TSHR signaling promotes hippocampal dependent memory formation through modulating Wnt5a/ß-catenin mediated neurogenesis.

Subclinical hyperthyroidism is defined biochemically as a low or undetectable thyroid-stimulating hormone (TSH) with normal thyroid hormone levels. Low TSHR signaling is considered to associate with cognitive impairment. However, the underlying molecular mechanism by which TSHR signaling modulates memory is poorly understood. In this study, we found that Tshr-deficient in the hippocampal neurons impairs the learning and memory abilities of mice, accompanying by a decline in the number of newborn neurons. Notably, Tshr ablation in the hippocampus decreases the expression of Wnt5a, thereby inactivating the ß-catenin signaling pathway to reduce the neurogenesis. Conversely, activating of the Wnt/ß-catenin pathway by the agonist SKL2001 results in an increase in hippocampal neurogenesis, resulting in the amelioration in the deficits of memory caused by Tshr deletion. Understanding how TSHR signaling in the hippocampus regulates memory provides insights into subclinical hyperthyroidism affecting cognitive function and will suggest ways to rationally design interventions for neurocognitive disorders.

Superior predictive value of estimated pulse wave velocity for all-cause and cardiovascular disease mortality risk in U.S. general adults.

BACKGROUND: Estimated pulse wave velocity (ePWV) has been proposed as a potential approach to estimate carotid-femoral pulse wave velocity. However, the potential of ePWV in predicting all-cause mortality (ACM) and cardiovascular disease mortality (CVM) in the general population is unclear. METHODS: We conducted a prospective cohort study using the data of 33,930 adults (age ≥ 20 years) from the National Health and Nutrition Examination Survey (NHANES) from 1999 to 2014 until the end of December 2019. The study outcomes included ACM and CVM. Survey-weighted Cox proportional hazards models were used to assess hazard ratios (HRs) and 95% confidence intervals (CIs) to determine the association between ePWV and ACM and CVM. To further investigate whether ePWV was superior to traditional risk factors in predicting ACM and CVM, comparisons between ePWV and the Framingham Risk Score (FRS) and Pooled Cohort Equations (PCE) models were performed. Integrated Discriminant Improvement (IDI) and Net Reclassification Improvement (NRI) were employed to analyze differences in predictive ability between models. RESULTS: The weighted mean age of the 33,930 adults included was 45.2 years, and 50.28% of all participants were men. In the fully adjusted Cox regression model, each 1 m/s increase in ePWV was associated with 50% and 49% increases in the risk of ACM (HR 1.50; 95% CI, 1.45-1.54) and CVM (HR 1.49; 95% CI, 1.41-1.57), respectively. After adjusting for FRS, each 1 m/s increase in ePWV was still associated with 29% (HR 1.29; 95% CI, 1.24-1.34) and 34% (HR 1.34; 95% CI, 1.23-1.45) increases in the risk of ACM and CVM, respectively. The area under the curve (AUC) predicted by ePWV for 10-year ACM and CVM were 0.822 and 0.835, respectively. Compared with the FRS model, the ePWV model improved the predictive value of ACM and CVM by 5.1% and 3.8%, respectively, with no further improvement in event classification. In comparison with the PCE model, the ePWV model's ability to predict 10-year ACM and CVM was improved by 5.1% and 3.5%, and event classification improvement was improved by 34.5% and 37.4%. CONCLUSIONS: In the U.S. adults, ePWV is an independent risk factor for ACM and CVM and is independent of traditional risk factors. In the general population aged 20 to 85 years, ePWV has a robust predictive value for the risk of ACM and CVM, superior to the FRS and PCE models. The predictive power of ePWV likely originates from the traditional risk factors incorporated into its calculation, rather than from an indirect association with measured pulse wave velocity.

Thyroid hormone deprival and TSH/TSHR signaling deficiency lead to central hypothyroidism-associated intestinal dysplasia.

BACKGROUND: Central hypothyroidism (CH) is characterized by low T4 levels and reduced levels or bioactivity of circulating TSH. However, there is a lack of studies on CH-related intestinal maldevelopment. In particular, the roles of TH and TSH/TSHR signaling in CH-related intestinal maldevelopment are poorly understood. Herein, we utilized Tshr-/- mice as a congenital hypothyroidism model with TH deprival and absence of TSHR signaling. METHODS: The morphological characteristics of intestines were determined by HE staining, periodic acid-shiff staining, and immunohistochemical staining. T4 was administrated into the offspring of homozygous mice from the fourth postnatal day through weaning or administrated after weaning. RT-PCR was used to evaluate the expression of markers of goblet cells and intestinal digestive enzymes. Single-cell RNA-sequencing analysis was used to explore the cell types and gene profiles of metabolic alternations in early-T4-injected Tshr-/- mice. KEY FINDINGS: Tshr deletion caused significant growth retardation and intestinal maldevelopment, manifested as smaller and more slender small intestines due to reduced numbers of stem cells and differentiated epithelial cells. Thyroxin supplementation from the fourth postnatal day, but not from weaning, significantly rescued the abnormal intestinal structure and restored the decreased number of proliferating intestinal cells in crypts of Tshr-/- mice. Tshr-/- mice with early-life T4 injections had more early goblet cells and impaired metabolism compared to Tshr+/+ mice. SIGNIFICANCE: TH deprival leads to major defects of CH-associated intestinal dysplasia while TSH/TSHR signaling deficiency promotes the differentiation of goblet cells and impairs nutrition metabolism.