| ObjectivesThe aim of this study was to observe the activation of nuclear factor kappa B (NF-κB) and the level of partial proinflammatory factors'mRNA in early diabetic retinopathy (DR) in rats, and to observe the effect of sinomenine on them.Methods1.Among 100 adult healthy male SD rats,30 were randomly divided into normal control group (N group),70 were used for the establishment of diabetic animal model with STZ.64 rats, successfully modeled, were randomly divided into:diabetes mellitus control group (DM group) 32; sinomenine treatment group (SN group) 32. SN group were given 2% hydrochloric acid sinomenine 100mg/(kg·d) intraperitoneal injection. N group and DM group was given equal volume of 0.9% sterile sodium chloride intraperitoneally. Body weight and blood glucose of rats were monitored.2.At week4 and week12,4 rats (8eyes)of each group were sacrificed. Retinal frozen sections were made.The expression of retinal NF-κB was observed by immunohistochemical method, and the level of NF-κB activation was analyzed relative quantitatively.3. At week4 and week12,8 rats(16eyes) were sacrificed from each group, and retinas were stripped. One retina of each rat was studied randomly.The method of real-time fluorescence quantitative PCR was used to detect the levels of interleukin-1β(IL-1β), tumor necrosis factor-alpha (TNF-α), monocyte chemoattractant protein-1 (MCP-1) and cyclooxygenase-2(COX-2) mRNA.The 2-ΔΔCT method was used to calculate the relative amount of target genes, and comparisons among groups were made.Results1. DR rats model were made with success rate of 91.43%.There is no significant difference among groups as incidental mortality of rats was concerned(P>0.05).At week4 and week12, in DM and SN group, the body weight were less than that of N group(P<0.01); the levels of blood glucose were higher (P<0.01); and there is no significant difference between DM and SN group(P>0.05).2. At week4 and week 12, in DM and SN group,besides ganglion cells the expression of NF-κB extended into inner and outer nuclear layer; the levels of NF-κB activation were higher than that in N group(P<0.01); at week12, the levels slightly increased compared with week4(DM group P<0.05,SN group P<0.01); the level in SN group was lower than that in DM group (P<0.01).3. At week4 and week12, in DM and SN group, the levels of retinal IL-1β, TNF-α, MCP-1 and COX-2 mRNA increased compared with N group (P<0.01);At week12, compared with week4, in DM and SN group, TNF-αand MCP-1 mRNA increased significantly(P<0.01 or P<0.05),IL-1βand COX-2 mRNA increased, but not significantly (P>0.05);At week4 and week12, the levels of IL-1β(P<0.05), TNF-αand MCP-1 mRNA (P<0.01) of SN group were lower than that of DM group,COX-2 mRNA did not decreased(P> 0.05).Conclusions1. STZ-induced DR rat model can be used in research related with DR.100mg/(kg·d) dose of sinomenine is safe in diabetic rats by intraperitoneal injection. During the 12-week observation period, sinomenine had no significant effect on body weight and level of blood glucose of diabetic rats.2. Levels of retinal NF-κB activation in early diabetic rats increased. With the development of DR, the activation of NF-κB sustained and increased progressively. Sinomenine partially inhibited the activation of NF-κB in the retina of diabetic rats.3. Levels of retinal IL-1β,TNF-a,MCP-1 and COX-2 mRNA in early diabetic rats increased. These proinflammatory factors may play an important role in the pathogenesis of early DR. Possibly through the inhibition of NF-κB activation, sinomenine partially inhibited retinal IL-1β, TNF-a and MCP-1 mRNA expression, but the level of COX-2 mRNA was not significantly affected.4. This study confirmed that inflammation may play an important role in early DR.
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