Diurnal expression of NGF1-A mRNA in retinal degeneration slow (rds) mutant mouse retina.

The retinal degeneration slow (rds) mutant mouse is a model for studying the retinal dystrophy for human disease, retinitis pigmentosa (RP). To continue our effort towards a possible mechanism of photoreceptor cell death in retinal dystrophies, we have studied the impact of the rds mutation on diurnal expression of a 'zinc-finger' DNA-binding protein, NGF1-A mRNA in the isolated retinas of rds mutant mice compared to those of BALB/c mice. Background levels of NGF1-A mRNA were maintained during the subjective light period. Higher levels of NGF1-A mRNA were observed immediately after the light offset and peaked two hours into the light offset for both the BALB/c and the rds mutant retinas and remained higher for several hours in the dark. If the animals were left continuously in light during the subjective dark period, NGF1-A mRNA levels were not induced and remained lower. On the other hand NGF1-A mRNA levels were transiently induced during the transition of the dark-to-light phase. The data suggest that NGF1-A mRNA is differentially regulated by light and dark stimuli in the retina and an absence of rod outer segments in the rds mutant retina does not alter the normal diurnal cycle of NGF1-A mRNA expression.