IBMX, taurine and 9-cis retinoic acid all act to accelerate rhodopsin expression in postmitotic cells

Birth dating studies in the rodent retina have shown that rod photoreceptors are generated throughout most of retinal development, yet the majority do not begin to express rhodopsin until the first postnatal week. We show that treatment with 3-isobutyl-1-methylxanthine (IBMX) enhances rod development in reaggregate, explant, and monolayer cultures of embryonic and newborn rat neural retina and is more potent than another rod-promoting factor, taurine, but less potent than 9-cis retinoic acid (RA). The effect of IBMX on rod development is not associated with an increase in precursor cell proliferation, rod survival, or a reduction in the development of other retinal cell types. We provide evidence that IBMX, as well as the rod promoting molecules taurine and RA, all act on postmitotic rhodopsin(-)cells to accelerate their differentiation into rhodopsin(+)cells.