P2Y1 receptor in Alzheimer’s disease

Alzheimer’s disease is the most frequent form of dementia characterized by the deposition of amyloid-beta plaques and neurofibrillary tangles consisting of hyperphosphorylated tau.Targeting amyloid-beta plaques has been a primary direction for developing Alzheimer’s disease treatments in the last decades.However,existing drugs targeting amyloid-beta plaques have not fully yielded the expected results in the clinic,necessitating the exploration of alternative therapeutic strategies.Increasing evidence unravels that astrocyte morphology and function alter in the brain of Alzheimer’s disease patients,with dysregulated astrocytic purinergic receptors,particularly the P2Y1 receptor,all of which constitute the pathophysiology of Alzheimer’s disease.These receptors are not only crucial for maintaining normal astrocyte function but are also highly implicated in neuroinflammation in Alzheimer’s disease.This review delves into recent insights into the association between P2Y1 receptor and Alzheimer’s disease to underscore the potential neuroprotective role of P2Y1 receptor in Alzheimer’s disease by mitigating neuroinflammation,thus offering promising avenues for developing drugs for Alzheimer’s disease and potentially contributing to the development of more effective treatments.

Therapeutic potential of extracellular ATP and P2 receptors in nervous system diseases

Extracellular adenosine 5’-triphosphate(ATP) is a key signaling molecule present in the central nervous system(CNS),and now is receiving greater attention due to its role as a messenger in the CNS during different physiological and pathological events. ATP is released into the extracellular space through vesicular exocytosis or from damaged and dying cells. Once in the extracellular environment,ATP binds to the specific receptors termed P2,which mediate ATP effects and are present broadly in both neurons an...

Role of P2X_7 receptors in neuronal death in the retina

Acknowledgments： I would like to express my appreciation to Professor Puro DG for leading me to this research topic during my stay as a research fellow in his laboratory at the University of Michigan in 2001, and also to Professor Ikeda T forgiving me the opportunity to study abroad and then to continue to investigate this topic in the Department of Ophthalmology at Osaka Medical College, lapan.

P2X receptors in maintenance and differentiation of neural progenitor cells

Purinergic receptors are among the first cell surface receptors expressed during embryonic development （Burnstock and Ulrich, 2011）. These are characterized based on their pharmacological properties of being activated by adenosine or purine/pyrimidine nucleotides as P1 and P2 receptors. P2 receptors are further classified by their structure as P2Y metabotropic and P2X ionotropic receptors.

Regulation of neural stem/progenitor cell functions by P2X and P2Y receptors

Neural stem/progenitor cells：Radial glial cells constitute multipotent cells in the ventricular zone,lining the wall of the lateral ventricle of the embryonic brain.They have the capacity to give rise to cells belonging to all three major linages（neurons,astrocytes and oligodendrocytes）of the nervous system（Tang and Illes,2017）.

Study of the roles of caspase-3 and nuclear factor kappa B in myenteric neurons in a P2X7 receptor knockout mouse model of ulcerative colitis

BACKGROUND The literature indicates that the enteric nervous system is affected in inflammatory bowel diseases(IBDs)and that the P2X7 receptor triggers neuronal death.However,the mechanism by which enteric neurons are lost in IBDs is unknown.AIM To study the role of the caspase-3 and nuclear factor kappa B(NF-κB)pathways in myenteric neurons in a P2X7 receptor knockout(KO)mouse model of IBDs.METHODS Forty male wild-type(WT)C57BL/6 and P2X7 receptor KO mice were euthanized 24 h or 4 d after colitis induction by 2,4,6-trinitrobenzene sulfonic acid(colitis group).Mice in the sham groups were injected with vehicle.The mice were divided into eight groups(n=5):The WT sham 24 h and 4 d groups,the WT colitis 24 h and 4 d groups,the KO sham 24 h and 4 d groups,and the KO colitis 24 h and 4 d groups.The disease activity index(DAI)was analyzed,the distal colon was collected for immunohistochemistry analyses,and immunofluorescence was performed to identify neurons immunoreactive(ir)for calretinin,P2X7 receptor,cleaved caspase-3,total caspase-3,phospho-NF-κB,and total NF-κB.We analyzed the number of calretinin-ir and P2X7 receptor-ir neurons per ganglion,the neuronal profile area(μm^(2)),and corrected total cell fluorescence(CTCF).RESULTS Cells double labeled for calretinin and P2X7 receptor,cleaved caspase-3,total caspase-3,phospho-NF-κB,or total NF-κB were observed in the WT colitis 24 h and 4 d groups.The number of calretinin-ir neurons per ganglion was decreased in the WT colitis 24 h and 4 d groups compared to the WT sham 24 h and 4 d groups,respectively(2.10±0.13 vs 3.33±0.17,P<0.001;2.92±0.12 vs 3.70±0.11,P<0.05),but was not significantly different between the KO groups.The calretinin-ir neuronal profile area was increased in the WT colitis 24 h group compared to the WT sham 24 h group(312.60±7.85 vs 278.41±6.65,P<0.05),and the nuclear profile area was decreased in the WT colitis 4 d group compared to the WT sham 4 d group(104.63±2.49 vs 117.41±1.14,P<0.01).The number of P2X7 receptor-ir neurons per ganglion was decreased in the WT colitis 24 h and 4 d groups compared to the WT sham 24 h and 4 d groups,respectively(19.49±0.35 vs 22.21±0.18,P<0.001;20.35±0.14 vs 22.75±0.51,P<0.001),and no P2X7 receptor-ir neurons were observed in the KO groups.Myenteric neurons showed ultrastructural changes in the WT colitis 24 h and 4 d groups and in the KO colitis 24 h group.The cleaved caspase-3 CTCF was increased in the WT colitis 24 h and 4 d groups compared to the WT sham 24 h and 4 d groups,respectively(485949±14140 vs 371371±16426,P<0.001;480381±11336 vs 378365±4053,P<0.001),but was not significantly different between the KO groups.The total caspase-3 CTCF,phospho-NF-κB CTCF,and total NF-κB CTCF were not significantly different among the groups.The DAI was recovered in the KO groups.Furthermore,we demonstrated that the absence of the P2X7 receptor attenuated inflammatory infiltration,tissue damage,collagen deposition,and the decrease in the number of goblet cells in the distal colon.CONCLUSION Ulcerative colitis affects myenteric neurons in WT mice but has a weaker effect in P2X7 receptor KO mice,and neuronal death may be associated with P2X7 receptor-mediated caspase-3 activation.The P2X7 receptor can be a therapeutic target for IBDs.

The bumpy road of purinergic inhibitors to clinical application in immune-mediated diseases

Purinergic signaling plays important roles throughout the body in the regulation of organ functions during and following the disruption of homeostasis.This is also reflected by the widespread expression of two families of purinergic receptors(P1 and P2)with numerous subtypes.In the last few decades,there has been increasing evidence that purinergic signaling plays an important role in the regulation of immune functions.Mainly,signals mediated by P2 receptors have been shown to contribute to immune system-mediated pathologies.Thus,interference with P2 receptors may be a promising strategy for the modulation of immune responses.Although only a few clinical studies have been conducted in isolated entities with limited success,preclinical work suggests that the use of P2 receptor inhibitors may bear some promise in various autoimmune diseases.Despite the association of P2 receptors with several disorders from this field,the use of P2 receptor antagonists in clinical therapy is still very scarce.In this narrative review,we briefly review the involvement of the purinergic system in immunological responses and clinical studies on the effect of purinergic inhibition on autoimmune processes.We then open the aperture a bit and show some preclinical studies demonstrating a potential effect of purinergic blockade on autoimmune events.Using suramin,a non-specific purinergic inhibitor,as an example,we further show that off-target effects could be responsible for observed effects in immunological settings,which may have interesting implications.Overall,we believe that it is worthwhile to further investigate this hitherto underexplored area.

Quercetin inhibits truncated isoform of dopamine-and cAMP-regulated phosphoprotein as adjuvant treatment for trastuzumab therapy resistance in HER2-positive breast cancer

Trastuzumab resistance is one of the causes of poor prognosis in patients with human epidermal growth factor receptor 2(HER2)-positive(HER2+)breast cancer(BC).The truncated isoform of dopamine-and cAMPregulated phosphoprotein(t-DARPP)has been reported to be involved in trastuzumab therapy resistance and promoting tumor progression.To evaluate the t-DARPP expression in BC,paired tumors and surrounding normal tissues were analyzed by real-time polymerase chain reaction and confirmed higher DARPP-32 kDa family mRNA expression in HER2+BC tumor tissues.We established 2 patient-derived xenografts(PDX)mice models to test the efficacy of trastuzumab,named model 1(non-responder)and model 2(responder).t-DARPP and p95-HER2 protein-protein interactions were detected in PDX tumor tissue from non-responders using Förster resonance energy transfer assays.Instead,there is no response from the responder.Furthermore,mechanistic studies using transwell and western blot assays demonstrated that t-DARPP could upregulate epithelial-mesenchymal transition signaling proteins,enhance p95-HER2 expression and promote cell migration.We found that quercetin effectively reduced t-DARPP expression in HER2+BC cells.In t-DARPP ShRNA-suppressed cells,quercetin synergistically enhanced trastuzumab-induced apoptotic cell death and G2/M phase arrest.In conclusion,the combination of quercetin and trastuzumab treatment by targeting t-DARPP in HER2+BC patients has the potential as a biomarker for mitigating drug resistance.

Effects of P2Y_1 receptor on glial fibrillary acidic protein and glial cell line-derived neurotrophic factor production of astrocytes under ischemic condition and the related signaling pathways

Objective The present study aimed to explore the role of P2Y1 receptor in glial fibrillary acidic protein （GFAP） production and glial cell line-derived neurotrophic factor （GDNF） secretion of astrocytes under ischemic insult and the related signaling pathways. Methods Using transient right middle cerebral artery occlusion （tMCAO） and oxygen-glucose-serum deprivation for 2 h as the model of ischemic injury in vivo and in vitro, immunofluorescence, quantitative real-time reverse transcription-polymerase chain reaction （RT-PCR）, Western blotting, enzyme linked immunosorbent assay （ELISA） were used to investigate location of P2Y1 receptor and GDNF, the expression of GFAP and GDNF, and the changes of signaling molecules. Results Blockage of P2Y1 receptor with the selective antagonist N^6-methyl-2′-deoxyadenosine 3′,5′-bisphosphate diammonium （MRS2179） reduced GFAP production and increased GDNF production in the antagonist group as compared with simple ischemic group both in vivo and in vitro. Oxygen-glucose-serum deprivation and blockage of P2Y1 receptor caused elevation of phosphorylated Akt and cAMP response element binding protein （CREB）, and reduction of phosphorylated Janus kinase2 （JAK2） and signal transducer and activator of transcription3 （STAT3, Ser727）. After blockage of P2Y1 receptor and deprivation of oxygen-glucose-serum, AG490 （inhibitor of JAK2） reduced phosphorylation of STAT3 （Ser727） as well as expression of GFAP; LY294002, an inhibitor of phosphatidylinositol 3-kinase （PI3-K）, decreased phosphorylation of Akt and CREB; the inhibitor of mitogen-activated protein kinase kinase 1/2 （MEK 1/2） U0126, an important molecule of Ras/extracellular signal- regulated kinase （ERK） signaling pathway, decreased the phosphorylation of JAK2, STAT3 （Ser727）, Akt and CREB. Conclusion These results suggest that P2Y1 receptor plays a role in the production of GFAP and GDNF in astrocytes under transient ischemic condition and the related signaling pathways may be JAK2/STAT3 and PI3-K/Akt/CREB, respectively, and that crosstalk probably exists between them.

Electroacupuncture at He-Mu points reduces P2X_4 receptor expression in visceral hypersensitivity

Electroacupuncture at Shangjuxu （ST37） and Tianshu （ST25） was reported to improve visceral hypersensitivity in rats, Colorectal distension was utilized to generate a rat model of chronic visceral hypersensitivity in irritable bowel syndrome, Results showed that abdominal withdrawal reflex scores noticeably increased after model establishment. Simultaneously, P2X4 receptor immunore- activity significantly increased in the colon and spinal cord. Electroacupuncture and pinaverium bromide therapy both markedly decreased abdominal withdrawal reflex scores in rats with visceral hypersensitivity, and significantly decreased P2X4 receptor immunoreactivity in the colon and spinal cord. These data suggest that electroacupuncture treatment can improve visceral hypersensitivity in rats with irritable bowel syndrome by diminishing P2X4 receptor immunoreactivity in the colon and spinal cord,

Electroacupuncture diminishes P2X_2 and P2X_3 purinergic receptor expression in dorsal root ganglia of rats with visceral hypersensitivity

Electroacupuncture at Shangjuxu （ST37） and Tianshu （ST25） can improve visceral hypersensitivity in rats. Colorectal distension was used to establish a rat model of chronic visceral hypersensitivity. Immunohistochemistry was used to detect P2X2 and P2X3 receptor expression in dorsal root ganglia from rats with chronic visceral hypersensitivity. Results demonstrated that abdominal withdrawal reflex scores obviously increased following establishment of the model, indicating visceral hypersensitivity. Simultaneously, P2X2 and P2X3 receptor expression increased in dorsal root ganglia. After bilateral electroacupuncture at Shangjuxu and Tianshu, abdominal withdrawal reflex scores and P2X2 and P2X3 receptor expression decreased in rats with visceral hypersensitivity. These results indicated that electroacupuncture treatment improved visceral hypersensitivity in rats with irritable bowel syndrome by reducing P2X2 and P2X3 receptor expression in dorsal root ganglia.

P2Y1R is involved in visceral hypersensitivity in rats with experimental irritable bowel syndrome

AIM To evaluate the role of P2Y1 R in visceral hypersensitivity in rats with experimental irritable bowel syndrome.METHODS A rat model of irritable bowel syndrome was generated by intra-colonic administration of acetic acid(AA) and assessed by histology and myeloperoxidase(m PO) activity assay. Then P2Y1 R expression in the colonic tissue was detected by Western blot. In order to explore the regulatory role of P2Y1 R in visceral hypersensitivity, an agonist(m RS2365) and an antagonist(m RS2179) of P2Y1 R were intra-colonically administered and effects were tested through a colorectal distension test. The abdominal withdrawal reflex and abdominal electromyography were tested during the course. RESULTS model assessment tests showed an obvious inflammatoryreaction that appeared on the 2^(nd) d after the AA injection, and the inflammatory reaction gradually recovered and almost disappeared on the 7^(th) d. The model finished on day 8 and showed a clear feature of IBS that had no organic lesion. The average expression of P2Y1 R was significantly higher in the AA group than in the na?ve group(0.319 ± 0.02 vs 0.094 ± 0.016, P < 0.001). m RS2365 could effectively raise the colonic hypersensitivity status at intervention doses of 10(AUC value from 0.30 ± 0.089 to 1.973 ± 0.127 mv?s, P < 0.01) and 100 μmol/L(AUC value from 0.290 ± 0.079 to 1.983 ± 0.195 mv?s, P < 0.01); m RS2179 could effectively reduce the hypersensitivity status at intervention dose of 100 μmol/L(from a mean baseline AUC value of 1.587 ± 0.099 mv?s to 0.140 ± 0.089 mv?s, P < 0.0001). Differences between the m RS2179 group(1.88 ± 1.45) and either the m RS2365 group(3.96 ± 0.19) or the combined treatment(m RS2179 and m RS2365) group(3.28 ± 0.11) were significant(P < 0.01).CONCLUSION P2Y1 R plays a regulatory role in visceral hypersensitivity in rats with experimental IBS. Specific antagonists of P2Y1 R may have potential therapeutic value in treating abdominal pain in IBS.

Distribution of the P2X2 receptor and chemical coding in ileal enteric neurons of obese male mice(ob/ob)

AIM:To investigate the colocalization,density and profile of neuronal areas of enteric neurons in the ileum of male obese mice.METHODS:The small intestinal samples of male mice in an obese group(OG)(C57BL/6J ob/ob)and a control group(CG)(+/+)were used.The tissues were analyzed using a double immunostaining technique for immunoreactivity(ir)of the P2X2 receptor,nitric oxide synthase(NOS),choline acetyl transferase(ChAT)and calretinin(Calr).Also,we investigated the density and profile of neuronal areas of the NOS-,ChAT-and Calrir neurons in the myenteric plexus.Myenteric neurons were labeled using an NADH-diaphorase histochemical staining method.RESULTS:The analysis demonstrated that the P2X2receptor was expressed in the cytoplasm and in the nuclear and cytoplasmic membranes only in the CG.Neuronal density values(neuron/cm2)decreased 31%(CG:6579±837;OG:4556±407)and 16.5%(CG:7796±528;OG:6513±610)in the NOS-ir and calretininir neurons in the OG,respectively(P<0.05).Density of ChAT-ir(CG:6200±310;OG:8125±749)neurons significantly increased 31%in the OG(P<0.05).Neuron size studies demonstrated that NOS,ChAT,and Calr-ir neurons did not differ significantly between the CG and OG groups.The examination of NADH-diaphorase-positive myenteric neurons revealed an overall similarity between the OG and CG.CONCLUSION:Obesity may exert its effects by promoting a decrease in P2X2 receptor expression and modifications in the density of the NOS-ir,ChAT-ir and CalR-ir myenteric neurons.

Expression of the P2X_2 receptor in different classes of ileum myenteric neurons in the female obese ob/ob mouse

AIM:To examine whether the ob/ob mouse model of obesity is accompanied by enteric nervous system ab-normalities such as altered motility METHODS:The study examined the distribution of the P2X 2 receptor (P2X 2 R) in myenteric neurons of female ob/ob mice. Specifically, we used immunohistochemistry to analyze the co-expression of the P2X 2 R with neuronal nitric oxide synthase (nNOS), choline acetyltrans-ferase (ChAT), and calretinin (CalR) in neurons of the small intestine myenteric plexus in ob/ob and control female mice In these sections, we used scanning confocal microscopy to analyze the co-localization of these markers as well as the neuronal density (cm 2 ) and area profile (μm2) of P2X 2 R-positive neurons In addition, enteric neurons were labeled using the nicotinamide adenine dinucleotide (NA H) diaphorase method and analyzed with light microscopy as an alternate means by which to analyze neuronal density and areaRESULTS:In the present study, we observed a 29 6% increase in the body weight of the ob/ob animals (OG) compared to the control group (CG) In addition, the average small intestine area was increased by approxi-mately 29 6% in the OG compared to the CG Immu-noreactivity (IR) for the P2X 2 R, nNOS, ChAT and CalR was detectable in the myenteric plexus, as well as in the smooth muscle, in both groups This IR appeared to be mainly cytoplasmic and was also associated with the cell membrane of the myenteric plexus neurons, where it outlined the neuronal cell bodies and their processes P2X 2 R-IR was observed to co-localize 100% with that for nNOS, ChAT and CalR in neurons of both groups In the ob/ob group, however, we observed that the neuronal density (neuron/cm 2 ) of P2X 2 R-IR cells was in-creased by 62% compared to CG, while that of NOS-IR and ChAT-IR neurons was reduced by 49% and 57%, respectively, compared to control mice The neuronal density of CalR-IR neurons was not different between the groups Morphometric studies further demonstrated that the cell body profile area (μm2) of nNOS-IR, ChAT-IR and CalR-IR neurons was increased by 34%, 20% and 55%, respectively, in the OG compared to controls Staining for NA H diaphorase activity is widely used to detect alterations in the enteric nervous system; however, our qualitative examination of NA H-diaphorase positive neurons in the myenteric ganglia revealed an overall similarity between the two groups CONCLUSION:We demonstrate increases in P2X2R expression and alterations in nNOS, ChAT and CalR IR in ileal myenteric neurons of female ob/ob mice compared to wild-type controls.

Electroacupuncture improves neuropathic pain Adenosine, adenosine 5'-triphosphate disodium and their receptors perhaps change simultaneously

Applying a stimulating current to acupoints through acupuncture needles–known as electroacupuncture–has the potential to produce analgesic effects in human subjects and experimental animals. When acupuncture was applied in a rat model, adenosine 5-triphosphate disodium in the extracellular space was broken down into adenosine, which in turn inhibited pain transmission by means of an adenosine A1 receptor-dependent process. Direct injection of an adenosine A1 receptor agonist enhanced the analgesic effect of acupuncture. The analgesic effect of acupuncture appears to be mediated by activation of A1 receptors located on ascending nerves. In neuropathic pain, there is upregulation of P2X purinoceptor 3 （P2X3） receptor expression in dorsal root ganglion neurons. Conversely, the onset of mechanical hyperalgesia was diminished and established hyperalgesia was significantly reversed when P2X3 receptor expression was downregulated. The pathways upon which electroacupuncture appear to act are interwoven with pain pathways, and electroacupuncture stimuli converge with impulses originating from painful areas. Electroacupuncture may act via purinergic A1 and P2X3 receptors simultaneously to induce an analgesic effect on neuropathic pain.

Enteric nervous system and inflammatory bowel diseases:Correlated impacts and therapeutic approaches through the P2X7 receptor

The enteric nervous system(ENS)consists of thousands of small ganglia arranged in the submucosal and myenteric plexuses,which can be negatively affected by Crohn’s disease and ulcerative colitis-inflammatory bowel diseases(IBDs).IBDs are complex and multifactorial disorders characterized by chronic and recurrent inflammation of the intestine,and the symptoms of IBDs may include abdominal pain,diarrhea,rectal bleeding,and weight loss.The P2X7 receptor has become a promising therapeutic target for IBDs,especially owing to its wide expression and,in the case of other purinergic receptors,in both human and model animal enteric cells.However,little is known about the actual involvement between the activation of the P2X7 receptor and the cascade of subsequent events and how all these activities associated with chemical signals interfere with the functionality of the affected or treated intestine.In this review,an integrated view is provided,correlating the structural organization of the ENS and the effects of IBDs,focusing on cellular constituents and how therapeutic approaches through the P2X7 receptor can assist in both protection from damage and tissue preservation.

P2X7 receptor as the regulator of T-cell function in intestinal barrier disruption

The intestinal mucosa is a highly compartmentalized structure that forms a directbarrier between the host intestine and the environment, and its dysfunction couldresult in a serious disease. As T cells, which are important components of themucosal immune system, interact with gut microbiota and maintain intestinalhomeostasis, they may be involved in the process of intestinal barrier dysfunction.P2X7 receptor (P2X7R), a member of the P2X receptors family, mediates the effectsof extracellular adenosine triphosphate and is expressed by most innate or adaptiveimmune cells, including T cells. Current evidence has demonstrated thatP2X7R is involved in inflammation and mediates the survival and differentiationof T lymphocytes, indicating its potential role in the regulation of T cell function.In this review, we summarize the available research about the regulatory role andmechanism of P2X7R on the intestinal mucosa-derived T cells in the setting ofintestinal barrier dysfunction.

P2X4 receptor and brain-derived neurotrophic factor in neuropathic pain

Objective:To investigate whether the activation of p38MAPK is involved in the neuropathic pain induced by P2X4 receptor,and the effects of activated P2X4 receptor and p38MAPK on expression of brain-derived neurotrophic factor (BDNF) in the chronic neuropathic pain.Methods:Lumbar intrathecal catheters were chronically implanted in male Sprague-Dawley rats.The right sciatic nerve was loosely ligated proximal to the sciatica's trifurcation at approximately 1.0 mm intervals with 4-0 silk sutures.The microglia inhibitor minocycline,P2X4 antagonist (TNP-ATP) and p38MAPK inhibitor (SB203580) were intrathecally administered every 12 h,3 d post-chronic constriction injury (CCI).Mechanical nociceptive thresholds were assessed with the paw withdrawal threshold (PWT) to von Frey filaments.The expression of P2X4 and BDNF were assessed by both immunohistochemical analysis and RT-PCR.Results:Intrathecal injection of minocycline or TNP-ATP or SB203580 significantly attenuated CCI-induced mechanical allodynia.The time courses of P2X4 receptor and BDNF expression were increased at all points after CCI and reached a peak level on postoperative d 7.Intrathecal injection of minocycline or TNP-ATP or SB203580 markedly suppressed the increase of CCI-induced P2X4 receptor and BDNF expression in the spinal cord.Conclusion:The activation of P2X4 receptor BDNF pathways contributes to neuropathic pain in CCI rats,and the activation of p38MAPK is involved in the neuropathic pain induced by P2X4 receptor.

Microencapsulated Schwann cell transplantation inhibits P2X3 receptor expression in dorsal root ganglia and neuropathic pain

Schwann cell transplantation is a promising method to promote neural repair, and can be used for peripheral nerve protection and myelination. Microcapsule technology largely mitigates immune rejection of transplanted cells. We previously showed that microencapsulated olfactory ensheathing cells can reduce neuropathic pain and we hypothesized that microencapsulated Schwann cells can also inhibit neuropathic pain. Rat Schwann cells were cultured by subculture and then microencapsulated and were tested using a rat chronic constriction injury（CCI） neuropathic pain model. CCI rats were treated with Schwann cells or microencapsulated Schwann cells and were compared with sham and CCI groups. Mechanical withdrawal threshold and thermal withdrawal latency were assessed preoperatively and at 1, 3, 5, 7, 9, 11 and 14 days postoperatively. The expression of P2X3 receptors in L4-5 dorsal root ganglia of the different groups was detected by double-label immunofluorescence on day 14 after surgery. Compared with the chronic constriction injury group, mechanical withdrawal threshold and thermal withdrawal latency were higher, but the expression of P2X3 receptors was remarkably decreased in rats treated with Schwann cells and microencapsulated Schwann cells, especially in the rats transplanted with microencapsulated Schwann cells. The above data show that microencapsulated Schwann cell transplantation inhibits P2X3 receptor expression in L4-5 dorsal root ganglia and neuropathic pain.

Electrophysiological evidence of P2X2 receptor expression in the neurons of intracardiac and paratracheal ganglia

Objective： To investigate the expression of P2X receptors on rat intracardiac and paratracheal ganglion neurons. Methods： For preparation of intracardiac neurons, hearts were excised, the atria were separated and the medial region containing intracardiac ganglia was isolated and cut into pieces. For preparation of paratracheal neurons, the tracheas were removed and the superficial membranous layer containing paratracheal ganglia was rapidly isolated. Intracardiac and paratracheal ganglion neurons were dissociated after digestion by collagenase and trypsin. Whole-cell patch clamp recording was used to identify the pharmacological properties of P2X receptors in cultured neurons. Results：Neurons from these two ganglia responded to ATP with a rapidly activating, sustained inward current, αβ-meATP failed to evoke any re- sponses in paratracheal ganglion neurons while a few of intracardiac ganglion neurons responded to αβ- meATP with a tiny sustained inward current. ADP and UTP had no effect on intracardiac neurons. Lowering pH potentiated ATP responses in neurons from these two ganglia whereas increasing pH inhibited ATP responses. Co-application of Zn^2＋ potentiated ATP responses in intracardiac and paratracheal ganglion neurons. Conclusion： The receptor subtypes involved in intracardiac and paratracheal ganglia appear to be homomeric P2X2, while heteromeric P2X2/3 could not be completely excluded from intracardiac neurons.