iNOS activity in the aged rat liver tissue.

ABSTRACT

Free radical damage to many cellular components has been proposed as the main mechanism underlying the aging process. In the liver, NO can be generated by iNOS, but also by the constitutively expressed endothelial NOS (eNOS). iNOS enzyme appears to be expressed in liver disease such as cirrhosis and fulminant hepatitis, while the eNOS is expressed in physiological conditions. Ten young and ten old Wistar rats were sacrificed and their livers were excised. Liver sections were incubated with an anti-iNOS antibody of rabbit origin. RT-PCR and Western blot analysis were performed and nitric oxide activity was calculated. A significant increase of iNOS immunoreactivity was seen in the aged liver sections versus young liver sections. iNOS protein is expressed in greater quantities in the aged group, compared to the young group. In this study we show, for the first time, that aging in the rat liver is accompanied by a spontaneous induction of iNOS mRNA, high levels of iNOS protein and immunohistochemistry/image analysis.