The Effect of dichloroacetate on brain lactate levels following incomplete ichemia in the hyperglycemic rat

Dichloroacetate (DCA) is known to prevent the phosphorylation of the pyrovate dehydrogenase complex (PDHC) by blocking the action of PDH kinase. This action allows the active PDHC to exert its effect on the metabolism of glucose, lactate and alanine to acetyl CoA. DCA has been shown to reduce serum lactate levels in humans and animals in such conditions as diabetes, phenformin-induced hepatic failure, exercise, and endotoxln-induced shock. Lactic acidosis in the brain has often been postulated as a cause of neuronal damage following ischemia and hypoxla. Therefore, we examined the effect of intravenously administered DCA (100 mg/kg) in rats that were rendered hyperglycemic by intravenous glucose (2 g/kg), and then made to undergo IS minutes of incomplete cerebral ischemia by bilateral carotid ligation and systemic hypotension (mean arterial pressure of 50 mm Hg). DCA significantly reduced serum lactate levels pre-ischemia, but had no effect on serum lactate levels after ischemia induction. Brain levels of lactate, ATP and PCr after 15 minutes of Incomplete ischemia were unaffected by DCA. We conclude that in this in-vivo model the control of PDHC activity hi the brain may be different than that in the periphery, and that DCA was not effective in reducing brain tissue lactate levels.