Effect of γ-Hydroxybutyrate on Local and Global Glucose Metabolism in the Anesthetized Cat Brain

Abstract

This study addresses three topics in the chloralose-anesthetized cat: (a) distribution of local CMRglc: values ranging from 5 to 109 μmol/100 g/min were found in 37 brain structures and the mean CMRglc over all examined structures was 30.6 μmol/100 g/min; (b) effect of γ-hydroxybutyrate (GHB, 250 mg/kg i.v.) on local CMRglc, which was significantly ( p < 0.05) depressed in 16 of 37 structures, most prominently in the auditory system, and the mean CMRglc over all structures after GHB was 20.4 μmol/100 g/min; and (c) global values of CMRglc, CMRO2, and CBF before and after GHB: in these experiments, a modified Kety–Schmidt technique was employed measuring saturation/desaturation of inhaled H2 and concentrations of glucose and oxygen in aortic and sagittal sinus blood. CBF and CMRO2 were not altered after GHB, whereas CMRglc was significantly decreased from 35.7 to 28.8 μmol/100 g/min. The values of CMRglc obtained with both techniques (autoradiography and the Kety–Schmidt technique) are concordant, especially when considering the different sampling areas of both methods. The main finding of the present study is a reduction in cerebral glucose consumption after GHB, irrespective of the technique of measurement. This reduction occurs at an unchanged CMRO2 and CBF.