Low expression of rhodopsin kinase in pineal gland in Royal College of Surgeons rat

The Royal College of Surgeons (RCS) rat has been extensively characterized as a model for inherited retinal dystrophy such as retinitis pigmentosa. We have found that significantly low levels of expression of rhodopsin kinase (RK) and alphaA-crystallin may be involved in the pathogenesis of retinal degeneration in the RES rat (Invest Ophthalmol Vis Sci. 1999,40:2788-2794). In the present study, we examined the expression of photoreceptor specific proteins in the pineal gland (PG) including rhodopsin kinase (RK), arrestin and recoverin, which are known to be commonly present in both photoreceptor and PG, in order to elucidate the pathological relationship between retina and PG during retinal degeneration. Among these proteins, RK expression was significantly decreased with advancing age (3-5 weeks old) in RCS rat. However, in contrast, arrestin expression in RCS PG was comparable with control PG and no expressions of recoverin and other G-protein coupled receptor kinases (GRKs 2, 5 and 6) were detected in RCS PG during 3-5 weeks of age. By administration of nilvadipine, an effective Ca2+ antagonist that was shown to preserve RES retinal degeneration, RK expression was significantly enhanced.