Distribution of ROCK2 in Normal and N–Methyl–D–Aspartate Injected Rat Retinas

Abstract

Abstract: : Purpose: We have previously shown that the Rho/ROCK pathway may be involved in N–methyl–D–aspartate (NMDA)–induced retinal neurotoxicity. The current study examined the localization of ROCK2 expression in the rat retina. Methods: The eyes were enucleated at 1 day after 20–200 nmoles of NMDA intravitreal injection. Immunohistochemistry was performed with antibodies against ROCK2, Thy–1, calbindin or vimentin. Images were examined using a digital confocal microscopic fluorescent imaging system. Results: ROCK2 possitive cells were abundant in the ganglion cell layer (GCL) and inner nuclear layer (INL) in normal retinas. Vehicle (phosphate–buffered saline; PBS)– or NMDA–treated retinas showed decreased ROCK2 immunoreactivity. However, NMDA also increased the number of ROCK2 immunopositive cells when compared to PBS–treated retinas. Double immunohistochemical studies showed some colocalization of ROCK2 and Thy–1. Conclusions: In normal condition, ROCK2 is ubiquitously expressed in inner retinal neuronal cells including retinal ganglion cells. ROCK2 may play a different role under pathological conditions such as excitotoxicity.

Keywords: immunohistochemistry • excitatory amino acid receptors • retina: proximal (bipolar, amacrine, and ganglion cells)