CEREBELLAR HYPOPLASIA IN GUNN RATS: EFFECTS OF BILIRUBIN ON POSTNATAL CHANGES IN CEREBELLAR CONSTITUENTS

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Abstract
Age-related changes in cerebellar wet weight distribution, dry weight, protein and lipid concentrations, DNA and RNA contents, [14C]leucine incorporation and ornithine decarboxylase activity in homozygous Gunn rats were investigated compared with those in heterozygotes. After postnatal day 10, cerebellar wet weights showed a skew distribution. There was a low-cerebellar-wet weight group which was similar in frequency pattern to homozygotes on day 10 (the severe group). The average wet weights in the severe group were almost the same on and after day 13. From days 10-15, protein concentration slowly increased as a whole, but it remained unchanged in the severe group. The average concentrations were significantly lower on and after day 10. Total DNA content in the severe group on day 30 was markedly reduced compared to that on day 13 and DNA contents on a wet weight basis in the whole homozygotes were lower on both days than in the controls. Increase of water content on day 13 and lipid concentration on day 30 was observed. Inverse and positive correlations of lipid and protein concentrations with cerebellar wet weight on day 30 were mirror images of each other. [14C]Leucine incorporation into proteins was considerably lower on day 13. No early postnatal elevation of ornithine decarboxylase activity was shown. Accelerated cell degradation and disorders of protein synthesis and/or degradation systems in homozygous Gunn rat cerebellum were suggested.