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Dipyridamole increases oxygen-glucose deprivation-induced injury in cortical cell culture
1Department of Neurology, Washington University School of Medicine, St Louis, Mo. 63110.
Background And Purpose:
Adenosine transport inhibitors attenuate ischemic central neuronal damage in vivo, but the locus of this protective action is presently unknown. To help address the question of whether adenosine transport inhibitors have a protective effect directly on brain parenchyma, we tested the effect of the adenosine transport inhibitor dipyridamole on neuronal loss induced by oxygen-glucose deprivation in vitro.
Methods:
Murine cortical cultures were exposed to combined oxygen and glucose deprivation, N-methyl-D-aspartate, or kainate. The extracellular concentrations of glutamate and adenosine were measured by high-performance liquid chromatography; neuronal cell death was assessed by morphological examination and measurement of lactate dehydrogenase release.
Results:
Cultures exposed to oxygen-glucose deprivation for 30 to 75 minutes exhibited an insult-dependent increase in extracellular adenosine, followed shortly by an increase in extracellular glutamate and 24 hours later by neuronal death. Addition of the A1 receptor antagonist 8-cyclopentyltheophylline during oxygen-glucose deprivation enhanced both glutamate release and neuronal damage. Addition of 10 mumol/L dipyridamole decreased extracellular adenosine and also enhanced extracellular glutamate and neuronal death. In contrast, dipyridamole increased the levels of extracellular adenosine stimulated by N-methyl-D-aspartate or kainate.
Conclusions:
These results are consistent with the idea that endogenous adenosine has a neuroprotective effect directly on cortical cells exposed to oxygen-glucose deprivation. However, inhibition of adenosine transport with dipyridamole was surprisingly not an effective strategy for enhancing this protective effect. The beneficial effects of adenosine transport inhibitors observed in vivo may be mediated indirectly--for example, by effects on the vasculature.
Insights
Endogenous adenosine protects brain cells from oxygen-glucose deprivation. However, inhibiting adenosine transport with dipyridamole did not enhance this neuroprotection in vitro, suggesting indirect mechanisms in vivo.
Area of Science:
- Neuroscience
- Neuroprotection
- Ischemic Brain Injury
Background:
- Adenosine transport inhibitors show promise in reducing ischemic neuronal damage in animal models.
- The precise location and mechanism of this neuroprotective action remain unclear.
Purpose of the Study:
- To investigate whether adenosine transport inhibitors exert a direct protective effect on brain cells.
- To evaluate the impact of dipyridamole, an adenosine transport inhibitor, on neuronal loss in an in vitro model of oxygen-glucose deprivation.
Main Methods:
- Murine cortical cultures were subjected to oxygen-glucose deprivation, N-methyl-D-aspartate, or kainate.
- Extracellular glutamate and adenosine levels were quantified using high-performance liquid chromatography.
- Neuronal cell death was assessed morphologically and by measuring lactate dehydrogenase release.
Main Results:
- Oxygen-glucose deprivation led to increased extracellular adenosine, followed by glutamate release and subsequent neuronal death.
- Dipyridamole decreased extracellular adenosine but paradoxically enhanced glutamate release and neuronal death.
- The adenosine receptor antagonist 8-cyclopentyltheophylline exacerbated glutamate release and neuronal damage.
Conclusions:
- Endogenous adenosine appears to provide direct neuroprotection to cortical cells during oxygen-glucose deprivation.
- Inhibiting adenosine transport with dipyridamole was ineffective in enhancing this protective effect in vitro.
- The neuroprotective benefits of adenosine transport inhibitors observed in vivo may involve indirect mechanisms, potentially related to vascular effects.