Inhibitory Impact of Quercetin Nanoparticles on Polyol Pathway in Hyperthyroidism Rats.

The polyol pathway is a primary mechanism for the formation of sorbitol, and its accumulation is a major factor in many diseases' complications. Importantly, there have previously been some indications that there is a relationship between polyol intermediates and thyroid hormones in hyperthyroidism state. Hence, this study aimed to shed light on the therapeutic impact of nano-quercetin (QT-NPs) on hyperthyroidism via inhibiting the polyol pathway. Besides control groups, hyperthyroidism was triggered in the rats by 100 μg/kg of l-thyroxin and further treated with quercetin (QT) and nano-quercetin (10 mg/kg body weight). Additionally, levels of thyroid hormones (T3 and T4), oxidative markers, and the antioxidant system were monitored. Besides histological investigation of thyroid gland, the level of aldose reductase was estimated by qPCR. The obtained findings indicated an elevation of T3 and T4 which indicated hyperthyroidism. This hyperthyroid state was accompanied by an elevation in oxidative stress and a decline in antioxidant status. Importantly, the expression level of aldose reductase was elevated, as was the level of sorbitol. The treatment with QT and QT-NPs potentially reduced the expression level of aldose reductase and the concentration of sorbitol, indicating the inhibition capability of QT and QT-NPs on the polyol pathway key enzyme. Furthermore, rat groups treated with QT and QT-NPs showed an elevation in the antioxidant system (GSH, GPx) with a notable decline in the oxidative stress marker MDA. Furthermore, histopathological examination of the thyroid tissue of hyperthyroidism group treated with QT-NPs confirms the potential effect of QT-NPs on the thyroid tissue. In conclusion, QT-NPs showed therapeutic superiority over QT in hyperthyroidism treatment through inhibition of aldose reductase, which is the key enzyme in the polyol pathway. [ABSTRACT FROM AUTHOR]