Silymarin reduces retinal microvascular damage in streptozotocin-induced diabetic rats

Abstract

Diabetic retinopathy is a severe microvascular problem in diabetes mellitus. Silymarin is a flavonoid compound, and according to previous studies, it is a bioactive compound with potent antioxidant and anti-inflammatory properties. This investigation aims to peruse the impact of silymarin against diabetic retinopathy in streptozotocin (STZ)-provoked rats. Thirty-two adult male Wistar rats were randomly allocated into the control group, STZ group, STZ + silymarin (50 mg/kg), and STZ + silymarin (100 mg/kg). STZ rats received silymarin every day until 2 months after diabetes induction. The serum and retinal tissues were collected 2 months after silymarin treatment to determine biochemical and molecular analyses. Silymarin markedly lowered the serum glucose concentration in diabetic rats. Silymarin reduced the increased levels of advanced glycosylated end products (AGEs), the receptors for AGEs (RAGE), and reactive oxygen species (ROS) in diabetic rats. Silymarin also attenuated the phosphorylation of p38 MAP kinase and nuclear factor (NF)-κB p65 and diminished diabetes-induced overexpression of inflammatory cytokines, vascular endothelial growth factor (VEGF), adhesion molecules, and extracellular matrix proteins in STZ rats. Our data suggested that silymarin has protective effects against diabetic retinopathy, which might be related to the inhibition of the AGEs/RAGE axis and its antioxidant and anti-inflammatory activities.

Okra (Abelmoschus esculentus) Intake Improves Lipid Profile and Liver Transaminases in Pre-diabetic Adults: A Randomized Double-blinded Trial

“…Herbal medicine can effectively be used as an alternative remedy for lowering diabetes-induced complications. As a result, several natural plants have received special attention due to their ameliorative effects against T2DM and pre-diabetes (10,20).…”

Impacts of Supplementation with Silymarin on Cardiovascular Risk Factors: A Systematic Review and Dose–Response Meta-Analysis

“…Silymarin has been shown to contribute to the restoration of pancreatic function [88]. Animal studies have demonstrated that SIL and its components have the potential to improve glucose regulation in diabetic rats [89,90]. It could promote the restoration of pancreatic function by upregulating insulin and glucagon proteins, leading to the normalization of blood glucose levels and the restoration of insulin serum levels [88].…”

Current Treatments and Innovations in Diabetic Retinopathy and Diabetic Macular Edema

“…AGEs bind to RAGEs and trigger the production of reactive oxygen species (ROS), with upregulation of the pro-inflammatory molecule NFκ-β [ 88 ]. AGEs also increase VEGF expression; this makes it a target for novel treatments to improve microvascular damage in DR. With the objective of blocking or reducing the effects of this pathway, two molecules had been tested in induced diabetic rats: silymarin and fangchinoline [ 89 , 90 ]. The former is a flavonoid compound isolated from Silybum marianum with antioxidant and anti-inflammatory properties.…”

“…In diabetic rats, it demonstrated an improvement through a decrease in AGEs, RAGEs, and ROS levels, a reduction in p38 MAP kinase and NFκ-β pp65 phosphorylation which was reflected in the inhibition of adhesion molecules and extracellular matrix proteins. The latter is an alkaloid isolated from Stephania tetranda ; it acts by attenuating the expression of IL-6, IL-1, TNF-α, and cyclooxygenase [ 89 , 91 ]. Treatment with fangchinoline reduced the plasma concentration of HbA1c, glucose, and AGEs in the retinal tissues of DR rats [ 90 ].…”