Resumen:
Experimental arthritis induced by Freund-adjuvant administration is a model of chronic inflammation and rheumatoid arthritis associated with a decrease in pituitary growth hormone (GH) and hepatic insulin-like growth factor I (IGF-I) gene expression. Excessive nitric oxide (NO) synthesis by inducible NO synthase (iNOS) has been implicated in the pathogenesis of inflammatory illness. Moreover, NO participates in the regulation of GH secretion at both the hypothalamus and the pituitary. We have examined the role of iNOS activation in producing the changes in the GH-IGF-I axis in arthritic rats. Adult male Wistar rats received aminoguanidine or vehicle from day 20, after adjuvant or vehicle injection, until day 28. Two hours and 30 min after the last aminoguanidine injection, all rats were killed by decapitation. Arthritis increased hypothalamic expression of somatostatin mRNA while it decreased pituitary GH mRNA expression, and both effects were prevented by aminoguanidine administration. In arthritic rats, the parallel decrease in serum IGF-I, and in hepatic IGF-I content and mRNA expression, correlates with the decrease in circulating GH concentrations. Aminoguanidine administration to arthritic ...