IN-SITU HYBRIDIZATION STUDY OF MYELIN PROTEIN MESSENGER-RNA IN RATS WITH AN EXPERIMENTAL DIABETIC NEUROPATHY

Distribution of protein zero (P-o) and myelin basic protein (MBP) mRNA s in the sciatic nerve from rats with alloxan-induced diabe- tes was a nalyzed at two different time points using in situ hybridization. Some animals of each diabetic group were treated with insulin. Densitometr ic quantitation of silver clusters revealed that 5 weeks after diabete s induction P-o mRNA only is significantly increased, while at 14 week s both P-o and MBP mRNA contents are markedly higher than controls. In sulin treatment normalizes glycemia levels and slightly counteracts in creased Po mRNA at both stages of diabetes. An increase in MBP mRNA is observed in chronic diabetic animals only, and is unaltered by the no rmoglycemic effect of insulin. The increased transcript levels of Po a nd MBP suggest that Schwann cells can modulate gene expression of myel in-specific proteins in response to diabetic-induced metabolic derange ment. Such a change may represent a higher turnover of myelin proteins as an attempt by the Schwann cells to repair the diabetes-induced ner ve damage. The observed pattern of transcript amount is only slightly influenced by insulin treatment.