Korean J Anesthesiol.  2003 Aug;45(2):271-277. 10.4097/kjae.2003.45.2.271.

Role of Morphine in the Glutamate-Induced Oxidative Damage of C6 Glial Cells

• Lee J
• Kim MS
• Lee C
• Kim HY
• Choi DH
• Kim TY
• Son Y
• Park R

• KMID: 2236726
• DOI: http://doi.org/10.4097/kjae.2003.45.2.271

Abstract

BACKGROUND: Although many studies regarding several neurotransmitters and receptors have been conducted to define the mechanism involved in the development of dependence on opioids, definitive evidence has still not been presented. This study was designed to investigate the effect of morphine on glutamate-induced cytotoxicity of rat C6 glial cells.
METHODS
The 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyl-tetrazolium bromide (MTT) assay was used for cell viability. Morphology of nuclei was observed by fluorescent microscopy. Reduced glutathione (GSH) contents were measured in acid-soluble cell fractions. Generation of hydrogen peroxide (H2O2) was measured from the cultured supernatant of C6 glial cells using the scopoletin-horseradish peroxidase (HRP) assay.
RESULTS
Glutamate induced the death of C6 glial cells in a time- and dose-dependent manner. Glutamate-induced cytotoxicity was protected by morphine and antioxidants, such as GSH and N-acetyl-L-cysteine (NAC). However, morphine antagonist, naloxone did not inhibit the protective effect of morphine on glutamate-induced cytotoxicity. In addition, the specific agonists, [D-Ala2, N-Me-Phe4, Gly5-ol]-Enkephalin acetate salt (DAMGO), [D-Pen2,5]-Enkephalin (DPDPE) and U69593 did not protect C6 glial cells from glutamate-induced cytotoxicity. Furthermore, morphine recovered the depletion of GSH by glutamate and inhibited the generation of H2O2 by glutamate in C6 glial cells.
CONCLUSIONS
We suggest that morphine protects C6 glial cells from glutamate-induced cytotoxicity via the inhibition of GSH depletion and the generation of H2O2 by glutamate.

Keyword

C6 glial cells; glutamate; reduced glutathione; H2O2; morphine

MeSH Terms

Acetylcysteine
Analgesics, Opioid
Animals
Antioxidants
Cell Survival
Glutamic Acid
Glutathione
Hydrogen Peroxide
Microscopy
Morphine*
Naloxone
Neuroglia*
Neurotransmitter Agents
Peroxidase
Rats
Acetylcysteine
Analgesics, Opioid
Antioxidants
Glutamic Acid
Glutathione
Hydrogen Peroxide
Morphine
Naloxone
Neurotransmitter Agents
Peroxidase