Contribution of mitogen-activated protein kinases to NMDA-induced neurotoxicity in the rat retina.
We examined the contributions of the mitogen-activated protein kinases (MAPKs) family [extracellular signal-regulated kinase (ERK), p38 kinase (p38), and c-Jun N-terminal kinase (JNK)] to N-methyl-D-aspartate (NMDA)-induced neurotoxicity in the rat retina. Detection of apoptotic cell death in the retinal ganglion cell layer (RGCL) and the inner nuclear layer (INL) by terminal deoxynucleotidyl transferase-mediated dUTP-biotin nick-end labeling (TUNEL) staining began 6 h after intravitreal NMDA (100 nmol) injection and continued to increase thereafter. Western blot analysis showed that phosphorylated MAPKs (p-MAPKs) were expressed in the retina following a temporal manner: maximal expression of phosphorylated ERK (p-ERK) at 1 h, maximal expression of phosphorylated p38 (p-p38) at 6 h, and beginning of phosphorylated JNK (p-JNK) significant increase at 6 h after injection. An immunohistochemical/TUNEL co-localization study showed that p-JNK- and p-p38-positive cells in the RGCL were frequently TUNEL-positive, whereas few p-ERK-positive cells were TUNEL-positive. Moreover, co-injection of inhibitors for JNK (0.2 nmol SP600125) and/or p38 (2.0 nmol SB203580) with NMDA was effective in ameliorating NMDA-induced apoptotic cell loss in the RGCL 12 h after injection, as shown by TUNEL-positive cell counts. These inhibitors also protected the inner retina as shown by morphometric studies such as cell counts in the RGCL and measurement of the IPL thickness 7 days after injection. On the other hand, an ERK inhibitor (2.0 nmol U0126) did not suppress NMDA-induced cell death in the RGCL nor thinning of the IPL. These findings suggest that JNK and p38 are proapoptotic in NMDA-induced cell death in the RGCL, but not ERK.
Munemasa
Yasunari
Y
Department of Ophthalmology, Saint Marianna University School of Medicine, 2-16-1 Sugao, Kawasaki-shi, Kanagawa 216-8511, Japan.
Ohtani-Kaneko
Ritsuko
R
Kitaoka
Yasushi
Y
Kuribayashi
Kohei
K
Isenoumi
Kazuyuki
K
Kogo
Jiro
J
Yamashita
Kayoko
K
Kumai
Toshio
T
Kobayashi
Shinichi
S
Hirata
Kazuaki
K
Ueno
Satoki
S
D000818:Animals; D000873:Anthracenes / Q000494:pharmacology; D015153:Blotting, Western; D002452:Cell Count / Q000379:methods; D016923:Cell Death / Q000187:drug effects; D004305:Dose-Response Relationship, Drug; D004347:Drug Interactions; D004791:Enzyme Inhibitors / Q000494:pharmacology; D018846:Excitatory Amino Acids / Q000633:toxicity*; D015971:Gene Expression Regulation, Enzymologic / Q000187:drug effects*; D005904:Glial Fibrillary Acidic Protein / Q000378:metabolism; D007150:Immunohistochemistry / Q000379:methods; D020287:In Situ Nick-End Labeling / Q000379:methods; D008297:Male; D020928:Mitogen-Activated Protein Kinases / Q000378:metabolism*; D016202:N-Methylaspartate / Q000633:toxicity*; D051381:Rats; D017208:Rats, Wistar; D012160:Retina / Q000166:cytology / Q000187:drug effects*; D015398:Signal Transduction / Q000187:drug effects / Q000502:physiology; D018800:Thy-1 Antigens / Q000378:metabolism; D013997:Time Factors
D000873:Anthracenes; D004791:Enzyme Inhibitors; D018846:Excitatory Amino Acids; D005904:Glial Fibrillary Acidic Protein; D018800:Thy-1 Antigens; C432165:pyrazolanthrone; D016202:N-Methylaspartate; D020928:Mitogen-Activated Protein Kinases