Abstract
Purpose :
Protease-activated receptor-1 (PAR1) is activated by the action of serine protease Thrombin. Thrombin plays a role in neurological dysfunction in diabetes. Recent studies have indicated that PAR1 and its activating protease thrombin are expressed in the ocular microenvironment of patients with diabetic retinopathy (DR). The aim of this study is to characterize the distribution of PAR1 in the neuroretina, under physiological conditions, and in diabetes.
Methods :
Diabetes was induced in 8 weeks old C57BL/6J male mice by intraperitoneal injection of Streptozotocin (STZ, 150 mg/kg). Five weeks following diabetes induction eyes were removed from diabetic mice (n=12) and healthy C57BL/6J male mice (n=12) and were processed for indirect immunofluorescence analysis. PAR1-/- mice were used as control (n=3). In addition, western blot analysis was performed on mouse neuroretina, optic nerve, brain, and platelets samples.
Results :
Significant PAR1 staining was observed in the nuclei of all neuroretinal cell layers (retinal ganglion cells, inner and outer nuclear layers) in diabetic mice (glucose blood > 200mg/dl). Significantly weaker staining was observed in control non-diabetic mice. No staining was observed in PAR1-/- mice. Co-staining of PAR1 with photoreceptor markers demonstrated co-localization of PAR1 and rhodopsin in rod outer and inner segments. By contrast, no PAR1 staining was observed in cone outer segments. The specificity of immunofluorescence staining was confirmed with Western blot analysis.
Conclusions :
To the best of our knowledge, this is the first demonstration of PAR1 expression in rod retinal photoreceptors and inner nuclear layer cells. This study suggests that PAR1/thrombin pathway may play a role in the pathophysiology of rods in diabetic retinopathy.
This is a 2021 ARVO Annual Meeting abstract.