EFFECT OF VITAMIN-D DEFICIENCY AND 1,25-DIHYDROXYVITAMIN-D3 ON METABOLISM AND D-GLUCOSE TRANSPORT IN RAT CEREBRAL-CORTEX

We previously demonstrated that feeding rats Steenbock and Black's ric kets-inducing diet produces remarkable changes in the metabolic patter n of the intestinal mucosa, kidney, and liver and in some membrane tra nsport systems of intestinal mucosa and kidney. 1,25-Dihydroxyvitamin D3 administration to rachitic rats did not always prove to be effectiv e in restoring normal values. We have now investigated the effect of 1 ,25-dihydroxyvitamin D3 on the levels of some metabolites in rat cereb ral cortex, on the activity of some enzymes, and on the transport of 2 -deoxy-D-glucose and D-glucose in synaptosomes. Our experiments were c arried out on three rat groups: control, rachitic, and rachitic treate d with 1,25-dihydroxyvitamin D3. The decrease in phosphorus content an d the increase in citrate concentration observed in rachitic rat cereb ral cortex were corrected by 1,25-dihydroxyvitamin D3 treatment. The a ctivity of acetylcholinesterase, glucose-6-phosphate dehydrogenase, an d acyl phosphatase significantly increased in rachitic rat synaptosome s, as well as NAD+-dependent isocitrate dehydrogenase in cerebral cort ex mitochondria; the administration of 1,25-dihydroxyvitamin D3 to rac hitic rats restored enzyme levels to normal. The transport of 2-deoxy- D-glucose and D-glucose in rachitic rat synaptosomes was lower than in the control group and returned to control values in consequence of 1, 25-dihydroxyvitamin D3 treatment. The results reported here support th e hypothesis of a participation of 1,25-dihydroxyvitamin D3 in some as pects of cerebral cortex metabolism. (C) 1993 Wiley-Liss, Inc.