The expression of c-fos gene in retina of flickering light-induced and form deprivation myopia / 中华实验眼科杂志

ABSTRACT

Background Flickering light is different from the normal light environment.Animal experiment proved that flickering light can induce myopia.But its mechanism remains unclear.Objective This study was to investigate the expression of c-fos gene in retina of myopic C57BL/6J mice induced by flickering light and monocular form deprivation.Methods Ninety clean C57BL/6J mice aged 28-day-old with the similar refraction in both eyes were randomly assigned to five groups.Fifteen mice in the control group were exposed to continuous white light environment.The white flickering light with the frequency of 10,5,2 Hz were used to irradiate the mice respectively in high frequency flickering group (15 mice),moderate frequency flickering group (15 mice) and low frequency flickering group (15 mice),respectively.The right eyes of other 30 mice were monocularly occluded with a semitransparent hemispherical thin plastic shell to establish the form deprivation models and then were exposed to white light environment.The diopter and ocular axial length were measured by murine-specific eccentric infrared photorefraction and A-scan ultrasonography before experiment and two weeks after the treatments.At the end of experiment,the mice were sacrificed by neck dislocation.Mice eyes were enucleated and retinal samples were prepared for the detect of c-fos protein and its mRNA by immunohistochemistry,Western blot and reverse transcription polymerase chain reaction (RT-PCR),respectively.Results Immunohistochemistry showed that the expressing rate ofc-fos protein in retina was (68.000±10.368)％,(51.000±6.519)％,(46.000±6.519)％,(31.000±7.416)％ and (25.000 ± 7.071)％ in the control group,high frequency flickering group,moderate frequency flickering group,low frequency flickering group and form deprivation group respectively 2 weeks after experiment.The expression rates of c-fos protein in retina in different frequencies of flickering light groups and form deprivation group were significantly lower than that in the control group (t =3.104,4.017,6.490,7.661,all P＜0.05),with the lowest rate in the form deprivation group (P＜0.05).The expression of c-fos detected by Western blot assay exhibited that the relative values of c-fos protein in retina (c-fos/GAPDH) was 0.804±0.050,0.687±0.047,0.667±0.036,0.558±0.036 and 0.532 ±0.056,respectively in the control group,high frequency flickering group,moderate frequency flickering group,low frequency flickering group and form deprivation group,illustrating significantly lowing in different frequencies of flickering light groups and form deprivation group compared with control group (t =2.961,3.184,6.971,6.276,all P＜0.05),whereas the c-fos in the low frequency group and form deprivation group,c-fos protein was less expressed in comparison with the higher frequency flicking group (P＜0.05).The expression level of c-fos mRNA (c-fos mRNA/GAPDH mRNA) in retina was 0.820±0.056,0.663±0.061,0.627±0.034,0.521±0.041 and 0.474 ±0.045 in the control group,high frequency flickering group,moderate frequency flickering group,low frequency flickering group and form deprivation group,respectively.These results demonstrated a significant decline in the expression of c-fos mRNA in different frequencies of flickering group and form deprivation group compared with the control group(t=3.262,5.070,7.173,8.305,all P＜0.05),and the inhibition ability of low frequency of flickering group and form deprivation group was much stronger.Conclusions The c-fos gene level in the retina has a negative relationship with the severity of myopia induced by flickering light and form deprivation.