Chonnam Med J.  2002 Jun;38(2):83-88.

High Glucose Potentiates PC12 Cell Apoptosis Induced by Hypoxia through Reactive Oxygen Species

• Byun JS
• Lee SH
• Lee KY

Abstract

Diabetic hyperglycemia increases brain damage after cerebral ischemia, although the underlining mechanisms remain unclear. Some experimental evidences of the high glucose effects on the cell death were shown on the necrotic condition by hypoxia. This study was performed to evaluate the effect of high glucose on hypoxia-induced apoptotic cell death in PC12 cells. PC12 cells exposed to various concen- trations of glucose were evaluated after incubation for 6 hr in hypoxia pouch and reoxygenated for another 18 hr. Apoptotic cell deaths were evaluated by DNA fragmentation on the agarose gel electrophoresis. The apoptosis was quantified with Boehringer-Mannheim apoptotic elisa kit and MTT assay. The generation of reactive oxygen species (ROS) was measured by dichlorofluorescein fluorescence of cells treated with hypoxia for 6 hr. Membrane lipid peroxidation of cells was measured by thiobarbituric acid (TBA) method. DNA fragmentation was noted on the agrose gel electrophoresis in the PC12 cells with 5 mM glucose treated with hypoxia for 6 hr and reoxygenation for another 18 hr. The amount of DNA fragmentation was increased by 50% in the hypoxic cells with 20 mM glucose. ROS and TBA reactive materials were increased by hypoxia for 6 hr. The ROS and TBA reactive materials in hypoxic cells with 20 mM and 40 mM glucose were increased further. The cells only incubated with high glucose (40 mM) increased ROS production without cell injury and increasing of TBA reactive material. These data suggest that high glucose potentiates the hypoxic apoptosis by increase of ROS and membrane lipid peroxidation. The potentiation of ROS generation by high glucose may due to depletion of NADPH by aldose reductase reaction.

Keyword

High-glucose; Hypoxia; PC12; Apoptosis; Reactive oxygen species (ROS)

MeSH Terms

Aldehyde Reductase
Animals
Anoxia*
Apoptosis*
Brain
Brain Ischemia
Cell Death
DNA Fragmentation
Electrophoresis
Electrophoresis, Agar Gel
Enzyme-Linked Immunosorbent Assay
Fluorescence
Glucose*
Hyperglycemia
Lipid Peroxidation
Membranes
NADP
PC12 Cells*
Reactive Oxygen Species*
Aldehyde Reductase
Glucose
NADP
Reactive Oxygen Species