Immunohistochemical study on inducible type of nitric oxide (iNOS), basic fibroblast growth factor (bFGF) and tumor growth factor-beta1 (TGF-beta1) in arteritis induced in rats by fenoldopam and theophylline, vasodilators.

Arteritis induced in rats by vasodilators, fenoldopam and theophylline, was examined immunohistochemically for expressions of inducible type of nitric oxide synthase (iNOS), basic fibroblast growth factor (bFGF) and tumor growth factor-beta1 (TGF-beta1). Rats were administered fenoldopam for 24 hours by intravenous infusion with or without following repeated daily oral administrations of theophylline. Irrespective of theophylline administration, iNOS antigens were remarkably abundant in ED-1-positive cells on day 5 and 8 post-fenoldopam-infusion (DPI); bFGF antigens were remarkably abundant in ED-1-positive cells on 1 and 3 DPI; TGF-beta1 antigens were observed in ED-1-positive cells on and after 5 DPI. These results suggest that the peak expression of iNOS antigen was followed by that of bFGF antigen, and bFGF may have a suppressive effect on iNOS expression in these rat arteritis models. On the other hand, TGF-beta1 was not considered to have a suppressive effect on iNOS expression in these models.

Nitrofurazone induces non-regenerative hepatocyte proliferation in rats.

The antibiotic nitrofurazone (NF) has been known for its testicular toxicity; in contrast, much less is known about its effect on the liver. NF was given to male rats for up to 7 consecutive days to evaluate NF-induced effects on the liver. NF increased hepatocyte DNA synthesis and liver weight in a dose-dependent manner, with no apparent histological or biochemical evidence of cell damage or loss. The hepatocyte proliferation ceased after a few days despite the continuation of treatment. The absence of cell damage indicates that NF-induced hepatocyte proliferation is different from regenerative proliferation that is seen after partial hepatectomy or cell necrosis.