Endothelin-1 and endothelin-3-like immunoreactivity in the eyes of diabetic and non-diabetic BB/W rats.

Endothelins (ETs) are a family of vasoactive peptides implicated in several disorders of the microvasculature. In the present study, the distribution of immunoreactive ET-1 and ET-3 was investigated in eyes from 8 month spontaneously diabetic BB/W rats and in age matched control animals. Both peptides showed similar immunoreactivity. In non-diabetic animals, corneal epithelium and endothelium, ciliary epithelium, lens epithelium, iris and the microvasculature of the sclera and choroid showed positive immunoreactivity. In the retina, photoreceptor inner segments showed positivity. In the inner nuclear layer, cells of both neuronal and glial origins showed positive immunoreactivity. Both the nuclei and the cytoplasm of the ganglion cells were positively stained. Retinal pigment epithelium showed patchy but consistent immunoreactivity. Capillary endothelial cells showed inconsistent positive staining. The pericytes were uniformly negative. In diabetic animals although overall intensity was increased, retinal pigment epithelium and ciliary epithelium showed no immunoreactivity. The corneal epithelium showed increased but patchy immunoreactivity. The altered intensity and distribution of ETs in diabetes suggest that ETs may be of importance in the pathogenesis of chronic occular complications in the diabetic BB/W rat.