Leptin and interleukin-1beta modulate neuronal glutamate release and protect against glucose-oxygen-serum deprivation.
Molecular mechanism underlying leptin-mediated neuronal protection against glucose-oxygen-serum deprivation (GOSD) insult was investigated by focusing on the interactions among leptin, Interleukin-1beta (IL-1beta) and glutamate and their impacts on the growth of neurons under GOSD. The trypan blue dye exclusion assay, 4', 6-diamidino-2-phenylindole (DAPI) assay, cytokine antibody array assay, immunocytochemical staining assay, glutamate determination kit, immunoblocking and chemical blocking strategies were applied to serve the study goal. Results showed that in response to 6 h of GOSD, cortical neurons can secrete significant amounts of leptin and IL-1beta to protect neurons from GOSD-induced cell damage. Serine/threonine kinase Akt (Akt) and extracellular signal-related kinase (ERK) inhibitors significantly reversed leptin-mediated neuroprotection. GOSD-induced IL-1beta was further enhanced by leptin in Akt/ERK-dependent manner. Blockade of endogenous leptin with specific antibodies significantly inhibited GOSD-induced IL-1beta expression and increased glutamate release from GOSD neurons. IL-1 blockade with IL-1 receptor antagonist (IL-1ra) on the other hand, inhibited leptin-mediated neuroprotection and suppression of glutamate release from GOSD neurons. Pre-treating GOSD neurons with leptin and IL-1beta in combined significantly increased their survival but decreased their releases of glutamate. The results indicate that leptin may act through Akt and ERK signaling pathways to protect neurons from GOSD insult; the protection was in part IL-1beta dependent and through which the glutamate release from GOSD neurons was inhibited. Therapeutic values of leptin and IL-1beta were suggested in the treatment of cerebral ischemia at early stage.
Wang
Chen-Hsuan
CH
Department of Life Sciences, National Chung Hsing University, 250 Kuo Kuang Rd., Taichung, Taiwan.
Wang
Wei-Ti
WT
Cheng
Shu-Yun
SY
Hung
Wan-Ting
WT
Wu
Tzu-Lien
TL
Hsueh
Chi-Mei
CM
D000704:Analysis of Variance; D000818:Animals; D002478:Cells, Cultured; D002540:Cerebral Cortex / Q000166:cytology / Q000187:drug effects / Q000378:metabolism*; D005947:Glucose / Q000172:deficiency; D018698:Glutamic Acid / Q000378:metabolism* / Q000494:pharmacology; D000860:Hypoxia / Q000517:prevention & control*; D007150:Immunohistochemistry; D053583:Interleukin-1beta / Q000378:metabolism* / Q000494:pharmacology; D020738:Leptin / Q000378:metabolism* / Q000494:pharmacology; D009474:Neurons / Q000166:cytology / Q000187:drug effects / Q000378:metabolism*; D051057:Proto-Oncogene Proteins c-akt / Q000378:metabolism; D051381:Rats; D017207:Rats, Sprague-Dawley; D015398:Signal Transduction / Q000187:drug effects; D013997:Time Factors
D053583:Interleukin-1beta; D020738:Leptin; D018698:Glutamic Acid; D051057:Proto-Oncogene Proteins c-akt; D005947:Glucose