title: P2 receptor-mediated stimulation of the PI3-K/Akt-pathway in vivo.
abstract: ATP acts as a growth factor as well as a toxic agent by stimulating P2 receptors. The P2 receptor-activated signaling cascades mediating cellular growth and cell survival after injury are only incompletely understood. Therefore, the aim of the present study was to identify the role of the phosphoinositide 3 kinase (PI3-K/Akt) and the mitogen-activated protein kinase/extracellular signal regulated protein kinase (MAPK/ERK) pathways in P2Y receptor-mediated astrogliosis after traumatic injury and after microinfusion of ADP beta S (P2Y(1,12,13) receptor agonist) into the rat nucleus accumbens (NAc). Mechanical damage and even more the concomitant treatment with ADP beta S, enhanced P2Y(1) receptor-expression in the NAc, which could be reduced by pretreatment with the P2X/Y receptor antagonist PPADS. Quantitative Western blot analysis indicated a significant increase in phosphorylated (p)Akt and pERK1/2 2 h after ADP beta S-microinjection. Pretreatment with PPADS or wortmannin abolished the up-regulation of pAkt by injury alone or ADP beta S-treatment. The ADP beta S-enhanced expression of the early apoptosis marker active caspase 3 was reduced by PPADS and PD98059, but not by wortmannin. Multiple immunofluorescence labeling indicated a time-dependent expression of pAkt and pMAPK on astrocytes and neurons and additionally the colocalization of pAkt, pMAPK, and active caspase 3 with the P2Y(1) receptor especially at astrocytes. In conclusion, the data show for the first time the involvement of PI3-K/Akt-pathway in processes of injury-induced astroglial proliferation and anti-apoptosis via activation of P2Y(1) receptors in vivo, suggesting specific roles of P2 receptors in glial cell pathophysiology in neurodegenerative diseases.
authors.affiliation: Rudolf-Boehm-Institute of Pharmacology and Toxicology, University of Leipzig, Leipzig, Germany. frah@medizin.uni-leipzig.de
authors.forename: H
authors.initials: H
authors.lastname: Franke
authors.forename: C
authors.initials: C
authors.lastname: Sauer
authors.forename: C
authors.initials: C
authors.lastname: Rudolph
authors.forename: U
authors.initials: U
authors.lastname: Krügel
authors.forename: J G
authors.initials: JG
authors.lastname: Hengstler
authors.forename: P
authors.initials: P
authors.lastname: Illes
mesh_terms: D000244:Adenosine Diphosphate / Q000031:analogs & derivatives / Q000494:pharmacology; D000730:Androstadienes / Q000494:pharmacology; D000818:Animals; D017209:Apoptosis / Q000187:drug effects / Q000502:physiology; D001253:Astrocytes / Q000378:metabolism* / Q000473:pathology; D001930:Brain Injuries / Q000378:metabolism* / Q000473:pathology / Q000503:physiopathology; D004195:Disease Models, Animal; D004789:Enzyme Activation / Q000187:drug effects / Q000502:physiology; D004791:Enzyme Inhibitors / Q000494:pharmacology; D005419:Flavonoids / Q000494:pharmacology; D005911:Gliosis / Q000378:metabolism* / Q000473:pathology / Q000503:physiopathology; D020935:MAP Kinase Signaling System / Q000187:drug effects / Q000502:physiology; D008297:Male; D009714:Nucleus Accumbens / Q000187:drug effects / Q000378:metabolism; D019869:Phosphatidylinositol 3-Kinases / Q000378:metabolism*; D010766:Phosphorylation / Q000187:drug effects; D010975:Platelet Aggregation Inhibitors / Q000494:pharmacology; D051057:Proto-Oncogene Proteins c-akt / Q000378:metabolism*; D011732:Pyridoxal Phosphate / Q000031:analogs & derivatives / Q000494:pharmacology; D051381:Rats; D017208:Rats, Wistar; D018048:Receptors, Purinergic P2 / Q000187:drug effects / Q000378:metabolism*; D058472:Receptors, Purinergic P2Y1; D013873:Thionucleotides / Q000494:pharmacology; D015854:Up-Regulation / Q000187:drug effects / Q000502:physiology; D000077191:Wortmannin
chemical_list: D000730:Androstadienes; D004791:Enzyme Inhibitors; D005419:Flavonoids; C546384:P2ry1 protein, rat; D010975:Platelet Aggregation Inhibitors; D018048:Receptors, Purinergic P2; D058472:Receptors, Purinergic P2Y1; D013873:Thionucleotides; C077792:pyridoxal phosphate-6-azophenyl-2',4'-disulfonic acid; C030812:adenosine 5'-O-(2-thiodiphosphate); D011732:Pyridoxal Phosphate; D000244:Adenosine Diphosphate; D019869:Phosphatidylinositol 3-Kinases; D051057:Proto-Oncogene Proteins c-akt; C093973:2-(2-amino-3-methoxyphenyl)-4H-1-benzopyran-4-one; D000077191:Wortmannin