Background:The channel-forming protein Pannexin1(Panx1)has been implicated in both human studies and animal models of chronic pain,but the underlying mechanisms remain incompletely understood.Methods:Wild-type(WT,n=24...Background:The channel-forming protein Pannexin1(Panx1)has been implicated in both human studies and animal models of chronic pain,but the underlying mechanisms remain incompletely understood.Methods:Wild-type(WT,n=24),global Panx1 KO(n=24),neuron-specific Panx1 KO(n=20),and glia-specific Panx1 KO(n=20)mice were used in this study at Albert Einstein College of Medicine.The von Frey test was used to quantify pain sensitivity in these mice following complete Freund’s adjuvant(CFA)injection(7,14,and 21 d).The qRT-PCR was employed to measure mRNA levels of Panx1,Panx2,Panx3,Cx43,Calhm1,andβ-catenin.Laser scanning confocal microscopy imaging,Sholl analysis,and electrophysiology were utilized to evaluate the impact of Panx1 on neuronal excitability and morphology in Neuro2a and dorsal root ganglion neurons(DRGNs)in which Panx1 expression or function was manipulated.Ethidium bromide(EtBr)dye uptake assay and calcium imaging were employed to investigate the role of Panx1 in adenosine triphosphate(ATP)sensitivity.β-galactosidase(β-gal)staining was applied to determine the relative cellular expression levels of Panx1 in trigeminal ganglia(TG)and DRG of transgenic mice.Results:Global or neuron-specific Panx1 deletion markedly decreased pain thresholds after CFA stimuli(7,14,and 21 d;P<0.01 vs.WT group),indicating that Panx1 was positively correlated with pain sensitivity.In Neuro2a,global Panx1 deletion dramatically reduced neurite extension and inward currents compared to the WT group(P<0.05),revealing that Panx1 enhanced neurogenesis and excitability.Similarly,global Panx1 deletion significantly suppressed Wnt/β-catenin dependent DRG neurogenesis following 5 d of nerve growth factor(NGF)treatment(P<0.01 vs.WT group).Moreover,Panx1 channels enhanced DRG neuron response to ATP after CFA injection(P<0.01 vs.Panx1 KO group).Furthermore,ATP release increased Ca2+responses in DRGNs and satellite glial cells surrounding them following 7 d of CFA treatment(P<0.01 vs.Panx1 KO group),suggesting that Panx1 in glia also impacts exaggerated neuronal excitability.Interestingly,neuron-specific Panx1 deletion was found to markedly reduce differentiation in cultured DRGNs,as evidenced by stunted neurite outgrowth(P<0.05 vs.Panx1 KO group;P<0.01 vs.WT group or GFAP-Cre group),blunted activation of Wnt/β-catenin signaling(P<0.01 vs.WT,Panx1 KO and GFAP-Cre groups),and diminished cell excitability(P<0.01 vs.GFAP-Cre group)and response to ATP stimulation(P<0.01 vs.WT group).Analysis ofβ-gal staining showed that cellular expression levels of Panx1 in neurons are significantly higher(2.5-fold increase)in the DRG than in the TG.Conclusions:The present study revealed that neuronal Panx1 is a prominent driver of peripheral sensitivity in the setting of inflammatory pain through cell-autonomous effects on neuronal excitability.This hyperexcitability dependence on neuronal Panx1 contrasts with inflammatory orofacial pain,where similar studies revealed a prominent role for glial Panx1.The apparent differences in Panx1 expression in neuronal and non-neuronal TG and DRG cells are likely responsible for the distinct impact of these cell types in the two pain models.展开更多
Brachial plexus avulsion(BPA)is a combined injury involving the central and peripheral nervous systems.Patients with BPA often experience severe neuropathic pain(NP)in the affected limb.NP is insensitive to the existi...Brachial plexus avulsion(BPA)is a combined injury involving the central and peripheral nervous systems.Patients with BPA often experience severe neuropathic pain(NP)in the affected limb.NP is insensitive to the existing treatments,which makes it a challenge to researchers and clinicians.Accumulated evidence shows that a BPA-induced pain state is often accompanied by sympathetic nervous dysfunction,which suggests that the excitation state of the sympathetic nervous system is correlated with the existence of NP.However,the mechanism of how somatosensory neural crosstalk with the sympathetic nerve at the peripheral level remains unclear.In this study,through using a novel BPA C7 root avulsion mouse model,we found that the expression of BDNF and its receptor TrκB in the DRGs of the BPA mice increased,and the markers of sympathetic nervous system activity includingα1 andα2 adrenergic receptors(α1-AR andα2-AR)also increased after BPA.The phenomenon of superexcitation of the sympathetic nervous system,including hypothermia and edema of the affected extremity,was also observed in BPA mice by using CatWalk gait analysis,an infrared thermometer,and an edema evaluation.Genetic knockdown of BDNF in DRGs not only reversed the mechanical allodynia but also alleviated the hypothermia and edema of the affected extremity in BPA mice.Further,intraperitoneal injection of adrenergic receptor inhibitors decreased neuronal excitability in patch clamp recording and reversed the mechanical allodynia of BPA mice.In another branch experiment,we also found the elevated expression of BDNF,TrκB,TH,α1-AR,andα2-AR in DRG tissues from BPA patients compared with normal human DRGs through western blot and immunohistochemistry.Our results revealed that peripheral BDNF is a key molecule in the regulation of somatosensory-sympathetic coupling in BPA-induced NP.This study also opens a novel analgesic target(BDNF)in the treatment of this pain with fewer complications,which has great potential for clinical transformation.展开更多
Tweety-homolog 1(Ttyh1)is expressed in neural tissue and has been implicated in the generation of several brain diseases.However,its functional significance in pain processing is not understood.By disrupting the gene ...Tweety-homolog 1(Ttyh1)is expressed in neural tissue and has been implicated in the generation of several brain diseases.However,its functional significance in pain processing is not understood.By disrupting the gene encoding Ttyh1,we found a loss of Ttyh1 in nociceptors and their central terminals in Ttyh1-deficient mice,along with a reduction in nociceptor excitability and synaptic transmission at identified synapses between nociceptors and spinal neurons projecting to the periaqueductal grey(PAG)in the basal state.More importantly,the peripheral inflammationevoked nociceptor hyperexcitability and spinal synaptic potentiation recorded in spinal-PAG projection neurons were compromised in Ttyh1-deficient mice.Analysis of the paired-pulse ratio and miniature excitatory postsynaptic currents indicated a role of presynaptic Ttyh1 from spinal nociceptor terminals in the regulation of neurotransmitter release.Interfering with Ttyh1 specifically in nociceptors produces a comparable pain relief.Thus,in this study we demonstrated that Ttyh1 is a critical determinant of acute nociception and pain sensitization caused by peripheral inflammation.展开更多
Abdominal pain is the most common symptom of chronic pancreatitis(CP)and is often debilitating for patients and very difficult to treat.To date,there exists no cure for the disease.Treatment strategies focus on sympto...Abdominal pain is the most common symptom of chronic pancreatitis(CP)and is often debilitating for patients and very difficult to treat.To date,there exists no cure for the disease.Treatment strategies focus on symptom management and on mitigation of disease progression by reducing toxin exposure and avoiding recurrent inflammatory events.Traditional treatment protocols start with medical management followed by consideration of procedural or surgical intervention on selected patients with severe and persistent pain.The incorporation of adjuvant therapies to treat comorbidities including psychiatric disorders,exocrine pancreatic insufficiency,mineral bone disease,frailty,and malnutrition,are in its early stages.Recent clinical studies and animal models have been designed to improve investigation into the pathophysiology of CP pain,as well as to improve pain management.Despite the array of tools available,many therapeutic options for the management of CP pain provide incomplete relief.There still remains much to discover about the neural regulation of pancreas-related pain.In this review,we will discuss research from the last 5 years that has provided new insights into novel methods of pain phenotyping and the pathophysiology of CP pain.These discoveries have led to improvements in patient selection for optimization of outcomes for both medical and procedural management,and identification of potential future therapies.展开更多
基金This work was NIH(R01NS092466),NSFC(U2004201)Central Plains Thousand People Plan of Henan Province(204200510013)+1 种基金Henan Overseas Expertise Introduction Center for Discipline Innovation(CXJD2021002)Key Special Project of Zhengzhou University Disciplinary Construction(XKZDJC202001)。
文摘Background:The channel-forming protein Pannexin1(Panx1)has been implicated in both human studies and animal models of chronic pain,but the underlying mechanisms remain incompletely understood.Methods:Wild-type(WT,n=24),global Panx1 KO(n=24),neuron-specific Panx1 KO(n=20),and glia-specific Panx1 KO(n=20)mice were used in this study at Albert Einstein College of Medicine.The von Frey test was used to quantify pain sensitivity in these mice following complete Freund’s adjuvant(CFA)injection(7,14,and 21 d).The qRT-PCR was employed to measure mRNA levels of Panx1,Panx2,Panx3,Cx43,Calhm1,andβ-catenin.Laser scanning confocal microscopy imaging,Sholl analysis,and electrophysiology were utilized to evaluate the impact of Panx1 on neuronal excitability and morphology in Neuro2a and dorsal root ganglion neurons(DRGNs)in which Panx1 expression or function was manipulated.Ethidium bromide(EtBr)dye uptake assay and calcium imaging were employed to investigate the role of Panx1 in adenosine triphosphate(ATP)sensitivity.β-galactosidase(β-gal)staining was applied to determine the relative cellular expression levels of Panx1 in trigeminal ganglia(TG)and DRG of transgenic mice.Results:Global or neuron-specific Panx1 deletion markedly decreased pain thresholds after CFA stimuli(7,14,and 21 d;P<0.01 vs.WT group),indicating that Panx1 was positively correlated with pain sensitivity.In Neuro2a,global Panx1 deletion dramatically reduced neurite extension and inward currents compared to the WT group(P<0.05),revealing that Panx1 enhanced neurogenesis and excitability.Similarly,global Panx1 deletion significantly suppressed Wnt/β-catenin dependent DRG neurogenesis following 5 d of nerve growth factor(NGF)treatment(P<0.01 vs.WT group).Moreover,Panx1 channels enhanced DRG neuron response to ATP after CFA injection(P<0.01 vs.Panx1 KO group).Furthermore,ATP release increased Ca2+responses in DRGNs and satellite glial cells surrounding them following 7 d of CFA treatment(P<0.01 vs.Panx1 KO group),suggesting that Panx1 in glia also impacts exaggerated neuronal excitability.Interestingly,neuron-specific Panx1 deletion was found to markedly reduce differentiation in cultured DRGNs,as evidenced by stunted neurite outgrowth(P<0.05 vs.Panx1 KO group;P<0.01 vs.WT group or GFAP-Cre group),blunted activation of Wnt/β-catenin signaling(P<0.01 vs.WT,Panx1 KO and GFAP-Cre groups),and diminished cell excitability(P<0.01 vs.GFAP-Cre group)and response to ATP stimulation(P<0.01 vs.WT group).Analysis ofβ-gal staining showed that cellular expression levels of Panx1 in neurons are significantly higher(2.5-fold increase)in the DRG than in the TG.Conclusions:The present study revealed that neuronal Panx1 is a prominent driver of peripheral sensitivity in the setting of inflammatory pain through cell-autonomous effects on neuronal excitability.This hyperexcitability dependence on neuronal Panx1 contrasts with inflammatory orofacial pain,where similar studies revealed a prominent role for glial Panx1.The apparent differences in Panx1 expression in neuronal and non-neuronal TG and DRG cells are likely responsible for the distinct impact of these cell types in the two pain models.
基金supported by grants from the National Natural Science Foundation of China(82072526,82171212,and 81870867).
文摘Brachial plexus avulsion(BPA)is a combined injury involving the central and peripheral nervous systems.Patients with BPA often experience severe neuropathic pain(NP)in the affected limb.NP is insensitive to the existing treatments,which makes it a challenge to researchers and clinicians.Accumulated evidence shows that a BPA-induced pain state is often accompanied by sympathetic nervous dysfunction,which suggests that the excitation state of the sympathetic nervous system is correlated with the existence of NP.However,the mechanism of how somatosensory neural crosstalk with the sympathetic nerve at the peripheral level remains unclear.In this study,through using a novel BPA C7 root avulsion mouse model,we found that the expression of BDNF and its receptor TrκB in the DRGs of the BPA mice increased,and the markers of sympathetic nervous system activity includingα1 andα2 adrenergic receptors(α1-AR andα2-AR)also increased after BPA.The phenomenon of superexcitation of the sympathetic nervous system,including hypothermia and edema of the affected extremity,was also observed in BPA mice by using CatWalk gait analysis,an infrared thermometer,and an edema evaluation.Genetic knockdown of BDNF in DRGs not only reversed the mechanical allodynia but also alleviated the hypothermia and edema of the affected extremity in BPA mice.Further,intraperitoneal injection of adrenergic receptor inhibitors decreased neuronal excitability in patch clamp recording and reversed the mechanical allodynia of BPA mice.In another branch experiment,we also found the elevated expression of BDNF,TrκB,TH,α1-AR,andα2-AR in DRG tissues from BPA patients compared with normal human DRGs through western blot and immunohistochemistry.Our results revealed that peripheral BDNF is a key molecule in the regulation of somatosensory-sympathetic coupling in BPA-induced NP.This study also opens a novel analgesic target(BDNF)in the treatment of this pain with fewer complications,which has great potential for clinical transformation.
基金the National Natural Science Foundation of China(31671088 and 31730041)the Natural Science Foundation of Shaanxi Province,China(2017ZDJC-01)。
文摘Tweety-homolog 1(Ttyh1)is expressed in neural tissue and has been implicated in the generation of several brain diseases.However,its functional significance in pain processing is not understood.By disrupting the gene encoding Ttyh1,we found a loss of Ttyh1 in nociceptors and their central terminals in Ttyh1-deficient mice,along with a reduction in nociceptor excitability and synaptic transmission at identified synapses between nociceptors and spinal neurons projecting to the periaqueductal grey(PAG)in the basal state.More importantly,the peripheral inflammationevoked nociceptor hyperexcitability and spinal synaptic potentiation recorded in spinal-PAG projection neurons were compromised in Ttyh1-deficient mice.Analysis of the paired-pulse ratio and miniature excitatory postsynaptic currents indicated a role of presynaptic Ttyh1 from spinal nociceptor terminals in the regulation of neurotransmitter release.Interfering with Ttyh1 specifically in nociceptors produces a comparable pain relief.Thus,in this study we demonstrated that Ttyh1 is a critical determinant of acute nociception and pain sensitization caused by peripheral inflammation.
文摘Abdominal pain is the most common symptom of chronic pancreatitis(CP)and is often debilitating for patients and very difficult to treat.To date,there exists no cure for the disease.Treatment strategies focus on symptom management and on mitigation of disease progression by reducing toxin exposure and avoiding recurrent inflammatory events.Traditional treatment protocols start with medical management followed by consideration of procedural or surgical intervention on selected patients with severe and persistent pain.The incorporation of adjuvant therapies to treat comorbidities including psychiatric disorders,exocrine pancreatic insufficiency,mineral bone disease,frailty,and malnutrition,are in its early stages.Recent clinical studies and animal models have been designed to improve investigation into the pathophysiology of CP pain,as well as to improve pain management.Despite the array of tools available,many therapeutic options for the management of CP pain provide incomplete relief.There still remains much to discover about the neural regulation of pancreas-related pain.In this review,we will discuss research from the last 5 years that has provided new insights into novel methods of pain phenotyping and the pathophysiology of CP pain.These discoveries have led to improvements in patient selection for optimization of outcomes for both medical and procedural management,and identification of potential future therapies.
