Augmented retinal endothelin-1 endothelin-3 endothelinA and endothelinB gene expression in chronic diabetes

Purpose. Endothelins (ETs) belong to a family of vasoactive peptides implicated in several disorders of the microvasculature. In the present study, we investigated ET-1 and ET-3 peptide mRNAs and ETA, ETB receptor mRNAs in the retina of diabetic BB/W rats and age-matched, non-diabetic control animals, following six months of diabetes. Methods. Total mRNA was extracted from each retina and was subjected to reverse transcriptase polymerase chain reaction for ET-1, ET-3, ETA and ETB. Simultaneously, beta-globin was amplified and used as a housekeeping gene. The products were analyzed on agarose gels and the specificity of the amplification was established by hybridization with amplification-specific biotinylated oligoprobes. For quantification, the products from the linear phase of amplification were subjected to serial dilution slot-blot hybridization and densitometry. Results. ETs and their receptor mRNA expressions were present in the retina. Retinas from the diabetic animals showed significant increases in ET-1, ET-3 ETA, ETB mRNA expressions compared to those from control rats. Conclusions. These findings indicate that retinal ET-1, ET-3, ETA and ETB mRNA expression is increased in the chronically diabetic BB/W rat. Augmented gene expression of ETs and their receptors potentially may be of importance in the pathogenesis of retinal microangiopathy in diabetes.