Effects of methylprednisolone on glomerular and medullary mRNA levels for extracellular matrices in puromycin aminonucleoside nephrosis.

We examined the effects of methylprednisolone (MPSL) on type IV collagen, laminin and heparan sulfate proteoglycan (HSPG) mRNA levels in the renal glomeruli and medulla of puromycin aminonucleoside (PAN) nephrosis. mRNA levels encoding for type IV collagen and laminin increased markedly, whereas those for HSPG decreased significantly in glomeruli of PAN nephrosis. Administration of MPSL partially ameliorated the abnormal gene expression for basement membrane components. Furthermore, we showed that medullary mRNA levels for all these basement membrane components decreased with age in PAN nephrosis with or without MPSL treatment, suggesting that neither PAN nor MPSL has any effect on basement membrane component mRNA levels in the renal medulla. In contrast, mRNA levels for the interstitial collagens including alpha 1 (I) and alpha 1 (III) chains in glomeruli showed little change with or without MPSL treatment, whereas those in medulla increased significantly in PAN nephrosis when compared with the control. MPSL ameliorated the abnormal gene expression of alpha 1 (I) and alpha 1 (III) collagen in renal medulla. These results indicate that PAN affects both glomerular mRNA encoding for basement membrane components and medullary mRNA encoding for interstitial collagens, and that MPSL has marked effects on the amelioration of abnormal gene expression in both glomeruli and medulla of PAN nephrosis.