This study aims to explore the therapeutic potential of thymoquinone (TQ) in DR by assessing its effects on Müller cell apoptosis through modulation of the miR-29b/SP1 pathway in a diabetic animal model.Healthy C57BL/6 mice (25 g) were used in the study. Retinal samples were collected from both normal and diabetic mice subjected to various treatments: TQ (1 mg/kg/day), glibenclamide (GLB, 250 mg/kg/day), sitagliptin (STG, 10 mg/kg/day), and metformin (MET, 5 mg/kg/day) over a period of 28 days. The study measured miR-29b and SP1 mRNA levels using qRT-PCR. Protein expressions of SP1, Bax, and bcl-2 were analyzed through western blotting, while Caspase-3 activity using an ELISA assay kit, and apoptosis levels by annexin V.TQ administration resulted in a 52% reduction in blood glucose levels. Similarly, GLB, STG, and MET treatments reduced blood glucose by 60%, 57%, and 61%, respectively (p<0.05). In addition, TQ upregulated miR-29b by 51.28% and downregulated SP1 mRNA by 32.52% (p<0.05). Bax protein expression levels were decreased by 64.99%, while Bcl-2 protein expression increased by 62.92% in the TQ treatment group as compared to the untreated diabetic controls. Furthermore, Caspase-3 activity was downregulated by 40.03% with TQ treatment (p<0.05). Interestingly, the effect TQ on SP1 mRNA expression was inhibited by a miR-29b blocker (p<0.05), while an miR-29b mimic enhanced this effect; this was associated with a mitigation of apoptosis of retinal Müller cells as measured by flow cytometry (p<0.05).These results indicate that TQ might be a possible option for DR via its effect on the miR-29b/SP1 pathway; and therefore, playing a significant role in the mechanism against cell death.
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