with circadian rhythms.In this review,we summarize and discuss the role of CCCs in circadian rhythms,and highlight these recent advances which attest to CCC’s growing potential as strong research and therapeutic targets.展开更多
基金supported by the National Natural Science Foundation of China,No.30160026(to JQS)the High Level Talent Research Project of Shihezi University of China,No.RCSX201705(to YW)
文摘Sodium-potassium-chloride cotransporter 1 (NKCC1) and potassium-chloride cotransporter 2 (KCC2) are associated with the transmission of peripheral pain.We investigated whether the increase of NKCC1 and KCC2 is associated with peripheral pain transmission in dorsal root ganglion neurons.To this aim,rats with persistent hyperalgesia were randomly divided into four groups.Rats in the control group received no treatment,and the rat sciatic nerve was only exposed in the sham group.Rats in the chronic constriction injury group were established into chronic constriction injury models by ligating sciatic nerve and rats were given bumetanide,an inhibitor of NKCC1,based on chronic constriction injury modeling in the chronic constriction injury + bumetanide group.In the experiment measuring thermal withdrawal latency,bumetanide (15 mg/kg) was intravenously administered.In the patch clamp experiment,bumetanide (10 μg/μL) and acutely isolated dorsal root ganglion neurons (on day 14) were incubated for 1 hour,or bumetanide (5 μg/μL) was intrathecally injected.The Hargreaves test was conducted to detect changes in thermal hyperalgesia in rats.We found that the thermal withdrawal latency of rats was significantly decreased on days 7,14,and 21 after model establishment.After intravenous injection of bumetanide,the reduction in thermal retraction latency caused by model establishment was significantly inhibited.Immunohistochemistry and western blot assay results revealed that the immune response and protein expression of NKCC1 in dorsal root ganglion neurons of the chronic constriction injury group increased significantly on days 7,14,and 21 after model establishment.No immune response or protein expression of KCC2 was observed in dorsal root ganglion neurons before and after model establishment.The Cl^– (chloride ion) fluorescent probe technique was used to evaluate the change of Cl^– concentration in dorsal root ganglion neurons of chronic constriction injury model rats.We found that the relative optical density of N-(ethoxycarbonylmethyl)-6-methoxyquinolinium bromide (a Cl^– fluorescent probe whose fluorescence Cenintensity decreases as Cl– concentration increases) in the dorsal root ganglion neurons of the chronic constriction injury group was significantly decreased on days 7 and 14 after model establishment.The whole-cell patch clamp technique revealed that the resting potential and action potential frequency of dorsal root ganglion neurons increased,and the threshold and rheobase of action potentials decreased in the chronic constriction injury group on day 14 after model establishment.After bumetanide administration,the above indicators were significantly suppressed.These results confirm that CCI can induce abnormal overexpression of NKCC1,thereby increasing the Cl^– concentration in dorsal root ganglion neurons;this then enhances the excitability of dorsal root ganglion neurons and ultimately promotes hyperalgesia and allodynia.In addition,bumetanide can achieve analgesic effects.All experiments were approved by the Institutional Ethics Review Board at the First Affiliated Hospital,College of Medicine,Shihezi University,China on February 22,2017 (approval No.A2017-169-01).
基金supported by a Commonwealth Ph D Scholarship(S.S.J.)NSFC grants to Y.W.(31771188,31471027)+1 种基金the University of Exeter Medical School start-up fund(J.Z.)NIH Grants R01 NS109358(J.Z.)。
文摘The circadian system plays an immense role in controlling physiological processes in our body.The suprachiasmatic nucleus (SCN) supervises this system,regulating and harmonising the circadian rhythms in our body.Most neurons present in the SCN are GABAergic neurons.Although GABA is considered the main inhibitory neurotransmitter of the CNS,recent studies have shown that excitatory responses were recorded in this area.These responses are enabled by an increase in intracellular chloride ions[Cl;];levels.The chloride (Cl;) levels in GABAergic neurons are controlled by two solute carrier 12 (SLC12)cation-chloride-cotransporters (CCCs):Na^(+)/K^(+)/Cl^(-)co-transporter (NKCC1) and K^(+)/Cl^(-)cotransporter (KCC2),that respectively cause an influx and efflux of Cl^(-).Recent works have found altered expression and/or activity of either of these co-transporters in SCN neurons and have been associated with circadian rhythms.In this review,we summarize and discuss the role of CCCs in circadian rhythms,and highlight these recent advances which attest to CCC’s growing potential as strong research and therapeutic targets.
