Study On The Changes Of Zinc In Tissues After Radiation And The Effects Of Supplementary Of Zinc In Skin Cells Exposed To Radiation

Objective Radiation-induced skin injury is a common complication after tumor radiation therapy,nuclear accident and bone marrow transplantation,with unclear mechanism and ineffective treatment.Zinc are often thought to be an antioxidant and antiinflammatory factor,and there are more than 3,000 proteins have known sites binding with zinc,and about 10% of the proteins in the human body contain zinc,and this amount may also grow In the future.Therefore,we assume that the supplement of exogenous zinc ions,can reduce radiation damage to the skin cells by increasing the expression of antioxidant protein and removing reactive oxygen free radicals(ROS)caused by ionizing radiation.And tried to investigate whether this effect is achieved by activating the nuclear receptor RXRA.Methods 36 seven-week-old male C57/6 N mice were divided into dose-dependent groups(0,2,4,8 Gy)and time-dependent groups(0,1,2,5,28 days).A single dose of 45 Gy electron beam radiation was delivered to the skin of SD rats to establish the animal model of radiation induced skin injury.After being exposed to the radiation according to the plan,inductively coupled plasma mass spectrometry(ICP-MS)was used to detect the concentrations of zinc in serum and skin.Human immortalized epidermal cell HaCat and human epidermal fibroblast cell WS1 was selected as the main cell lines of this study.MTT assay was used to detect the effect of exogenous zinc ions on the proliferation of skin cells after irradiation.Lactate dehydrogenase release assay was used to detect the cell membrane stability.JC-1 was used to detect the changes of mitochondrial membrane potential.Immunoflorescence and luciforece reporter assay were used to measure the distribution and transcriptional acitivity of RXRA in skin cell after pretreated with different concentration of zinc chloride.AnnexinV/7-AAD staining based flowcytometry,western blot assay and DCF-DA based ROS detection were used to reveal the apoptosis and ROS generation of skin cell.Results The whole body irradiated model showed that the content of serum zinc decreased with the dose increasing in the dose-dependent group after irradiation,and the content of serum zinc in the time-dependent group decreased to the lowest level on the first day and did not return to the initial level after 28 days.The rat skin lesion model showed that erythema appeared on the seventh day after irradiation,and the zinc content in the skin tissue was significantly lower than that in the non-irradiated group.The content of zinc in the skin cells were also decreased.After pretreated by zinc chloride,MTT and clonely test Indicated that the proliferation of skin cells after irradiation is stronger than that of control group.The results of LDH showed that the cell membrane stability of WS1 was significantly improved after 24 h and 48 h after 10 Gy X-ray irradiation.The content of reactive oxygen species in the pretreatment group was significantly lower than that in the control group.Compared with the control group,the mitochondrial membrane potential of WS1 cells was more stable than that of the control group.Luciferase reporter gene experiments showed that zinc chloride could activate the promoter of RXRA.The results of western-blot showed that zinc chloride pretreatment could increase the expression of RXRA protein,and the results of Real-time quantitative RT-PCR showed that zinc chloride pretreatment could increase the expression of RXRA mRNA.The immunofluorescence showed that zinc chloride could activate nuclear receptor RXRA into the nucleus.The results of western-blot showed that the expression of RXRA was decreased after irradiation.The results of immunofluorescence showed that the content of RXRA in nucleus was decreased,LDH release assay showed that RXRA agonist can make cell membrane more stable,ROS accumulation and apoptosis of WS1 cells were also decreased,thereby reducing the ionizing radiation on skin tissue damage.Therefore RXRA could eliminate free radicals induced by ionizing radiation,and reduce the ionizing radiation damage to the skin tissue.Conclusion Zinc chloride can effectively reduce the free radical level and the mitochondria and cell membrane stability of skin cells after ionizing radiation,and its mechanism is related to the activation of retinoic acid X receptor A(RXRA).This study revealed the effect of zinc chloride on RXRA on radiation damage to skin cells and provides a new approach for the treatment of radiation-induced skin injury.