Mechanistic Role of Varuna (Crataeva Nurvala) Extract on Thyroid Gland and Its Histology Through Iodothyronine Deiodinases

Abstract

Objective: Crataeva nurvala (CN) is used for its therapeutic effects, but its effect on the thyroid gland in euthyroid conditions and mechanism behind its thyrotropic activity in hypothyroidism is still not explored. This study screened the pharmacological effect of the ethanolic extract of the bark of CN on thyroid hormones, free and total thyroxine (FT4 and T4), triiodothyronine (T3), thyroid-stimulating hormone (TSH) levels, and thyroid histology in normal Swiss albino female mice.Methods: Eighteen animals of 28–33 g were segregated into three groups: Group I treated with vehicle (NOR+VEH), Group II administered CN 400 mg/kg (NOR+CN 400), and Group III given CN 600 mg/kg (NOR+CN 600), for 15 days, per os (p.o.). The variation in the T4, FT4, T3, and TSH levels was recorded using ELISA, 24 h after the last dose, and T3/T4 ratio thus calculated along with the histopathological studies of the thyroid gland.Results: The findings were presented as mean ± standard error of the mean, using one-way ANOVA, followed by Dunnett’s post-tests to compare all columns with the control. NOR+CN 600 has shown thyroid protective effect through retaining euthyroid profile, normal T3/T4 ratio, and near-normal histology. However, NOR+CN 400 had shown the significant decline in T3/T4 ratio and pathological changes in thyroid histology, in comparison with the control and NOR+VEH group.Conclusion: The higher dose of CN was found to sustain the euthyroid levels through retention of iodothyronine deiodinases activity, facilitating the peripheral conversion of T4 to T3, and in retaining normal histoarchitecture of the thyroid gland in contrary to a lower dose.

Effect of Ethanolic Extract of Crataeva nurvala Bark on Iodothyronine Deiodinases Oxidative Stress and Thyroid Histology in 6-Propyl-2-Thiouracil Induced Hypothyroid Mice Model

“…Pre-clinically it has been demonstrated that CN bark extract can elevate free thyroxine (FT4) and lower the raised cholesterol levels (Kaur et al 2017). However the mechanism behind CN thyrotropic activity, mainly via iodothyronine deiodinases, effect on thyroid gland histology and physiological parameters in hypothyroid mice needs to be explored in comparison with its per se effects in normal healthy mice (Kaur et al 2018). So, this study is aimed to evaluate the mechanism of thyroprotective activity and effects on thyroid histopathology and physiological parameters in hypothyroid mice, whose thyroid status was altered by using (6-propyl-2-thiouracil) PTU, as an inducing agent, that selectively inhibits iodothyronine deiodinases type I (DIO1) mediated thyroxine (T 4 ) conversion to Triidothyronine (T 3 ) at thyroid gland and at periphery over iodothyronine deiodinases type II (DIO 2 ) and results in disruption of thyroid histology with physiological changes Moriyama et al, 2007).…”