Obesity and Thyroid Axis

Roles of thyroid and leptin hormones and their crosstalk in male reproductive functions: an updated review

PURPOSE

This review aims to provide updated information regarding the role of thyroid and leptin hormones and their crosstalk in affecting the male reproductive function in hypothyroid and obesity conditions.

METHOD

A wide literature search was made using online search engines on published articles using keywords including thyroid hormone, hypothyroidism, leptin hormone, hyperleptinemia, obesity, the relationship between thyroid and leptin hormones and male reproduction, and hypothyroidism, obesity, and male reproduction.

RESULTS

All information pertaining thyroid and leptin hormone effects on male reproduction, hypothyroidism, hyperleptinemia, and obesity effect on male fertility as well as the related molecular mechanisms are obtained.

CONCLUSION

Thyroid and leptin hormones individually play a significant role in male reproduction. Alterations of these hormones' levels could adversely affect the male reproductive functions. PI3K/AKT signaling was found to be the major signaling pathway involved in mediating the effect of both hormones on male reproduction. Impaired crosstalk between the two hormones may occur in hypothyroidism with obesity which would contribute towards male reproductive dysfunction.

Relationship of comprehensive dietary antioxidant index and hypothyroidism risk: evidence from the National Health and Nutrition Examination Surveys 2007-2012

BACKGROUND

Hypothyroidism is a common thyroid disease affecting the health of the global population and oxidative stress and inflammation are involved in the pathophysiological process of hypothyroidism. Comprehensive dietary antioxidant index (CDAI), representing the overall dietary antioxidant capacity, has been proved to be associated with a variety of diseases. However, association between CDAI and hypothyroidism risk remains unclear. This study aims to evaluate the association of CDAI and hypothyroidism risk.

METHODS

Data of this study were extracted from the National Health and Nutrition Examination Surveys (NHANES) database 2007-2012. CDAI, represents the overall dietary nutrients capacity, was calculated by selenium, zinc, magnesium, vitamin A, C and E. Thyroid stimulating hormone (TSH) > 5.6 mIU/L was defined as hypothyroidism. The weighted multivariate logistic regression models and propensity score matching (PSM) analysis were utilized to evaluate the relationship between CDAI and hypothyroidism, with odds ratio (ORs) and 95% confidence intervals (CIs). Subgroup and sensitivity analysis were further evaluated the relationship between CDAI and hypothyroidism. Moreover, the association between the components of CDAI and hypothyroidism was also explored.

RESULTS

Totally, 7,959 subjects with information of complete dietary intake and thyroid function measurement were included. Of whom, 213 (2.68%) subjects had hypothyroidism. After adjusted all covariates, we observed high CDAI was related to low hypothyroidism risk (OR = 0.44, 95%CI: 0.27-0.71). This relationship was prominent in subjects with aged < 65 years old (OR = 0.32, 95%CI: 0.16-0.62), male (OR = 0.39, 95%CI: 0.15-0.99) and BMI ≥ 25 kg/m2 (OR = 0.38, 95%CI: 0.19-0.76). The association between high CDAI and low hypothyroidism risk remained significant when subjects using thyroid hormones were excluded (OR = 0.47, 95%CI: 0.27-0.81).

CONCLUSION

High CDAI was related to low hypothyroidism risk among U.S. adults. Our finding showed that the intake of an antioxidant-rich dietary is a potential method to reduce the risk of hypothyroidism.

Associations between indicators of lipid and glucose metabolism and hypothyroidism

BACKGROUND

Hypothyroidism, a prevalent thyroid hormone abnormality identified by biochemical indicators, is prone to serious consequences because of its insidious clinical manifestations and easy underdiagnosis. This research aimed to elucidate the relationships between indicators of lipid and glucose metabolism and hypothyroidism and to assess the value of metabolic indicators for hypothyroidism.

METHODS

Prevalence surveys were conducted utilizing information from 3254 NHANES individuals who passed screening between 2007 and 2012. Comparisons of baseline characteristics, assessment of logistic regression and subgroup analyses, visualization of restricted cubic splines curves, and validation of causal mediation analyses were performed to obtain a comprehensive view of the relationships between indicators of lipid and glucose metabolism and hypothyroidism.

RESULTS

Lipid and glucose metabolism indicators, especially the unconventional parameters triglyceride‒glucose index (TyG) and remnant cholesterol (RC) and the conventional parameter triglyceride (TG), exhibited robust positive relationships with hypothyroidism and served as crucial mediators in the pathways by which hypothyroidism affects health outcomes. Indicators were varying suggestive for hypothyroidism in distinct populations, with TyG being relatively more valuable.

CONCLUSIONS

Indicators of lipid and glucose metabolism (TyG, TG, and RC) were intimately associated with hypothyroidism, with potential applications in the assessment and management of hypothyroidism.

Thyroid Function and Anthropometric Measures: A Systematic Review and Meta-Analysis

OBJECTIVE

Although often enquired about by patients, the association of thyroid function with anthropometric measures in the general population is unclear. We summarized population-based studies and randomized controlled trials (RCTs) on the association between thyroid function and anthropometric measures.

METHODS

We systematically searched Embase, Medline (Ovid), and Cochrane Central Register of Controlled Trials from inception until June 28, 2023. We included studies in adults examining thyroid function or thyroid disease as exposure and anthropometric measures as outcome (eg, body mass index [BMI], weight). We used random effect meta-analyses to pool the results.

RESULTS

We included 64 studies in the qualitative synthesis, and 21 in the quantitative synthesis (total participants n = 107 734 for cross-sectional studies, n = 22 010 for longitudinal studies, n = 80 for RCTs). The evidence was limited and heterogeneous, particularly for longitudinal studies. Cross-sectionally, we described an association for thyroid-stimulating hormone (TSH) concentrations and BMI (B per 1 mIU/L increase of TSH = 0.21; 95% confidence interval [CI], 0.09-0.32) and for free thyroxine (FT4) and BMI (B = -0.14; 95% CI, -0.23 to -0.05). Longitudinally, increasing TSH concentrations were related to weight gain and increasing FT4 concentrations to weight loss.

CONCLUSION

We showed a relation between higher TSH concentrations and higher BMI or weight, and between higher FT4 concentrations and lower BMI or weight, although effect sizes were modest. We highlight the need of more high-quality longitudinal studies. Despite the relevance of the association between thyroid (dys-)function and anthropometric measures, evidence is scarce.

Adiposity is associated with a higher number of thyroid nodules and worse fine-needle aspiration outcomes

Background

Adiposity may be associated with thyroid nodularity. However, its impact on the number of nodules and the risk of malignancy is unclear.

Aim

To evaluate the impact of adiposity on thyroid nodules using body mass index (BMI), ultrasonographic (US) data and cytological data.

Methods

A retrospective cohort study of 310 patients with thyroid nodules was performed. Patients were categorized based on their BMI, and grayscale US data and fine-needle aspiration cytology results were evaluated.

Results

Patients with BMI ≥ 25 kg/m2 were found to have a higher number of thyroid nodules compared to those with BMI < 25 kg/m2 (4.25 ± 2.42 vs 3.66 ± 1.93) (P value = 0.05). Patients with BMI ≥ 25 kg/m2 had more suspicious and malignant cytology than those with BMI < 25 kg/m2 (P value = 0.029). Patients with BMI ≥ 25 kg/m2 had more nodules with intermediate and high suspicion sonographic patterns. However, this did not reach statistical significance.

Conclusion

Overweight and obese patients have a trend for more thyroid nodules and have a higher risk of being diagnosed with thyroid malignancy.

Association Between Euthyroidism and Muscular Parameters in Adults with an Excess of Fat Mass: A Preliminary Study

BACKGROUND/OBJECTIVES

Thyroid hormones (THs) are correlated with body composition regardless of the presence of thyroid dysfunctions, whereas little is known regarding THs' influence on muscular fitness components. This cross-sectional study investigated whether THs may affect muscular parameters in adults who are overweight and affected obesity.

METHODS

One hundred and five volunteers (65 females and 40 males, BMI: 33.5 (8.0) kg/m2) in an euthyroid state were enrolled. Body composition was evaluated using bioelectrical impedance analysis. Muscular parameters of interest were grip strength-evaluated using the handgrip test (HG) and muscular performance -evaluated using the 10-repetition chair-stand test (CST). Free-triiodothyronine (FT3), free-thyroxine (FT4) and their ratio (FT3/FT4) were evaluated to assess thyroid function.

RESULTS

In the female group, the Pearson linear regression analysis revealed a positive correlation between FT3 and HG (R = 0.261, p = 0.036) and a negative correlation between FT3/FT4 and CST (R= -0.266, p= 0.032). In the male group, a positive correlation between FT3 and skeletal muscle mass was found (R = 0.354, p = 0.025). No correlations were found between THs of interest and adiposity indexes (BMI, fat mass) in either group (p > 0.05).

CONCLUSION

FT3 and FT3/FT4 ratio levels in euthyroidism may influence muscular parameters differently in females and males affected by an excess of fat mass. More research is needed to understand the mechanisms behind this correlation and whether THs could be a potential biomarker for muscle-related parameters.

Association between non-high-density lipoprotein cholesterol to high-density lipoprotein cholesterol ratio and serum thyroid function measures: Recent Findings from NHANES 2007-2012 and Mendelian randomization

Objective

There is limited epidemiological data regarding the association of blood lipids with thyroid hormones. Thus, the present article aims to explore whether there is an association between non-high-density to high-density lipoprotein cholesterol ratio (NHHR) and thyroid hormones.

Methods

We analyzed samples from 3,881 adults aged 20 years and above who took part in the National Health and Nutrition Examination Survey (NHANES) spanning 2007 to 2012. The study tested for thyroid hormones, including total triiodothyronine (TT3), free triiodothyronine (FT3), total thyroxine (TT4), free thyroxine (FT4), as well as thyroid-stimulating hormone (TSH). Survey-weighted linear regression and restricted cubic spline (RCS) models were employed to investigate the relationship between NHHR and thyroid hormones. Subsequently, subgroup analyses were conducted. In Mendelian randomization (MR), the inverse variance weighting method (IVW) is used as the primary analytical approach.

Results

This study finally comprised 3,881 adults aged 20 years and older. After extensive adjustments for covariables, the regression analysis revealed significant negative associations between NHHR and FT4 (β: -0.11, 95% confidence interval [CI]: -0.18, -0.04), FT4/FT3 (β: -0.06, 95% CI: -0.08, -0.04), and TT4/TT3 (β: -0.001, 95% CI: -0.001, 0.000). Both observational and Mendelian randomization studies suggest that high-density lipoprotein cholesterol, low-density lipoprotein cholesterol, and total cholesterol may not significantly influence the risk of hyperthyroidism or hypothyroidism.

Conclusions

The study indicates negative associations between NHHR and FT4, as well as the ratios of FT4/FT3 and TT4/TT3. This suggests that NHHR may reflect changes in thyroid function, highlighting its potential clinical significance in assessing thyroid function and metabolic health.

When Should the Treatment of Obesity in Thyroid Disease Begin?

Obesity often coexists with thyroid diseases, and the prevalence of these disorders has been on the rise for years. While hypothyroidism can contribute to excess fat tissue, the relationship between Body Mass Index (BMI) and thyroid function hormones is bidirectional. Research confirms that fat tissue reduction can positively impact thyroid function. Thus, delaying the initiation of therapies beyond substitution treatment to achieve optimal weight reduction in individuals with thyroid dysfunction seems unwarranted. The authors summarize current knowledge on this topic in the article.

Elevated thyroid autoantibodies as risk factors for metabolic dysfunction-associated fatty liver disease in type 2 diabetes mellitus

Objective

This study aims to explore the relationship between thyroid peroxidase antibody (TPOAb) and thyroglobulin antibody (TgAb) levels and metabolic dysfunction-associated fatty liver disease (MAFLD) in patients with type 2 diabetes mellitus (T2DM), providing a theoretical basis for MAFLD prevention and treatment.

Methods

From June 2020 to May 2023, 534 T2DM patients were selected from the Endocrinology Department of Xiangyang Hospital affiliated with Wuhan University of Science and Technology. After applying exclusion criteria, 432 subjects were included. Based on abdominal ultrasound and MAFLD diagnostic criteria, subjects were divided into non-MAFLD (n=163) and MAFLD (n=260) groups. Differences in various indicators between the two groups were compared. Correlation analysis assessed the relationship between TPOAb, TgAb, and other indicators, and the prevalence of MAFLD was analyzed under different thyroid function and antibody levels. Multivariate logistic regression identified risk factors for MAFLD in T2DM patients. According to the FIB-4 index, the group with MAFLD was divided into low-risk (FIB-4< 1.30, n=150), medium-risk (1.30≤FIB-4 ≤ 2.67, n=100), and high-risk liver fibrosis groups (FIB-4 > 2.67, n=10). Differences in thyroid function and autoantibody levels among the three groups were compared.

Results

Compared to non-MAFLD patients, 73.46% of MAFLD patients were overweight or obese, were younger, and had a shorter duration of diabetes. Under normal thyroid function, MAFLD patients had higher levels of TSH, TgAb, and TPOAb (P<0.05). The prevalence of TgAb+, TPOAb+, and TgAb/TPOAb+ was significantly higher at 21.9%, 22.1%, and 29.6%, respectively, with higher prevalence in females. Spearman's correlation showed a positive correlation between TgAb, TPOAb, and AST, and between TPOAb and FINS. MAFLD prevalence varied among quartiles of TSH, TPOAb, and TgAb levels, with significant differences in TPOAb and TgAb components (P<0.05). MAFLD prevalence was positively correlated with TgAb and TPOAb levels. Thyroid autoantibody-positive patients had a significantly higher MAFLD prevalence (P=0.010) at 71.96%. Multivariate logistic analysis found elevated TSH and TPOAb levels as risk factors for MAFLD in T2DM patients [(OR 1.441, 95% CI: 1.213-1.712, P<0.001), (OR 1.005, 95% CI: 1.000-1.010, P=0.040)]. Medium-risk liver fibrosis patients had higher TgAb and TPOAb levels than low-risk and high-risk groups [TgAb: 1.04(0.59,2.83) vs 1.54(0.76,7.35) vs 0.55(0.27,1.32), P=0.035; TPOAb: 1.0(0.29,3.83) vs 2.42(0.5,23.08) vs 0.17(0.09,2.71), P=0.002]. Further comparisons revealed a significant difference in TgAb levels between the medium-risk and high-risk groups (P = 0.048). Additionally, significant differences in TPOAb levels were observed between the low-risk and medium-risk groups and between the medium-risk and high-risk groups (P = 0.016,P = 0.014).

Conclusion

In T2DM patients with MAFLD, elevated TSH, TgAb, and TPOAb levels are observed under normal thyroid function. Elevated TSH and TPOAb levels are risk factors for MAFLD in T2DM patients. TgAb and TPOAb levels vary among liver fibrosis risk groups, showing an inverted "V" pattern, suggesting a role in MAFLD progression to liver fibrosis.

Distinct characteristics of various autoimmune liver diseases: A 22-year hospital-based study in Taiwan

BACKGROUND AND AIM

The characteristics of autoimmune liver diseases (AILDs), including primary biliary cholangitis (PBC), autoimmune hepatitis (AIH), and PBC-AIH overlap syndrome (OS), have rarely been investigated and compared in Asia.

METHODS

At the Taiwan tertiary referral center, 330 PBC patients (87% treated with ursodeoxycholic acid [UDCA]), 143 AIH patients (94.4% treated with immunosuppressive therapy [IST]) and 21 PBC-AIH OS patients (85.7% treated with UDCA and IST) were enrolled.

RESULTS

Compared with AIH patients, PBC patients were older at baseline and had greater female-to-male sex ratios, alkaline phosphatase (ALP) and γ-glutamyl transferase (γ-GT) levels, and liver cirrhosis (LC), dyslipidemia, and hepatic and cardiometabolic complication rates. PBC patients had the lowest transaminase levels, whereas AIH patients had the highest transaminase levels. PBC patients had greater 22-year all-cause mortality and liver transplantation (ACMaLT) (43.5 vs 25.4%, P = 0.004), LC (75 vs 58.5%, P < 0.01), dyslipidemia (54.4 vs 45.9%, P = 0.001), and cerebrovascular accident (11.3 vs 0.8%, P = 0.019) cumulative incidences (CIs) than did AIH patients; PBC-AIH OS patients had greater systemic lupus erythematosus (28.9 vs 8.9%, P = 0.009) CI than did PBC patients. Baseline ALP (hazard ratio: 1.001), albumin (0.514), platelet count (0.997), and LC (3.438) were associated with ACMaLT; age (1.110), albumin (0.350), cirrhosis (46.219), and hepatitis C virus antibody positivity (5.068) were associated with hepatocellular carcinoma (HCC); and female sex (2.183) and body mass index (1.054) were associated with autoimmune diseases.

CONCLUSIONS

Compared with AIH patients, PBC patients had greater cardiometabolic CI, and ACMaLT CI, which was associated with cholestasis, liver functional reserve and LC. Older AILD patients with LC and females with obesity demand special caution for the development of HCC and extrahepatic autoimmune diseases, respectively.

Integrated analysis of omics reveals the role of scapular fat in thermogenesis adaptation in sunite sheep

Inhabiting some of the world's most inhospitable climatic regions, the Sunite Mongolian sheep generates average temperatures as low as 4.3 °C and a minimum temperature of -38.8 °C; in these environments, they make essential cold adaptations. In this regard, scapular fat tissues from Mongolian sheep were collected both in winter and summer for transcriptomic and proteomic analyses to identify genes related to adaptive thermogenesis. In the transcriptome analysis, 588 differentially expressed genes were identified to participate in smooth muscle activity and fat metabolism, as well as in nutrient regulation. There were 343 upregulated and 245 downregulated genes. GO and KEGG pathway analyses on these genes revealed their participation in regulating smooth muscle activity, metabolism of fats, and nutrients. Proteomic analysis showed the differential expression of 925 proteins: among them, there are 432 up- and 493 down-expressed proteins. These proteins are mainly involved in oxidative phosphorylation, respiratory chain complex assembly, and ATP production by electron transport. Furthermore, using both sets at a more detailed level of analysis revealed over-representation in gene ontology categories related to hormone signaling, metabolism of lipids, the pentose phosphate pathway, the TCA cycle, and especially the process of oxidative phosphorylation. The identified essential genes and proteins were further validated by quantitative real-time polymerase chain reaction and Western blotting, respectively; key metabolic network constriction was constructed. The present study emphasized the critical role of lipid turnover in scapular fat for thermogenic adaptation in Sunite sheep.

Resting metabolic rate in obesity

The prevalence of obesity has continued to rise, and obesity and its attendant metabolic disorders are major global health threat factors. Among the current interventions for obesity, none have demonstrated sustained efficacy in achieving long-term outcomes. So, the identification of therapeutic targets is of paramount importance in the advancement and sustainability of obesity. Resting metabolic rate (RMR) constitutes 60%-75% of total energy expenditure and serves a crucial function in maintaining energy balance. Nevertheless, there exists considerable heterogeneity in RMR among individuals. Low RMR is associated with weight gain, elevating the susceptibility to obesity-related ailments. Hence, RMR will be the main focus of interest in the study of obesity treatment. In this review, we will elucidate the influence factors and mechanisms of action of RMR in obesity, with particular emphasis on the effects of obesity treatment on RMR and the alterations and influence factors of RMR in special types of populations with obesity.

THSR Mediated MiR374b Targeting C/EBP β/FOXO1 to Accelerate Thyroid Stimulating Hormone-Induced Hepatic Steatosis

Purpose

Thyroid-stimulating hormone (TSH) has been identified as an independent risk factor for non-alcoholic fatty liver disease (NAFLD), TSH binds to the TSH receptor (TSHR) to exert its function. However, the underlying mechanisms by which TSHR influences NAFLD development remain unclear. This study investigates the role of miR374b in NAFLD progression.

Methods

Firstly, a rat model of non-alcoholic fatty liver was constructed and divided into a normal group and a model group. The liver tissue pathology and fat accumulation were detected by Oil Red O staining and hematoxylin-eosin staining. Western blot and Real time PCR were used to detect for the impact of TSHR/miR-374b/C/EBP β/ FoxO1 pathway in the NAFLD model, and the expression of relevant inflammatory factors in each group was detected by ELISA assay. A NAFLD cell model was constructed using HepG2 cells, TSHR overexpression and interference, combined with miR-374b inhibitor and mimics, were transfected simultaneously to demonstrate TSHR/miR-374b/C/EBP β/ The mechanism of FoxO1 adipogenesis in vitro.

Results

TSHR stimulates miR374b secretion in human liver cancer cells (HepG2) and promotes lipid accumulation in the liver. Deficiency of miR374b in HepG2 cells attenuated NAFLD progression. Mechanistically, TSH increases miR374b expression, which then suppresses the transcription of its target genes, CCAAT/enhancer binding protein-b (C/EBP β) and Forkhead Box Protein O1 (FOXO1). This suppression influences the expression of downstream lipid metabolism proteins, including PPARγ, SREBP2, and SREBP1c. Additionally, miR374b directly targets the 3'UTR of C/EBP β and FOXO1, establishing a negative feedback loop in lipid metabolism.

Conclusion

These findings suggest that TSHR-induced upregulation of miR374b accelerates NAFLD progression by modulating lipid metabolism pathways through C/EBP β and FOXO1.

Association between sleep duration and three obesity indicators among middle-aged and elderly adults: findings from the NHANES 2005-2014

Objective

Obesity has emerged as a worldwide problem. In recent years, it has been verified that there is an association between sleep duration and obesity indicators. This provides a new approach to control obesity. In this study, the relationship between duration of sleep and body mass index (BMI), waist circumference (WC), and waist-to-height ratio (WHtR) among Americans ≥45 years old was investigated.

Methods

Data was collected from the National Health and Nutrition Examination Survey (NHANES) between 2005 and 2014. The link between sleep duration and obesity indicators was analysed using multiple regression models and weighted smoothed curve fitting. Subgroup analysis was conducted to assess the consistency of the connection between sleep duration and obesity indicators across various groups.

Results

This study involved 7,118 males and 7,265 females, with an average age of 62.09. After total adjustment, sleep duration was negatively correlated with BMI (β = -0.19, 95%CI: -0.26, -0.12), WC (β = -0.36, 95%CI: -0.53, -0.19) and WHtR (β = -0.27, 95%CI: -0.38, -0.17). Subgroup analyses revealed more significant negative associations between sleep duration and BMI, WC, and WHtR among non-Hispanic White participants, and those without diabetes and hypertension.

Conclusion

Sleep duration was significantly negatively associated with BMI, WC, and WHtR, suggesting that longer sleep duration may contribute to lower obesity indicators in middle-aged and elderly Americans. Subgroup analysis showed that their negative correlation differed between races, diabetes, or hypertension status. However, additional prospective studies are required to validate these findings and investigate potential causal relationships.

Tissue adaptation to metabolic stress: insights from SUMOylation

Post-translational modification (PTM) plays a crucial role in adaptation of mammals to environmental changes, enabling them to survive in stressful situations. One such PTM is SUMO modification, which is evolutionarily conserved. It involves the covalent and reversible attachment of a small ubiquitin-like modifier (SUMO) to lysine (Lys) residues in the target protein. SUMOylation regulates various functions, including cell proliferation, differentiation, apoptosis, senescence, and maintenance of specific cellular activities. It achieves this by influencing protein-protein interactions, subcellular localization, protein stability, and DNA binding activity. Mounting evidence suggests that SUMOylation is implicated in the pathogenesis of metabolic disorders such as obesity, insulin resistance, and fatty liver. This review aims to provide an overview of the role of SUMOylation in regulating tissue adaptation to metabolic stress. Recent advancements in spectroscopic techniques have shed light on potential targets of SUMOylation and the underlying regulatory mechanisms have been elucidated, laying the theoretical foundation for the development of targeted SUMOylation interventions for metabolic syndrome while minimizing side effects.

Relationship of serum iron and thyroid hormone in obesity and after laparoscopic sleeve gastrectomy

BACKGROUND

Iron is an essential element for thyroid function. However, no study focuses on the association between iron and thyroid in individuals with obesity. Our research aimed to investigate the iron status in relation to baseline thyroid hormone levels and after laparoscopic sleeve gastrectomy (LSG).

METHODS

A total of 216 subjects with obesity were enrolled and divided into low and high iron groups depending on the median value. The association between iron and thyroid hormone was analyzed and compared before and after LSG at the 6-month follow-up in patients who underwent LSG.

RESULTS

1) In all, Total Triiodothyronine (TT3) was significantly higher in high iron than low iron group (P = 0.008). TT3 and thyroid stimulating hormone (TSH) were significantly higher in high iron than low iron group (1.92 ± 0.61 vs. 1.69 ± 0.28 nmol/l, P = 0.029; 2.93 ± 1.66 vs. 1.88 ± 1.03 mU/l, P = 0.002) in females while not in males (all P > 0.05). 2) Iron was significantly positively associated with free triiodothyronine (FT3), free thyroxine (FT4), TT3 and TSH (all P < 0.05). Adjusted for body mass index (BMI), total cholesterol (TCH), high-density lipoprotein cholesterol (HDL-C), fasting insulin (FINS) and homeostatic model assessment of insulin resistance (HOMA-IR), FT3, FT4 and TSH were still significantly associated with iron (all P < 0.05). 3). Regression analysis showed that iron was significantly associated with FT4 (β = 0.338, P = 0.038). 3) LSG led to decreased FT3, FT3, TT3, total thyroxine (TT4) and TSH at 6 months follow-up (all P < 0.05). Changed FT4 was significantly associated with changed iron (r = 0.520, P = 0.009). Subjects with iron decreased had more significant decreased TT4 than subjects without iron decreased (P = 0.021).

CONCLUSION

Serum iron overload is significantly associated with impaired thyroid function in subjects with obesity. LSG led to improved thyroid function which is associated with a change in iron.

TRIAL REGISTRATION

NCT04548232 registration date is on October 9, 2022, registered in https://register.

CLINICALTRIALS

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Exercise as a Therapeutic Strategy for Obesity: Central and Peripheral Mechanisms

Obesity is a complex, multifactorial condition involving excessive fat accumulation due to an imbalance between energy intake and expenditure, with its global prevalence steadily rising. This condition significantly increases the risk of chronic diseases, including sarcopenia, type 2 diabetes, and cardiovascular diseases, highlighting the need for effective interventions. Exercise has emerged as a potent non-pharmacological approach to combat obesity, targeting both central and peripheral mechanisms that regulate metabolism, energy expenditure, and neurological functions. In the central nervous system, exercise influences appetite, mood, and cognitive functions by modulating the reward system and regulating appetite-controlling hormones to manage energy intake. Concurrently, exercise promotes thermogenesis in adipose tissue and regulates endocrine path-ways and key metabolic organs, such as skeletal muscle and the liver, to enhance fat oxidation and support energy balance. Despite advances in understanding exercise's role in obesity, the precise interaction between the neurobiological and peripheral metabolic pathways remains underexplored, particularly in public health strategies. A better understanding of these interactions could inform more comprehensive obesity management approaches by addressing both central nervous system influences on behavior and peripheral metabolic regulation. This review synthesizes recent insights into these roles, highlighting potential therapeutic strategies targeting both systems for more effective obesity interventions.

Physical activity affects dysthyreosis by thyroid hormones sensitivity: a population-based study

Objective

Physical activity (PA) plays an important role in human health. However, the relationship between the PA and dysthyreosis was not clear. This study aimed to explore this question.

Methods

We performed a population-based study on the basis of the participant's information that was collected from the National Health and Nutrition Examination Survey (NHANES) database. The association of the thyroid hormone and total PA metabolic equivalent task (MET) were assessed via linear regression analysis with adjusting for different covariates. Moreover, we also used path analysis to explore the causality between PA, thyroid hormone index, and dysthyreosis. The restricted cubic spline analysis was used to explore the non-linear relationship between the thyroid hormone index and the PA total MET.

Results

A total of 2118 participants aged≥20, including 969 females and 1149 males, were collected from NHANES. The linear regression with multivariate adjustment suggested a linear relationship between the PA total MET and Thyroid-Stimulating Hormone Index (TSHI), and Thyroid Feedback Quantile-Based Index (TFQI), respectively. And TFQI and dysthyresis occurrence were significantly correlated (P<0.05). The path analysis showed that the PA total MET affected dysthyreosis occurrence by TFQI. In addition, we found a non-linear relationship between the total PA met and dysthyreosis via restricted cubic spline analysis.

Conclusions

PA was significantly correlated with dysthyreosis via thyroid hormone sensitivity. Therefore, it can be considered to prevent the occurrence of dysthyreosis by regulating thyroid hormone sensitivity through PA in daily life.

Effect of Endogenous Hormone Levels on Basal Metabolic Rate in Men With Obesity

OBJECTIVE

Basal metabolic rate (BMR) is an important factor in weight management and is influenced by fat-free mass (FFM), fat mass (FM) and age. Current knowledge of the influence of hormonal levels on BMR is based on studies with small populations, studies that investigate exogenous administration and studies frequently lacking correction for body composition.

DESIGN

Cross-sectional study.

PATIENTS

All men (n = 457) who were referred to our centre for a metabolic work-up were eligible for inclusion. Median age was 47 (18-78) years and the vast majority had obesity (BMI ≥ 30 kg/m², 90.9%).

MEASUREMENTS

All men had a measurement of BMR, body composition and measurement of testosterone, sex hormone binding globulin (SHBG), dehydroepiandrosterone sulphate (DHEAS), insulin-like growth factor 1 (IGF-1), thyroid-stimulating hormone (TSH) and free thyroxine (fT4). Men with low, normal and/or high levels of each of these hormones were compared. The association between hormone levels and BMR was assessed through linear regression models. All analyses were controlled for FFM, FM and age.

RESULTS

In men with obesity, testosterone (total or free) was not associated with BMR. Linear regression analysis showed that DHEAS was positively associated with BMR in a sample of men with obesity and normal endogenous DHEAS levels, with the following equation: BMR (adjusted R² = 0.72): (BMR [kcal/d] = 513.402 + 18.940 × FFM [kg] + 9.507 × FM [kg] - 3.362 × age [years] + 0.307 × DHEAS [µg/dL]) (p < 0.01). TSH, fT4 and IGF-1 were not associated with BMR.

CONCLUSION

In men with obesity, endogenous DHEAS is positively associated with BMR. Testosterone, TSH, fT4 and IGF-1 were not associated with BMR in men with obesity. Since we examined the specific population of men with obesity and only examined endogenous hormone levels, no extrapolation of results to other populations or the overall population can be made.

Associations Between Obesity and Risk of Thyroid Cancer: A Meta-Analysis of Cohort Studies

Previous cohort studies have shown conflicting findings on the associations between obesity and the risk of thyroid cancer. This meta-analysis aimed to investigate the associations between them by using a meta-analysis of cohort studies. PubMed and EMBASE were searched using keywords from inception until November 2023 to identify relevant studies on this topic. Two authors independently reviewed and selected relevant studies according to the predefined criteria. Out of 475 studies searched from the databases, a total of 22 cohort studies were included in the final analysis. In a random-effects meta-analysis, obesity was significantly associated with an increased risk of thyroid cancer [odds ratio (OR), relative risk (RR), or hazard ratio (HR) = 1.33; 95% confidence interval (CI) 1.24 - 1.43]. Obesity was consistently associated with the increased risk of thyroid cancer in the subgroup meta-analyses by various factors such as study type (prospective or retrospective cohort study), gender (male or female), continent (America, Europe, or Asia), and study quality (high or low). This meta-analysis of cohort studies suggests that obesity increases the risk of thyroid cancer.

The Downregulation of the Liver Lipid Metabolism Induced by Hypothyroidism in Male Mice: Metabolic Flexibility Favors Compensatory Mechanisms in White Adipose Tissue

In mammals, the maintenance of energy homeostasis relies on complex mechanisms requiring tight synchronization between peripheral organs and the brain. Thyroid hormones (THs), through their pleiotropic actions, play a central role in these regulations. Hypothyroidism, which is characterized by low circulating TH levels, slows down the metabolism, which leads to a reduction in energy expenditure as well as in lipid and glucose metabolism. The objective of this study was to evaluate whether the metabolic deregulations induced by hypothyroidism could be avoided through regulatory mechanisms involved in metabolic flexibility. To this end, the response to induced hypothyroidism was compared in males from two mouse strains, the wild-derived WSB/EiJ mouse strain characterized by a diet-induced obesity (DIO) resistance due to its high metabolic flexibility phenotype and C57BL/6J mice, which are prone to DIO. The results show that propylthiouracil (PTU)-induced hypothyroidism led to metabolic deregulations, particularly a reduction in hepatic lipid synthesis in both strains. Furthermore, in contrast to the C57BL/6J mice, the WSB/EiJ mice were resistant to the metabolic dysregulations induced by hypothyroidism, mainly through enhanced lipid metabolism in their adipose tissue. Indeed, WSB/EiJ mice compensated for the decrease in hepatic lipid synthesis by mobilizing lipid reserves from white adipose tissue. Gene expression analysis revealed that hypothyroidism stimulated the hypothalamic orexigenic circuit in both strains, but there was unchanged melanocortin 4 receptor (Mc4r) and leptin receptor (LepR) expression in the hypothyroid WSB/EiJ mice strain, which reflects their adaptability to maintain their body weight, in contrast to C57BL/6J mice. Thus, this study showed that WSB/EiJ male mice displayed a resistance to the metabolic dysregulations induced by hypothyroidism through compensatory mechanisms. This highlights the importance of metabolic flexibility in the ability to adapt to disturbed circulating TH levels.

Metabolic Syndrome, Thyroid Dysfunction, and Cardiovascular Risk: The Triptych of Evil

The triad formed by thyroid dysfunction, metabolic syndrome (MetS), and cardiovascular (CV) risk forms a network with many connections that aggravates health outcomes. Thyroid hormones (THs) play an important role in glucose and lipid metabolism and hemodynamic regulation at the molecular level. It is noteworthy that a bidirectional association between THs and MetS and their components likely exists as MetS leads to thyroid dysfunction, whereas thyroid alterations may cause a higher incidence of MetS. Thyroid dysfunction increases insulin resistance, the circulating levels of lipids, in particular LDL-C, VLDL-C, and triglycerides, and induces endothelial dysfunction. Furthermore, THs are important regulators of both white and brown adipose tissue. Moreover, the pathophysiological relationship between MetS and TH dysfunction is made even tighter considering that these conditions are usually associated with inflammatory activation and increased oxidative stress. Therefore, the role of THs takes place starting from the molecular level, then manifesting itself at the clinical level, through an increased risk of CV events in the general population as well as in patients with heart failure or acute myocardial infarction. Thus, MetS is frequently associated with thyroid dysfunction, which supports the need to assess thyroid function in this group, and when clinically indicated, to correct it to maintain euthyroidism. However, there are still several critical points to be further investigated both at the molecular and clinical level, in particular considering the need to treat subclinical dysthyroidism in MetS patients.

Thyroid Hormone Clearance in the Paraventricular Nucleus of Male Mice Regulates Lean Mass and Physical Activity

INTRODUCTION

The actions of thyroid hormones (THs) in the central nervous system are relevant to food intake and energy expenditure. TH receptors exhibit high expression in brain areas modulating energy balance, including the arcuate, paraventricular (PVN), supraoptic, and ventromedial (VMH) hypothalamic nuclei.

METHODS

To examine the role of THs in the regulation of energy balance via action in specific hypothalamic nuclei of the adult mouse, we performed experiments of conditional inactivation of DIO3, the enzyme responsible for the clearance of THs, in the lateral hypothalamus (LH), and VMH and PVN hypothalamic nuclei. We accomplished DIO3 genetic inactivation via stereotaxic injection of the AAV-cre vector into adult mice homozygous for a "floxed" Dio3 allele.

RESULTS

Dio3 inactivation in the LH and VMH of males or females did not result in significant changes in body weight 8 weeks after injection. However, inactivation of Dio3 in the PVN resulted in increased body weight (both fat mass and lean mass) and locomotor activity, and decreased hypothalamic Mc4r expression in male, but not female mice. However, PNV-specific Dio3 KO did not cause hyperphagia.

CONCLUSION

These results suggest local TH action influences MC4R signaling and possibly other PVN-associated circuitries, with consequences for body composition and energy balance endpoints, but not for orexigenic pathways. They also support a regulatory role for PVN Dio3 in the central regulation of energy homeostasis in adult life.

Sex and obesity influence the relationship between perfluoroalkyl substances and lean body mass: NHANES 2011-2018

Objective

Polyfluoroalkyl substances (PFAS) are known endocrine disruptors, that have been the subject of limited research regarding their impact on human lean body mass. The aim of this study was to investigate the effects of PFAS exposure on lean body mass.

Methods

We performed a cross-sectional data analysis involving 1022 adolescents and 3274 adults from the National Health and Nutrition Examination Survey (NHANES) 2011-2018, whose lean body mass was measured by dual-energy X-ray absorptiometry. The lean mass index (LMI) was calculated as lean body mass dividing by the square of height. The association between PFAS and LMI was examined through a multivariate-adjusted weighted generalized linear model. Moreover, weighted quantile sum (WQS) regression models were employed to futher examine the relationship between the mixture of PFAS and LMI.

Results

Regression analyses revealed an inverse correlation between PFAS exposure and LMI after adjusting for potential covariates. Adults with higher serum PFAS concentrations manifested a reduction in whole LMI ( β  = -0.193, 95 % confidence interval (CI): -0.325 to -0.06). Notably, this correlation was particularly significant in adult females and individuals with obesity, and it was observed across diverse anatomical regions, including lower limbs, right arm, trunk, and whole lean body mass. In adult females, the association between PFAS and whole LMI was statistically significant ( β  = -0.294, 95 % CI: -0.495 to -0.094), and a similar trend was found in obese individuals ( β  = -0.512, 95 % CI: -0.762 to -0.261). WQS regression analyses supported the results obtained from weighted linear regression analyses.

Conclusions

Our study suggests that exposure to PFAS, whether individually or in combination, is associated with decreased lean body mass in specific body areas, with sex and obesity serving as major influencing factors.

Association between total body muscle-fat ratio and risk of thyroid disorders: a cross-sectional study

BACKGROUND

Thyroid disorders(TD) poses a significant health threat to Americans due to its high incidence rate. Obesity, a common factor linked to thyroid disorders, has garnered increasing attention. While Body mass index (BMI) is a widely used obesity index, it fails to account for the distribution of muscle and fat in the body. Recently, tMFR has emerged as a crucial obesity index in clinical research, warranting further investigation into its association with TD.

OBJECTIVE

Exploring the association between tMFR and thyroid disorders.

METHOD

A comprehensive survey and data analysis were conducted using the NHANES database to investigate the relationship between tMFR and the risk of TD. This study utilized multiple logistic regression, smooth curve fitting, and subgroup analysis across four periods from 2011 to 2018.

RESULT

A total of 11,912 subjects were included in the study, showing a prevalence of 7.14% for TD. The research indicated that tMFR had an inverse correlation with the risk of TD in a comprehensive model (OR = 0.90, 95% CI 0.82 to 1.00). When tMFR was divided into quartiles (Q1-Q4), individuals in the highest quartile had a 28% lower risk of TD than those in Q1 (OR = 0.72, 95% CI 0.57 to 0.91). Analysis using smoothed curve fitting demonstrated a nonlinear relationship between tMFR and TD risk, with the inflection point for tMFR saturation effect identified as 1.5. Subgroup analysis further confirmed the strong association between tMFR and TD risk. Receiver operating characteristic (ROC) curve analysis indicated that tMFR exhibited superior predictive ability for TD relative to BMI.

CONCLUSION

The study found a negative association between tMFR and the risk of TD; however, additional prospective studies are required to validate these findings.

Triiodothyronine (T3) promotes browning of white adipose through inhibition of the PI3K/AKT signalling pathway

Obesity arises from an imbalance between energy consumption and energy expenditure, and thyroid hormone levels serve as a determinant of energy expenditure. We conducted experiments at the animal and cellular levels and combined those findings with clinical data to elucidate the role of triiodothyronine (T3) in facilitating the browning of white adipose tissue (WAT) and its underlying mechanism. The results showed (i) the impaired metabolic function of local WAT and the compensatory elevation of systemic thermogenesis in obesity; (ii) T3 treatment of white adipocytes in vitro and local WAT in vivo induced a shift towards a morphologically "brown" phenotype, accompanied by upregulation of mRNA and protein expression of browning-related and mitochondrial function markers, which suggest that T3 intervention promotes the browning of WAT; and (iii) the aforementioned processes could be modulated through inhibition of the PI3K/AKT signalling pathway; however, whether T3 affects the PI3K/AKT signalling pathway by affecting insulin signalling remains to be studied and clarified. The results of our study indicate that T3 treatment promotes browning of WAT through inhibition of the PI3K/AKT signalling pathway; these findings offer novel perspectives regarding the potential of localised therapies for addressing WAT volume in individuals with obesity.

Changes in thyroid hormones predict weight regain in patients with obesity who undergo metabolic surgery

AIM

To investigate the relationship between thyroid function and weight regain in patients with obesity after metabolic surgery.

METHODS

This retrospective study enrolled 162 patients who underwent metabolic surgery. Correlations between decreases in thyroid hormone levels and changes in weight, waist circumference (WC) and the Chinese visceral adiposity index (CVAI) were assessed. Binary logistic regression and receiver operating characteristic (ROC) curves were used to identify predictors and clinically useful cut-off values, respectively.

RESULTS

The levels of thyroid-stimulating hormone (TSH) and free triiodothyronine (FT3) decreased markedly at 1 year after surgery, as did weight, body mass index (BMI), triglycerides, total cholesterol, high-density lipoprotein cholesterol, low-density lipoprotein cholesterol, WC and CVAI. Decreases in TSH and FT3 after metabolic surgery were associated with changes in weight, BMI and CVAI. Binary logistic regression and ROC curve analyses confirmed that decreases in TSH can predict good weight loss after metabolic surgery to some extent. Finally, binary logistic regression and ROC curve analyses confirmed that changes in TSH can predict weight regain after metabolic surgery.

CONCLUSIONS

Changes in TSH and FT3 after metabolic surgery were correlated with changes in weight and CVAI. Changes in thyroid hormones can predict weight regain in patients with obesity who underwent metabolic surgery.

A Case-Control Study of the Correlation Between Blood Parameters and Obesity

BACKGROUND

 Obesity has become a global health crisis in adults, and is linked to conditions like diabetes, cardiovascular diseases, and cancer. This study explored associations between body mass index (BMI) and laboratory parameters in healthy individuals to identify risk factors and guide targeted interventions in Turkey. It was found that screening and lifestyle changes can help prevent and manage obesity-related health issues.

METHODS

This retrospective case-control study analyzed 2153 adult participants using medical records between 2021 and 2024. The study included those with good overall health; those under 18 years of age or had organ failure, chronic metabolic disorders, obesity complications, or were on multiple obesity-related medications were excluded. Data collected included demographic details, waist-to-hip ratio (WHR), BMI, and laboratory findings. Statistical analyses, including Pearson and Spearman correlations, Mann-Whitney U test and t test, and receiver operating characteristic analysis, were performed using SPSS 24.0 (IBM Corp., Armonk, NY).

RESULTS

The study, comprising 1016 men and 1137 women, revealed that 31.8% of adults were obese. Gender disparities were evident, with a higher prevalence of obesity observed in women: 76.5%, 68.8%, and 45.3% for classes 1, 2, and 3, respectively, compared to corresponding rates of 23.5%, 31.2%, and 54.7% in men. BMI significantly correlated with WHR. Despite the disparity between BMI and WHR between men and women, positive correlations were found between BMI and age (r=0.4) and serum uric acid (SUA) levels (r=0.5). The Mann-Whitney U test also demonstrated a significant association between BMI and fasting plasma glucose level, low-density lipoprotein (LDL), triglycerides, alanine aminotransferase (ALT), uric acid, platelet count, and lymphocyte count (all p values<0.005). Despite the poor correlation with BMI, SUA levels emerged as a potential obesity predictor, with a 4.1 mg/dl cutoff value, exhibiting 50% sensitivity and 34% specificity (p<0.001; area under the curve, or AUC, 0.67; 95% CI 0.65-0.70). There was no significant link between BMI and aspartate aminotransferase, hemoglobin, mean platelet volume, neutrophil and lymphocyte count, vitamin D, thyroid-stimulating hormone, and free thyroxine 4 levels.

CONCLUSION

This study found significant associations between BMI and laboratory parameters, including serum uric acid, fasting glucose, LDL, triglycerides, and ALT. WHR was also closely linked to BMI, with notable gender differences in body composition. These significant findings underscore the complex nature of obesity and highlight the importance of gender-specific considerations and biomarkers in research and management strategies that are crucial for understanding and addressing this global health crisis.

The association between serum soluble α-Klotho and thyroid profile among adults from NHANES 2007-2012

BACKGROUND

Thyroid hormone is the key endocrine regulator of growth, development, metabolism, and other bodily functions. α-Klotho has been involved in the aging process and acts as an endocrine factor involved in the regulation of various metabolic processes in humans. However, the relationship between α-Klotho and thyroid profile has not been uniformly recognize.

OBJECTIVE

To determine the relationship between α-Klotho and thyroid profile in adult individuals.

METHODS

Population data of 4614 adult individuals were obtained from the NHANES database during the period of 2007-2012. Weighted multivariable regression analysis was performed using a general linear model with serum α-Klotho as the independent variable and thyroid profile as the dependent variables, respectively. The generalized additive model was used for smoothing curve fitting and threshold effect analysis.

RESULTS

α-Klotho was associated with a slightly higher FT3, TT3 and TT4 level in unadjusted and adjusted regression models. However, a higher α-Klotho level was associated with a lower TSH level. After α-Klotho was grouped as quantiles with reference (Q1), α-Klotho still showed a statistically significant positive correlation with FT3 and TT3 levels in Q2, Q3 and Q4. In addition, α-Klotho was positively corrected with TT4, but negatively associated with TSH in Q4.

CONCLUSIONS

Serum soluble α-Klotho was positively associated with FT3, TT3 and TT4, but negatively correlated with TSH. The significant effect of α-Klotho on thyroid profile suggests its potential as a predictive marker of thyroid functions, indicating its possible involvement in the regulation of thyroid hormone secretion.

The growing complexity of the control of the hypothalamic pituitary thyroid axis and brown adipose tissue by leptin

The balance between food intake and energy expenditure is precisely regulated to maintain adipose stores. Leptin, which is produced in and released from adipose in direct proportion to its size, is a major contributor to this control and initiates its homeostatic responses largely via binding to leptin receptors (LepR) in the hypothalamus. Decreases in hypothalamic LepR binding signals starvation, leading to hunger and reduced energy expenditure, whereas increases in hypothalamic LepR binding can suppress food intake and increase energy expenditure. However, large gaps persist in the specific hypothalamic sites and detailed mechanisms by which leptin increases energy expenditure, via the parallel activation of the hypothalamic pituitary thyroid (HPT) axis and brown adipose tissue (BAT). The purpose of this review is to develop a framework for the complex mechanisms and neurocircuitry. The core circuitry begins with leptin binding to receptors in the arcuate nucleus, which then sends projections to the paraventricular nucleus (to regulate the HPT axis) and the dorsomedial hypothalamus (to regulate BAT). We build on this core by layering complexities, including the intricate and unsettled regulation of arcuate proopiomelanocortin neurons by leptin and the changes that occur as the regulation of the HPT axis and BAT is engaged or modified by challenges such as starvation, hypothermia, obesity, and pregnancy.

No causal associations of genetically predicted birth weight and life course BMI with thyroid function and diseases

OBJECTIVE

Observational studies have suggested associations of birth weight, childhood BMI, and adulthood BMI with thyroid function or diseases. However, the causal relationships remain unclear due to residual confounding inherent in conventional epidemiological studies.

METHODS

We performed a two-sample Mendelian randomization (MR) study to investigate causal relationships of genetically predicted birth weight, childhood BMI, and adulthood BMI with a range of clinically relevant thyroid outcomes. Additionally, we conducted a reverse MR analysis on adulthood BMI. Data on exposures and outcomes were obtained from large-scale genome-wide association study meta-analyses predominantly composed of individuals of European ancestry.

RESULTS

The MR analysis revealed no evidence of causal associations of birth weight or BMI at different life stages with thyrotropin (TSH) levels, hypothyroidism, hyperthyroidism, autoimmune thyroid disorders, or thyroid cancer. Contrarily, thyroid cancer demonstrated a significant causal relationship with increased adulthood BMI (β = 0.010, 95% CI: 0.006-0.015; p = 5.21 × 10-6).

CONCLUSIONS

Our comprehensive MR did not find causal links of birth weight, childhood BMI, or adulthood BMI with thyroid diseases but provided evidence that thyroid cancer may play a role in weight gain. Our research findings offer valuable insights into the intricate relationship between body weight and thyroid health throughout an individual's life.

The impacts of obesity in rheumatoid arthritis and insights into therapeutic purinergic modulation

Rheumatoid Arthritis (RA) is an autoimmune condition responsible for the impairment of synovia and joints, endangering the functionality of individuals and contributing to mortality. Currently, obesity is increasing worldwide, and recent studies have suggested an association between such condition and RA. In this sense, obese individuals present a lower capacity for achieving remission and present more intense symptoms of the disease, demonstrating a link between both disorders. Different studies aim to understand the possible connection between the conditions; however, few is known in this sense. Therefore, knowing that obesity can alter the activity of multiple body systems, this work's objective is to evaluate the main modifications caused by obesity, which can be linked to the pathophysiology of RA, highlighting as relevant topics obesity's negative impact triggering systemic inflammation, intestinal dysbiosis, endocrine disbalances. Furthermore, the relationship between oxidative stress and obesity also deserves to be highlighted, considering the influence of reactive oxygen species (ROS) accumulation in RA exacerbation. Additionally, many of those characteristics influenced by obesity, along with the classic peculiarities of RA pathophysiology, can also be associated with purinergic signaling. Hence, this work suggests possible connections between the purinergic system and RA, proposing potential therapeutic targets against RA to be studied.

Prevalence and clinical correlates of abnormal lipid metabolism in older Chinese patients with first-episode drug-naïve major depressive disorder

BACKGROUND

Older major depressive disorder (MDD) patients have more complex clinical symptoms and higher abnormal lipid metabolism (ALM) rates. This study aimed to compare clinical differences between those with and without ALM in a sample of older first-episode drug naïve (FEDN) patients.

METHODS

We recruited 266 older MDD patients. Socio-demographic variables, clinical data, and lipid parameters were obtained. The Hamilton Depression Rating Scale (HAMD), Hamilton Anxiety Rating Scale (HAMA), and the positive subscale of the Positive and Negative Syndrome Scale (PANSS-P) were conducted to evaluate patients' depression, anxiety and psychotic symptoms, respectively.

RESULTS

In this study, we found that the prevalence of comorbid ALM was 86.1% in older MDD patients. Compared with the non-abnormal lipid metabolism (NALM) group, the ALM group had a higher duration of illness, higher clinical global impression of severity scale (CGI-S) and HAMD scores, higher thyroid stimulating hormone (TSH) and glucose levels. Logistic regression analysis indicated that duration of illness (OR = 1.11, P = 0.023, 95%CI = 1.015-1.216) and CGI-S score (OR = 2.28, P = 0.014, 95%CI = 1.18-4.39) were associated with ALM in older MDD patients.

CONCLUSION

The importance of regular lipid assessment in older MDD patients needs to be taken into account.

Risk Factors for Thyroid Dysfunction in Pregnancy: An Individual Participant Data Meta-Analysis

Background: International guidelines recommend targeted screening to identify gestational thyroid dysfunction. However, currently used risk factors have questionable discriminative ability. We quantified the risk for thyroid function test abnormalities for a subset of risk factors currently used in international guidelines. Methods: We included prospective cohort studies with data on gestational maternal thyroid function and potential risk factors (maternal age, body mass index [BMI], parity, smoking status, pregnancy through in vitro fertilization, twin pregnancy, gestational age, maternal education, and thyroid peroxidase antibody [TPOAb] or thyroglobulin antibody [TgAb] positivity). Exclusion criteria were pre-existing thyroid disease and use of thyroid interfering medication. We analyzed individual participant data using mixed-effects regression models. Primary outcomes were overt and subclinical hypothyroidism and a treatment indication (defined as overt hypothyroidism, subclinical hypothyroidism with thyrotropin >10 mU/L, or subclinical hypothyroidism with TPOAb positivity). Results: The study population comprised 65,559 participants in 25 cohorts. The screening rate in cohorts using risk factors currently recommended (age >30 years, parity ≥2, BMI ≥40) was 58%, with a detection rate for overt and subclinical hypothyroidism of 59%. The absolute risk for overt or subclinical hypothyroidism varied <2% over the full range of age and BMI and for any parity. Receiver operating characteristic curves, fitted using maternal age, BMI, smoking status, parity, and gestational age at blood sampling as explanatory variables, yielded areas under the curve ranging from 0.58 to 0.63 for the primary outcomes. TPOAbs/TgAbs positivity was associated with overt hypothyroidism (approximate risk for antibody negativity 0.1%, isolated TgAb positivity 2.4%, isolated TPOAb positivity 3.8%, combined antibody positivity 7.0%; p < 0.001), subclinical hypothyroidism (risk for antibody negativity 2.2%, isolated TgAb positivity 8.1%, isolated TPOAb positivity 14.2%, combined antibody positivity 20.0%; p < 0.001) and a treatment indication (risk for antibody negativity 0.2%, isolated TgAb positivity 2.2%, isolated TPOAb positivity 3.0%, and combined antibody positivity 5.1%; p < 0.001). Twin pregnancy was associated with a higher risk of overt hyperthyroidism (5.6% vs. 0.7%; p < 0.001). Conclusions: The risk factors assessed in this study had poor predictive ability for detecting thyroid function test abnormalities, questioning their clinical usability for targeted screening. As expected, TPOAb positivity (used as a benchmark) was a relevant risk factor for (subclinical) hypothyroidism. These results provide insights into different risk factors for gestational thyroid dysfunction.

Impaired Sensitivity to Thyroid Hormones Is Associated With the Change of Abdominal Fat in Euthyroid Type 2 Diabetes Patients: A Retrospective Cohort Study

Background and Aims: This study is aimed at investigating the potential correlation of thyroid hormone sensitivity with visceral fat area (VFA), subcutaneous fat area (SFA), and body mass index (BMI) among euthyroid type 2 diabetes mellitus (T2DM) subjects. Methods: Thyroid hormone sensitivity indices were calculated by thyroid feedback quantile-based index (TFQI), TSH index (TSHI), thyrotropin thyroxine resistance index (TT4RI), and free thyroxine (fT4)/free triiodothyronine (fT3) ratio. These indices were then categorized into quartiles for analysis. The outcomes were the change rates in VFA, SFA, and BMI among the participants. Result: The present study included 921 patients, with a median follow-up of 2.2 years. In multivariate linear regression, when compared to the first quartile, SFA demonstrated a notable decline in the fourth quartile of TFQI, TSHI, and TT4RI (β coefficient = -5.78, -7.83, and - 6.84 cm2 per year), while it significantly increased in the fourth quartile of fT4/fT3 ratio (β coefficient = 6.13 cm2 per year). Similarly, in the fourth quartile of TFQI, TSHI, and TT4RI, VFA decreased significantly, evidenced by β coefficients of -5.14, -4.80, and -4.08 cm2 per year. Yet, among the quartiles of the fT4/fT3 ratio, no discernible trend in VFA was observed. There was no significant association between indices of thyroid hormone sensitivity and change in BMI. Conclusion: Impaired central sensitivity to thyroid hormones was significantly associated with the reduction of VFA and SFA, while impaired peripheral sensitivity was associated with an increase of SFA in euthyroid individuals with T2DM.

The effect of intermittent fasting on preventing obesity-related early aging from a molecular and cellular perspective

Obesity is a global health concern owing to its association with numerous degenerative diseases and the fact that it may lead to early aging. Various markers of aging, including telomere attrition, epigenetic alterations, altered protein homeostasis, mitochondrial dysfunction, cellular senescence, stem cell disorders, and intercellular communication, are influenced by obesity. Consequently, there is a critical need for safe and effective approaches to prevent obesity and mitigate the onset of premature aging. In recent years, intermittent fasting (IF), a dietary strategy that alternates between periods of fasting and feeding, has emerged as a promising dietary strategy that holds potential in counteracting the aging process associated with obesity. This article explores the molecular and cellular mechanisms through which IF affects obesity-related early aging. IF regulates various physiological processes and organ systems, including the liver, brain, muscles, intestines, blood, adipose tissues, endocrine system, and cardiovascular system. Moreover, IF modulates key signaling pathways such as AMP-activated protein kinase (AMPK), sirtuins, phosphatidylinositol 3-kinase (PI3K)/Akt, mammalian target of rapamycin (mTOR), and fork head box O (FOXO). By targeting these pathways, IF has the potential to attenuate aging phenotypes associated with obesity-related early aging. Overall, IF offers promising avenues for promoting healthier lifestyles and mitigating the premature aging process in individuals affected by obesity.

Metabolic Dysfunction-Associated Fatty Liver Disease (MAFLD) and Thyroid Function in Childhood Obesity: A Vicious Circle?

Metabolic dysfunction-associated fatty liver disease (MAFLD) is a multisystem disorder characterized by the presence of fatty liver degeneration associated with excess adiposity or prediabetes/type 2 diabetes or metabolic dysregulation. An intricate relationship between the liver and thyroid has been reported in both health and disease. Simultaneously, there is a strong correlation between obesity and both MAFLD and thyroid dysfunction. In this narrative review, we highlighted the relationship between MAFLD and thyroid function in children and adolescents with obesity in order to explore how thyroid hormones (THs) act as predisposing factors in the onset, progression, and sustainability of MAFLD. THs are integral to the intricate balance of metabolic activities, ensuring energy homeostasis, and are indispensable for growth and development. Regarding liver homeostasis, THs have been suggested to interact with liver lipid homeostasis through a series of processes, including stimulating the entry of free fatty acids into the liver for esterification into triglycerides and increasing mitochondrial β-oxidation of fatty acids to impact hepatic lipid accumulation. The literature supports a correlation between MAFLD and obesity, THs and obesity, and MAFLD and THs; however, results in the pediatric population are very limited. Even though the underlying pathogenic mechanism involved in the relationship between MAFLD and thyroid function remains not fully elucidated, the role of THs as predisposing factors of MAFLD could be postulated. A potential vicious circle among these three conditions cannot be excluded. Identifying novel elements that may contribute to MAFLD could offer a practical approach to assessing children at risk of developing the condition.

Maternal undernutrition results in transcript changes in male offspring that may promote resistance to high fat diet induced weight gain

Maternal nutrition during embryonic development and lactation influences multiple aspects of offspring health. Using mice, this study investigates the effects of maternal caloric restriction (CR) during mid-gestation and lactation on offspring neonatal development and on adult metabolic function when challenged by a high fat diet (HFD). The CR maternal model produced male and female offspring that were significantly smaller, in terms of weight and length, and females had delayed puberty. Adult offspring born to CR dams had a sexually dimorphic response to the high fat diet. Compared to offspring of maternal control dams, adult female, but not male, CR offspring gained more weight in response to high fat diet at 10 weeks. In adipose tissue of male HFD offspring, maternal undernutrition resulted in blunted expression of genes associated with weight gain and increased expression of genes that protect against weight gain. Regardless of maternal nutrition status, HFD male offspring showed increased expression of genes associated with progression toward nonalcoholic fatty liver disease (NAFLD). Furthermore, we observed significant, sexually dimorphic differences in serum TSH. These data reveal tissue- and sex-specific changes in gene and hormone regulation following mild maternal undernutrition, which may offer protection against diet induced weight gain in adult male offspring.

Spexin may induce mitochondrial biogenesis in white and brown adipocytes via the hypothalamus-pituitary-thyroid (HPT) axis

AIM

The present study aimed to investigate the effect of the intracerebroventricular (icv) administration of spexin on the hypothalamus-pituitary-thyroid (HPT) axis (TRH, TSH, T4 and T3 hormones) and energy expenditure (PGC-1α and UCP1 genes) in white adipose (WAT) and brown adipose tissues (BAT) in rats. Furthermore, the study aimed to determine the effects of spexin on food-water consumption and body weight of rats.

MATERIAL AND METHOD

The study was conducted with 40 male rats that were divided into 4 groups: Control, Sham, Spexin 30 and Spexin 100 (n = 10). Spexin (1 μl/hour) was administered to rats other than those in the control group for 7 days with osmotic minipumps intracerebroventricularly, artificial cerebrospinal fluid (vehicle) was administered to the Sham group, and 30 nMol and 100 nMol spexin was infused to the Spexin 30 and Spexin 100 groups, respectively. Food-water consumption and body weight of the rats were monitored during the experiments. After the seven-day infusion, the rats were decapitated and serum TSH, fT4 and fT3 levels were determined with ELISA on rat blood samples. Also, TRH gene expression levels from the hypothalamus tissues and PGC-1α and UCP1 expression levels from WAT and BAT were determined by real-time PCR.

FINDINGS

It was determined that icv spexin infusion reduced daily food consumption and body weight without leading to a significant change in water consumption (p < 0.05). Icv spexin infusion significantly decreased serum TSH, and increased fT4 and fT3 levels when compared to control and sham groups (p < 0.05). Moreover, icv spexin infusion increased the TRH expressions in the hypothalamus tissues and PGC-1α UCP1 in the WAT and BAT (p < 0.05).

CONCLUSION

Icv Spexin infusion may have effects on food consumption and body weight as well as, thyroid hormones and energy metabolism.

Overweight or Obesity Rate and Risk Factors in First-Episode and Drug-Naïve Patients with Major Depressive Disorder with Comorbid Abnormal Lipid Metabolism: A Large-Scale Cross-Sectional Study

Overweight and obesity are frequent symptoms in patients with major depressive disorder (MDD) and abnormal lipid metabolism (ALM). There are no studies on the rate, risk factors, and underlying mechanisms of overweight/obesity in Chinese patients with MDD with comorbid ALM. The purpose of this study was to examine the rate of overweight/obesity and the associated risk factors among Chinese patients with MDD first-episode and drug-naïve (FEDN) with comorbid ALM. This study was a cross-sectional research work. A total of 1718 patients were enrolled. Their clinical and laboratory data were obtained. All participants were assessed with the 17-item Hamilton Depression Rating Scale (HAMD), the Hamilton Anxiety Rating Scale (HAMA), and the Positive and Negative Syndrome Scale (PANSS) positive subscale. The plasma total cholesterol (TC), low-density lipoprotein cholesterol (LDL-C), high-density lipoprotein cholesterol (HDL-C), triacylglycerols (TG), blood glucose concentrations, thyroid peroxidase antibody (A-TPO), thyoglubulin antibody (A-TG), thyroid-stimulating hormone (TSH), free thyoxine (FT4) and free triiodothyronine (FT3), and blood glucose concentrations were measured. ALM was identified as elevations in the plasma lipid values in this study. Of all the included subjects, the rate of ALM was 81.1%. The rate of obesity and overweight was 3.94% and 57.21%, respectively. Logistic regression analysis showed that TSH was the independent risk factor for overweight or obesity in MDD patients (adjusted OR = 1.158, 95%CI = 1.081-1.24, p < 0.001). The risk of developing overweight or obesity in MDD with ALM with comorbid TSH abnormalities was 2.176 times higher than those without TSH abnormalities (p < 0.001). Further linear regression showed TSH level (B = 0.1, t = 3.376, p = 0.001) and systolic blood pressure (B = 0.015, t = 2.351, p = 0.019) were risk factors for a higher body mass index (BMI). Our results demonstrate that being overweight is very frequent among patients with FEDN MDD with comorbid ALM but not obesity. TSH was the risk factor for overweight and obesity in MDD patients with comorbid ALM.

Thyroid hormone levels and BMI-SDS changes in adolescents with obesity

Background

Thyroid hormones play an important role in energy metabolism and weight control, explained mostly by inducing thermogenesis and increasing basal metabolic rate. It has recently been shown that FT4 levels are associated with food preferences, which might also play a role in modulating body weight. The aim of this longitudinal follow-up study was to analyze the relationship of thyroid hormones levels (FT4, TSH) at baseline with weight/BMI-SDS changes in children and adolescents with obesity.

Methods

Three hundred seventy-seven children and adolescents have been enrolled to this study and followed up without a systematic intervention program for 5.59 ± 1.85months. Children and adolescents were divided into three subgroups: 1) 144 adolescents with obesity (15-19 years), 2) 213 children with obesity (10-14.9 years), and 3) 20 lean adolescents (15-19 years). Thyroid hormones were measured at the baseline, and anthropometry was performed at the baseline and during the follow-up. For further analyses, participants were divided according to the BMI-SDS change into two groups: 1. with BMI-SDS decrease, and 2. with BMI-SDS increase.

Results

Adolescents with obesity from the BMI-SDS decrease group had significantly lower baseline serum levels of TSH compared to the BMI-SDS increase group (2.4 ± 1.0 vs. 3.2 ± 2.0mIU/l; p=0.005). Similar difference was found for FT4 levels (14.7 ± 2.2 in the BMI-SDS decrease group vs. 15.5 ± 2.7pmol/l in the BMI-SDS increase group, p=0.048). Moreover, the BMI-SDS decrease was present in significantly higher percentage of adolescents with obesity with lower than median TSH level compared to those with higher than median TSH level at baseline (61.1% vs 38.6%, p=0.011). Likewise, the BMI-SDS decrease was present in significantly higher percentage of adolescent females with obesity and lower than median FT4 compared to those with higher than median FT4 level at baseline (70.6% vs. 23.5%, p<0.001). No associations of baseline thyroid hormones with the BMI-SDS change were observed in children with obesity or lean adolescents.

Conclusion

Adolescents with obesity and increased BMI-SDS during the follow-up had significantly higher baseline levels of both TSH and FT4 compared to BMI-SDS decrease group. These results support the previous findings that higher FT4 in individuals with obesity may influence weight gain.

Knowledge, experiences, and perceptions relating to obesity management among primary care physicians in the Lazio Region, Italy

Background

Primary care providers (PCPs) play an essential role in obesity care as they represent the first contact for patients seeking weight loss interventions.

Objective

This study explored the knowledge, experiences, and perceptions of PCPs in the Lazio Region of Italy in the management of obesity.

Design and subjects

We conducted an anonymous survey delivered from March to July 2022 via the newsletter of Rome Provincial Order of Physicians and Dentists and at the annual meeting of the regional section of the Italian Obesity Society.

Approach

The survey consisted of 24 closed-ended questions grouped into 5 sections: sociodemographic and work information; assessment of obesity; management of obesity; connections with regional Centres for Obesity Management; attitudes towards obesity.

Key results

A total of 92 PCPs accessed the survey. Of those, 2.2% were excluded because they did not see any patients with obesity. A total of 68 PCPs (75.6%) had complete questionnaires and were included in this analysis. All participants reported asking their patients about their eating habits, lifestyle, and clinical complications at the first assessment. Body weight and blood pressure were measured by 98.5% of participants and 82% calculate body mass index (BMI), while a small proportion of PCPs analysed body composition and fat distribution. Over 80% prescribed laboratory tests and ECG. Approximately 40% of PCPs did not refer patients for nutritional counselling, and most prescribed a low-calorie diet. Sixty-three percent referred patients to an endocrinologist, 48.5% to a psychotherapist, and a minority to specialists for obesity complications. Twenty-three percent prescribed anti-obesity medications and 46.5% referred patients for bariatric surgery only in severe cases. Ninety-one percent stated that obesity is "a complex and multifactorial disease" and 7.4% considered obesity to be secondary to other conditions.

Conclusions

Despite most PCPs adopt a correct approach to manage patients with obesity, many aspects could be improved to ensure optimal and multidisciplinary management.

Thyroid dysfunction in children and adolescents affected by undernourished and overnourished eating disorders

Eating disorders (ED) are one of the most prevalent chronic disorders in adolescents and young adults, with a significantly increasing prevalence in younger children, particularly in girls. Even if obesity in essence is not framed as an eating disorder and has always been considered a separate pathology, ED and obesity could be considered part of a continuum. It has become evident that one condition can lead to another, such as binge eating disorder (BED) and bulimia nervosa, and that they share the same repercussions in terms of psychosocial, metabolic, and nutritional health. This narrative review aims to investigate the hypothalamic-pituitary-thyroid axis in undernourished and overnourished patients with ED, including obesity, in order to highlight the relationship between weight control and thyroid function and its effects and to consider therapeutic and preventive strategies in children and adolescents. Literature data report that thyroid alterations occur in patients with ED, both underweight and overweight, and represent a continuum of changes depending on the severity and time course of the disease involving the endocrine system. Considering the relevant role thyroid hormones (TH) play not only in energy expenditure (EE) but also in metabolic control and cardiovascular risks related to dysmetabolism and mood regulation, continuous monitoring of thyroid homeostasis in patients with ED is mandatory to prevent severe complications and to start early treatment when necessary.

Lifestyle and Quality of Life of Women with Diagnosed Hypothyroidism in the Context of Metabolic Disorders

The lifestyle causes of metabolic disorders in patients with hypothyroidism should be investigated. We aimed to assess the lifestyle and quality of life of women diagnosed with hypothyroidism and search for the presence of differences between the lifestyle and quality of life of women with and without diagnosed lipid metabolism disorders. This study included 311 women. To assess the differences between the groups with and without metabolic disorders, a non-parametric Mann-Whitney U test was performed. Of the products that were potentially beneficial for health, statistically significant differences in the average frequency of consumption were observed for legume seeds (p = 0.014), and of the products potentially unbeneficial for health, the frequencies of consumption of fried dishes (p = 0.016) and fast-food products (p = 0.001) were significant. Only 11.9% rated their free-time physical activity as high. The quality of life was significantly different between the groups. The lifestyle was moderately appropriate. Compared with women with lipid metabolism disorders, women without them exhibited a higher frequency of correct dietary behaviors regarding the consumption of products with a potentially beneficial effect and sleeping duration. Women without lipid metabolism disorders had a better quality of life. Women with hypothyroidism should be educated about the beneficial aspects of the regular consumption of vegetables, fruits, legumes, and fish and sleeping for the optimal amount of time.

Gene coexpression network analysis reveals perirenal adipose tissue as an important target of prenatal malnutrition in sheep

We have previously demonstrated that pre- and early postnatal malnutrition in sheep induced depot- and sex-specific changes in adipose morphological features, metabolic outcomes, and transcriptome in adulthood, with perirenal (PER) as the major target followed by subcutaneous (SUB) adipose tissue. We aimed to identify coexpressed and hub genes in SUB and PER to identify the underlying molecular mechanisms contributing to the early nutritional programming of adipose-related phenotypic outcomes. Transcriptomes of SUB and PER of male and female adult sheep with different pre- and early postnatal nutrition histories were used to construct networks of coexpressed genes likely to be functionally associated with pre- and early postnatal nutrition histories and phenotypic traits using weighted gene coexpression network analysis. The modules from PER showed enrichment of cell cycle regulation, gene expression, transmembrane transport, and metabolic processes associated with both sexes' prenatal nutrition. In SUB (only males), a module of enriched adenosine diphosphate metabolism and development correlated with prenatal nutrition. Sex-specific module enrichments were found in PER, such as chromatin modification in the male network but histone modification and mitochondria- and oxidative phosphorylation-related functions in the female network. These sex-specific modules correlated with prenatal nutrition and adipocyte size distribution patterns. Our results point to PER as a primary target of prenatal malnutrition compared to SUB, which played only a minor role. The prenatal programming of gene expression and cell cycle, potentially through epigenetic modifications, might be underlying mechanisms responsible for observed changes in PER expandability and adipocyte-size distribution patterns in adulthood in both sexes.

Subcutaneous adipose tissue alteration in aging process associated with thyroid hormone signaling

BACKGROUND

Functional changes in subcutaneous adipose tissue (SAT) occur earlier in the aging process and play an important role in the occurrence and development of age-related metabolic diseases. The mechanism of this phenomenon is still unclear, and the change in adipose tissue with age is poorly understood.

METHODS

We used transcriptome sequencing (RNA seq) to screen differentially expressed genes at the mRNA level, and analyzed the functional characteristics of the differential genes through GO and KEGG analysis in human SAT of all ages. In order to clarify the specific mechanism of the functional change, we analyzed the chromatin accessibility in the promoter region in the same SAT used in the RNA seq by the assay for transposase-accessible chromatin with high throughput sequencing (ATAC-seq) and obtained the functional genes in SAT changed with age. To verify these changes, we enlarged our sample content of human SAT. The primary mice adipocytes were extracted and stimulated by thyroid hormone of different concentration to construct an animal model, and the expression of the genes were determined through real-time Polymerase Chain Reaction(RT-PCR). The oxygen consumption test and immunofluorescence staining were used to determine the mitochondrial function of SAT.

RESULTS

RNA-seq showed characteristic gene expression of young and old human SAT, in which 331 genes were up-regulated and 349 genes were down-regulated. ATAC-seq, RNA-seq, combined with the mouse prediction model, determined the functional changed characteristics of seven genes. All these genes expressed differently in SAT of different ages, in which, NCF1, NLRP3, DUOX1 showed positive correlation with age; The expression of IFI30, P2RX1, P2RX6, PRODH, however, decreased with age. And all these genes showed dose dependent alternations under treatment of triiodothyroxine in mice SAT. The oxygen consumption rate revealed significant changes of the mitochondrial function and ROS accumulation in human SAT of different ages.

CONCLUSION

In elderly individuals, the function, in addition to distribution, of SAT undergoes significant changes, primarily in mitochondria, which may be due to insensitivity to thyroid hormone signaling. These results identified seven novel genes regulated by thyroid hormone, exhibiting significant changes in SAT of different age, and are probably related to the dysfunction of the aged SAT due to the mitochondrial damage and ROS accumulation.

The memory impairment by hypothyroidism in mice is dependent on time-of-day and sex

Hypothyroidism is an endocrine-metabolic disorder, and as such it compromises a wide range of physiological functions. Memory deficits and, the most recently described, circadian rhythm disruption are among the impairments caused by thyroid dysfunctions. However, although highly likely, there is no evidence connecting these two effects of hypothyroidism. Here, we hypothesized the time-of-day interferes with the memory deficit caused by hypothyroidism. C57BL/6 J mice from both sexes were subjected to novel object recognition (NOR) task during the rest and active phases, corresponding to ZT 2-4 and 14-16, respectively (ZT: Zeitgeber time; ZT 0: lights on at 07:00 am). First, we showed that neither sex nor ZT altered object recognition memory (ORM) in euthyroid mice. Next, animals were divided into control (euthyroid) and hypothyroid [induced with methimazole (0.01%) and perchlorate (0.1%) treatment in the drinking water for 21 days] groups. Under euthyroid conditions, male and female mice recognized the novel object regardless of the time-of-day. However, hypothyroidism impaired ORM at rest phase (ZT 2-4) in both sexes. Surprisingly, in the active phase (ZT 14-16), the hypothyroid males performed the NOR, though a longer time to execute the task was required. In contrast, female hypothyroid mice showed a greater impairment in ORM. Our results suggest that hypothyroidism may disrupt the circadian rhythm in brain areas related to mnemonic processes since in euthyroid condition ORM is not affected by the time-of-day. Furthermore, our findings in an animal model indicate a pronounced deleterious effect of hypothyroidism in women.

Higher Sensitivity to Thyroid Hormones May Be Linked to Maintaining the Healthy Metabolic Condition in People with Obesity: New Insight from NHANES

INTRODUCTION

Obesity contributes to the pathogenesis of diverse metabolic diseases, yet the mechanism underlying metabolically healthy obesity (MHO) remains elusive. Thyroid hormones and sensitivity to them have a major impact on metabolism. Our study aimed to investigate the association between MHO and thyroid hormone sensitivity.

METHODS

Thyroid hormone indices, including the thyroid-stimulating hormone (TSH) index (TSHI), the Thyrotroph Thyroxine Sensitivity Index (TTSI), the Thyroid Feedback Quantile-Based Index (TFQI), and the Parametric Thyroid Feedback Quantile-Based Index (PTFQI), were calculated based on a non-institutionalized US sample in the National Health and Nutrition Examination Survey (NHANES, 2007-2012). Participants were divided into four groups (metabolically healthy non-obesity [MHNO], metabolically unhealthy non-obesity [MUNO], MHO, and metabolically unhealthy obesity [MUO]) according to their body mass index and metabolic profiles. Linear regression, logistic regression, and restricted cubic splines were employed to analyze the association between thyroid hormone indices and metabolic phenotypes.

RESULTS

A total of 4,857 participants (49.6% men; mean age, 42.6 years) were included, with 1,539 having obesity and 235 identified as MHO. Participants in the MHO group exhibited lower levels of TSH, TSHI, TTSI, TFQI, and PTFQI compared with the MHNO group (all p < 0.05), while the differences among MHNO, MUNO, and MUO groups were not statistically significant (all p > 0.05). Among participants with obesity, TSH, TSHI, TTSI, TFQI, and PTFQI were positively associated with metabolic abnormality (all p < 0.05).

CONCLUSION

Participants with MHO exhibited higher thyroid hormone sensitivity among various obesity phenotypes, even when compared with those with MHNO. A positive association was observed between metabolic abnormality and thyroid hormone sensitivity, while the trend of TSH was observed to be consistent with sensitivity to thyroid hormone indices in discriminating metabolic abnormality. Hence, TSH has the potential to serve as a convenient index for detecting sensitivity to thyroid hormones and further metabolic conditions.

Elevated Serum Concentration of Adipocyte Fatty Acid-Binding Protein Correlates with the Markers of Abdominal Obesity Independently of Thyroid Hormones in Non-Obese Women with Polycystic Ovary Syndrome

Adipocyte fatty acid-binding protein (A-FABP) is mainly expressed in adipocytes. The risk of abdominal obesity and autoimmune thyroid disease is increased in women with polycystic ovary syndrome (PCOS). The objective of this study was to explore the relationship of serum concentration of A-FABP with parameters of obesity, e.g., waist to hip ratio (WHR) and the amount of adipose tissue assessed by bioelectrical impedance analysis (BIA), and thyroid hormone homeostasis in women with PCOS. We examined 66 women with PCOS and 67 healthy women. Serum concentrations of A-FABP and thyroid hormones were measured; the FT3/FT4 ratio, thyroid-stimulating hormone index (TSHI), thyrotrope thyroxine resistance index (TT4RI) and thyroid feedback quantile-based index (TFQI) were calculated. In the PCOS group, serum concentrations of A-FABP, FT3 and the FT3/FT4 ratio were significantly higher in comparison to the control group (all p < 0.05). A correlation of A-FABP with WHR (r = 0.26, p = 0.04) and the percentage of adipose tissue (r = 0.33, p = 0.01) has been found only in women with PCOS. We observed no correlation between serum levels of A-FABP and TSHI, TT4RI or TFQI in women with PCOS (all p > 0.05). Our results indicate that A-FABP is an adipokine that may be connected with abdominal obesity independently of thyroid hormone homeostasis in PCOS patients.

Neuro-Vulnerability in Energy Metabolism Regulation: A Comprehensive Narrative Review

This comprehensive narrative review explores the concept of neuro-vulnerability in energy metabolism regulation and its implications for metabolic disorders. The review highlights the complex interactions among the neural, hormonal, and metabolic pathways involved in the regulation of energy metabolism. The key topics discussed include the role of organs, hormones, and neural circuits in maintaining metabolic balance. The review investigates the association between neuro-vulnerability and metabolic disorders, such as obesity, insulin resistance, and eating disorders, considering genetic, epigenetic, and environmental factors that influence neuro-vulnerability and subsequent metabolic dysregulation. Neuroendocrine interactions and the neural regulation of food intake and energy expenditure are examined, with a focus on the impact of neuro-vulnerability on appetite dysregulation and altered energy expenditure. The role of neuroinflammation in metabolic health and neuro-vulnerability is discussed, emphasizing the bidirectional relationship between metabolic dysregulation and neuroinflammatory processes. This review also evaluates the use of neuroimaging techniques in studying neuro-vulnerability and their potential applications in clinical settings. Furthermore, the association between neuro-vulnerability and eating disorders, as well as its contribution to obesity, is examined. Potential therapeutic interventions targeting neuro-vulnerability, including pharmacological treatments and lifestyle modifications, are reviewed. In conclusion, understanding the concept of neuro-vulnerability in energy metabolism regulation is crucial for addressing metabolic disorders. This review provides valuable insights into the underlying neurobiological mechanisms and their implications for metabolic health. Targeting neuro-vulnerability holds promise for developing innovative strategies in the prevention and treatment of metabolic disorders, ultimately improving metabolic health outcomes.