ABSTRACT
Objective To observe the ethanol extract from Dendrobium chrysotoxum Lindl. (DC) on the amelioration of diabetic retinopathy (DR) in mice induced by streptozotocin (STZ), and further investigate the engaged mechanism. Methods Diabetes was induced by STZ injection in C57 mice and then the diabetic mice were orally given with DC. The retinal neovascularization was evaluated by staining with cluster of differentiation 31 (CD31) and histological assessment of retinas by hematoxylin-eosin (HE) staining. The mRNA expression of signals involved in vascular endothelial growth factor (VEGF) signaling pathway was detected by realtime PCR assay. The amount of VEGF in serum and vitreous bodies was detected by enzyme-linked immunosorbent assay (ELISA). Results DC (50 and 200 mg/kg) reduced the increased retinal vessels in STZ-induced diabetic mice. Results of real-time PCR showed that DC reduced the increased mRNA expression of retinal hypoxia inducible factor-1α (HIF-1α), VEGF and its receptors including VEGFR1 and VEGFR2 in STZ- induced diabetic mice. ELISA results further demonstrated that DC reduced the increased VEGF level in serum and vitreous bodies of STZ-induced diabetic mice. Conclusions DC ameliorates DR via inhibiting retinal angiogenesis by reducing the expression of VEGF and VEGF-regulated signaling pathway.
ABSTRACT
Objective: To observe the amelioration of ethanol extract from Dendrobium chrysotoxum (EEDC) on non-proliferative diabetic retinopathy (NPDR) induced by streptozotocin (STZ), and further to investigate its engaged mechanism. Methods: NPDR was induced by STZ injection in C57 mice and then the diabetic mice were orally given EEDC. The retinal blood-retinal barrier (BRB) breakdown was evaluated using Evans blue leakage assay. The mRNA expression of interleukin (IL)-1β, IL-6, tumor necrosis factor (TNF) α, early growth response-1 (Egr-1), tissue factor (TF), and Serpine 1 in retinas was detected by real-time PCR. The amount of IL-1β, IL-6, TNF-α, TF, and Serpine 1 in serum was detected by enzyme-linked immunosorbent assay (ELISA). Results: EEDC at both doses reduced the increased Evans blue leakage in STZ-induced NPDR in mice. Results: of Real-Time PCR showed that EEDC reduced the increased retinal mRNA expression of IL-1β, IL-6, TNFα and Egr-1, TF, Serpine 1 in STZ-induced NPDR in mice. ELISA results also confirmed that EEDC reduced the increased serum levels of IL-1β, IL-6, TNF-α, TF, and Serpine 1 in STZ-induced NPDR in mice. Conclusion: EEDC could ameliorate the STZ-induced NPDR in mice via inhibiting retinal BRB breakdown by reducing the expression of pro-inflammatory cytokines including IL-1β, IL-6, TNF-α, and coagulation-fibrinolysis related signals such as TF and Serpine 1.