Possible retinotoxicity of long-term vardenafil treatment.

Phosphodiesterase (PDE) inhibitors - such as vardenafil - are used primarily for treating erectile dysfunction via increasing cyclic guanosine monophosphate (cGMP) levels. Recent studies have also demonstrated their significant cardioprotective effects in several diseases, including diabetes, upon long-term, continuous application. However, PDE inhibitors are not specific for PDE5 and also inhibit the retinal isoform.

Detailed Evaluation of Possible Ganglion Cell Loss in the Retina of Zucker Diabetic Fatty (ZDF) Rats.

A thinning of the inner retina is one of the earliest potential markers of neuroretinal damage in diabetic subjects. The histological background is uncertain; retinal ganglion cell (RGC) loss and changes in the structure or thickness of the inner plexiform layer (IPL) have been suspected. Studies conducted on animal models on RGC pathology gave contradictory results.

Histological Evaluation of Diabetic Neurodegeneration in the Retina of Zucker Diabetic Fatty (ZDF) Rats.

In diabetes, retinal dysfunctions exist prior to clinically detectable vasculopathy, however the pathology behind these functional deficits is still not fully established. Previously, our group published a detailed study on the retinal histopathology of type 1 diabetic (T1D) rat model, where specific alterations were detected. Although the majority of human diabetic patients have type 2 diabetes (T2D), similar studies on T2D models are practically absent.

Characterization of connexin36 gap junctions in the human outer retina.

Retinal connexins (Cx) form gap junctions (GJ) in key circuits that transmit average or synchronize signals. Expression of Cx36, -45, -50 and -57 have been described in many species but there is still a disconcerting paucity of information regarding the Cx makeup of human retinal GJs. We used well-preserved human postmortem samples to characterize Cx36 GJ constituent circuits of the outer plexiform layer (OPL).