Abstract
Abstract: :
Purpose: To investigate the localization and circadian rhythmic pattern in the mammalian retina, we examined the protein expression of two representative clock genes, per2 and clock in the mouse retina. Method: ICR mice were housed at a constant temperature of 21 °C under 12h light/12h dark condition (LD 12:12) at least two week before experiments. Eyes of group 1 mice were enucleated at 0.5, 1, 2, 6 and 11 hours after light exposure and 2, 6 and 11 hours after dark. The other mice were housed under constant darkness (DD) for 3 days. Then eyes were enucleated at 2, 6 and 11 hours of subjective day and 2, 6, 11 hours of subjective night. Tissues were fixed in 4% paraformaldehyde, sucrose infiltrated, embedded in OCT, and cryopreserved. Ten µm cryosections were examined by immunohistochemical procedure for per2 and clock proteins. Results: Per2 and clock proteins existed in entire neurosensory retina. Especially the ganglion cell layer showed strong positive immnostaining of per2. The ganglion cell layer and inner nuclear layer showed strong positive immnostaining of clock. The circadian rhythmic expression of both per2 and clock proteins in the retina was detected. The high expression peak of both proteins appeared at 0.5, 1 and 2 hours after light exposure under LD 12:12 and at 2 hours of subjective day under DD. Expressions were decreased time dependently. The low expression peak of both proteins appeared at 11 hours after light exposure under LD 12:12 and at 11 hours of subjective night under DD. Conclusions: Two representative clock genes, per2 and clock proteins existed in the mouse retina and have a circadian rhythmic expression.
Keywords: immunohistochemistry • gene/expression • physiological optics