Effect of inducible nitric oxide synthase inhibition by aminoguanidine on insulin-like growth factor binding protein-3 in adjuvant-induced arthritic rats

Abstract

This study was designed to investigate whether nitric oxide (NO) mediates changes in insulin-like growth factor binding protein-3 (IGFBP-3) levels in rats with adjuvant-induced arthritis. Male Wistar rats were injected with complete Freund's adjuvant, and 20 days afterwards arthritic and control rats were injected daily with an inhibitor of inducible NO synthase (iNOS), aminoguanidine, or vehicle for 8 days. The increase in serum levels of IGFBP-3 induced by arthritis was exacerbated by aminoguanidine treatment. Arthritis increased IGFBP-3 mRNA levels in the kidney but not in the liver. The inhibition of iNOS did not modify IGFBP-3 gene expression in the kidney or in the liver in arthritic rats. However, the inhibitory effect of arthritis on the proteolysis of IGFBP-3 in serum was potentiated by aminoguanidine administration. These results indicate that arthritis increases serum IGFBP-3 by increasing its synthesis in the kidney and decreasing its proteolysis in serum and that these effects are not mediated by NO.