Effects Of Tail Vein Injection A-melanocyte Stimulating Hormone On The Early Inflammatory Response In Heavy-degree Scald Rats

Objective: To investigate the impacts of tail vein injection a-MSH on the earlysystemic and local inflammation reaction in heavy-degree scald rats to explorethe mechanisms of α-MSH release scald induced inflammation reaction.Method: Eighteen adult SD rats, Male or female, were randomly assigned tothree groups (n=6).α-MSH solution of which the concentration was1mg/mlprepared with distilled water. Rats in treated group A received α-MSH solutioninjection through caudal vein with a dose of1ml/(kg·d)for three continuousdays after scalded. Rats in control group B were injected with physiologicalsaline1ml/(kg·d) three days after scalded. Rats in group C were normal controlgroup and received no additional treatment. After scalding24h,48h and72h, theskin scab formation,dissolution and shedding time of the scald wounds werenaked-eye examination and1-2ml venous blood was obtained from each ratafter scalding6h,12h,24h,48h and72h to measure the levels of cytokineIL-10,TNF-a by enzyme-linked immunosorbent assay(ELISA).After that thescald wounds tissue was harvested from sacrificed rats and HE stain wasperformed to observe the histopathological changes. Results were showed asmeans±standard deviations (x±s)and statistical analysis SPSSl9.0software wasused to perform t-test and one-way ANOVA, less than0.05was consideredstatistical signific-ance.Result:(1)After scalding,the wound surface of group A and B becomecongested and edematous. After scalding24h,48h,72h, The color of the woundsurface became darken and the eschar gradually arises. There is a appearancethat the black eschar of group A is fewer than group B and the localinflammatory reaction of group A is milder than group B through the macroscopic observation.(2)The levels of IL-10in group A and B significantlyhigher than in group C(P<0.05) and the expression of IL-10in group A and Bwere increased first and then decreased with the scalding time lasting, reachedthe peak after24h. There was no statistical difference of the levels of IL-10ingroup C at different time points. After scalding6h,12h,24h,48h and72h,thelevels of IL-10in group A were significantly higher than in group B and C(P<0.05) and the levels of IL-10in group B were significantly higher than ingroup C (P<0.05).The expression of IL-10at the five time-points in groupA:(44.26±2.15) pg/ml,(49.79±1.61) pg/ml,(174.44±4.38) pg/ml,(131.37±2.51)pg/ml,(82.50±2.38) pg/ml; The expression of IL-10at the five time-points ingroup B:(29.30±1.38) pg/ml,(36.24±1.07) pg/ml,(102.29±1.87) pg/ml,(93.08±3.46) pg/ml,(58.88±1.60) pg/ml; The expression of IL-10at the fivetime-points in group C:(26.45±0.97) pg/ml,(28.58±1.07) pg/ml,(28.85±0.81)pg/ml,(29.28±1.35) pg/ml,(30.66±1.08) pg/ml.(3)The levels of TNF-a ingroup A and B significantly higher than in group C (P<0.05), and increasedwith the scalding time lasting. There was no statistical difference of the levelsof TNF-a in group C at different time points. After scalding6h,12h,24h,48h and72h, the levels of TNF-a in group A were significantly lower than in group B(P<0.05). The expression of IL-10at the five time-points in group A:(33.43±2.57) pg/ml,(37.25±3.55) pg/ml,(75.78±3.05) pg/ml,(91.75±4.87)pg/ml,(130.31±4.23) pg/ml; The expression of TNF-a at the five time-points ingroup C:(49.30±4.60) pg/ml,(58.99±1.77) pg/ml,(132.11±2.89) pg/ml,(132.65±6.82) pg/ml,(169.84±3.97) pg/ml; The expression of TNF-a at the fivetime-points in group C:(34.39±1.12) pg/ml,(33.94±1.74) pg/ml,(35.60±2.16)pg/ml,(34.61±2.13) pg/ml,(33.34±2.06) pg/ml.(4) The HE section in group Aand B after scald72h wounds tissue showed that engorgement, cell edema,necrosis and inflammation cells infiltration in group A were milder than that ingroup B.Conclusion: a-MSH can inhibiting the expression of inflammation factors TNF-a and promote the expression of anti-inflammation factors IL-10to releasethe system inflammation reaction and the local inflammation reaction of mitig-ting edema, necrosis and inflammation reaction.Consequence,we concludethat a-MSH may be used as drugs to treat the inflammation reaction after severescald in rats at early stage.