Ghrelin, obestatin and the ghrelin/obestatin ratio as potential mediators for food intake among obese children: a case control study

Antioxidative effects of ghrelin on human trabecular meshwork cells

Glaucoma is a group of neurodegenerative diseases characterized by loss of retinal ganglion cells and visual field defects and is one of the major causes of irreversible blindness worldwide. Primary open-angle glaucoma (POAG) is one of the classifications of glaucoma. Oxidative stress in trabecular reticulated cells is one of the possible mechanisms of the development of glaucoma. At present, there is still a lack of effective methods to treat glaucoma. Ghrelin is characterized by its wide distribution and high potency and has anti-inflammatory, antioxidant, and anti-apoptotic effects, which may be beneficial in the treatment of glaucoma. In this study, we investigated whether ghrelin can protect human trabecular meshwork cells (HTMCs) from oxidative damage induced by hydrogen peroxide (H2O2), as well as the possible mechanism of action. CCK8 and flow cytometry results revealed that treatment of HTMCs with ghrelin showed a dose-dependent protective effect against H2O2-induced damage. Ghrelin significantly decreased the rate of apoptosis and levels of reactive oxygen species (ROS) and malondialdehyde (MDA) and increased the level of superoxide dismutase (SOD) and catalase (CAT) in HTMCs. The difference was statistically significant compared with the H2O2 group. Ghrelin activated Nrf2/HO-1/NQO-1 signaling pathways and decreased HIF-1α level in H2O2-injured HTMCs as shown on qPCR and Western blot. In conclusion, ghrelin can protect HTMCs from oxidative damage induced by H2O2 and reduce apoptosis in HTMCs, which can be a new approach to treating POAG. The underlying therapeutic mechanism may be related to Nrf2/HO-1/NQO-1 signaling pathways and HIF-1α.

Crucial Regulatory Role of Organokines in Relation to Metabolic Changes in Non-Diabetic Obesity

Obesity is characterized by an excessive accumulation of fat leading to a plethora of medical complications, including coronary artery disease, hypertension, type 2 diabetes mellitus or impaired glucose tolerance and dyslipidemia. Formerly, several physiological roles of organokines, including adipokines, hepatokines, myokines and gut hormones have been described in obesity, especially in the regulation of glucose and lipid metabolism, insulin sensitivity, oxidative stress, and low-grade inflammation. The canonical effect of these biologically active peptides and proteins may serve as an intermediate regulatory level that connects the central nervous system and the endocrine, autocrine, and paracrine actions of organs responsible for metabolic and inflammatory processes. Better understanding of the function of this delicately tuned network may provide an explanation for the wide range of obesity phenotypes with remarkable inter-individual differences regarding comorbidities and therapeutic responses. The aim of this review is to demonstrate the role of organokines in the lipid and glucose metabolism focusing on the obese non-diabetic subgroup. We also discuss the latest findings about sarcopenic obesity, which has recently become one of the most relevant metabolic disturbances in the aging population.

AMP-activated protein kinase is a key regulator of obesity-associated factors

An imbalance between caloric intake and energy expenditure leads to obesity. Obesity is an important risk factor for the development of several metabolic diseases including insulin resistance, metabolic syndrome, type 2 diabetes mellitus, and cardiovascular disease. So, controlling obesity could be effective in the improvement of obesity-related diseases. Various factors are involved in obesity, such as AMP-activated protein kinases (AMPK), silent information regulators, inflammatory mediators, oxidative stress parameters, gastrointestinal hormones, adipokines, angiopoietin-like proteins, and microRNAs. These factors play an important role in obesity by controlling fat metabolism, energy homeostasis, food intake, and insulin sensitivity. AMPK is a heterotrimeric serine/threonine protein kinase known as a fuel-sensing enzyme. The central role of AMPK in obesity makes it an attractive molecule to target obesity and related metabolic diseases. In this review, the critical role of AMPK in obesity and the interplay between AMPK and obesity-associated factors were elaborated.

Influence of Maternal Body Fat on Levels of Insulin, Insulin-Like Growth Factor-1, and Obestatin

BACKGROUND

Insulin, insulin-like Growth Factor-1 (IGF-1), and obestatin in human milk originate from the circulation. There is also limited knowledge about the influence of body fat on the levels of these hormones in human milk.

RESEARCH AIM

To determine (1) the influence of body fat on levels of insulin, IGF-1, and obestatin in human milk and serum/plasma during the postpartum period; (2) the changes in the levels of these hormones in human milk and serum/plasma postpartum; and (3) the presence of IGF-1 mRNA in human milk.

METHODS

In this prospective, longitudinal, observational cohort study, levels of insulin, IGF-1, and obestatin were measured up to 30 days postpartum in milk and serum/plasma of 58 participants with adequate (≤ 32%) or excess (> 32%) total body fat determined by electrical bioimpedance. Student's t test and repeated-measures analysis of variance were used to evaluate the differences between groups. Pearson's test was used to analyze the associations.

RESULTS

The milk from participants with excess body fat had higher insulin and IGF-1 levels and lower obestatin levels than that of participants with adequate body fat at 3-7, 14-15, and 30 days postpartum (adjusted p < .001). The levels of insulin, IGF-1, and obestatin were significantly higher in human milk than in serum/plasma (p < .05) and correlated with maternal body fat (p < .001).

CONCLUSIONS

Maternal body fat was associated with elevated insulin and IGF-1 levels and decreased obestatin levels in human milk up to 30 days postpartum.

Narrative-focused Group Counseling Improves Intervention Outcomes in Women With Obesity

OBJECTIVE

To investigate the effects of narrative group counseling combined with diet modification and exercise plans on weight loss in Iranian women with obesity.

DESIGN

Parallel 2-arm clinical trial.

PARTICIPANTS

Fifty-six Iranian women with obesity (aged 18-50 years).

INTERVENTION

The intervention group included weekly diet, exercise, and narrative-focused group counseling, whereas the comparison group included dietary modification and exercise sessions for 8 months (32 sessions).

MAIN OUTCOME MEASURE

Anthropometric and body composition parameters, blood biochemical parameters (high-density lipoproteins, low-density lipoproteins, triglycerides, fasting blood sugar, ghrelin, obestatin), physical activities, and appetite scores.

ANALYSIS

McNemar test was used for the variables that were not normally distributed and for scaling. Furthermore, t tests were used to compare quantitative variables with normal distributions. The original P (0.05) was adjusted to P = 0.0031 using the Bonferroni correction.

RESULTS

Weight, body mass index, body fat proportion, and hip circumference decreased significantly in the intervention vs comparison group. Serum low-density lipoproteins, triglycerides, total cholesterol, fasting blood sugar, appetite score, and ghrelin decreased, whereas obestatin increased significantly in the intervention vs comparison group.

CONCLUSIONS AND IMPLICATIONS

Narrative-focused group counseling combined with traditional strategies was effective in achieving significant changes in weight, body mass index, and appetite. Future studies with a more diverse audience and a longer follow-up are warranted.

Protective role of melatonin against adipose-hepatic metabolic comorbidities in experimentally induced obese rat model

Background

Adipose and hepatic metabolic dysfunctions are critical comorbidities that also aggravate insulin resistance in obese individuals. Melatonin is a low-cost agent and previous studies suggest that its use may promote metabolic health. However, its effects on some comorbidities associated with obesity are unknown. Herein, we investigated the hypothesis that melatonin supplementation would attenuate adipose-hepatic metabolic dysfunction in high fat diet (HFD)-induced obesity in male Wistar rats.

Materials and methods

Twenty-four adult male Wistar rats (n = 6/group) were used: Control group received vehicle (normal saline), obese group received 40% high fat diet, melatonin-treated group received 4 mg/kg of melatonin, and obese plus melatonin group received 40% HFD and melatonin. The treatment lasted for 12 weeks.

Results

HFD caused increased food intake, body weight, insulin level, insulin resistance and plasma and liver lipid but decreased adipose lipid. In addition, HFD also increased plasma, adipose and liver malondialdehyde, IL-6, uric acid and decreased Glucose-6-phosphate dehydrogenase, glutathione, nitric oxide and circulating obestatin concentration. However, these deleterious effects except food intake were attenuated when supplemented with melatonin.

Conclusion

Taken together, the present results indicate that HFD exposure causes adipose-hepatic metabolic disturbance in obese animals, which are accompanied by oxidative stress and inflammation. In addition, the present results suggest that melatonin supplementation attenuates adipose-hepatic metabolic dysfunction, accompanying obesity by suppression of oxidative stress/inflammation-dependent mechanism and increasing circulating obestatin.

Maternal and paternal obesity are associated with offspring obestatin levels in the Nutritionists' Health Study

OBJECTIVES

The aim of this study was to examine whether paternal and maternal body mass indexes (BMIs) were independently associated with obestatin and visfatin levels in adult offspring.

METHODS

This cross-sectional analysis included 124 women who participated in the Nutritionists' Health Study (NutriHS) at baseline. Early life events, anthropometry, dual-energy x-ray absorptiometry-determined body composition and blood sample were obtained. Associations of parental BMI with outcomes (obestatin and visfatin) were tested by multiple linear regression, using minimal sufficient adjustments recommended by Directed Acyclic Graph. Participants' mean BMI was 25 ± 5 kg/m² and 74% were metabolically healthy. Median obestatin and visfatin levels were 56.4 pg/mL (42-72) and 17.7 ng/mL (14-21.8), respectively. Eleven percent of mothers and 39% of fathers were overweight/obese.

RESULTS

Daughters born from overweight/obese mothers had higher BMI than those born from normal weight women (P = 0.003). In adjusted regression model, offspring obestatin levels were associated with maternal BMI (β = -0.03; P = 0.045) and paternal BMI (β = -0.02; P = 0.048) independently of maternal and paternal education, maternal age, and maternal use of tobacco, alcohol, and/or drugs. No association was detected with visfatin levels.

CONCLUSION

Inverse associations of maternal and paternal BMIs with offspring obestatin concentrations in women could suggest a utility of this biomarker of energy regulation determined in early adulthood. Whether obestatin could be an indicator of protection against obesity-related disorders in the life course requires investigation in studies designed to test such hypothesis.

Appetite control: hormones or diet strategies?

PURPOSE OF REVIEW

Appetite control results from metabolic, behavioral, and environmental factors that influence hunger and the desire to eat. We summarize the latest advances in the hormonal and nutritional strategies to control appetite and reduce hunger.

RECENT FINDINGS

The fed-hunger-state is regulated by central and peripheric hormones, which modulate energy balance. Leptin, insulin, ghrelin, peptide YY (PYY), and other gut-derived peptides represent the main appetite controllers. The role of orexins, obestatin, and liver-expressed antimicrobial peptide 2 has been uncovered recently. New insights have demonstrated the role of hippocampal activity as a possible mechanism of action. Glucagon-like peptide 1 (GLP1) receptor agonists are well known agents controlling appetite. Association of GLP1 receptor agonist, PYY, or glucose-dependent insulinotropic polypeptide agonists have been tested as new approaches. Appetite-control hormones have also risen as factors involved in the efficacy of bariatric procedures. High-protein, ketogenic diet, and intermittent fasting have been described as nutritional strategies to reduce appetite, although the physiological mechanism and long-term safety remains unclear.

SUMMARY

Appetite control has been an important target for the treatment of obesity and associated disorders. New studies have demonstrated promising adoption of dietary approaches, hormone-based drugs, and bariatric surgery to control energy intake. Further research will establish a significant association, benefits, and safety of these new therapies.