Comparison of the sensitivity of histopathological and immunohistochemical analyses and blood hormone levels for early detection of antithyroid effects in rats treated with thyroid peroxidase inhibitors.

Although measurements of blood triiodothyronine (T3), thyroxine (T4), and thyroid-stimulating hormone (TSH) levels in rodent toxicity studies are useful for detection of antithyroid substances, assays for these measurements are expensive and can show high variability depending on blood sampling conditions. To develop more efficient methods for detecting thyroid disruptors, we compared histopathological and immunohistochemical findings in the thyroid and pituitary glands with blood hormone levels. Six-week-old male and female Sprague-Dawley rats (five rats per group) were treated with multiple doses of the thyroid peroxidase inhibitors propylthiouracil (PTU) and methimazole by gavage for 28 days. Significant decreases in serum T3 and T4 and increases in TSH were observed in the ≥1 mg/kg PTU and ≥3 mg/kg methimazole groups. An increase in TSH was also detected in male rats in the 0.3 mg/kg PTU group. Histopathological and immunohistochemical analyses revealed that follicular cell hypertrophy and decreased T4 and T3 expressions in the thyroid gland were induced at doses lower than doses at which significant changes in serum hormone levels were observed, suggesting that these findings may be more sensitive than blood hormone levels. Significant increases in thyroid weights, Ki67-positive thyroid follicular cell counts, and TSH-positive areas in the pituitary gland were detected at doses comparable with those at which changes in serum T4 and TSH levels were observed, indicating that these parameters may also be useful for evaluation of antithyroid effects. Combining these parameters may be effective for detecting antithyroid substances without relying on hormone measurements.

Metabolomic insights into the therapeutic mechanisms of costus (Saussurea costus (Falc.) Lipsch.) root extract in propylthiouracil-induced hypothyroidism rat model.

ETHNOPHARMACOLOGICAL RELEVANCE: Saussurea costus (Falc.) Lipschitz. is one of the most reputed medicinal plants as a traditional medicine in the Arab and Middle East regions in the treatment of thyroid disorders, however, more investigations are needed to fully understand its effectiveness and mechanism of action. AIM OF THE STUDY: The primary objective of the study was to assess the impact of Saussurea costus (COST) on the metabolic profiles of propylthiouracil (PTU)-induced hypothyroidism in rats. This involves a comprehensive examination of serum metabolites using UPLC/QqQ-MS analysis aiming to identify differential metabolites, elucidate underlying mechanisms, and evaluate the potential pharmacological effect of COST in restoring metabolic homeostasis. MATERIALS AND METHODS: Hypothyroidism was induced in female Sprague-Dawley rats by oral administration of propylthiouracil (PTU). UPLC/QqQ MS analysis of serum samples from normal, PTU, and PTU + COST rats was utilized for annotation of intrinsic metabolites with the aid of online Human metabolome database (HMDB) and extensive literature surfing. Multivariate statistical analyses, including orthogonal partial least squares discriminant analysis (OPLS-DA), discerned variations between the different groups. Serum levels of T3, T4 and TSH in addition to arachidonic acid (ARA), eicosapentaenoic acid (EPA), and docosahexaenoic acid (DHA) levels in thyroid gland tissues; Phospholipase A2 group IIA (PLA2G2A), and lipoprotein lipase (LPL) in liver tissues were assessed by specific ELISA kits. Gene expression for key proteins of the primary evolved pathwayswere quantified by one-step qRT-PCR technique. Histopathological evaluation of thyroid gland tissue was performed by an investigator blinded to the experimental group using light microscope. RESULTS: Distinct clustering in multivariate statistical analysis models indicated significant variations in serum chemical profiles among normal, disease, and treated groups. VIP values guided the selection of differential metabolites, revealing significant changes in metabolite concentrations. Subsequent to COST treatment, 43 differential intrinsic metabolites exhibited a notable tendency to revert towards normal levels. Annotated metabolites, such as lysophosphatidylcholine (LPC), L-acetylcarnitine, gamma-glutamylserine, and others, showed differential regulation in response to PTU and subsequent S. costus treatment. Notably, 21 metabolites were associated with polyunsaturated fatty acids (PUFAs) biosynthesis, arachidonic acid (ARA) metabolism, and glycerophospholipid metabolism exhibited significant changes on conducting metabolic pathway analysis. CONCLUSIONS: COST improves PTU-induced hypothyroidism by regulating biosynthesis of PUFAs signified by n-3/n-6, ARA and glycerophospholipid metabolism. The study provides us a novel mechanism to explain the improvement of hypothyroidism and associated dyslipidemia by COST, depicts a metabolic profile of hypothyroidism, and gives us another point cut for further exploring the biomarkers and pathogenesis of hypothyroidism.

Effect of melatonin on reproductive function in propylthiouracil induced hypothyroidism in adult male rats.

OBJECTIVE: Thyroid hormones are essential for regulating metabolism, reproduction, and growth. Hypothyroidism is connected with lower sperm count and motility, leading to male infertility. Oxidative stress is likely to be linked to this interaction. Melatonin, being known as an oxidative scavenger, may offer a feasible treatment method for reproductive dysfunction accompanying hypothyroidism in adult male rats. The purpose of this investigation was to determine the mechanism by which melatonin treatment affected spermatogenic and steroidogenic function in an experimental model-induced hypothyroidism in adult male rats. MATERIALS AND METHODS: Twenty-one male albino adult rats weighing between 150 and 210 g were used in this experiment. Rats were split into three groups and studied for 11 weeks. The control euthyroid group, in which rats received 0.9% Sodium Chloride (NaCl) solution by intraperitoneal injection [solvent for 6-propyl 2-thouracil (PTU)], 6 days/week for 8 weeks; the PTU-induced hypothyroid group, in which chemical thyroidectomy was induced by intraperitoneal injection of PTU at a dose of 10 mg/kg body weight, 6 days/week for 8 weeks; and the melatonin-treated hypothyroid group, which received 3 mg/kg melatonin intraperitoneally daily for 21 days plasma free Triiodothyronine (T3), free Thyroxin (T4), thyroid stimulating hormone (TSH), free testosterone, Follicle Stimulating Hormone (FSH), Luteinizing Hormone (LH) and prolactin were measured. Also, semen analysis, testicular tissue malondialdehyde (MDA), and tumor necrosis factor-α (TNF-α) were accessed. RESULTS: The results indicated that melatonin significantly increased sperm viability and motility compared to the untreated PTU-induced hypothyroid group (p<0.001). Testicular MDA and TNF-α showed a significant decrease in the melatonin-treated hypothyroid group compared with the PTU-induced hypothyroid group (p<0.05). In addition, plasma testosterone levels were significantly increased, accompanied by a significant reduction of plasma prolactin levels compared to the untreated hypothyroid group (p<0.05 for both). CONCLUSIONS: Based on the study findings, melatonin could mitigate gonadal dysfunction induced by hypothyroidism by improving several components of semen analysis, such as sperm motility and sperm viability, as well as by enhancing testosterone production focusing on oxidative and inflammatory stress as the underlying mechanisms.

The generation gap in endocrine disruption: Can the integrated fish endocrine disruptor test (iFEDT) bridge the gap by assessing intergenerational effects of thyroid hormone system disruption?

Thyroid hormones (THs) act early in ontogenesis, even prior to the differentiation of thyrocytes. Maternal transfer of THs is therefore known to play an essential role in early development. Current OECD test guidelines for the assessment of TH system disruption (THSD) do not address inter- or transgenerational effects. The integrated fish endocrine disruptor test (iFEDT), a test combining parental and developmental exposure of filial fish, may fill this gap. We tested the ability of the iFEDT to detect intergenerational effects in zebrafish (Danio rerio): Parental fish were exposed to propylthiouracil (PTU), an inhibitor of TH synthesis, or not exposed. The offspring was submitted to a crossed experimental design to obtain four exposure scenarios: (1) no exposure at all, (2) parental exposure only, (3) embryonic exposure only, and (4) combined parental and embryonic exposure. Swim bladder inflation, visual motor response (VMR) and gene expression of the progeny were analysed. Parental, but not embryonic PTU exposure reduced the size of the swim bladder of 5 d old embryos, indicating the existence of intergenerational effects. The VMR test produced opposite responses in 4.5 d old embryos exposed to PTU vs. embryos derived from exposed parents. Embryonic exposure, but not parental exposure increased gene expression of thyroperoxidase, the target of PTU, most likely due to a compensatory mechanism. The gene expression of pde-6h (phosphodiesterase) was reduced by embryonic, but not parental exposure, suggesting downregulation of phototransduction pathways. Hence, adverse effects on swim bladder inflation appear more sensitive to parental than embryonic exposure and the iFEDT represents an improvement in the testing strategy for THSD.

Efeito hepatotoxico do propiltiouracil no tratament do hipertiroidismo / Hepatotoxic effect of propilthiouracil in hypertireoidism treatment

A terapeutica com propiltiouracil e indicada na doenca de Basedow Graves.Entretanto e possivel ocorrer efeito hepatotoxico com seus derivados.O efeito hepatotoxico pode ocorrer em dias a anos.Os efeitos da hepatite toxica sao demonstrados com biopsis hepatica e estudo histopatologico.Portanto,quando estiver utilizando propiltiouracil e importante avaliacao hepatica periodica