Hypothyroidism and hyperthyroidism modulates Ras-MAPK intracellular pathway in rat thyroids

Investigating causal associations among gut microbiota, metabolites and autoimmune hypothyroidism: a univariable and multivariable Mendelian randomization study

Background

Accumulating evidence suggests that the gut microbiota and its metabolites may be involved in autoimmune hypothyroidism. However, the causal association between gut microbiota, metabolites and autoimmune hypothyroidism remains to be determined.

Methods

Instrumental variables were screened from the GWAS datasets of 211 gut microbiota taxonomic groups, gut microbiota-derived metabolites, and autoimmune hypothyroidism. Univariable Mendelian randomization (MR) and multivariable Mendelian randomization (MVMR) were used to analyse the potential causal relationship between autoimmune hypothyroidism, these metabolites, or these microbiota. During the MR analysis, we alternated multiple MR methods with different model assumptions to assess the consistency and robustness of the findings: inverse variance weighted (IVW), weighted median, MR pleiotropy residual sum and outlier (MRPRESSO) and MR-Egger methods. Reverse MR analysis was performed to assess the possibility of reverse causality. Finally, enrichment analyses were used to investigate potential biofunctions.

Results

The IVW results of univariable MR showed that the phyla Actinobacteria, genus DefluviitaleaceaeUCG011, genus Eggerthella, family Defluviitaleaceae, genus Subdoligranulum, genus RuminococcaceaeUCG011, and genus Intestinimonas were associated with autoimmune hypothyroidism. After FDR adjustment, the absence of a causal relationship between gut microbiota and autoimmune hypothyroidism (PFDR > 0.05) suggested a possible marginal association. The results on gut metabolites showed that N-(3-furoyl)glycine, pipecolate, phenylalanine, allantoin, indololactate and alanine were associated with autoimmune hypothyroidism. After FDR correction, only indololactate was associated with hypothyroidism (OR=1.592; 95% CI, 1.228-2.065; PFDR= 0.036). Family Defluviitaleaceae and genus DefluviitaleaceaeUCG011 were suggestively significant in the MVMR. The results of reverse MR analysis showed no reverse causality between autoimmune hypothyroidism and the identified gut microbiota. Enrichment analysis revealed that several key regulatory pathways were significantly enriched.

Conclusion

This study supported that there were beneficial or detrimental causal effects of gut microbiota and its metabolites on autoimmune hypothyroidism risk, which provides more theoretical support for mechanistic research on the "thyroid-gut" axis.

The management and metabolic characterization: hyperthyroidism and hypothyroidism

Hyperthyroidism and hypothyroidism are common diseases resulting from thyroid dysfunction, and are simple to diagnose and treat. The traditional treatment for hypothyroidism is thyroid hormone replacement therapy. The traditional treatments for hyperthyroidism include antithyroid drug, iodine radiotherapy, and surgery. Thyroid disease can be fatal in severe cases if untreated. Current statistical reference ranges used for diagnosis based on relevant biochemical parameters have been debated, and insufficient treatment can result in long-term thyroid hormone deficiency, which is associated with increased risk of cardiovascular disease and persistent symptoms. In contrast, overtreatment can result in heart disease and osteoporosis, particularly in older people and pregnant women. Therefore, under- or over-treatment should be avoided and treatment regimens should be monitored closely. A significant proportion of patients who achieve biochemical treatment goals still complain of significant symptoms. Systematic literature review was performed through the Embase (Elsevier), PubMed and Web of Science databases, and studies summarized evidence regarding treatment and management of hypothyroidism and hyperthyroidism, and reviewed clinical practice guidelines. We also reviewed the latest research on the metabolic mechanisms of hyperthyroidism and hypothyroidism, which contributed to understanding of thyroid diseases in the clinic. A reliable algorithm is needed to management, assessment, and treatment patients with hyperthyroidism and hypothyroidism, which can not only improve management efficiency, but also providing a broad application. In addition, the thyroid disorder showed a lipid metabolism tissue specificity in the Ventromedial Hypothalamus, and effect oxidative stress and energy metabolism of whole body. This review summarizes an algorithm for thyroid disease and the latest pathogenesis that would be useful to generalist and subspecialty physicians and others providing care for patients with this condition.

Integrate metabolomics strategy and target prediction to reveal the ameliorate effect of four typical 'cold' property herbs on hyperthyroidism rats

ETHNOPHARMACOLOGICAL RELEVANCE

The 'cold' property herbs are commonly applied in heat syndrome. Unfortunately, the underlying mechanisms of the 'cold' property herbs on heat syndrome has not been investigated.

AIM OF THE STUDY

The study aimed to probe the activities of the four typical 'cold' property herbs on hyperthyroidism.

MATERIALS AND METHODS

Firstly, the four typical 'heat' property herbs were set as contrasting experiment. Then. the physical sign, thyroid function and metabolism profile (multivariate statistical analysis) were assessing the difference between the four typical 'cod' property herbs and the four typical 'heat' property herbs. H&E staining were used to confirmed the influence of the typical 'cold' property herbs on hyperthyroidism. A metabolomics approach combine with network pharmacology were explored the effected mechanism of the typical 'cold' property herbs on hyperthyroidism. the gene expression of UCP-1 was detected by RT-PCR. The metabolites pathway and target-associated metabolites were verified Na⁺/K⁺-ATP enzyme and GSH, as well IL6, IL17, MAPK and PPAR-γ, which detected by commercial kits and Western blot.

RESULTS

It is proved that the four typical 'cold' property herbs effectively ameliorate the physical sign, thyroid function and metabolism profile in hyperthyroidism rats, but the four typical 'heat' property herbs showed no benefit. Moreover, the four typical 'cold' property herbs regulated energy metabolism, glutathione metabolism, taurine hypotaurine metabolism, thyroid hormone synthesis, arachidonic acid metabolism and linoleic acid metabolism and the inflammation mediated by inflammatory factor (IL6, IL17), Ca²⁺ and MAPK signaling pathway. And the levels of UCP-1, Na⁺/K⁺-ATP enzyme, GSH, and the targets protein of IL6, IL17, MAPK and PPAR-γ were ameliorated by the four typical 'cold' property herbs.

CONCLUSION

The four typical 'cold' property herbs could alleviate hyperthyroidism by ameliorate thyroid hormone synthesis, restraining inflammation and oxidative stress via regulating energy metabolism, glutathione metabolism, taurine hypotaurine metabolism, arachidonic acid metabolism and linoleic acid metabolism and Ca ²⁺/MAPK signaling pathway, which might be a useful strategy for treating hyperthyroidism.

The Change of Left Ventricular Function in Rats with Subclinical Hypothyroid and the Effects of Thyroxine Replacement

OBJECTIVE

The main purpose of this study was to explore the relationships between serca2a, Ryr2, adipokines, and the left ventricular function in the subclinical hypothyroidism with different TSH levels and to determine the impact of L-T4 treatment on these indexes.

METHODS

Sixty-five male Wistar rats were randomly divided into five groups: control group; sHT A, B, and C group; and sHT + T4 group. The sHT rats were induced by methimazole (MMI), and the sHT + T4 rats were administered with L-T4 treatment after 8 weeks of MMI administration. Serum TT4, TSH, APN, chemerin, and TNF-α were detected by radioimmunoassay kits and ELISA kits; left ventricular function was measured by PowerLab system via subclavian artery catheter. The expression of Serca2a, Ryr2, APN, chemerin, and TNF-α were detected by RT-PCR, Western blot, and immunohistochemistry.

RESULTS

The sHT groups had significantly higher TSH, chemerin, and TNF-α and lower Serca2a, Ryr2, and APN. The left ventricular pressure and heart rate in sHT groups were significantly lower in control and sHT + T4 group. Histopathological examination revealed the pathological changes in the sHT rats' heart. L-T4 administration reduced TSH level and improved left ventricular function.

CONCLUSIONS

TSH can impair left ventricular function by regulating several factors, and L-T4 treatment ameliorates it in sHT rats.

Endothelial Functioning and Hemodynamic Parameters in Rats with Subclinical Hypothyroid and the Effects of Thyroxine Replacement

OBJECTIVE

Subclinical hypothyroidism (SCH) and its associations with atherosclerosis (AS) and cardiovascular disease remain controversial. The purpose of our study was to observe changes in endothelial functioning and hemodynamics in rats with SCH and to determine whether L-thyroxine (L-T4) administration affects these changes.

METHODS

In total, sixty male Wistar rats were randomly divided into the following three groups with 20 rats each: control euthyroid rats, SCH rats and SCH rats that had been treated with thyroxine (SCH+T4). The SCH rats were induced by administration of 10 mg x kg(-1) x d(-1) methimazole (MMI) once daily by gavage for 3 months. The SCH+T4 rats were administered the same dose of MMI for three months in addition to 2 μg x kg(-1) x d(-1) L-T4 once daily by gavage after 45 days of MMI administration. The control rats received physiological saline via gavage.

RESULTS

The SCH group had significantly higher thyroid-stimulating hormone (TSH), total cholesterol (TC), low-density lipoprotein cholesterol (LDL-C), and endothelin (ET) levels and a lower nitric oxide (NO) level than the control and SCH+T4 groups. The tail and carotid artery blood pressures, left ventricular systolic pressure, heart rate and aorta ventralis blood flow were significantly lower in the SCH group than in the control and SCH+T4 groups. ACH treatment caused concentration-dependent relaxation, which was reduced in the SCH arteries compared with the control and SCH+T4 arteries. Histopathological examination revealed the absence of pathological changes in the SCH rat arteries.

CONCLUSIONS

These findings demonstrate that L-T4 treatment ameliorates endothelial dysfunction and hemodynamic changes in SCH rats.

Thyroid hormones regulate skeletal muscle regeneration after acute injury

We evaluated the effects of hypo- and hyperthyroid statuses during the initial phase of skeletal muscle regeneration in rats. To induce hypo- or hyperthyroidism, adult male Wistar rats were treated with methimazole (0.03%) or T4 (10 μg/100 g), respectively, for 10 days. Three days before sacrifice, a crush injury was produced in the solear muscles of one half of the animals, while the other half remained intact. T3, T4, TSH, and leptin serum levels were not affected by the injury. Serum T3 and T4 levels were significantly increased in hyperthyroid and hyper-injury animals. Hypothyroidism was confirmed by the significant increase in serum TSH levels in hypothyroid and hypo-injury animals. Injury increased cell infiltration and macrophage accumulation especially in hyperthyroid animals. Both type 2 and type 3 deiodinases were induced by lesion, and the opposite occurred with the type 1 isoform, at least in the control and hyperthyroid groups. Injury increased both MyoD and myogenin expression in all the studied groups, but only MyoD expression was increased by thyroidal status only at the protein level. We conclude that thyroid hormones modulate skeletal muscle regeneration possibly by regulating the inflammatory process, as well as MyoD and myogenin expression in the injured tissue.

The beneficial effects of olibanum on memory deficit induced by hypothyroidism in adult rats tested in Morris water maze

Functional consequences of hypothyroidism include impaired learning and memory and inability to produce long-term potentiation (LTP) in hippocampus. Olibanum has been used for variety of therapeutic purposes. In traditional medicine, oilbanum is used to enhance learning and memory. In the present study the effect of olibanum on memory deficit in hypothyroid rats was investigated. Male wistar rats were divided into four groups and treated for 180 days. Group 1 received tap drinking water while in group 2, 0.03% methimazol was added to drinking water. Group 3 and 4 were treated with 0.03% methimazole as well as 100 and 500 mg/kg olibanum respectively. The animals were tested in Morris water maze. The swimming speed was significantly lower and the distance and time latency were higher in group 2 compared with group 1. In groups 3 and 4 the swimming speed was significantly higher while, the length of the swim path and time latency were significantly lower in comparison with group 2. It is concluded that methimazole-induced hypothyroidism impairs learning and memory in adult rats which could be prevented by using olibanum.

Nitric oxide contributes to learning and memory deficits observed in hypothyroid rats during neonatal and juvenile growth

INTRODUCTION

Severe cognitive impairment follows thyroid hormone deficiency during the neonatal period. The role of nitric oxide (NO) in learning and memory has been widely investigated.

METHODS

This study aimed to investigate the effect of hypothyroidism during neonatal and juvenile periods on NO metabolites in the hippocampi of rats and on learning and memory. Animals were divided into two groups and treated for 60 days from the first day of lactation. The control group received regular water, whereas animals in a separate group were given water supplemented with 0.03% methimazole to induce hypothyroidism. Male offspring were selected and tested in the Morris water maze. Samples of blood were collected to measure the metabolites of NO, NO2, NO3 and thyroxine. The animals were then sacrificed, and their hippocampi were removed to measure the tissue concentrations of NO2 and NO3.

DISCUSSION

Compared to the control group's offspring, serum thyroxine levels in the methimazole group's offspring were significantly lower (P<0.01). In addition, the swim distance and time latency were significantly higher in the methimazole group (P<0.001), and the time spent by this group in the target quadrant (Q1) during the probe trial was significantly lower (P<0.001). There was no significant difference in the plasma levels of NO metabolites between the two groups; however, significantly higher NO metabolite levels in the hippocampi of the methimazole group were observed compared to controls (P<0.05).

CONCLUSION

These results suggest that the increased NO level in the hippocampus may play a role in the learning and memory deficits observed in childhood hypothyroidism; however, the precise underlying mechanism(s) remains to be elucidated.

Perspectives on the Trypanosoma cruzi-host cell receptor interactions

Chagas disease is caused by the parasite Trypanosoma cruzi. The critical initial event is the interaction of the trypomastigote form of the parasite with host receptors. This review highlights recent observations concerning these interactions. Some of the key receptors considered are those for thromboxane, bradykinin, and for the nerve growth factor TrKA. Other important receptors such as galectin-3, thrombospondin, and laminin are also discussed. Investigation into the molecular biology and cell biology of host receptors for T. cruzi may provide novel therapeutic targets.