ABSTRACT
AIM: To investigate the preventive effect and optimal drug dose of lipoic acid-niacin(N2L)against blue light-induced retinal damage in SD rats, and to explore its possible protective mechanism.METHODS: A total of 36 specific pathogen free-grade male SD rats of 150-200 g were selected and randomly divided into normal control group, blue light injury group, N2L low-dose group(1.0 mg/kg), N2L medium-dose group(2.5 mg/kg), N2L high-dose group(5.0 mg/kg), and physiological saline group, with 6 rats in each group. The normal control group was reared in a 12 h dark and light cycle, and the rest of the groups received 9 h of daily light exposure, 3 h of blue light irradiation with a wavelength of 455 nm and an intensity of 3000±50 lx, and 12 h of darkness to establish the injury model, and were exposed to light exposure for 14 d. For 14 consecutive durations, a 1 mL dose of the corresponding drug was injected intraperitoneally. The rats were reared for another 5 d with a regular 12 h light-dark cycle and were examined by electroretinography. Specimens were prepared by over anesthesia, HE staining, and the thickness of the outer nuclear layer was observed under a optical microscope; superoxide dismutases(SOD)activity was detected by CheKineTM SOD Activity Assay Kit; and the retinal Caspase-3, quinone oxidoreductase 1(NQO1), glutathione S transferase(GST), Bcl-2, and Bax protein expression in rat retina were detected by Western blot.RESULTS: The amplitude of b-wave in dark-vision ERG 3.0 and 10.0(cd·s)/m2 stimulated light, b-wave in bright-vision ERG 3.0(cd·s)/m2 stimulated light, and the amplitude of the 2nd wave peak of oscillatory potential were significantly lower in blue light injury group than that in the normal control group(all P<0.01), while the amplitude was significantly higher in the N2L medium-dose group than in the blue light injury group(all P<0.05), and was not statistically different from that of the normal control group; the thickness of the retina in the blue light injury group was decreased in the ONL compared with that of the normal control group(P<0.001), while in the N2L medium dose group, it was thicker than that of the blue light injury group(P<0.001), and there was no statistically significant difference from the normal control group; SOD activity was significantly higher in the N2L medium-dose group than in the remaining 5 groups(P<0.05); the expression of Caspase-3, Bax, and NQO1 in the blue light injury group was higher than that of the normal control group(all P<0.01), and expression of Bax and Caspase-3 was significantly lower in the N2L medium-dose group compared with the blue light injury group(all P<0.001), whereas GST, NQO1 and Bcl-2 were significantly increased(all P<0.01).CONCLUSION:A concentration of 2.5 mg/kg N2L can effectively antagonize the damaging effect of blue light on the retina of SD rats, and it is expected to be a preventive and curative drug for it.
ABSTRACT
Objective To investigate the correlation between the proportion of peripheral blood follicular T helper cells(Tfh cells)and intracellular interleukin-21(IL-21)content with blue light retinal injury.Methods Brown Norway(BN)rats were randomly divided into 4 groups and were exposed to blue light for 3 hours a day to establish retinal light damage model.According to the duration of illumination,the rats was divided into 0 days(control group),3 days(3 d group),7 days(7 d group)and 14 days(14 d group).The proportion of Tfh cells and content of IL-21 in Tfh cells in peripheral blood of each group was detected by flow cytometry and ELISA sepa-rately after illumination.Electroretinogram(ERG)was used to evaluate retinal function.The changes of fundus in rats were observed by fundus photography.The thickness of outer nuclear layer of retina was analyzed by HE staining.Results After retinal blue light injury,with the extension of illumination time,the proportion of Tfh cells in peripheral blood and intracellular IL-21 content both increased(P<0.05).ERG showed that retinal function decreased after light damage and aggravated with the extension of illumination time,the latency and ampli-tudes of A-wave and B-wave increased and decreased respectively(P<0.05).The retinal fundus of rats showed depigmentation in 3 d,and the retinal vessels became thinner and exudate with the extension of illumination time.HE staining showed that the outer nuclear layer of retina(ONL)became thinner(P<0.05).Correlation analy-sis indicated that the proportion of Tfh cells in peripheral blood and the intracellular IL-21 content could jointly reflect the degree of injury(P<0.000 1),and the proportion of Tfh cells in peripheral blood was negatively corre-lated with ONL thickness and the amplitude of a and b waves,positively correlated with the peak time of a and b waves,(P<0.0001).Conclusion The proportion of Tfh cells in peripheral blood and the intracellular IL-21 content were increased after blue light damage to retina,and were significantly increased with the extension of light time with a certain correlation.