Abstract
Purpose: :
Sigma-1 receptors (s1rs) have been reported to have neuroprotective effects in the prefrontal cortex, hippocampal tissue, and retina. The purpose of this study was to determine if there are changes in s1rs expression in vivo in the retina, following elevation of the intraocular pressure (IOP) in rats.
Methods: :
IOP elevation was carried out in one eye of adult male Brown Norway rats using the Morrison’s method (by injection of hypertonic saline through episcleral veins), while the contralateral eye served as the control. Following intraocular pressure elevation, rats were maintained for 2, 4, and 16 weeks and sacrificed. Retinal sections were obtained from control and IOP elevated rat eyes and analyzed for changes in s1rs expression by immunohistochemistry.
Results: :
Two weeks of elevated IOP produced minimal changes in s1rs expression in the retinal ganglion cell (RGC) layer as determined by immunohistochemical analysis. However, at the 4 week and 16 week time points, immunohistochemical analysis showed a decrease in s1rs expression in retinal ganglion cells in IOP elevated rat eyes when compared to the corresponding contralateral control eyes.
Conclusions: :
IOP elevation produced a decrease in s1r’s expression in retinal ganglion cells in rat eyes. The decrease in s1r’s expression could have a correlation with loss of RGCs following sustained elevation of ocular pressure. Previous studies have shown that s1r activation have neuroprotective effects in neuronal tissue, and further studies need to be done to better define the role of s1r in RGC survival.
Keywords: neuroprotection • receptors: pharmacology/physiology • retina