Ginsenoside Rg_2(GRg2) is a triterpenoid compound found in Panax notoginseng. This study explored its effects and mechanisms on diabetic retinopathy and angiogenesis. The study employed endothelial cell models induced by glucose or vascular endothelial growth factor(VEGF), the chorioallantoic membrane(CAM) model, the oxygen-induced retinopathy(OIR) mouse model, and the db/db mouse model to evaluate the therapeutic effects of GRg2 on diabetic retinopathy and angiogenesis. Transwell assays and endothelial tube formation experiments were conducted to assess cell migration and tube formation, while vascular area measurements were applied to detect angiogenesis. The impact of GRg2 on the retinal structure and function of db/db mice was evaluated through retinal thickness and electroretinogram(ERG) analyses. The study investigated the mechanisms of GRg2 by analyzing the activation of Yes-associated protein(YAP) and Toll-like receptors(TLRs) pathways. The results indicated that GRg2 significantly reduced cell migration numbers and tube formation lengths in vitro. In the CAM model, GRg2 exhibited a dose-dependent decrease in the vascular area ratio. In the OIR model, GRg2 notably decreased the avascular and neovascular areas, ameliorating retinal structural disarray. In the db/db mouse model, GRg2 increased the total retinal thickness and enhanced the amplitudes of the a-wave, b-wave, and oscillatory potentials(OPs) in the ERG, improving retinal structural disarray. Transcriptomic analysis revealed that the TLR signaling pathway was significantly down-regulated following YAP knockdown, with PCR results consistent with the transcriptome sequencing findings. Concurrently, GRg2 downregulated the expression of Toll-like receptor 4(TLR4), TNF receptor-associated factor 6(TRAF6), and nuclear factor-kappaB(NF-κB) proteins in high-glucose-induced endothelial cells. Collectively, GRg2 inhibits cell migration and tube formation and significantly reduces angiogenesis in CAM and OIR models, improving retinal structure and function in db/db mice, with its pharmacological mechanism likely involving the down-regulation of YAP expression.
Animals ; Ginsenosides/pharmacology* ; Diabetic Retinopathy/physiopathology* ; Mice ; YAP-Signaling Proteins ; Humans ; Male ; Signal Transduction/drug effects* ; Cell Movement/drug effects* ; Adaptor Proteins, Signal Transducing/genetics* ; Mice, Inbred C57BL ; Neovascularization, Pathologic/metabolism* ; Drugs, Chinese Herbal/administration & dosage* ; Panax notoginseng/chemistry* ; Endothelial Cells/metabolism* ; Transcription Factors/genetics* ; Angiogenesis

Diabetic retinopathy, a prevalent and vision-threatening microvascular complication of diabetes mellitus, is the leading cause of blindness among middle-aged and elderly individuals. Natural diterpenoids isolated from Siegesbeckia pubescens demonstrate potent anti-inflammatory properties. This study aimed to identify novel bioactive diterpenoids from S. pubescens and investigate their effects on oxidative stress and inflammatory responses in diabetic retinopathy, both in vitro and in vivo. Three new ent-pimarane-type diterpenoids (1-3) and six known compounds (4-9) were isolated from the aerial parts of S. pubescens. Their structures were elucidated through spectroscopic data interpretation, and absolute configurations were determined by comparing calculated and experimental electronic circular dichroism (ECD) spectra. Among these compounds, 14β,16-epoxy-ent-3β,15α,19-trihydroxypimar-7-ene (5) exhibited the most potent protective effect against high glucose and interleukin-1β (IL-1β)-stimulated human retinal endothelial cells. Mechanistically, compound 5 promoted endothelial cell survival while ameliorating oxidative stress and inflammatory response in diabetic retinopathy, both in vivo and in vitro. These findings not only suggest that diterpenoids such as compound 5 are important anti-inflammatory constituents in S. pubescens, but also indicate that compound 5 may serve as a lead compound for preventing or treating vascular complications associated with diabetic retinopathy.
Diabetic Retinopathy/metabolism* ; Humans ; Oxidative Stress/drug effects* ; Animals ; Diterpenes, Kaurane/administration & dosage* ; Asteraceae/chemistry* ; Male ; Endothelial Cells/drug effects* ; Abietanes/administration & dosage* ; Molecular Structure ; Mice ; Anti-Inflammatory Agents/chemistry* ; Plant Extracts/chemistry* ; Mice, Inbred C57BL

Objective To investigate the neuroprotective effect of methylene blue on diabetic retinopathy in rats. Methods Thirty SD rats were randomly divided into blank, control and experimental groups. The control and experimental groups were induced with diabetes by streptozotocin (STZ) intraperitoneal injection. After 6 weeks of successful modeling, the experimental group received intravitreal injection of methylene blue at a dose of [0.2 mg/(kg.d)], while the control group received an equal amount of dimethyl sulfoxide (DMSO) intravitreal injection, both continuously injected for 7 days. ELISA was used to detect the levels of retinal superoxide dismutase (SOD), 8-iso-prostaglandin F2alpha (iPF2α) and interleukin-1β (IL-1β) in rats. Western blot analysis was used to detect the expression of retinal extracellular signal-regulated kinase 1/2 phosphorylation (p-ERK1/2) and phosphorylated protein kinase B (p-AKT), and PAS staining was used to detect retinal morphological changes. Results Compared with the blank group rats, the retinal SOD activity in the control and experimental group rats was significantly reduced. iPF2α, IL-1β and p-ERK1/2 level increased, while p-AKT level decreased. Compared with the control group, the SOD activity of the experimental group rats increased. iPF2α and IL-1β level went down, while p-ERK1/2 and p-AKT level went up significantly. The overall thickness of the retinal layer and the number of retinal ganglion cells were significantly reduced. Conclusion Methylene blue improves diabetic retinopathy in rats by reducing retinal oxidative stress and enhancing ERK1/2 and AKT phosphorylation.
Rats ; Animals ; Diabetic Retinopathy/metabolism* ; Proto-Oncogene Proteins c-akt/metabolism* ; Mitogen-Activated Protein Kinase 3/metabolism* ; Interleukin-1beta/metabolism* ; Methylene Blue/pharmacology* ; Phosphorylation ; Rats, Sprague-Dawley ; MAP Kinase Signaling System ; Diabetes Mellitus, Experimental/drug therapy* ; Superoxide Dismutase/metabolism*

OBJECTIVE: To investigate the effects of wogonoside on high glucose-induced dysfunction of human retinal microvascular endothelial cells (hRMECs) and streptozotocin (STZ)-induced diabetic retinopathy in rats and explore the underlying molecular mechanism. METHODS: HRMECs in routine culture were treated with 25 mmol/L mannitol or exposed to high glucose (30 mmol/L glucose) and treatment with 10, 20, 30, 40 μmol/L wogonoside. CCK-8 assay and Transwell assay were used to examine cell proliferation and migration, and the changes in tube formation and monolayer cell membrane permeability were tested. ROS, NO and GSH-ST kits were used to evaluate oxidative stress levels in the cells. The expressions of IL-1β and IL-6 in the cells were examined with qRT-PCR and ELISA, and the protein expressions of VEGF, HIF-1α and SIRT1 were detected using Western blotting. We also tested the effect of wogonoside on retinal injury and expressions of HIF-1α, ROS, VEGF, TNF-α, IL-1β, IL-6 and SIRT1 proteins in rat models of STZ-induced diabetic retinopathy. RESULTS: High glucose exposure caused abnormal proliferation and migration, promoted angiogenesis, increased membrane permeability (P < 0.05), and induced inflammation and oxidative stress in hRMECs (P < 0.05). Wogonoside treatment concentration-dependently inhibited high glucose-induced changes in hRMECs. High glucose exposure significantly lowered the expression of SIRT1 in hRMECs, which was partially reversed by wogonoside (30 μmol/L) treatment; interference of SIRT1 obviously attenuated the inhibitory effects of wogonoside against high glucose-induced changes in proliferation, migration, angiogenesis, membrane permeability, inflammation and oxidative stress in hRMECs. In rat models of STZ-induced diabetic retinopathy, wogonoside effectively suppressed retinal thickening (P < 0.05), alleviated STZ-induced retinal injury, and increased the expression of SIRT1 in the retinal tissues (P < 0.001). CONCLUSION Wogonoside alleviates retinal damage caused by diabetic retinopathy by up-regulating SIRT1 expression.
Animals ; Diabetes Mellitus/metabolism* ; Diabetic Retinopathy/metabolism* ; Endothelial Cells ; Flavanones ; Glucose/pharmacology* ; Glucosides ; Inflammation/metabolism* ; Interleukin-6/metabolism* ; Neovascularization, Pathologic/metabolism* ; Rats ; Reactive Oxygen Species/metabolism* ; Sirtuin 1/metabolism* ; Streptozocin/pharmacology* ; Vascular Endothelial Growth Factor A/metabolism*

Ginsenoside Rg_1, one of the main active components of precious traditional Chinese medicine Ginseng Radix et Rhizoma, has the anti-oxidative stress, anti-inflammation, anti-aging, neuroprotection, and other pharmacological effects. Diabetic retinopathy(DR), the most common complication of diabetes, is also the main cause of impaired vision and blindness in the middle-aged and the elderly. The latest research shows that ginsenoside Rg_1 can protect patients against DR, but the protection and the mechanism are rarely studied. This study mainly explored the protective effect of ginsenoside Rg_1 against DR in type 2 diabetic mice and the mechanism. High fat diet(HFD) and streptozotocin(STZ) were used to induce type 2 diabetes in mice, and hematoxylin-eosin(HE) staining was employed to observe pathological changes in the retina of mice. The immunohistochemistry was applied to study the localization and expression of nucleotide-binding oligomerization domain-like receptors 3(NLRP3) and vascular endothelial growth factor(VEGF) in retina, and Western blot was used to detect the expression of nuclear factor-kappa B(NF-κB), p-NF-κB, NLRP3, caspase-1, interleukin-1β(IL-1β), transient receptor potential channel protein 6(TRPC6), nuclear factor of activated T-cell 2(NFAT2), and VEGF in retina. The results showed that ginsenoside Rg_1 significantly alleviated the pathological injury of retina in type 2 diabetic mice. Immunohistochemistry results demonstrated that ginsenoside Rg_1 significantly decreased the expression of NLRP3 and VEGF in retinal ganglion cells, middle plexiform layer, and outer plexiform layer in type 2 diabetic mice. According to the Western blot results, ginsenoside Rg_1 significantly lowered the expression of p-NF-κB, NLRP3, caspase-1, IL-1β, TRPC6, NFAT2, and VEGF in retina of type 2 diabetic mice. These findings suggest that ginsenoside Rg_1 can significantly alleviate DR in type 2 diabetic mice, which may be related to inhibition of NLRP3 inflammasome and VEGF. This study provides experimental evidence for the clinical application of ginsenoside Rg_1 in the treatment of DR.
Aged ; Animals ; Diabetes Mellitus, Experimental/metabolism* ; Diabetes Mellitus, Type 2/genetics* ; Diabetic Retinopathy/genetics* ; Ginsenosides/pharmacology* ; Humans ; Inflammasomes/metabolism* ; Mice ; Middle Aged ; NF-kappa B/metabolism* ; NLR Family, Pyrin Domain-Containing 3 Protein/metabolism* ; Signal Transduction ; Vascular Endothelial Growth Factor A/genetics*

OBJECTIVETo investigate the effect of MiR-200b on human retinal endothelial cells (hRECs) cultured in high glucose and explore the mechanism.

METHODShRECs cultured in high glucose or in normal media were examined for MiR-200b mRNA expression using real-time PCR. The effect of MiR-200b transfection on hREC proliferation in high-glucose culture was evaluated with MTT assay, and real-time PCR and Western blotting were performed to determine vascular endothelial growth factor (VEGF) and transforming growth factor β1 (TGFβ1) expression in the transfected cells.

RESULTSThe cells in high-glucose culture showed significantly decreased MiR-200b expression and active proliferation. Compared with those in normal control cells, VEGF and TGFβ1 mRNA and protein expressions increased markedly in cells cultured in high glucose (P<0.05). MiR-200b transfection of the cells caused significantly increased cellular expression of MiR-200b but decreased expression levels of VEGF and TGFβ1 mRNA and protein, and suppressed hREC proliferation in high glucose culture (P<0.05).

CONCLUSIONMiR-200b can regulate REC growth and proliferation by changing VEGF and TGFβ1 expressions and thus play a role in the pathogenesis and progression of diabetic retinopathy.

Blotting, Western ; Cell Proliferation ; Cells, Cultured ; Culture Media ; chemistry ; Diabetic Retinopathy ; Endothelial Cells ; cytology ; Glucose ; chemistry ; Humans ; MicroRNAs ; metabolism ; RNA, Messenger ; Real-Time Polymerase Chain Reaction ; Retina ; cytology ; Transfection ; Transforming Growth Factor beta1 ; metabolism ; Vascular Endothelial Growth Factor A ; metabolism

Cell Hypoxia ; physiology ; Cells, Cultured ; Diabetic Retinopathy ; metabolism ; Female ; Humans ; Intercellular Adhesion Molecule-1 ; metabolism ; Male ; Middle Aged ; Monocytes ; metabolism ; Prospective Studies ; Vascular Endothelial Growth Factors ; metabolism

BACKGROUNDDiabetes-related pathogenic factors can cause retinal ganglion cell (RGC) apoptosis, but the specific mechanism is not very clear. The aim of this study is to investigate the correlation between glycogen synthase kinase-3 (GSK-3) activation and retinal neuron apoptosis.

METHODSIn an in vitro experiment, the number of apoptotic RGC-5 cells differentiated by staurosporine was evaluated via flow cytometry and nuclei staining using Hoechst 33258. GSK-3 phosphorylation and caspase-3 activation in RGC-5 cells after serum deprivation were determined using Western blotting. Mitochondrial membrane potential was detected using the dye 5, 5', 6, 6'tetrachloro-1, 1', 3, 3'-tetrethyl benzimidalyl carbocyanine iodide, and reactive oxygen species (ROS) levels were measured with dihydroethidium. In an in vivo experiment, the number of apoptotic retinal neurons was evaluated via terminal transferase dUTP nick-end labeling (TUNEL), and GSK-3 phosphorylation was determined using Western blotting, in the retinal nerve epithelial tissue of rats in which diabetes was induced by intravenous tail-vein injection of streptozotocin for 4 weeks.

RESULTSThe levels of phosphorylated Ser21/9 in GSK-3α/β and p-T308/S473-AKT were lower and the cleaved caspase-3 levels were higher in the serum-deprived model (P < 0.05). Lithium chloride treatment was associated with a slower rate of apoptosis, increased mitochondrial membrane potential, and decreased ROS levels in differentiated RGC-5 cells (P < 0.05). The level of blood glucose and the number of TUNEL-positive cells in the whole-mounted retinas were higher (P < 0.01), and the levels of phosphorylated Ser21/9 in GSK-3α/β and body weight were lower (P < 0.05). However, the thickness of the retinal nerve epithelial layer was not significantly less in diabetic rats compared with control group. Lithium chloride intravitreal injection increased the levels of phosphorylated Ser21/9 in GSK-3α/β and decreased TUNEL-positive cells in the whole-mounted retinas.

CONCLUSIONGSK-3 kinase is closely related to retinal neuron apoptosis, and the application of the GSK-3 inhibitor lithium chloride can reduce retinal neuron apoptosis in early diabetic retinopathy.

Animals ; Apoptosis ; genetics ; physiology ; Cell Line ; Cell Survival ; physiology ; Diabetic Retinopathy ; enzymology ; genetics ; metabolism ; Flow Cytometry ; Glycogen Synthase Kinase 3 ; genetics ; metabolism ; Male ; Neurons ; cytology ; metabolism ; Rats ; Rats, Sprague-Dawley ; Retina ; cytology ; enzymology

OBJECTIVETo optimize the hydrolysis process of linarin by response surface methodology, and to use the model of aldose reductase to study the acacetin's activity of aldose reductase inhibitory.

METHODThe model of acacetin enzyme in vitro was established by the determination of fluorescence absorption of NADPH, the inhibition rate of acacetin aldose reductase was calculated, and then the IC50 of hydrolysis was obtained. The hydrolysis process of linarin hydrolysis condition was optimized by using response surface method.

RESULTThe results indicated that the IC50 of acacetin (2.74 mg x L(-1)) was less than the IC50 of linarin (3.53 mg x L(-1)). Hydrolyzation time of 7.4 h, sulphuric acid concentration of 0.54 mol x L(-1) and the ratio of material to liquid of 3 : 1 were the optimum conditions.

CONCLUSIONHydrolyzate acacetin has preferable inhibitory activity of aldose reductase. The optimized hydrolysis condition of linarin is convenient to use with good predictability.

Aldehyde Reductase ; antagonists & inhibitors ; metabolism ; Animals ; Diabetic Retinopathy ; enzymology ; Drugs, Chinese Herbal ; chemistry ; pharmacology ; Enzyme Inhibitors ; chemistry ; pharmacology ; Flavones ; chemistry ; Glycosides ; chemistry ; pharmacology ; Glycosylation ; Humans ; Hydrolysis ; Male ; Rats ; Rats, Wistar ; Retina ; enzymology

OBJECTIVEThis review focuses on the role of the large conductance calcium-activated potassium (BKCa) channels in diabetic vascular complications.

DATA SOURCESRelevant articles published in English or Chinese from 1981 to present were selected from PubMed. The search terms were "BKCa channels" and "diabetes". Important references from selected articles were also retrieved.

STUDY SELECTIONArticles regarding the role of BKCa channels in diabetic vascular complications and relevant mechanisms were selected.

RESULTSThe BKCa channels are abundantly expressed in vascular smooth cells and play an important role in regulation of vascular tone. Multiple studies indicated that the expression and function of BKCa channels are altered by different mechanisms in diabetic vascular diseases such as coronary arterial disease, cerebral arterial disease, and diabetic retinopathy.

CONCLUSIONBKCa channels may play an important role in diabetic vascular complications and may be an effective therapeutic target for relieving and reducing the burden of diabetic vascular complications.

Cerebral Arterial Diseases ; metabolism ; Coronary Artery Disease ; Diabetic Angiopathies ; metabolism ; Diabetic Retinopathy ; metabolism ; Humans ; Large-Conductance Calcium-Activated Potassium Channels ; metabolism