Erythropoietin is neuroprotective on GABAergic neurons against kainic acid-excitotoxicity in the rat spinal cell cultures.
The aim of this study was to investigate whether erythropoietin (EPO) protect the spinal GABAergic neurons against kainic acid (KA)-excitotoxic damage in rat spinal cord cell cultures. We performed immunohistochemical staining and Western blotting of glutamate decarboxylase 67 (GAD67), one isoform of GABA-producing enzyme, which was considered to have involved in nonsynaptic functions, such as energy metabolism or trophic support. T exposure to KA significantly reduced the intensity of GAD67 expression in the GABAergic neurons and whole cell lysate, indicating that the excitotoxic damage on the GABAergic neurons may lead to reduction of the GAD67 production following KA-exposure. We found that post-treatment of EPO for 48 h after KA-injury remarkably enhanced the expression level of GAD67 and erythropoietin receptors (EpoR), which were deteriorated by KA. Our confocal images clearly demonstrated a remarkably enhanced expression of EpoR on the surface of the GABAergic neurons by post-treated EPO after KA-damage. This result suggests that the neuroprotective effect of post-treated EPO on the GABAergic neurons can be related to the EPO-mediated EpoR upregulation following KA-excitotoxicity. We observed that the post-applied EPO clearly increased expression of tyrosine Janus kinase 2 (JAK2), which is known to be the first step of EpoR-stimulation. In conclusion, the post-treated EPO is a potent protector of the spinal GABAergic neurons against KA-excitotoxicity and regulates production of GAD67 for the multiple trophic roles after KA-induced disturbance. We suggested that the protective effect of post-treated EPO on the GABAergic neurons is mediated by signal transduction involving EpoR-dependent JAK2 pathway.
Won
You Jin
YJ
Department of Anatomy and Cell Biology, University of Ulsan College of Medicine, 388-1 Pungnap-dong, Songpa-gu, Seoul 138-736, South Korea.
Yoo
Jong Yoon
JY
Lee
Jong Hwan
JH
Hwang
Seung Jun
SJ
Kim
Donghou
D
Hong
Hea Nam
HN
D000818:Animals; D000831:Animals, Newborn; D002452:Cell Count / Q000379:methods; D002478:Cells, Cultured; D004347:Drug Interactions; D004921:Erythropoietin / Q000494:pharmacology*; D018690:Excitatory Amino Acid Agonists / Q000494:pharmacology*; D015870:Gene Expression / Q000187:drug effects; D005968:Glutamate Decarboxylase / Q000378:metabolism; D007527:Isoenzymes / Q000378:metabolism; D053614:Janus Kinase 2 / Q000378:metabolism; D007608:Kainic Acid / Q000494:pharmacology*; D009474:Neurons / Q000187:drug effects; D018696:Neuroprotective Agents / Q000494:pharmacology*; D010751:Phosphopyruvate Hydratase / Q000378:metabolism; D051381:Rats; D017207:Rats, Sprague-Dawley; D017467:Receptors, Erythropoietin / Q000378:metabolism; D013116:Spinal Cord / Q000166:cytology*; D005680:gamma-Aminobutyric Acid / Q000378:metabolism*
D018690:Excitatory Amino Acid Agonists; D007527:Isoenzymes; D018696:Neuroprotective Agents; D017467:Receptors, Erythropoietin; D004921:Erythropoietin; D005680:gamma-Aminobutyric Acid; D053614:Janus Kinase 2; D005968:Glutamate Decarboxylase; C402565:glutamate decarboxylase 1; D010751:Phosphopyruvate Hydratase; D007608:Kainic Acid