Reduction of energy metabolism in rat hippocampus by arginine administration

Hyperargininemia is an inherited metabolic disease biochemically characterized by tissue accumulation of arginine. Mental retardation and other neurological features are common symptoms in hyperargininemic patients. Considering that the underlying mechanisms of brain damage in this disease are poorly established, in this work we investigated the effect of arginine administration to adult Wistar rats on some parameters of energy metabolism (CO2 production, glucose uptake, lactate release and the activities of succinate dehydrogenase, complexes II and IV of the respiratory chain) in rat hippocampus. The action Of L-NAME, an inhibitor of oxide nitric oxide synthase, on the effects produced by arginine was also tested. Sixty-day-old rats were treated with a single intraperitoneal injection of saline (group 1, control), arginine (0.8 g/kg) (group 11) or arginine (0.8 g/kg) Plus L-NAME (2 mg/kg) (group 111) and were killed 1 It later. Results showed that arginine administration significantly increased lactate release and diminished CO2 production, glucose uptake, succinate dehydrogenase and complex 11 activities. In contrast, complex IV (cytochrome c oxidase) activity was not changed by this amino acid. Furthermore, simultaneous injection Of L-NAME prevented some of these effects, except CO2 production and lactate release. The present data indicate that in vivo arginine administration impairs some parameters of energy metabolism in hippocampus of rats probably through NO formation. (C) 2003 Elsevier B.V. All rights reserved.