Roles Of Edema Related Proteins In The Multi-Organ Damage Of Melatonin-Intervened HIBD Neonatal Rats

Objective To observe the expression change of aquaporins and Tight JunctionProteins in hypoxic ischemic brain damage neonatal rats with/without melatoninintervention and discuss their roles in the cytotoxic/vasogenic brain edema. At the sametime we’ll find out whether AQPs and TJPs play a role in the damage of peripheral organsand the effects of melatonin on them as to get a whole view of the mechanisms of HIBDand to give out a theoretical basis for the integrated treatment of HIBD.Methods HIBD model was established according to the modified Rice-Vannuccimethod, using SD rats7days of age.192SD rats were randomly divided into three groups(Sham operation group(Sham group), Model group(Mod group), MT treatment group(MTgroup))and then subdivided into4subgroups at3h,6h,24h and72h after HIBD operation.We used Dry-Wet weight method, light microscopy after HE staining and transmissionelectron microscopy for the observation of edema and Real-Time PCR to measure AQP4,Zo-1and Occludin mRNA expression.ResultsCotex：1. Compared with Sham group, Mod group demonstrated edema changes asearly as3h after HIBD operation and aggravated till24h while relieved much at72h. In theMT group, things got much better at each time point compared with Mod group.2. In theMod group, expression of AQP4mRNA was elevated as early as3h after HIBD operationand reached its peak at24h. There was no difference between Sham group and MT groupexcept at6h. For Zo-1mRNA, expression reduced since6h for Mod and MT group andrelieved much at72h; the expression rised For Occludin mRNA, they demonstrated acomplete opposite expression trend with AQP4mRNA, highest but lower than the Modgroup at3h and lowest at24h and then recovered. For MT group, their expression levelwas higher compared to Mod group especially at each time point except3h.Renal cortical：For Mod group, the progression of tubules and interstitial edema and glomerulus damage were similar to that of cotex under microscope. Expression of AQP4mRNA was of no difference at any time point while Zo-1mRNA expression of Mod groupwas significantly lower at6h, reaching the trough at24h and showed no difference at72hcompared to Sham group. For MT group, it showed higher expression level compared withMod group at24h. And the Occludin mRNA showed less variation.Colon：Pathological alterations could be seen under transmission electron microscopyat3h after operation and the developing trend was similar to that of cortex and renalcortical. Expression of AQP4mRNA rose firstly to its peak and then went down in Modgroup while there was no difference between MT group and Sham group. And Zo-1mRNAexpression of Mod group went down at6h till reached its trough and there was nodifference at72h. For MT group, it showed no difference compared with Sham groupexcept at24h.Occludin mRNA in Mod group and MT group got lower compared withSham group.Conclusions1. AQPs and TJPs, two of the most important edema related proteins,could indicate the severity of edema as well as act in the early stage edema formationcaused by hypoxic ischemic damage. The former protein relates positively with theseverity of edema while the latter relates negatively.2. Melatonin could improve the early stage hypoxic-ischemicmulti-organ edema, by means of changing AQPs and TJPs expression, both of which mayrepresent edema separately.