| This topic studied the effects of long and low intensity artificial light on morphology and function of the rats'retina, and circadian clock gene-Cryl expression, and the intervention role of traditional Chinese medicine(TCM) to light damage to retina and circadian clock gene disorder.Objective:To study of artificial circadian rhythm on the retina and circadian clock gene-Cryl and traditional Chinese medicine intervention function by rats experiment.Methods:This experiment planed to simulate light environment of the human ordinary room.The Sprague-Dawley(SD) rats were exposed to low intensity artificial light intermittently for a long time, daylight lamp as experiment lamp. SD rats 48 without any eye diseases were divides into 4 groups randomly, each group of 12. The control group were exposed to natural light. Experimental groups were divided into one model group and tow traditional Chinese medicine groups A and B. Experimental groups were exposed to artificial light (light:dark=18h:6h) which simulated indoor light of human. The rats of medicine groups were given traditional Chinese medicine twice to fill the stomach. According to the TCM theory of correspondence between human and natural environment, and rats habits of life, we used TCM doctor Xia Guicheng's prescription, group A rats were given Yang herbs to fill the stomach at 10:00 AM, were given Yin herbs to fill the stomach at 22:00 PM. Group B rats were given Yin herbs to fill the stomach at 10:00 AM, and were given Yang herbs to fill the stomach at 22:00 AM. After three months, routine inspection, F-ERG, retina histopathology inspection(optical microscope and transmission electron microscope,gene Cryl content were carried throught to every group. Optical parameter was measured to daylight lamp.Results:The eye tissue profile of each group had not seen the obvious difference. HE staining:Retina was normal in the control group. The cells' arrangement of the control group was clear and orderly by optical microscope. The outer nuclear layer were about 10 to 12 layer thickness, while the inner nuclear layer about 4 to 5. The inner plexiform layer was thicker than outer plexiform layer. The ganglion cells were in nerve fiber layer. The entire retina of the model group was atrophy by optical microscope. The cells'arrangement of the model group was disorderly. The outer and inner node of photoreceptors disappeared. There was no clear line between outer and inner nuclear layer. The nuclear layer reduced to about 3 to 5 layer thickness. The inner plexiform layer was thinner than that of control group. What to see by optical microscope in medicine A group were similar to model group. But the cell arrangement of medicine B group was poor. The outer and inner node of photoreceptors disappeared. There was no clear line between outer and inner nuclear layer. The nuclear layer reduced more. The inner plexiform layer was thinner. The ganglion cell and nerve fiber layer were swelled. Observed by transmission electron microscope, the structure of retina in the control group was histologically well-defined. Ganglion cells with regular shape and the chromatin was clear and uniform, endoplasmic reticulum and mitochondria were normal. In the model group, vesiculation occurred in the ganglion cell layer, inner nuclear layer and outer nuclear layer, and some of mitochondria showed swelling. The intramembranous structure of external segments became disorganized. Medicine A group was similar to model group. In medicine B group, vesiculation and swelling occurred in the ganglion cell layer and inner nuclear layer, with disruption of the cell membrane. Vesiculation and swelling were also found in the outer nuclear layer with reduction in cell quantity. The structure was disorganized, with disorganized cell membrane, obvious swelling of mitochondria, disorganized intramembranous structure of external segments, and loss and vesiculation of the laminal structure. F-ERG of control group was more typical, but experiment groups were not. In model group, latent period of Rod-R b was prolonged. The amplitude of a-wave and b-wave of Max-R decreased also. The amplitude of a-wave and b-wave of Cone-R decreased. The amplitude of OS of Ops and N1-P1 of 30Hz Flicker decreased too. The amplitude of ERG in model group were lower than that in control group (P<0.05). ERG of medicine A group were similar to model group. Latent period of Rod-R b was prolonged. a-wave and b-wave of Max-R, Cone-R, Ops OS,30Hz Flicker N1-P1 were lower than that of control group (P<0.05). The amplitude of a-wave and b-wave of Max-R and the amplitude of b-wave of Cone-R in medicine A group were higher than model group (P<0.05). The amplitude of b-wave of Max-R and latent period of Max-R a in medicine B group were lower than model group (P<0.05). Retinal circadian clock genes-Cry1 located in ganglion cell layer. RT-PCR:the control group Cryl content were higher than model group and medicine A group (P<0.05), same as medicine B group. SD rats of control group were quiet while other experimental groups were restless and alarmed. Daylight lamp brightness was not stable and contained much ultraviolet rays.Conclusion:It suggests that artificial circadian rhythm with low intensity daylight can injure retinal function and structure over a long period of time. To some extent traditional Chinese medicine A is helpful to protect retina. While traditional Chinese medicine B was aggravated damage to the retina. But this opinion needs to discuss further. Violating the TCM theory of correspondence between human and natural environment will increase circadian rhythm disorders. It infers that poor light environment is one of very important reasons to increase the risk of retinal diseases. But this opinion needs to discuss further.
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