Protective Effect Of Dexmedetomidine On Acute Stress-induced Kidney Injury In Rats By Regulating NE/ROS/JNK

Acute stress,as an important cause or inducement of many diseases,seriously affects livestock production and animal health.The kidney is one of the most vulnerable organs in stress.Kidney injury can induce water intoxication and brain edema,often life-threatening.Currently,exploring the molecular mechanism and effective drugs for prevention and treatment of acute stress-induced kidney injury in rats is a hot and difficult issue in veterinary clinical research.In view of the scientific phenomenon that dexmedetomidine(DEX)has renoprotective effect of rats found in previous studies,the research group established an acute stress model in rats and applied DEX intervention to explore the molecular mechanism and injury site of the kidney injury induced by acute stress in rats.Moreover,from the perspective of inhibiting oxidative stress and apoptosis,the protective mechanism of DEX on acute stress-induced renal injury was explored.It provides new research ideas and intervention means for veterinary clinic to study the treatment and related mechanism of acute stress-induced kidney injury,and provides reliable experimental basis for clinical application of DEX in anti-stress.Forty-two healthy male Wistar rats were selected for the current experiment.First,24 rats were divided into control group(C group),DEX high-dose group(HD group),DEX medium-dose group(MD group)and DEX low-dose group(LD group).Rats in HD group,MD group and LD group were injected with DEX 50 μg/kg,40 μg/kg and 30 μg/kg,respectively.After 30 min,the behavior of rats was observed.Blood samples were taken for blood routine and biochemical examination to screen safe and non-toxic dose of DEX.Then,the remaining 18 Wistar rats were equally divided into control group(C group),acute stress group(AS group)and DEX pretreatment group(D + AS group).Rat acute stress model was established by forced swimming for 15 min and restraint stress for 3 h.The model was validated by the open field text.Biochemical examination,H&E staining,transmission electron microscopy,ELISA,TUNEL method,immunohistochemical method and Western blot were used to explore the molecular mechanism and specific sites of kidney injury induced by acute stress in rats,and the protective mechanism of DEX on kidney injury induced by acute stress in rats.The safe DEX dose was 30 μg/kg.The open field text proved that the rat acute stress model was established successfully.Renal function test results: The levels of BUN and CREA in the AS group were the highest,and the D + AS group was significantly different from the AS group(P < 0.05).Renal histological observation results: focal renal hemorrhage,neutrophil infiltration,focal tubular necrosis and vacuolar degeneration were observed in the renal tissues of rats in the AS group,while no neutrophil infiltration and hemorrhage were observed in the D + AS group,only a small amount of tubular necrosis and vacuolar degeneration were observed.Morphological observation of kidney: In AS group,the nuclei of renal cells were condensed and stained,and the mitochondria were swollen.In D + AS group,the structure of kidney cells was relatively complete,with only a few vacuoles in mitochondria.Results of oxidative stress index test: MDA concentration in AS group was dramatically higher than that in C group and D + AS group(P < 0.01),while SOD activity and GSH level were dramatically lower than those in D + AS group(P < 0.01).TUNEL detection results: kidney tissue of AS group had the most apoptotic cells,which was signally different from that of C group and D + AS group(P < 0.01).Immunohistochemical results: the expression levels of cleaved caspase 3 and P-JNK in the AS group were markedly different from those in the C group and the D + AS group(P < 0.01),and were mainly concentrated in the renal tubules.Western blot results: the expression levels of caspase 8、TNF-α、GRP78、nuclear XBP-1、cytoplasm XBP-1、CHOP and cleaved caspase 12 in kidney tissues of AS group were not significantly different from those of C group and D + AS group.The expression levels of Bax,cytochrome C,cleaved caspase 9,cleaved caspase 3 and P-JNK protein were signally higher than that of C group and D + AS group(P < 0.01).Hormone test results: serum levels of norepinephrine(NE)and epinephrine(E)in the AS group were apparently higher than those in the C group(P < 0.01),and CORT content was not obviously different from that in the C group.The content of NE in the D + AS group was significantly lower than that in the AS group.Reactive oxygen species(ROS)results: the ROS concentration in the AS group was significantly higher than that in the C group(P < 0.01),and the D + AS group was markedly lower than the AS group(P < 0.05).In summary,acute stress mainly induces apoptosis of renal tubular cells by initiating mitochondrial apoptosis pathway,which in turn induces kidney injury in rats.DEX protects against renal injury induced by acute stress,mainly by regulating NE release,enhancing the body’s antioxidant capacity,reducing ROS content,inhibiting JNK phosphorylation,and thereby downregulating Bax,cytochrome C,cleaved caspase 9 and cleaved caspase 3 protein expression.