No abstract

Background and Aims A novel bioactive peptide, mitochondrial‐derived peptide (MOTS‐c), has recently attracted attention as a potential prevention or therapeutic option for obesity and type 2 diabetes mellitus (T2DM). MOTS‐c profiles have not yet been reported in human obesity and T2DM. We aimed to determine circulating MOTS‐c levels in obesity and explore the association between MOTS‐c levels and various metabolic parameters. Methods In this case‐control study, 40 obese children and adolescents (27 males) and 57 controls (40 males) were recruited in the Hubei Province of China in 2017. Circulating MOTS‐c levels were measured, clinical data (eg, glucose, insulin, and lipid profile) were recorded, and anthropometric measurements were performed. Finally, we investigated correlations between MOTS‐c levels and related variables. Results MOTS‐c levels were significantly decreased in the obese group compared with the control group (472.61 ±22.83 vs 561.64 ±19.19 ng/mL, P <.01). After classification by sex, MOTS‐c levels were significantly decreased in obese male children and adolescents compared to their counterparts (465.26 ±24.53 vs 584.07 ±21.18 ng/mL, P <.001), while they were comparable between the obese and healthy female subjects (487.89 ±49.77 vs 508.85 ±38.76 ng/mL, P >.05). Further, MOTS‐c levels were negatively correlated with body mass index (BMI), BMI SD score, waist circumference, waist‐to‐hip ratio, fasting insulin level, homeostasis model assessment of insulin resistance (HOMA‐IR), and glycated hemoglobin (HbA1c) in the male cohort. Conclusions Circulating MOTS‐c levels were decreased in obese male children and adolescents and correlated with markers of insulin resistance and obesity.

Certain experimental models support morphine can play a beneficial role against damage in the neuronal system. In this study, we find morphine as well as endomorphin-1 and endomorphin-2 can protect against intracellular amyloid ␤ (iA␤) toxicity in human and rat primary neuronal cultures and in rat brains in vivo. Morphine reverses the electrophysiological changes induced by iA␤, including current density, resting membrane potential and capacitance. Also morphine improves the spatial memory performance in rats infected by iA␤ packaged virus and in APP/PS1 mice in Morris water maze tests. Morphine protection is mediated through inducing estradiol release in hippocampal neurons measured by ELISA and liquid chromatography-mass spectrometry, possibly by increasing P450 cytochrome aromatase activity. Released estradiol induces upregulation of heat shock protein 70 (Hsp70). Hsp70 protects against intracellular amyloid toxicity by rescuing proteasomal activity which is impaired by iA␤. This is the first time, to our knowledge, that induction of estradiol release in hippocampal neurons by morphine is reported. Our data may contribute to both Alzheimer's disease therapy and pain clinics where morphine is widely used.

These results demonstrated that circulating betatrophin levels were increased in insulin-resistant obese children or adolescents and might act as a potential biomarker of insulin resistance in these populations. Furthermore, serum betatrophin concentrations might vary during the development of children and adolescents, as well as between genders.