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P2X Receptors (p2x + receptor)

Distribution by Scientific Domains

Medical Sciences	75%
Life Sciences	25%

Selected Abstracts

Roles of P2X receptors and Ca2+ sensitization in extracellular adenosine triphosphate-induced hyperresponsiveness in airway smooth muscle

CLINICAL & EXPERIMENTAL ALLERGY, Issue 6 2007
T. Oguma
Summary Background The release of adenosine triphosphate (ATP) from the airway epithelial cells during the inflammatory process is considered to play an important role in the pathophysiology of asthma and chronic obstructive pulmonary disease. Objective This study was designed to determine whether extracellular ATP is involved in the bronchial hyperresponsiveness as an interaction between epithelium and smooth muscle in the airways. Methods We examined the contractile response to methacholine (MCh) before and after exposure to low concentrations (10 ,m) of ATP in isolated, epithelium-denuded guinea-pig tracheal smooth muscle by measuring isometric tension. Intracellular Ca2+ concentrations ([Ca2+]i) were assessed by fluorescent intensities of fura-2. Results MCh-induced contractile force was increased with no change in [Ca2+]i after exposure to 10 ,m ATP for 15 min. The ability of ATP to enhance the MCh-induced contraction was markedly attenuated by suramin, a non-selective P2 receptor inhibitor. Pre-incubation with ATP,S, a non-hydrolysable analogue of ATP and ,,,-meATP, a P2X agonist, also enhanced the MCh-induced contraction. In contrast, uracil triphosphate, a P2Y agonist, did not affect the MCh-induced contraction. Y-27632, a Rho-kinase inhibitor, suppressed the ability of ATP to enhance the MCh-induced contraction. Moreover, PP1 and PP2, Src tyrosin kinase inhibitors, suppressed the enhancement of MCh-induced contraction by ATP. Conclusion Pre-treatment with ATP induces hyperresponsiveness to MCh mediated by Ca2+ sensitization via the P2X receptor in airway smooth muscle. The present findings suggest the possible involvement of both the Rho-kinase and Src pathways in the intracellular mechanism of this phenomenon. [source]

Evolutionary origins of the purinergic signalling system

ACTA PHYSIOLOGICA, Issue 4 2009
G. Burnstock
Abstract Purines appear to be the most primitive and widespread chemical messengers in the animal and plant kingdoms. The evidence for purinergic signalling in plants, invertebrates and lower vertebrates is reviewed. Much is based on pharmacological studies, but important recent studies have utilized the techniques of molecular biology and receptors have been cloned and characterized in primitive invertebrates, including the social amoeba Dictyostelium and the platyhelminth Schistosoma, as well as the green algae Ostreococcus, which resemble P2X receptors identified in mammals. This suggests that contrary to earlier speculations, P2X ion channel receptors appeared early in evolution, while G protein-coupled P1 and P2Y receptors were introduced either at the same time or perhaps even later. The absence of gene coding for P2X receptors in some animal groups [e.g. in some insects, roundworms (Caenorhabditis elegans) and the plant Arabidopsis] in contrast to the potent pharmacological actions of nucleotides in the same species, suggests that novel receptors are still to be discovered. [source]

Peripheral sensitization in migraine,role for P2X purinergic receptors in the dura,vascular sensory pathway

DRUG DEVELOPMENT RESEARCH, Issue 6 2007
Ernest A. Jennings
Abstract Peripheral sensitization is still considered a prime contributor underlying the mechanisms of migraine. Trigeminal primary afferent neurons are the first neurons in the dural nociceptive pathway, and activation results in conscious perception of pain. Peripheral sensitization can lower the activation threshold of primary afferent neurons, rendering them more excitable, allowing for increases in release of neurotransmitter from both central and peripheral terminals. Increase in neurotransmitter release from central terminals contributes to excitation of second-order neurons, while the release of peptides from peripheral terminals has been implicated in neurogenic inflammation. Adenosine 5,-triphosphate (ATP) causes pain in human studies, and depolarize sensory neurons. There is evidence of the action of ATP at many levels in the dura,vascular sensory pathway. Animal studies have shown that some P2X receptors are located in neurons innervating the dura, including the P2X3 receptor, which is most often shown to be involved in nociceptive pathways. In this article, we briefly review peripheral sensitization in relation to migraine and provide emphasis for P2X receptor involvement where it is available. Drug Dev Res 68:321,328, 2007. © 2007 Wiley-Liss, Inc. [source]

Characterization and expression of ATP P2X4 receptor from embryonic chick skeletal muscle

DRUG DEVELOPMENT RESEARCH, Issue 1 2001
Xuenong Bo
Abstract Previous pharmacological experiments have indicated the existence of ATP P2X receptors in chick embryonic skeletal muscles. In this study we cloned a P2X4 -like cDNA encoding a protein of 385 amino acids, which shares 75% and 76% identity with rat and human P2X4 receptors, respectively. Functional studies of this cP2X4 receptor expressed in Xenopus oocytes showed that ATP induced a fast inward current, which was partially desensitized upon prolonged application of ATP. The ATP-induced currents were concentration-dependent, with an EC50 of 9.5 ,M. Adenosine 5,- O -(thio)triphosphate and 2-methylthioATP very weak agonists. ,,,-methyleneATP was almost inactive. In contrast to their potentiating effects on recombinant rat P2X4 receptors, both suramin and pyridoxalphosphate-6-azophenyl-2,,4,-disulfonic acid partially blocked ATP-induced currents. TrinitrophenylATP was able to block ATP-induced response completely, with an IC50 of 4.7 ,M. Northern blot and RT-PCR analysis showed that cP2X4 mRNAs were mainly expressed in skeletal muscle, brain, and gizzard of day 10 chick embryos. Lower levels of expression were also detected in liver, heart, and retina. Whole-mount in situ hybridization showed that cP2X4 mRNAs were expressed in the brain, spinal cord, notochord, gizzard, and skeletal muscle. The physiological functions of cP2X4 receptors in embryonic skeletal muscle remain unclear at present. Drug Dev. Res. 53:22,28, 2001. © 2001 Wiley-Liss, Inc. [source]

Evidence for the involvement of purinergic P2X7 receptors in outer retinal processing

EUROPEAN JOURNAL OF NEUROSCIENCE, Issue 1 2006
Theresa Puthussery
Abstract Extracellular ATP mediates fast excitatory neurotransmission in many regions of the central nervous system through activation of P2X receptors. Although several P2X receptor subunits have been identified in the mammalian retina, little is known about the functional role of these receptors in retinal signalling. The purpose of the present study was to investigate whether purinergic P2X7 receptors are involved in outer retinal processing by assessing receptor localization, degradation of extracellular ATP and the effect of functional activation of P2X7 receptors on the electroretinogram (ERG). Using light and electron microscopy, we demonstrated that P2X7 receptors are expressed postsynaptically on horizontal cell processes as well as presynaptically on photoreceptor synaptic terminals in both the rat and marmoset retina. Using an enzyme cytochemical method, we showed that ecto-ATPases are active in the outer plexiform layer of the rat retina, providing a mechanism by which purinergic synaptic transmission can be rapidly terminated. Finally, we evaluated the role of P2X7 receptors in retinal function by assessing changes to the ERG response of rats after intravitreal delivery of the P2X7 receptor agonist benzoyl benzoyl ATP (BzATP). Intravitreal injection of BzATP resulted in a sustained increase (up to 58%) in the amplitude of the photoreceptor-derived a-wave of the ERG. In contrast, BzATP caused a transient reduction in the rod- and cone-derived postreceptoral responses. These results provide three lines of evidence for the involvement of extracellular purines in outer retinal processing. [source]

Independent receptors for diadenosine pentaphosphate and ATP in rat midbrain single synaptic terminals

EUROPEAN JOURNAL OF NEUROSCIENCE, Issue 6 2001
M. Díaz-Hernández
Abstract Diadenosine pentaphosphate (Ap5A) and adenosine 5,-triphosphate (ATP) stimulate a intrasynaptosomal calcium concentration [Ca2+]i increase via specific purinergic receptors in rat midbrain synaptosomes, although nothing is known about their distribution in presynaptic terminals. A microfluorimetric technique to measure [Ca2+]i increase using the dye FURA-2AM, has permitted study of the presence of dinucleotide and P2X receptors in independent isolated synaptic terminals. Our results demonstrate the existence of three populations of synaptosomes: one with dinucleotide receptors (12%), another with P2X receptors (20%) and a third with both (14%). It has been possible to demonstrate that the activation of these receptors occurs only in the presence of extracellular Ca2+ and that it is also coupled with voltage-dependent Ca2+ channels. Finally 54% of the synaptosomes that responded to K+ did not present any calcium increase mediated by the nucleotides used. In summary, ATP and dinucleotides exhibit specific ionotropic receptors that can coexist or not on the same synaptic terminal. [source]

A Putative Alternatively Spliced Variant of the P2X1 Purinoreceptor in Human Bladder

EXPERIMENTAL PHYSIOLOGY, Issue 4 2000
L. A. Hardy
Activation of purinergic P2X receptors, putatively P2X1, may be important in the initiation of contraction in human detrusor. Purinergic transmission may be more important in muscle taken from patients with bladder instability. In this study the presence of the P2X1 receptor subtype was confirmed using RT-PCR. In addition, the results indicate, at the mRNA level, the presence of a splice variant of P2X1 that is lacking part of the second transmembrane domain. It is therefore possible that human bladder expresses multiple isoforms of the P2X1 receptor which may be potential sites for modifying or regulating putative purinergic activation of the human bladder. [source]

Opposite effects of uracil and adenine nucleotides on the survival of murine cardiomyocytes

JOURNAL OF CELLULAR AND MOLECULAR MEDICINE, Issue 2 2008
Alessia Mazzola
Abstract We previously showed that the human heart expresses all known P2X and P2Y receptors activated by extra-cellular adenine or uracil nucleotides. Despite evidence that, both in humans and rodents, plasma levels of ATP and UTP markedly increase during myocardial infarction, the differential effects mediated by the various adenine- and uracil-preferring myocardial P2 receptors are still largely unknown. Here, we studied the effects of adenine and uracil nucleotides on murine HL-1 cardiomyocytes. RT-PCR analysis showed that HL-1 cardiomyocytes express all known P2X receptors (except for P2X2), as well as the P2Y2,4,6,14 subtypes. Exposure of cardiomyocytes to adenine nucleotides (ATP, ADP or BzATP) induced apoptosis and necrosis, as determined by flow-cytometry. Cell death was exacerbated by tumour necrosis factor (TNF)-,, a cytokine implicated in chronic heart failure progression. Conversely, uracil nucleotides (UTP, UDP and UDPglucose) had no effect ,per se', but fully counteracted the deleterious effects induced by adenine nucleotides and TNF-,, even if added to cardiomyocytes after beginning exposure to these cell death-inducing agents. Thus, exposure of cardiomyocytes to elevated concentrations of ATP or ADP in the presence of TNF-, contributes to cell death, an effect which is counteracted by uracil-preferring P2 receptors. Cardiomyocytes do not need to be ,primed' by uracil nucleotides to become insensitive to adenine nucleotides-induced death, suggesting the existence of a possible ,therapeutic' window for uracil nucleotides-mediated protection. Thus, release of UTP during cardiac ischaemia and in chronic heart failure may protect against myocardial damage, setting the basis for developing novel cardioprotective agents that specifically target uracil-preferring P2Y receptors. [source]

P2X2, P2X2,2 and P2X5 receptor subunit expression and function in rat thoracolumbar sympathetic neurons

JOURNAL OF NEUROCHEMISTRY, Issue 5 2001
H. Schädlich
The present study investigated the pharmacological properties of excitatory P2X receptors and P2X2 and P2X5 receptor subunit expression in rat-cultured thoracolumbar sympathetic neurons. In patch-clamp recordings, ATP (3,1000 µm; applied for 1 s) induced inward currents in a concentration-dependent manner. Pyridoxal-phosphate-6-azophenyl-2,,4,-disulfonate (PPADS; 30 µm) counteracted the ATP response. In contrast to ATP, ,,,-meATP (30 µm; for 1 s) was virtually ineffective. Prolonged application of ATP (100 µm; 10 s) induced receptor desensitization in a significant proportion of sympathetic neurons in a manner typical for P2X2,2 splice variant-mediated responses. Using single-cell RT-PCR, P2X2, P2X2,2 and P2X5 mRNA expression was detectable in individual tyrosine hydroxylase-positive neurons; coexpression of both P2X2 isoforms was not observed. Laser scanning microscopy revealed both P2X2 and P2X5 immunoreactivity in virtually every TH-positive neuron. P2X2 immunoreactivity was largely distributed over the cell body, whereas P2X5 immunoreactivity was most distinctly located close to the nucleus. In summary, the present study demonstrates the expression of P2X2, P2X2,2 and P2X5 receptor subunits in rat thoracolumbar neurons. The functional data in conjunction with a preferential membranous localization of P2X2/P2X2,2 compared with P2X5 suggest that the excitatory P2X responses are mediated by P2X2 and P2X2,2 receptors. Apparently there exist two types of P2X2 receptor-bearing sympathetic neurons: one major population expressing the unspliced isoform and another minor population expressing the P2X2,2 splice variant. [source]

Molecular mechanisms of cross-inhibition between nicotinic acetylcholine receptors and P2X receptors in myenteric neurons and HEK-293 cells

NEUROGASTROENTEROLOGY & MOTILITY, Issue 8 2010
D. A. Decker
Abstract Background, P2X2 and nicotinic acetylcholine receptors (nAChRs) mediate fast synaptic excitation in the enteric nervous system. P2X receptors and nAChRs are functionally linked. This study examined the mechanisms responsible for interactions between P2X2 and ,3,4subunit-containing nAChRs. Methods, The function of P2X2 and ,3,4 nAChRs expressed by HEK-293 cells and guinea pig ileum myenteric neurons in culture was studied using whole-cell patch clamp techniques. Key Results, In HEK-293 cells expressing ,3,4 nAChRs and P2X2 receptors, co-application of ATP and acetylcholine caused inward currents that were 56 ± 7% of the current that should occur if these channels functioned independently (P < 0.05, n = 9); we call this interaction cross-inhibition. Cross-inhibition did not occur in HEK-293 cells expressing ,3,4 nAChRs and a C-terminal tail truncated P2X2 receptor (P2X2TR) (P > 0.05, n = 8). Intracellular application of the C-terminal tail of the P2X2 receptor blocked nAChR-P2X receptor cross-inhibition in HEK-293 cells and myenteric neurons. In the absence of ATP, P2X2 receptors constitutively inhibited nAChR currents in HEK-293 cells expressing both receptors. Constitutive inhibition did not occur in HEK-293 cells expressing ,3,4 nAChRs transfected with P2X2TR. Currents caused by low (,30 ,mol L,1), but not high (,100 ,mol L,1) concentrations of ATP in cells expressing P2X2 receptors were inhibited by co-expression with ,3,4 nAChRs. Conclusions & Inferences, The C-terminal tail of P2X2 receptors mediates cross-inhibition between ,3,4 nAChR-P2X2 receptors. The closed state of P2X2 receptors and nAChRs can also cause cross-inhibition. These interactions may modulate transmission at enteric synapses that use ATP and acetylcholine as co-transmitters. [source]

Electrophysiological classification of P2X7 receptors in rat cultured neocortical astroglia

BRITISH JOURNAL OF PHARMACOLOGY, Issue 8 2010
W Nörenberg
Background and purpose:, P2X7 receptors are ATP-gated cation channels mediating important functions in microglial cells, such as the release of cytokines and phagocytosis. Electrophysiological evidence that these receptors also occur in CNS astroglia is rare and rather incomplete. Experimental approach:, We used whole-cell patch-clamp recordings to search for P2X7 receptors in astroglial,neuronal co-cultures prepared from the cerebral cortex of rats. Key results:, All the astroglial cells investigated responded to ATP with membrane currents, reversing around 0 mV. These currents could be also detected in isolated outside-out patch vesicles. The results of the experiments with the P2X [,,,-methylene ATP and 2,-3,-O-(4-benzoyl) ATP] and P2Y receptor agonists [adenosine 5,-O-(2-thiodiphosphate), uridine 5,-diphosphate, uridine 5,-triphosphate (UTP) and UDP-glucose] suggested the involvement of P2X receptors in this response. The potentiation of ATP responses in a low divalent cation or alkaline bath, but not by ivermectin, made it likely that a P2X7 receptor is operational. Blockade of the ATP effect by the P2X7 antagonists Brilliant Blue G, calmidazolium and oxidized ATP corroborated this assumption. Conclusions and implications:, Rat cultured cortical astroglia possesses functional P2X7 receptors. It is suggested that astrocytic P2X7 receptors respond to high local ATP concentrations during neuronal injury. [source]

Inhibition of adenylyl cyclase by neuronal P2Y receptors

BRITISH JOURNAL OF PHARMACOLOGY, Issue 3 2002
Ursula Unterberger
P2Y receptors inhibiting adenylyl cyclase have been found in blood platelets, glioma cells, and endothelial cells. In platelets and glioma cells, these receptors were identified as P2Y12. Here, we have used PC12 cells to search for adenylyl cyclase inhibiting P2Y receptors in a neuronal cellular environment. ADP and ATP (0.1 , 100 ,M) left basal cyclic AMP accumulation unaltered, but reduced cyclic AMP synthesis stimulated by activation of endogenous A2A or recombinant ,2 receptors. Forskolin-dependent cyclic AMP production was reduced by 1 ,M and enhanced by 10 , 100 ,M ADP; this latter effect was turned into an inhibition when A2A receptors were blocked. The nucleotide inhibition of cyclic AMP synthesis was not altered when P2X receptors were blocked, but abolished by pertussis toxin. The rank order of agonist potencies for the reduction of cyclic AMP was (IC50 values): 2-methylthio-ADP (0.12 nM)=2-methylthio-ATP (0.13 nM)>ADP,S (71 nM)>ATP (164 nM)=ADP (244 nM). The inhibition by ADP was not antagonized by suramin, pyridoxal-phosphate-6-azophenyl-2,,4,-disulphonic acid, or adenosine-3,-phosphate-5,-phosphate, but attenuated by reactive blue 2, ATP,S, and 2-methylthio-AMP. RT , PCR demonstrated the expression of P2Y2, P2Y4, P2Y6, and P2Y12, but not P2Y1, receptors in PC12 cells. In Northern blots, only P2Y2 and P2Y12 were detectable. Differentiation with NGF did not alter these hybridization signals and left the nucleotide inhibition of adenylyl cyclase unchanged. We conclude that P2Y12 receptors are expressed in neuronal cells and inhibit adenylyl cyclase activity. British Journal of Pharmacology (2002) 135, 673,684; doi:10.1038/sj.bjp.0704514 [source]

Effects of extracellular nucleotides and nucleosides on prostate carcinoma cells

BRITISH JOURNAL OF PHARMACOLOGY, Issue 2 2001
Rodolphe Janssens
The purpose of this work was to characterize the receptors involved in the action of nucleotides on the human prostate carcinoma cell lines LNCaP, PC-3 and DU145. Northern blotting revealed the presence of P2Y2, P2Y6 and P2Y11 messengers in the three cell lines. P2Y1 mRNA was only observed in the DU145 cells. In both PC-3 and DU145 cells, ATP and UTP stimulated inositol phosphate accumulation in an equipotent, equiactive and non-additive way, suggesting the involvement of P2Y2 receptors. ATP also increased cyclic AMP, but this effect is likely to result from degradation into adenosine and activation of A2 receptor. A2 receptor activation led to a synergistic enhancement of prostate-specific antigen secretion induced by vasoactive intestinal peptide. RT , PCR experiments detected the expression of the P2X4 and P2X5 receptors in the DU145 cells and the P2X4, P2X5 and P2X7 receptors in the PC-3 cells. The calcium influx induced by BzATP confirmed the functional expression of P2X receptors. ATP inhibited the growth of PC-3 and DU145 cells. This effect was mimicked neither by UTP nor by adenosine, indicating that it does not result from phospholipase C or adenylyl cyclase activation. On the contrary, in PC-3 cells, BzATP reproduced the effect of ATP, which was associated to a moderate decrease of proliferation and an increase of apoptosis. In DU145 cells, ATP was more potent than BzATP and growth inhibition was mainly associated with necrosis. We suggest that P2X receptors might be involved in the inhibition by nucleotides of prostate carcinoma cell growth. British Journal of Pharmacology (2001) 132, 536,546; doi:10.1038/sj.bjp.0703833 [source]

Multiple P2X receptors on guinea-pig pelvic ganglion neurons exhibit novel pharmacological properties

BRITISH JOURNAL OF PHARMACOLOGY, Issue 1 2001
Yu Zhong
Application of ATP and ,,,-methylene ATP (,,meATP) to voltage-clamped guinea-pig pelvic neurons produced three types of inward currents. A fast-desensitizing response was present in 5% (25/660) of neurons, 70% gave slowly-desensitizing currents, and the remainder had biphasic responses. Slowly-desensitizing responses were characterized pharmacologically. The response to ,,meATP 100 ,M was 46±27% (range 0 , 100%) of that evoked by ATP 100 ,M in the same cell. Cross-desensitization indicated the presence of ,,meATP-sensitive and -insensitive receptors. The concentration-response curve for ,,meATP had an EC50 of 55 ,M, and a Hill coefficient of 0.99, while at the ,,meATP-insensitive receptor, ATP had an EC50 of 73 ,M, with a Hill coefficient of 1.78. The response to ,,meATP was blocked by pyridoxalphosphate-6-azophenyl-2,,4,-disulphonic acid (PPADS), suramin and Cibacron blue. However, the ,,meATP-insensitive receptor was inhibited by PPADS, but not by the other two antagonists. 2,- (or 3,-) O -trinitrophenyl-ATP was 10 times more potent in inhibiting responses to ,,meATP than to ATP (at the ,,meATP-insensitive receptor). Lowering extracellular pH potentiated responses to ,,meATP and ATP, while raising pH attenuated them. Co-application of Zn2+ (3 , 300 ,M) inhibited the responses to ,,meATP and ATP, with IC50 values of 286 and 60 ,M, respectively. In conclusion, unlike rat and mouse pelvic ganglion neurons, which only express P2X2 homomers, at least three distinct P2X receptors are present in guinea-pig pelvic neurons, probably homomeric P2X2, P2X3 and heteromeric P2X2/3 receptors. However, some of the novel pharmacological properties observed suggest that the guinea-pig P2X receptor subtypes may differ from their rat orthologues. British Journal of Pharmacology (2001) 132, 221,233; doi:10.1038/sj.bjp.0703778 [source]

Roles of P2X receptors and Ca2+ sensitization in extracellular adenosine triphosphate-induced hyperresponsiveness in airway smooth muscle

FORMALIN-INDUCED INCREASE IN P2X3 RECEPTOR EXPRESSION IN DORSAL ROOT GANGLIA: IMPLICATIONS FOR NOCICEPTION

CLINICAL AND EXPERIMENTAL PHARMACOLOGY AND PHYSIOLOGY, Issue 8 2009
Ai-Hua Pan
SUMMARY 1ATP-gated P2X receptors in nociceptive sensory neurons participate in the transmission of pain signals from the periphery to the spinal cord. The effect of formalin on the expression of P2X3 receptors in dorsal root ganglia (DRG) was characterized using molecular and immunological approaches and the patch-clamp technique. 2Adult Sprague-Dawley rats were injected with 100 µL of 5% formalin in the planar surface of the hindpaw and were killed 30 min and 1, 3, 6, 12, 24 and 48 h later for in vitro analyses. The expression and distribution of P2X3 receptors in the lumbar spinal cord and in L5/L6 DRG were examined; 24 and 48 h after formalin injection, currents in neurons were examined using whole-cell patch-clamp recording. 3Western blots showed that anti-P2X3 antibody recognized a major monomer of approximately 64 kDa in DRG. Immunoreactivity for P2X3 receptors was detected predominantly in the cytoplasm and plasma membrane of small (< 25 µm) and middle-sized (25,50 µm) DRG neurons. Expression of the P2X3 transcript in the DRG was unchanged 30 min and 1 h after formalin injection, but increased after 12 h. There was no distinct change in P2X3 immunostaining of the spinal cord lamina at 30 min or 1 h after injection, but after 24 h P2X3 labelling increased. At 24 h after the formalin injection, currents in isolated small and middle-sized DRG neurons were increased by 1 µmol/L ,,,-methylene-ATP. These currents were completely inhibited by 1 µmol/L A-317491, a potent and selective P2X3 receptor antagonist. 4These data suggest that formalin injection leads to early upregulation of P2X3 expression in the spinal cord and DRG and that this may be one of the mechanisms giving rise to nociception. [source]

EXPRESSION OF P2X PURINOCEPTORS IN PC12 PHAEOCHROMOCYTOMA CELLS

CLINICAL AND EXPERIMENTAL PHARMACOLOGY AND PHYSIOLOGY, Issue 12 2007
Ji-Hu Sun
SUMMARY 1The PC12 cell line, which was cloned from a rat adrenal phaeochromocytoma, is a useful model system. It expresses neuronal properties after treatment with nerve growth factor (NGF). The nervous system-specific P2X receptor subtype P2X2 was initially cloned from PC12 cells, but little is known about the expression of other subtypes of P2X receptors in PC12 cells. The aim of the present study was to investigate whether PC12 cells express the other P2X receptors when exposed to NGF. 2Reverse transcription,polymerase chain reaction at the mRNA level and immunocytochemisty at the protein level showed that, among the seven P2X purinoceptor subtypes, only P2X2 was found to be expressed in undifferentiated PC12 phaeochromocytoma cells, but all seven P2X purinoceptor subtypes were expressed in differentiated PC12 cells treated with 50 µg/mL NGF. 3Electrophysiological recordings indicated that ATP (30 µmol/L) but not ,,,-methylene ATP (,,,-meATP; 30 µmol/L) evoked an inward current in undifferentiated PC12 cells, but both ,,,-meATP and ATP evoked inward currents in differentiated PC12 cells. The results indicate that the NGF-induced P2X receptors expressed in PC12 cells are functional channels. 4The present study suggests that the NGF-induced neuronal phenotype of PC12 cells may be a model for the study of P2X heteromeric receptors. [source]