REGIONAL CONCENTRATIONS OF CYCLIC-NUCLEOTIDES AFTER EXPERIMENTAL BRAIN INJURY

Regional concentrations of lactate, glucose, cAMP, and cGMP were measu red after lateral fluid percussion brain injury in rats, At 5 min afte r injury, while tissue concentrations of lactate were elevated in the cortices and hippocampi of both the ipsilateral and contralateral hemi spheres, those of glucose were decreased in these brain regions, By 20 min after injury, increases of lactate concentrations and decreases o f glucose concentrations were observed only in the cortices and in the hippocampus of the ipsilateral hemisphere, Whereas the cAMP concentra tions were unchanged in the cortices and hippocampi of the ipsilateral and contralateral hemispheres at 5 min after injury, decreases were f ound in the injured cortex and ipsilateral hippocampus at 20 min after injury, The tissue concentrations of cGMP were found to be elevated o nly in the ipsilateral hippocampus at 5 min after injury, The present observation that tissue glucose decreases in the injured cortex and th e ipsilateral hippocampus are consistent with the published findings o f increased hyperglycolysis and oxidative metabolism in brain immediat ely after injury, The present findings that the concentrations of cAMP and cGMP change in the cortex and hippocampus provide biochemical evi dence for the neurotransmitter's surge after brain injury.