ABSTRACT
@#In modern society, children and adolescents are experiencing an increasing incidence of myopia, resulting from the combined influence of genetic factor and environmental factor. Despite the influence of genetic factor, a great number of researches indicate that environmental factor has been playing a crucial role. Outdoor activity proves to be a major protective factor to reduce the incidence of children's myopia. Sunlight is one of the important ones among various factors of outdoor activity. The intensity, wavelength and rhythm of sunlight may all affect eyeball's refraction development. Varied sunlight environment may have different influences on eyeball's refraction development. The paper has summarized clinical and trial and animal experiment research results on how sunlight affects eyeball's refraction development, and it has offered references to further study on refractive error development mechanism and prevention strategy.
ABSTRACT
Objective Constant light exposure can lead to hypercatabolism. The aim of this study was to investigate the effects of different light rhythm on skeletal muscle metabolism in endotoxemia rats, and looked for the optimal light rhythm that could reduce skeletal muscle consumption and enhance the recovery of patients with sepsis. Methods 54 adult male S-D rats were randomly divided into 3 groups on average：Control group (intraperitoneal injection of normal saline +12h/12h light-dark cycle for 7 days), LPS- regular light group (intraperitoneal injection of lipopolysaccharide(LPS) +12h/12h light-dark cycle for 7 days) and LPS-constant light group (intraperitoneal injection of LPS + constant light for 7 days). All experimental animals were sacrificed on the 8th day. The level of skeletal muscle metabolites 3-methylhistidine (3-mh) and tyrosine, atrophy genes MAFbx and murf-1 mRNA and hypothalamic clock genes BMAL1, CLOCK and neuropeptide POMC were also detected. Results The food intake, weight growth ratio and the ratio of extensor digitorum longus/weight in the LPS-constant light group were significantly lower than those in the LPS-regular light group (P <0.05), and both groups were significantly lower than those in the control group (P <0.01). The skeletal muscle metabolites 3-methylhistidine(nmol/g) and tyrosine(nmol/g) in the LPS-constant light group rats (6.200±0.273 and 461.039±13.292) were significantly higher than those in the LPS- regular light group (5.197±0.263 and 375.744±20.308) and the control group (3.244±0.275 and 290.935±19.065,all P <0.05). The expression levels of atrophic genes MAFbx and murf-1 mRNA and tnf-alpha and il-1 mRNA in hypothalamus in the LPS-constant light group were significantly higher than those in the LPS- regular light group(P <0.05), and both groups were significantly higher than those in the control group (P <0.05). The expression of the clock genes(BMAL1 and CLOCK) in the showed obvious rhythm (SE (A) /A<0.3) in the LPS-regular light group and the control group. The expression of BMAL1 was highest at the beginning of the illumination period, while the expression of CLOCK was high during the illumination period and decreased during the darkness period. In the LPS-constant light group, the expression of BMAL1 and CLOCK rhythm lost rhythm. Conclusion Normal light rhythm can maintain the normal rhythm expression of hypothalamic clock gene in rats with endotoxemia and reduce POMC-mediated skeletal muscle consumption, which may be of positive significance for the enhanced recovery of sepsis.