Enhanced expression of adhesion molecules of the retinal vascular endothelium in spontaneous diabetic rats

Otsuka Long-Evans Tokushima Fatty (OLETF) rats are a spontaneously diabetic strain with clinical features resembling those of human noninsulin-dependent diabetes mellitus. These rats show increased leukocyte entrapment in the retina. The present study was designed to investigate the immunolocalization of intercellular adhesion molecules-1 (ICAM-1) and P-selectin in the retinas of OLETF rats. Four 72-week-old male OLETF rats and 4 age- and sex-matched Long-Evans Tokushima Otsuka (LETO) control rats were used. Western blot analysis and immunohistochemical study were performed using an anti-P-selectin monoclonal antibody (mAb) and an anti-ICAM-1 mAb. Western blot analysis showed increased expression of both ICAM-1 and P-selectin in the retinas of OLETF rats. Immunohistochemically, OLETF rats expressed greater amounts of ICAM-1 and P-selectin in the retinal vascular endothelium than did LETO rats. These findings demonstrated the upregulation of ICAM-1 and P-selectin in the retina of OLETF rats. The enhanced expression of these adhesion molecules might participate in the pathogenesis of early diabetic microangiopathy in the retina.