P2X(7) receptor stimulation in primary cultures of rat spinal microglia induces downregulation of the activity for glutamate transport.
It has been shown that spinal microglia expressing certain types of glutamate transporters function in the modulation of neuropathogenesis. In this study, the effect of ATP, potentially able to mediate the communication between neurons and glial cells in the spinal cord on the transport of glutamate in cultured spinal microglia, was investigated. Both GLAST and GLT-1 were detected in the cells. Preincubation with ATP or 2'-3'-O-(4-benzoyl-benzoyl) ATP (BzATP), a selective agonist for the P2X(7) receptor, significantly blocked the uptake of glutamate. The effect of BzATP was reversed by pretreatment with brilliant blue G or oxidized ATP, each a selective antagonist for P2X(7). The inhibitory effect of P2X(7) receptor activation also occurred in the absence of extracellular Na(+) or Ca(2+), suggesting that the receptor regulates glutamate transport by a metabotropic pathway. Furthermore, pretreatment with inhibitors of mitogen-activated protein kinase kinase, or antioxidants, significantly reversed the inhibitory effect of BzATP on the uptake of glutamate. Incubation with BzATP led to a marked decrease in the V(max), but not the K(m), of glutamate transport. However, treatment with BzATP did not induce the trafficking of glutamate transporters. These results suggest that the activation of P2X(7) receptors in spinal microglia is important in the regulation of glutamate transport via activation of the extracellular signal-regulated kinase cascade and production of oxidants.
Morioka
Norimitsu
N
Department of Dental Pharmacology, Division of Integrated Medical Science, Hiroshima University Graduate School of Biomedical Sciences, Hiroshima, Japan.
Abdin
Md Joynal
MJ
Kitayama
Tomoya
T
Morita
Katsuya
K
Nakata
Yoshihiro
Y
Dohi
Toshihiro
T
D000255:Adenosine Triphosphate / Q000031:analogs & derivatives / Q000494:pharmacology; D000818:Animals; D000831:Animals, Newborn; D019921:Biotinylation / Q000379:methods; D002118:Calcium / Q000378:metabolism; D002478:Cells, Cultured; D004305:Dose-Response Relationship, Drug; D015536:Down-Regulation / Q000187:drug effects / Q000502:physiology*; D004347:Drug Interactions; D004791:Enzyme Inhibitors / Q000494:pharmacology; D027341:Excitatory Amino Acid Transporter 1 / Q000235:genetics / Q000378:metabolism*; D027342:Excitatory Amino Acid Transporter 2 / Q000235:genetics / Q000378:metabolism*; D048049:Extracellular Signal-Regulated MAP Kinases / Q000378:metabolism; D018698:Glutamic Acid / Q000378:metabolism; D017628:Microglia / Q000187:drug effects / Q000378:metabolism*; D010975:Platelet Aggregation Inhibitors / Q000494:pharmacology; D051381:Rats; D018048:Receptors, Purinergic P2 / Q000502:physiology*; D058486:Receptors, Purinergic P2X7; D012964:Sodium / Q000378:metabolism; D013116:Spinal Cord / Q000166:cytology*; D013997:Time Factors
D004791:Enzyme Inhibitors; D027341:Excitatory Amino Acid Transporter 1; D027342:Excitatory Amino Acid Transporter 2; C546470:P2rx7 protein, rat; D010975:Platelet Aggregation Inhibitors; D018048:Receptors, Purinergic P2; D058486:Receptors, Purinergic P2X7; C493392:Slc1a3 protein, rat; D018698:Glutamic Acid; C033901:3'-O-(4-benzoyl)benzoyladenosine 5'-triphosphate; D000255:Adenosine Triphosphate; D012964:Sodium; D048049:Extracellular Signal-Regulated MAP Kinases; D002118:Calcium