Background
Neural networks that regulate binge eating remain to be identified, and effective treatments for binge eating are limited.
Methods
We combined neuroanatomical, pharmacological, electrophysiological, Cre-lox, and chemogenetic approaches to investigate the functions of 5-HT 2C receptor (5-HT2CR) expressed by dopamine (DA) neurons in the regulation of binge-like eating behavior in mice.
Results
We showed that 5-HT stimulates DA neural activity through a 5-HT2CR-mediated mechansim, and activation of this midbrain 5-HT-DA neural circuit effectively inhibits binge-like eating behavior in mice. Notably, 5-HT medications, including fluoxetine, d-Fenfluramine, and lorcaserin (a selective 5-HT2CR agonist), act upon 5-HT2CRs expressed by DA neurons to inhibit binge-like eating in mice.
Conclusions
We identified the 5-HT2CR population in DA neurons as one potential target for anti-binge therapies, and provided pre-clinical evidence that 5-HT2CR agonists could be used to treat binge eating.
Estrogens act upon estrogen receptor (ER)α to inhibit feeding and improve glucose homeostasis in female animals. However, the intracellular signals that mediate these estrogenic actions remain unknown. Here, we report that anorexigenic effects of estrogens are blunted in female mice that lack ERα specifically in proopiomelanocortin (POMC) progenitor neurons. These mutant mice also develop insulin resistance and are insensitive to the glucose-regulatory effects of estrogens. Moreover, we showed that propyl pyrazole triol (an ERα agonist) stimulates the phosphatidyl inositol 3-kinase (PI3K) pathway specifically in POMC progenitor neurons, and that blockade of PI3K attenuates propyl pyrazole triol-induced activation of POMC neurons. Finally, we show that effects of estrogens to inhibit food intake and to improve insulin sensitivity are significantly attenuated in female mice with PI3K genetically inhibited in POMC progenitor neurons. Together, our results indicate that an ERα-PI3K cascade in POMC progenitor neurons mediates estrogenic actions to suppress food intake and improve insulin sensitivity.
Objective
Estrogens can act in the brain to prevent body weight gain. Tremendous research efforts have been focused on estrogen physiology in the brain in the context of body weight control; estrogen receptors and the related signals have been attractive targets for development of new obesity therapies. The objective is to review recent findings in these aspects.
Methods
We reviewed recent studies, primarily from those using the conventional and conditional knockout mouse strains, regarding the cellular and molecular mechanisms for the beneficial effects of estrogens on body weight balance. We also discuss emerging genetic tools that could further benefit the field of estrogen research, and newly developed estrogen-based regimen that produce body weight-lowering benefits.
Results
The body weight-lowering effects of estrogens are mediated by multiple forms of estrogen receptors, in different brain regions through distinct but coordinated mechanisms. Both rapid signals and “classic” nuclear receptor actions of estrogen receptors appear to contribute to estrogenic regulation on body weight.
Conclusion
Estrogen receptors and associated signal networks are potential targets for obesity treatment, and further investigations are warranted.
Purpose
To study the prognostic value of
klotho (
KL) and its promoter DNA methylation in head and neck squamous cell carcinoma (HNSCC) and to assess their associations with the autophagy gene LC3 and the RNA transferase gene NSUN2.
Materials and methods
Upper quartile normalized RNA-seq V2 RSEM values of KL mRNA and beta value for KL methylation were retrieved from The Cancer Genome Atlas HNSCC dataset. Kaplan–Meier survival curves were used to assess the associations of KL expression and methylation with patient survival; multivariate Cox proportional hazards regression models were used to estimate the HRs and their 95% CIs.
Results
There is a negative relationship between KL gene expression and its promoter DNA methylation in HNSCC. KL gene expression was positively correlated with overall survival, while KL methylation was inversely correlated with the overall survival of HNSCC patients. Furthermore, KL methylation was significantly associated with gender (
P
=0.012), tumor grade (
P
=0.0009) and tumor site (
P
<0.0001). Finally, HNSCC patients with high KL gene expression or low KL DNA methylation had high LC3 but low NSUN2.
Conclusion
KL methylation silenced its gene expression in HNSCC. Low KL expression and high KL methylation can be potential biomarkers for worse prognosis in HNSCC. As the downstream targets,
LC3
and
NSUN2
could be responsible for the KL expression in HNSCC.
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