Thyrogrit, supplemented with a sub-optimal dose of levothyroxine, restores thyroid function in rat model of propylthiouracil-induced hypothyroidism

Abstract

Hypothyroidism is a common endocrine ailment, whose current standard of care is hormonal replacement therapy with levothyroxine (LT4). There is a medical need for alternative and safer therapies as LT4 is associated with special treatment considerations and adverse effects. Thyrogrit (THY) is a polyherbal formulation indicated for the treatment of hypothyroidism. The present study, describes the characterization of the phytocompounds present in THY and its in-vivo efficacy in rat model of hypothyroidism, in combination with a sub-optimal dose of LT4. Ultra High Performance Liquid chromatography was employed for the identification of the phytocompounds present in THY. For the evaluation of its in-vivo efficacy, female Wistar rats were administered THY orally, 15-days prior to disease induction, and continued throughout the experiment. Subsequently, hypothyroidism was induced by oral administration of propylthiouracil (PTU). From day 45 onwards, animals were administered orally with a sub-optimal dose of LT4 (2 μg/kg) till the end of the study. On day 79, animals were euthanized, blood was collected for measurement of thyroid hormones and other clinical chemistry parameters. Weights of liver, kidney and thyroid were recorded. Finally, the thyroid was subjected to histopathological evaluation through hematoxylin and eosin (H&E staining), immunohistochemistry as well as immunofluorescence. The principal phyto-components detected in THY by Ultra High Performance Liquid Chromatography included gallic acid, protocatechuic acid, corilagin, ellagic acid, piperine, guggulsterone E and Z, which are documented to exerted beneficial effects on thyroid function. In the in-vivo study, THY when supplemented with a low dose of levothyroxine restored the PTU-induced reduction in the serum levels of T3 and T4 and improved PTU-induced renal impairment. THY treatment ameliorated the hallmark histopathological changes associated with hypothyroidism and C-cell hyperplasia. Further, co-administration of THY and LT4 did not show any major non-clinical safety concerns even after the administration for more than twelve weeks. This study has demonstrated that co-administration of THY and LT4 improves the PTU-evoked alterations in the thyroid ultrastructure and function, abrogates hypothyroidism-associated renal impairment and exhibits an acceptable basic safety profile.