We previously demonstrated that feeding rats Steenbock and Black's rickets-inducing diet produces remarkable changes in the metabolic pattern of the intestinal mucosa, kidney, and liver and in some membrane transport systems of intestinal mucosa and kidney. 1,25-Dihydroxyvitamin D, administration to rachitic rats did not always prove to be effective in restoring normal values.
We have now investigated the effect of 1,25-dihydroxyvitamin D, on the levels of some metabolites in rat cerebral cortex, on the activity of some enzymes, and on the transport of 2-deoxy-D-glucose and D-glucose in synaptosomes. Our experiments were carried out on three rat groups: control, rachitic, and rachitic treated with 1,25-dihydroxyvitarnin D,. The decrease in phosphorus content and the increase in citrate concentration observed in rachitic rat cerebral cortex were corrected by 1,25-dihydroxyvitamin D, treatment. The activity of acetylcholinesterase, glucose-6-phosphate dehydrogenase, and acyl phosphatase significantly increased in rachitic rat synaptosomes, as well as NAD + -dependent isocitrate dehydrogenase in cerebral cortex mitochondria; the administration of 1,25-dihydroxyvitamin D, to rachitic 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 D, treatment.
The results reported here support the hypothesis of a participation of 1,25-dihydroxyvitarnin D, in some aspects of cerebral cortex metabolism.