Anti-Heat Stress Effect And Mechanism Of Chicken Embryo And Mouse Induced By LED Blue Light

Heat stress prevention and control are crucial in modern,intensive,large-scale farming of livestock and poultry.Chickens have underdeveloped sweat glands and their bodies are covered in feathers,making them susceptible to decreased productivity,reproductive performance,and even death due to heat stress.One way to improve chickens’ heat stress resistance is through thermal conditioning during embryo incubation,but the chronic heat stress hazards brought about by high-temperature incubation are often overlooked.In this study,we focused on the Chinese indigenous chicken breed Huangyu broiler(Yellow-footed chicken)and used physical agricultural engineering principles and new agricultural engineering lighting sources such as LED lamps as regulation methods to explore the regulatory effects of blue light LED on the damage caused by heat stress to the embryonic stage of broiler chickens from multiple levels such as tissue morphology,hormone secretion,and gene expression.Using multiple omics techniques such as proteomics and quantitative acetylation modification omics,we preliminarily revealed the potential response pathway of blue light LED to heat stress resistance.Furthermore,using ICR mice as model animals,we further investigated the differences in the regulatory effects and mechanisms of blue light LED on heat stress resistance,aiming to provide a practical and theoretical basis for the light environment regulation strategies and precision control of modern physical agricultural engineering in animal husbandry.Core research contents and main results of this paper:(1)The injury effect of heat stress and the regulating effect of blue LED on broiler embryo were studied.The negative heat stress effect of heat acclimatization in incubation period,a common heat stress relief measure in animal husbandry,was studied.The eggs of yellow-feet chicken were incubated in four treatment groups: 1)normal temperature white light group(37 °C + white light);2)blue light group(37 °C + blue light);3)heat acclimation white light group(40 °C + white light);4)heat acclimation blue light group(40 °C + blue light),histopathological characterization,embryo liver oxidation product content and antioxidant enzyme activity detection,heat stress protein and heat shock factor q PCR determination.The results showed that the morphology of chicken embryo tissue was damaged under white light heat stress,the central venous blood vessel wall was destroyed and the blood vessel wall became thinner,while there was no tissue morphological change under blue light heat stress.Blue light significantly reduced the concentrations of malondialdehyde(MDA)and corticosterone(Cort)in the liver of broilers during embryonic period,and increased the relative expression of superoxide dismutase(SOD)and hydrogen peroxide(CAT)genes.Blue light has a significant regulatory effect on the gene expression of heat shock protein HSPs and heat shock protein HSFs in chicken liver,but the regulatory effect between them is different.Therefore,the heat acclimatization of broiler embryo will produce the negative effect of heat stress,and blue light can slow down the negative effect and regulate the related sensitive genes,proteins,and biochemical indicators of heat stress response.(2)The molecular pathway of blue LED regulating heat stress injury in broiler embryos was revealed.Quantitative proteomics analysis and quantitative analysis of acetylation modification were performed on embryo livers incubated under white and blue LEDs during embryo thermal acclimation,and the mechanism of blue light on the regulation of chicken embryo thermal acclimation at the protein level was studied.The results showed that quantitative proteomics analysis showed that 108 differentially expressed proteins were enriched in 5 molecular pathways under white light,while 97 differentially expressed proteins were enriched in 2 molecular pathways under blue light.Further quantitative omics analysis using acetylation modification showed that 144 proteins were differentially modified under white light and enriched in 14 molecular pathways,while only 58 proteins were differentially modified under blue light and only 7 molecular pathways were involved.GO and KEGG enrichment analysis suggested that the main molecular mechanism of liver injury induced by heat acclimation was to promote the immune and inflammatory response of liver,while the molecular mechanism of blue light to reduce heat acclimation injury might be to reduce the secretion of stress hormones and enhance the metabolism of organic acids.(3)To compare the anti-heat stress effect of blue LED on cultured animals and model animals.The expression changes of heat stress related hormones and genes in ICR mice under controllable heat stress environment were studied,and the appropriate blue light regulation light intensity and the appropriate action time of acute heat stress test were explored,which laid a foundation for exploring the mechanism of heat stress laser environment regulation of domestic animals and poultry.Acute heat stress stimulation(Experiment 1)and chronic heat stress stimulation(Experiment 2)at different light intensities(5 lux,100 lux,1000 lux)were performed on mice cultured under white light and blue light for 1,6 and 12 hours.The expression of heat stress protein,heat shock protein,antioxidant and anti-inflammatory factors was determined.The results showed that blue light significantly reduced the concentration of corticosterone(Cort)and malondialdehyde(MDA)in experimental mice under heat stress to normal or below normal levels,similar to the heat stress response of cultured animals(broilers).In the acute heat stress experiment,the duration of 6h heat stress had the greatest damage to the heat stress of mice.In the chronic heat stress experiment,the anti-heat stress effect of 100 lux blue light with moderate light intensity was the best.Therefore,blue LED has anti-heat stress effect on both farm animals and model animals.(4)The molecular pathway differences of the anti-heat stress effect of blue LED in farm animals and model animals were revealed.The molecular mechanism of blue light tolerance to heat stress in ICR mice was studied.The experimental mice were stimulated by acute heat stress(36 °C for 1,6,12 hours)and chronic heat stress(36 °C for 2 hours for 4 days).The results showed that 1 hour of acute heat stress caused significant differential expression of 3432 genes(FDR<0.05;|log2FC|>1),6 and 12 hours of acute heat stress further caused significant differential expression of 3584 and 3620 genes,while chronic heat stress caused significant differential expression of 2909 genes.GO and KEGG enrichment analysis showed that blue LED mainly resisted heat stress through stress response,biological clock,autophagy,p53 signaling pathway and other functions or pathways.Further q PCR analysis showed that blue light could significantly reduce the m RNA expression of autophagy core Beclin1 and the m RNA expression of autophagy positive regulator Parkin.The m RNA expression of NIX,p62 and LC3-i in the autophagy pathway was similar.Therefore,although blue LED has anti-heat stress effects on both farmed animals and model animals,the mechanism of action is significantly different: Unlike the immune and inflammatory response molecular pathways of farmed animals,blue light mainly regulates the negative effects of heat stress through autophagy pathways.