Insulin and Growth Hormone Balance: Implications for Obesity

Altered structural node of default mode network mediated general cognitive ability in young adults with obesity

BACKGROUND

Obesity, characterized by excessive adiposity, is associated with brain structural abnormalities. Nevertheless, the relationships between altered structural nodes of default mode network (DMN), body mass index (BMI), general cognitive ability remained unclear in young adults.

METHODS

In this study, we divided a large sample of young adults into three BMI-based groups. We then conducted one-way analyses of variance and post-hoc tests with Bonferroni corrections to investigate abnormal structural brain regions associated with obesity. Furthermore, mediation effects models were built to explore whether the structural alterations influenced the relationship between BMI and general cognitive ability.

RESULTS

Compared to their lean and overweight counterparts, young adults with obesity exhibited significantly lower general cognitive ability, higher impulsivity traits, and worse sleep quality. Furthermore, compared with lean group, young adults with obesity exhibited altered cortical thickness of both the left temporal pole and right superior parietal lobule, and abnormal cortical surface area (CSA) of the left entorhinal cortex (EC), a hub within DMN. Moreover, CSA of the left EC mediated the relationship between BMI and general cognitive ability.

CONCLUSION

Obesity was linked to altered structural node of DMN, which mediated general cognitive ability in young adults. These findings indicated the negative effect of obesity on DMN and general cognitive ability in young adults.

Association between the weight-adjusted-waist index and circadian syndrome in findings from a nationwide study

Weight-adjusted-waist index (WWI) is an emerging parameter for evaluating obesity. We sought to ascertain the link between WWI and circadian syndrome (CircS). The study population consisted of 8275 eligible subjects who were included in the ultimate analysis from the NHANES 2011-2018. By using multivariable regression models, the association of WWI and CircS was analyzed. In subgroup analysis, we explored the relationship in different groups and tested the stability of the intergroup connection using interaction testing. To investigate whether WWI and CircS had a potential non-linear relationship, smooth curve fittings, and threshold effects tests were also constructed. In a multivariate linear regression model, WWI is significantly positively related to CircS (OR = 1.77, 95% CI 1.50-2.08). Through subgroup analysis and interaction testing, the stability of this positive association was also validated. It was further found that there was an inverted U-shaped association, with a turning point of 11.84, between WWI and CircS. Our findings supported a strong association between WWI values and CircS. Central obesity management is pivotal for preventing or alleviating CircS.

Deciphering Blood Flow Restriction Training to Aid Lipid Lowering in Obese College Students through Untargeted Metabolomics

(1) Objective: The aim of this study was to observe the lipid-lowering effects of blood flow restriction training (BFR) combined with moderate-intensity continuous training (MICT) in obese college students by observing lipid-lowering hormones and untargeted metabolomics. (2) Methods: In this study, 14 obese college students were convened into three groups-MICT, MICT+BFR, and high-intensity interval training (HIIT)-for a crossover experiment. Blood was drawn before and after exercise for the analysis of lipolytic agents and untargeted metabolomics. The study used a paired t-test and ANOVA for statistical analyses. (3) Results: The lipolytic agent results showed that MICT+BFR was superior to the other two groups in terms of two agents (p = 0.000 and p = 0.003), namely, GH and IL-6 (difference between before and after testing: 10,986.51 ± 5601.84 and 2.42 ± 2.49, respectively), and HIIT was superior to the other two groups in terms of one agent (p = 0.000), i.e., EPI (22.81 ± 16.12). No advantage was observed for MICT. The metabolomics results showed that, compared to MICT, MICT+BFR was associated with the upregulated expression of xanthine, succinate, lactate, N-lactoylphenylalanine, citrate, ureido acid, and myristic acid after exercise, with the possibility of the involvement of the citric acid cycle, alanine, aspartic acid, glutamate metabolism, butyric acid metabolism, and the histidylate metabolism pathway. (4) Conclusions: The superior lipid-lowering effect of MICT+BFR over MICT in a group of obese college students may be due to the stronger activation of GH and IL-6 agents, with the citric acid cycle and alanine, aspartate, and glutamate metabolic pathways being associated with this type of exercise.

Relationship between Serum Sirtuin 1 and Growth Hormone/Insulin-like Growth Factor 1 Concentrations in Children with Growth Hormone Deficiency and Idiopathic Short Stature

Sirtuin 1 (SIRT1) inhibits growth hormone (GH) intracellular signaling for the insulin-like growth factor 1 (IGF-1) synthesis via the janus kinase (JAK)/signal transducer and activator of transcription proteins (STATs) pathway. The aim of this study was to compare SIRT1 concentrations in children with GH deficiency (GHD) and so-called idiopathic short stature (ISS, non-GH deficient), in order to determine the possible impact of changes in serum SIRT1 concentrations on the GH-IGF-1 axis. The study group included 100 short-stature children: 38 with GHD and 62 with ISS (maxGH in two stimulation tests <10 and ≥10 ng/mL, respectively). The control group consisted of 47 healthy, normal-height children. For each child, the concentrations of SIRT1, IGF-1 and insulin-like growth factor-binding protein 3 (IGFBP-3) were determined and the IGF-1/IGFBP-3 molar ratio was calculated. The level of SIRT1 was significantly higher in both groups of short children than in the controls (p < 0.0001), but there were no differences between GHD and ISS (mean ± SD: 0.89 ± 0.45 for ISS; 1.24 ± 0, 86 for GHD; and 0.29 ± 0.21 for controls). A significant negative correlation was found between SIRT1 and height standard deviation score (SDS), IGF-1 and IGF-1/IGFBP-3, but not between SIRT1 and maxGH. Elevated SIRT1 levels may serve as one of the mechanisms through which the secretion of IGF-1 is reduced in children with short stature; however, further research is required to confirm this issue.

Short-Term Changes in Weight, Body Composition, and Metabolic Biomarkers After Laparoscopic Sleeve Gastrectomy in Patients with Obesity: A Comparative Prospective Study

PURPOSE

To investigate the changes in weight, body composition, and metabolic biomarkers in patients with obesity after laparoscopic sleeve gastrectomy (LSG) and compare those changes between patients with and without metabolic syndrome (MS).

MATERIALS AND METHODS

This retrospective longitudinal study included 76 patients who underwent LSG, among whom 32 had complete 1-year postoperative body composition and metabolic biomarkers. Body composition was measured by quantitative CT. Weight changes were compared between the MS and non-MS groups at 1-, 3-, 6-, and 12-month post-LSG in all patients; changes in body compositions and metabolic biomarkers from one day pre-LSG to 12-month post-LSG were also compared in those 32 patients.

RESULTS

MS occurred in 46% (35/76) of all patients and 44% (14/32) of patients with complete follow-up data. Excess weight loss was lower in the MS group than that in the non-MS group at 1-, 3-, 6-, and 12-month post-LSG; the 12-month difference was significant (MS vs. non-MS: 0.91 ± 0.22 vs. 1.07 ± 0.42, P = 0.04). The greatest rate of visceral fat area (VFA) change occurred 12-month post-LSG in both the non-MS [0.62(0.55,0.7)] and MS [0.6(0.51,0.63)] groups. The most significant reduction in ectopic fat occurred in liver fat (LF) [non-MS, 0.45(0.22,0.58); MS, 0.39(0.23,0.58)].

CONCLUSION

LGS significantly improves weight, body composition, and metabolic biomarkers in populations with obesity, regardless of whether they have MS. Among the body composition, VFA and LF were the most significantly improved body composition measurements.

Mechanism of Acupuncture in Treating Obesity: Advances and Prospects

Obesity is a common metabolic syndrome that causes a significant burden on individuals and society. Conventional therapies include lifestyle interventions, bariatric surgery, and pharmacological therapies, which are not effective and have a high risk of adverse events. Acupuncture is an effective alternative for obesity, it modulates the hypothalamus, sympathetic activity and parasympathetic activity, obesity-related hormones (leptin, ghrelin, insulin, and CCK), the brain-gut axis, inflammatory status, adipose tissue browning, muscle blood flow, hypoxia, and reactive oxygen species (ROS) to influence metabolism, eating behavior, motivation, cognition, and the reward system. However, hypothalamic regulation by acupuncture should be further demonstrated in human studies using novel techniques, such as functional MRI (fMRI), positron emission tomography (PET), electroencephalogram (EEG), and magnetoencephalography (MEG). Moreover, a longer follow-up phase of clinical trials is required to detect the long-term effects of acupuncture. Also, future studies should investigate the optimal acupuncture therapeutic option for obesity. This review aims to consolidate the recent improvements in the mechanism of acupuncture for obesity as well as discuss the future research prospects and potential of acupuncture for obesity.

Distinct microbiome of tongue coating and gut in type 2 diabetes with yellow tongue coating

The gut microbiome plays a critical role in the pathogenesis of type 2 diabetes mellitus (T2DM). However, the inconvenience of obtaining fecal samples hinders the clinical application of gut microbiome analysis. In this study, we hypothesized that tongue coating color is associated with the severity of T2DM. Therefore, we aimed to compare tongue coating, gut microbiomes, and various clinical parameters between patients with T2DM with yellow (YC) and non-yellow tongue coatings (NYC). Tongue coating and gut microbiomes of 27 patients with T2DM (13 with YC and 14 with NYC) were analyzed using 16S rDNA gene sequencing technology. Additionally, we measured glycated hemoglobin (HbA1c), random blood glucose (RBG), fasting blood glucose (FBG), postprandial blood glucose (PBG), insulin (INS), glucagon (GC), body mass index (BMI), and homeostasis model assessment of β-cell function (HOMA-β) levels for each patient. The correlation between tongue coating and the gut microbiomes was also analyzed. Our findings provide evidence that the levels of Lactobacillus spp. are significantly higher in both the tongue coating and the gut microbiomes of patients with YC. Additionally, we observed that elevated INS and GC levels, along with decreased BMI and HOMA-β levels, were indicative of a more severe condition in patients with T2DM with YC. Moreover, our results suggest that the composition of the tongue coating may reflect the presence of Lactobacillus spp. in the gut. These results provide insights regarding the potential relationship between tongue coating color, the gut microbiome, and T2DM.

PPARs at the crossroads of T cell differentiation and type 1 diabetes

T-cell-mediated autoimmune type 1 diabetes (T1D) is characterized by the immune-mediated destruction of pancreatic beta cells (β-cells). The increasing prevalence of T1D poses significant challenges to the healthcare system, particularly in countries with struggling economies. This review paper highlights the multifaceted roles of Peroxisome Proliferator-Activated Receptors (PPARs) in the context of T1D, shedding light on their potential as regulators of immune responses and β-cell biology. Recent research has elucidated the intricate interplay between CD4+ T cell subsets, such as Tregs and Th17, in developing autoimmune diseases like T1D. Th17 cells drive inflammation, while Tregs exert immunosuppressive functions, highlighting the delicate balance crucial for immune homeostasis. Immunotherapy has shown promise in reinstating self-tolerance and restricting the destruction of autoimmune responses, but further investigations are required to refine these therapeutic strategies. Intriguingly, PPARs, initially recognized for their role in lipid metabolism, have emerged as potent modulators of inflammation in autoimmune diseases, particularly in T1D. Although evidence suggests that PPARs affect the β-cell function, their influence on T-cell responses and their potential impact on T1D remains largely unexplored. It was noted that PPARα is involved in restricting the transcription of IL17A and enhancing the expression of Foxp3 by minimizing its proteasomal degradation. Thus, antagonizing PPARs may exert beneficial effects in regulating the differentiation of CD4+ T cells and preventing T1D. Therefore, this review advocates for comprehensive investigations to delineate the precise roles of PPARs in T1D pathogenesis, offering innovative therapeutic avenues that target both the immune system and pancreatic function. This review paper seeks to bridge the knowledge gap between PPARs, immune responses, and T1D, providing insights that may revolutionize the treatment landscape for this autoimmune disorder. Moreover, further studies involving PPAR agonists in non-obese diabetic (NOD) mice hold promise for developing novel T1D therapies.

Mechanism of the antidiabetic action of Nigella sativa and Thymoquinone: a review

Introduction

Long used in traditional medicine, Nigella sativa (NS; Ranunculaceae) has shown significant efficacy as an adjuvant therapy for diabetes mellitus (DM) management by improving glucose tolerance, decreasing hepatic gluconeogenesis, normalizing blood sugar and lipid imbalance, and stimulating insulin secretion from pancreatic cells. In this review, the pharmacological and pharmacokinetic properties of NS as a herbal diabetes medication are examined in depth, demonstrating how it counteracts oxidative stress and the onset and progression of DM.

Methods

This literature review drew on databases such as Google Scholar and PubMed and various gray literature sources using search terms like the etiology of diabetes, conventional versus herbal therapy, subclinical pharmacology, pharmacokinetics, physiology, behavior, and clinical outcomes.

Results

The efficiency and safety of NS in diabetes, notably its thymoquinone (TQ) rich volatile oil, have drawn great attention from researchers in recent years; the specific therapeutic dose has eluded determination so far. TQ has anti-diabetic, anti-inflammatory, antioxidant, and immunomodulatory properties but has not proved druggable. DM's intimate link with oxidative stress, makes NS therapy relevant since it is a potent antioxidant that energizes the cell's endogenous arsenal of antioxidant enzymes. NS attenuates insulin resistance, enhances insulin signaling, suppresses cyclooxygenase-2, upregulates insulin-like growth factor-1, and prevents endothelial dysfunction in DM.

Conclusion

The interaction of NS with mainstream drugs, gut microbiota, and probiotics opens new possibilities for innovative therapies. Despite its strong potential to treat DM, NS and TQ must be examined in more inclusive clinical studies targeting underrepresented patient populations.

Exploring the Therapeutic Potential of Targeting GH and IGF-1 in the Management of Obesity: Insights from the Interplay between These Hormones and Metabolism

Obesity is a growing public health problem worldwide, and GH and IGF-1 have been studied as potential therapeutic targets for managing this condition. This review article aims to provide a comprehensive view of the interplay between GH and IGF-1 and metabolism within the context of obesity. We conducted a systematic review of the literature that was published from 1993 to 2023, using MEDLINE, Embase, and Cochrane databases. We included studies that investigated the effects of GH and IGF-1 on adipose tissue metabolism, energy balance, and weight regulation in humans and animals. Our review highlights the physiological functions of GH and IGF-1 in adipose tissue metabolism, including lipolysis and adipogenesis. We also discuss the potential mechanisms underlying the effects of these hormones on energy balance, such as their influence on insulin sensitivity and appetite regulation. Additionally, we summarize the current evidence regarding the efficacy and safety of GH and IGF-1 as therapeutic targets for managing obesity, including in pharmacological interventions and hormone replacement therapy. Finally, we address the challenges and limitations of targeting GH and IGF-1 in obesity management.

Effects of ketogenic diet on health outcomes: an umbrella review of meta-analyses of randomized clinical trials

BACKGROUND

Systematic reviews and meta-analyses of randomized clinical trials (RCTs) have reported the benefits of ketogenic diets (KD) in various participants such as patients with epilepsy and adults with overweight or obesity. Nevertheless, there has been little synthesis of the strength and quality of this evidence in aggregate.

METHODS

To grade the evidence from published meta-analyses of RCTs that assessed the association of KD, ketogenic low-carbohydrate high-fat diet (K-LCHF), and very low-calorie KD (VLCKD) with health outcomes, PubMed, EMBASE, Epistemonikos, and Cochrane database of systematic reviews were searched up to February 15, 2023. Meta-analyses of RCTs of KD were included. Meta-analyses were re-performed using a random-effects model. The quality of evidence per association provided in meta-analyses was rated by the GRADE (Grading of Recommendations, Assessment, Development, and Evaluations) criteria as high, moderate, low, and very low.

RESULTS

We included 17 meta-analyses comprising 68 RCTs (median [interquartile range, IQR] sample size of 42 [20-104] participants and follow-up period of 13 [8-36] weeks) and 115 unique associations. There were 51 statistically significant associations (44%) of which four associations were supported by high-quality evidence (reduced triglyceride (n = 2), seizure frequency (n = 1) and increased low-density lipoprotein cholesterol (LDL-C) (n = 1)) and four associations supported by moderate-quality evidence (decrease in body weight, respiratory exchange ratio (RER), hemoglobin A_1c, and increased total cholesterol). The remaining associations were supported by very low (26 associations) to low (17 associations) quality evidence. In overweight or obese adults, VLCKD was significantly associated with improvement in anthropometric and cardiometabolic outcomes without worsening muscle mass, LDL-C, and total cholesterol. K-LCHF was associated with reduced body weight and body fat percentage, but also reduced muscle mass in healthy participants.

CONCLUSIONS

This umbrella review found beneficial associations of KD supported by moderate to high-quality evidence on seizure and several cardiometabolic parameters. However, KD was associated with a clinically meaningful increase in LDL-C. Clinical trials with long-term follow-up are warranted to investigate whether the short-term effects of KD will translate to beneficial effects on clinical outcomes such as cardiovascular events and mortality.

Mechanisms of ageing: growth hormone, dietary restriction, and metformin

Tackling the mechanisms underlying ageing is desirable to help to extend the duration and improve the quality of life. Life extension has been achieved in animal models by suppressing the growth hormone-insulin-like growth factor 1 (IGF-1) axis and also via dietary restriction. Metformin has become the focus of increased interest as a possible anti-ageing drug. There is some overlap in the postulated mechanisms of how these three approaches could produce anti-ageing effects, with convergence on common downstream pathways. In this Review, we draw on evidence from both animal models and human studies to assess the effects of suppression of the growth hormone-IGF-1 axis, dietary restriction, and metformin on ageing.

The Advantage of Growth Hormone Alone as an Adjuvant Therapy in Advanced Age and BMI ≥ 24 kg/m2 with In Vitro Fertilization Failure Due to Poor Embryo Quality

This study aimed to assess the effects of GH adjuvant therapy on the cumulative live birth rate in patients with poor embryo quality and to determine the characteristics of patients who are more responsive to GH. A retrospective cohort study was carried out in patients who have suffered from previous IVF failure due to poor embryonic development and underwent IVF with or without a 6-week pretreatment with GH in the subsequent cycle from January 2018 to December 2020. Clinical parameters including the cumulative live birth rate between the (-) GH and (+) GH groups were compared. Multivariate analysis was performed to ascertain associations between clinical parameters and cumulative live birth rate. Upon analysis of the clinical data from 236 IVF cycles, 84 patients received GH and 152 did not receive GH. In frozen embryo transfer cycles, compared with the (-) GH group, the implantation rate and live birth rate were significantly higher in the (+) GH group (p < 0.05). After adjusting for possible confounding factors, GH improved cumulative live birth per oocyte retrieval cycle by 1.96 folds (p = 0.032). Furthermore, when patients were subdivided based on age and BMI, a significant increase in the cumulative live birth rate was found in the (+) GH group of patients between 35 and 42 years old and BMI ≥ 24 kg/m², respectively (p < 0.05). GH may increase the live birth rate in women who experienced IVF failure because of poor embryonic development, particularly in obese patients and women with advanced age.

Physiological response of endurance exercise as a growth hormone mediator in adolescent women's

OBJECTIVES

Overweight status decreases the growth hormone (GH) secretion, thus, increasing the risk factors for medical complications. However, proper exercise is reported to enhance GH and affect the energy balance. Therefore, exercise is proclaimed to be an accurate and engaging therapy to increase GH in preventing overweight. This study aims to investigate the physiological response of exercise in mediating the increase of GH secretion in female adolescents.

METHODS

22 overweight women aged 19-20 years old, with maximal oxygen consumption of 27-35 mL/kg/min, were selected as sample size. They were divided into three groups, namely (CONT, n=7) Control, (MIEE, n=7) Moderate-intensity interval endurance exercise, and (MCEE, n=8) Moderate-intensity continuous endurance exercise. The exercise was carried out by running for 30-35 min using treadmills with an intensity of 60-70% HR_max. The blood sampling for GH examination was carried out four times before exercise, 10 min, 6 h, and 24 h after exercise. The enzyme-linked immunosorbent assay (ELISA) was used to measure the GH and IGF-1 levels. The data analysis was carried out using a one-way ANOVA test, with a significance level of 5%.

RESULTS

The results of the one-Way ANOVA test suggested a significantly different average GH and IGF-1 before and after the exercise between the three groups (CON, MIEE, and MCEE) (p≤0.05).

CONCLUSIONS

MCEE increases the GH and IGF-1 levels more considerably than MIEE. Therefore, exercise is a mediator to increase GH and IGF-1 secretion in overweight individuals. Exercise could be a viable therapy for overweight people.

Understanding the role of growth hormone in situations of metabolic stress

Growth hormone (GH) is secreted by the anterior pituitary gland and plays a key role in controlling tissue and body growth. While basal GH secretion is considerably reduced along adulthood and aging, several situations of metabolic stress can lead to robust increases in circulating GH levels. The objective of the present review is to summarize and discuss the importance of GH regulating different physiological functions in situations of metabolic stress, including prolonged food restriction, hypoglycemia, exercise, pregnancy, and obesity. The presented data indicate that GH increases hunger perception/food intake, fat mobilization, blood glucose levels, and insulin resistance and produces changes in energy expenditure and neuroendocrine responses during metabolic challenges. When all these effects are considered in the context of situations of metabolic stress, they contribute to restore homeostasis by (1) helping the organism to use appropriate energy substrates, (2) preventing hypoglycemia or increasing the availability of glucose, (3) stimulating feeding to provide nutrients in response to energy-demanding activities or to accelerate the recovery of energy stores, and (4) affecting the activity of neuronal populations involved in the control of metabolism and stress response. Thus, the central and peripheral effects of GH coordinate multiple adaptations during situations of metabolic stress that ultimately help the organism restore homeostasis, increasing the chances of survival.

Sexual dimorphism in the molecular mechanisms of insulin resistance during a critical developmental window in Wistar rats

Background

Insulin resistance (IR) is a condition in which the response of organs to insulin is impaired. IR is an early marker of metabolic dysfunction. However, IR also appears in physiological contexts during critical developmental windows. The molecular mechanisms of physiological IR are largely unknown in both sexes. Sexual dimorphism in insulin sensitivity is observed since early stages of development. We propose that during periods of accelerated growth, such as around weaning, at postnatal day 20 (p20) in rats, the kinase S6K1 is overactivated and induces impairment of insulin signaling in its target organs. This work aimed to characterize IR at p20, determine its underlying mechanisms, and identify whether sexual dimorphism in physiological IR occurs during this stage.

Methods

We determined systemic insulin sensitivity through insulin tolerance tests, glucose tolerance tests, and blood glucose and insulin levels under fasting and fed conditions at p20 and adult male and female Wistar rats. Furthermore, we quantified levels of S6K1 phosphorylated at threonine 389 (T389) (active form) and its target IRS1 phosphorylated at serine 1101 (S1101) (inhibited form). In addition, we assessed insulin signal transduction by measuring levels of Akt phosphorylated at serine 473 (S473) (active form) in white adipose tissue and skeletal muscle through western blot. Finally, we determined the presence and function of GLUT4 in the plasma membrane by measuring the glucose uptake of adipocytes. Results were compared using two-way ANOVA (With age and sex as factors) and one-way ANOVA with post hoc Tukey’s tests or t-student test in each corresponding case. Statistical significance was considered for P values < 0.05.

Results

We found that both male and female p20 rats have elevated levels of glucose and insulin, low systemic insulin sensitivity, and glucose intolerance. We identified sex- and tissue-related differences in the activation of insulin signaling proteins in p20 rats compared to adult rats.

Conclusions

Male and female p20 rats present physiological insulin resistance with differences in the protein activation of insulin signaling. This suggests that S6K1 overactivation and the resulting IRS1 inhibition by phosphorylation at S1101 may modulate to insulin sensitivity in a sex- and tissue-specific manner.

Cysteamine-supplemented diet for cashmere goats: A potential strategy to inhibit rumen biohydrogenation and enhance plasma antioxidant capacity

Cysteamine (CS), as a feed supplement, can increase the level of growth hormone (GH) in the blood, promote animal growth. However, little attention has been paid to the effects of CS on the rumen microbiome and metabolic profile in cashmere goats. This study aimed to assess the effects of rumen microbiota, metabolites, and plasma antioxidative capacity induced by CS supplementation in cashmere goats. We selected 30 Inner Mongolia white cashmere goat ewes (aged 18 months), and randomly separate the goats into three groups (n = 10 per group) to experiment for 40 days. Oral 0 (control group, CON), 60 (low CS, LCS), or 120 mg/kg BW^-1 (high CS, HCS) coated CS hydrochloride every day. Using 16S and internal transcribed spacer (ITS) rRNA gene amplicon sequencing, we identified 12 bacterial and 3 fungal genera with significant changes among the groups, respectively. We found a significant increase in rumen NH₃-N and total volatile fatty acid (TVFA) concentrations in the LCS and HCS groups compared with the CON. With untargeted LC-MS/MS metabolomics, we screened 59 rumen differential metabolites. Among the screened metabolites, many unsaturated and saturated fatty acids increased and decreased with CS treatment, respectively. CS supplementation increased the levels of plasma total antioxidant capacity (T-AOC), glutathione peroxidase (GSH-Px), superoxide dismutase (SOD), GH, and insulin-like growth factor-1(IGF-1). Spearman correlation analysis revealed that the abundance of U29-B03, Lactococcus, and Brochothrix were positively associated with the levels of δ2-THA, TVFA and antioxidant capacity. In conclusion, CS significantly affected rumen microbiota and fermentation parameters, and ultimately inhibited the biohydrogenation of rumen metabolites, enhanced plasma antioxidant capacity, and regulated some hormones of the GH-IGF-1 axis. This study provides an overall view into the CS application as a strategy to improve health production in cashmere goats.

Hormone supply to the pituitary gland: A comprehensive investigation of female‑related tumors (Review)

The hypothalamus acts on the pituitary gland after signal integration, thus regulating various physiological functions of the body. The pituitary gland includes the adenohypophysis and neurohypophysis, which differ in structure and function. The hypothalamus-hypophysis axis controls the secretion of adenohypophyseal hormones through the pituitary portal vein system. Thyroid-stimulating hormone, adrenocorticotropic hormone, gonadotropin, growth hormone (GH), and prolactin (PRL) are secreted by the adenohypophysis and regulate the functions of the body in physiological and pathological conditions. The aim of this review was to summarize the functions of female-associated hormones (GH, PRL, luteinizing hormone, and follicle-stimulating hormone) in tumors. Their pathophysiology was described and the mechanisms underlying female hormone-related diseases were investigated.

Association of cluster determinant 36, scavenger receptor class B type 1, and major facilitator superfamily domain containing the 2a genetic polymorphism with serum lipid profile in aging population with type 2 diabetes mellitus

Background

Lipid metabolism disorder commonly happens in subjects with Type 2 diabetes mellitus (T2DM) which may be linked to genetic variants of lipid metabolism-related genes. However, few studies have explored the relationship between lipid metabolism-related gene polymorphism and serum lipid profile in aging subjects with T2DM. The present study was designed to explore the impact of genetic polymorphism of cluster determinant 36 (CD36) (rs1049673, rs1054516, rs2151916), scavenger receptor class B type 1 (SCARB1) (rs5888), and major facilitator superfamily domain containing the 2a (MFSD2A) (rs12083239, rs4233508, rs12072037) on the relationship between circulating lipids in aging subjects with T2DM.

Methods

205 T2DM patients and 205 age and gender matched control subjects were recruited. Information on demographic characteristics was collected by using a self-administered questionnaire. Fasting venous blood samples were taken for lipid-related gene genotyping and serum lipid profile measurement. The Chi-square test was used to compare percentage differences and to calculate P-value for Hardy-Weinberg equilibrium. Logistic regression and multiple linear regression were used to explore the risk or correlation between variables, and general linear model (GLM) was used to compare the means of serum lipids between the groups.

Results

In T2DM group, CD36 rs1054516 and MFSD2A rs12072037 were correlated with serum TC level. In control group, CD36 rs1049673 was correlated with serum HDL-C level. Meanwhile, T2DM subjects with MFSD2A rs12083239 (CG), MFSD2A rs4233508 (TT), and MFSD2A rs12072037 (AA) had higher TG level than control subjects. T2DM subjects with CD36 rs1049673 (CG, GG), CD36 rs1054516 (CT), CD36 rs2151916 (TT, CT), SCARB1 rs5888 (GG), MFSD2A rs12083239 (GG, CG), MFSD2A rs4233508 (TT), and MFSD2A rs12072037 (CA, AA) had lower HDL-C level than control subjects. T2DM subjects with MFSD2A rs12072037 (AA) had lower LDL-C level than control subjects. In dominant model, major genotype (GG) of SCARB1 gene was associated with the risk of T2DM (OR = 0.636, P = 0.032).

Conclusion

The genetic polymorphism of CD36 (rs1049673, rs1054516, rs2151916), SCARB1 (rs5888), and MFSD2A (rs12083239, rs4233508, rs12072037) were associated with serum lipids in T2DM subjects. The SCARB1 rs5888 major genotype (GG) was a protective factor for T2DM. Large scale cohort study is required to determine the relationship between lipid metabolism-related gene polymorphism, serum lipid profile and T2DM in aging subjects.

The Modulatory Role of Growth Hormone in Inflammation and Macrophage Activation

Inflammation is a body's response to remove harmful stimuli and heal tissue damage, which is involved in various physiology and pathophysiology conditions. If dysregulated, inflammation may lead to significant negative impacts. Growth hormone (GH) has been shown responsible for not only body growth but also critical in the modulation of inflammation. In this review, we summarize the current clinical and animal studies about the complex and critical role of GH in inflammation. Briefly, GH excess or deficiency may lead to pathological inflammatory status. In inflammatory diseases, GH may serve as an inflammatory modulator to control the disease progression and promote disease resolution. The detailed mechanisms and signaling pathways of GH on inflammation, with a focus on the modulation of macrophage polarization, are carefully discussed with potential direction for future investigations.

Obesity and Breast Cancer Risk: The Oncogenic Implications of Metabolic Dysregulation

CONTEXT

Breast cancer is increasing in prevalence in parallel with rising rates of obesity worldwide. Obesity is recognized as a leading modifiable risk factor for the development of breast cancer; however, this association varies considerably by clinicopathologic features, and the underlying mechanisms are complex.

EVIDENCE ACQUISITION

Pubmed literature search using combinations of "obesity," "breast cancer risk," "diet," "exercise," "weight gain," "weight loss," "adipose tissue inflammation," "crown-like structure," "immune markers," "metformin," "gliflozins," "SGLT-2i," "GLP1-RA," and related terms.

EVIDENCE SYNTHESIS

Elevated body mass index and weight gain are associated with increased risk of postmenopausal, hormone receptor-positive breast cancer. Emerging evidence suggests that adverse measures of body composition in individuals of any weight can also confer increased breast cancer risk. Mechanistically, various factors including altered adipokine balance, dysfunctional adipose tissue, dysregulated insulin signaling, and chronic inflammation contribute to tumorigenesis. Weight loss and more specifically fat mass loss through lifestyle and pharmacologic interventions improve serum metabolic and inflammatory markers, sex hormone levels, and measures of breast density, suggesting a link to decreased breast cancer risk.

CONCLUSION

Incorporating markers of metabolic health and body composition measures with body mass index can capture breast cancer risk more comprehensively. Further studies of interventions targeting body fat levels are needed to curb the growing prevalence of obesity-related cancer.

Growth hormone deficiency and NAFLD: An overlooked and underrecognized link

Growth hormone and its mediator insulin‐like growth factor‐1 exert their effect on different organs and control various physiologic metabolic processes. Adult growth hormone deficiency (AGHD) presents with one or more components of metabolic syndrome and can be associated with nonalcoholic fatty liver disease (NAFLD). AGHD is present in spectrum of hypothalamic/pituitary disorders as well as cranial radiation of brain tumors and often remains underdiagnosed or untreated due to its nonspecific symptoms, relatively difficult diagnosis in some clinical scenarios, and various barriers to treatment. NAFLD usually develops soon after diagnosis of AGHD and might progress rapidly to nonalcoholic steatohepatitis (NASH) with advanced fibrosis, eventually requiring liver transplantation. A timely initiation of growth hormone replacement therapy might be important, although studies so far have demonstrated controversial results on NAFLD, primarily due to small sample size and different diagnostic methods of NAFLD. Increased awareness of the association between AGHD and NAFLD would facilitate early diagnosis of NAFLD and NASH if present. Therefore, a multidisciplinary approach involving hepatology and endocrinology should become a standard of care for these patients.

Ketogenic diets, physical activity and body composition: a review

Obesity remains a serious relevant public health concern throughout the world despite related countermeasures being well understood (i.e. mainly physical activity and an adjusted diet). Among different nutritional approaches, there is a growing interest in ketogenic diets (KD) to manipulate body mass (BM) and to enhance fat mass loss. KD reduce the daily amount of carbohydrate intake drastically. This results in increased fatty acid utilisation, leading to an increase in blood ketone bodies (acetoacetate, 3-β-hydroxybutyrate and acetone) and therefore metabolic ketosis. For many years, nutritional intervention studies have focused on reducing dietary fat with little or conflicting positive results over the long term. Moreover, current nutritional guidelines for athletes propose carbohydrate-based diets to augment muscular adaptations. This review discusses the physiological basis of KD and their effects on BM reduction and body composition improvements in sedentary individuals combined with different types of exercise (resistance training or endurance training) in individuals with obesity and athletes. Ultimately, we discuss the strengths and the weaknesses of these nutritional interventions together with precautionary measures that should be observed in both individuals with obesity and athletic populations. A literature search from 1921 to April 2021 using Medline, Google Scholar, PubMed, Web of Science, Scopus and Sportdiscus Databases was used to identify relevant studies. In summary, based on the current evidence, KD are an efficient method to reduce BM and body fat in both individuals with obesity and athletes. However, these positive impacts are mainly because of the appetite suppressive effects of KD, which can decrease daily energy intake. Therefore, KD do not have any superior benefits to non-KD in BM and body fat loss in individuals with obesity and athletic populations in an isoenergetic situation. In sedentary individuals with obesity, it seems that fat-free mass (FFM) changes appear to be as great, if not greater, than decreases following a low-fat diet. In terms of lean mass, it seems that following a KD can cause FFM loss in resistance-trained individuals. In contrast, the FFM-preserving effects of KD are more efficient in endurance-trained compared with resistance-trained individuals.

A randomized clinical trial demonstrating cell type specific effects of hyperlipidemia and hyperinsulinemia on pituitary function

Introduction

Obesity is characterized by elevated lipids, insulin resistance and relative hypogonadotropic hypogonadism, reducing fertility and increasing risk of pregnancy complications and birth defects. We termed this phenotype ‘Reprometabolic Syndrome’ and showed that it can be recapitulated by acute infusions of lipid/insulin into healthy, normal weight, eumenorrheic women. Herein, we examined the broader impact of hyperlipidemia and euglycemic hyperinsulinemia on anterior pituitary trophic hormones and their targets.

Methods

Serum FSH, LH, TSH, growth hormone (GH), prolactin (PRL), thyroid hormones (free T4, total T3), cortisol, IGF-1, adiponectin, leptin and creatinine were measured in a secondary analysis of an interventional crossover study of 12 normal weight cycling women who underwent saline and heparin (control) infusion, or a euglycemic insulin infusion with heparin and Intralipid^® (lipid/insulin), between days 2–5 in sequential menstrual cycles.

Results

In contrast to the decrease in gonadotropins, FSH and LH, infusion of lipid/insulin had no significant effects on other trophic hormones; TSH, PRL or GH. Thyroid hormones (fT4 and total T3), cortisol, IGF-1, adiponectin and creatinine also did not differ between saline or lipid/insulin infusion conditions. Leptin increased in response to lipid/insulin (p<0.02).

Conclusion

Acute hyperlipidemia and hyperinsulinemia exerted differential, cell type specific effects on the hypothalamic-pituitary-gonadal, adrenal and thyroid axes. Elucidation of mechanisms underlying the selective modulation of pituitary trophic hormones, in response to changes in diet and metabolism, may facilitate therapeutic intervention in obesity-related neuroendocrine and reproductive dysfunction.

CircRNA circ_0043533 facilitates cell growth in polycystic ovary syndrome by targeting miR-1179

Increasing evidence indicates that circular RNAs (CircRNAs) have an important role in human diseases, including polycystic ovary syndrome (PCOS). Recently, circ_0043533, a novel circRNA, was proposed to be involved in the progression of PCOS. However, its role in PCOS has not been explored. In this study, the expression levels of circ_0043533 and miR-1179 in ovarian granulosa cells (OGCs) were examined by qRT-PCR analysis. Moreover, knockdown of circ_0043533 in OGC lines COV434 and KGN, respectively, the cell viability, proliferation, apoptosis, and cycle-related markers of insulin-triggered OGCs were examined by CCK-8, EdU staining, flow cytometry, and western blot assays, respectively. The interaction between circ_0043533 and miR-1179 was examined by bioinformatics, dual-luciferase assay, and RNA immunoprecipitation. Besides, effects of the miR-1179 inhibitor on cell viability and apoptosis in OGC lines with circ_0043533 knockdown were also evaluated. OGCs and insulin-treated OGCs exhibited higher circ_0043533 levels in comparison to the IOSE80 cells. Additionally, knockdown of circ_0043533 remarkably inhibited the cell viability and proliferation and promoted the apoptosis of insulin-treated COV434 and KGN cells, respectively. Meanwhile, circ_0043533 knockdown could down-regulate the Bcl-2, CDK2, and Cyclin D1 expressions, and up-regulate the Bax levels. Furthermore, we demonstrated that circ_0043533 acted as a sponge to absorb miR-1179. Interestingly, miR-1179 inhibition remarkably attenuated the effect of circ_0043533 silence on cell proliferation and apoptosis in insulin-treated COV434 and KGN cells. Taken together, this study revealed that circ_0043533 knockdown restrained the malignant progression of PCOS via targeting miR-1179. Our data suggested that circ_0043533 would serve as a novel therapeutic target for PCOS.

Time-Restricted Feeding Restored Insulin-Growth Hormone Balance and Improved Substrate and Energy Metabolism in MC4RKO Obese Mice

BACKGROUND

Dysregulation of metabolic regulatory hormones often occurs during the progress of obesity. Key regulatory hormone insulin-growth hormone (GH) balance has recently been proposed to maintain metabolism profiles. Time-restricted feeding (TRF) is an effective strategy against obesity without detailed research on pulsatile GH releasing patterns.

METHODS

TRF was performed in an over-eating melanocortin 4 receptor-knockout (MC4RKO) obese mouse model using normal food. Body weight and food intake were measured. Series of blood samples were collected for 6-h pulsatile GH profile, glucose tolerance test, and insulin tolerance test at 5, 8, and 9 weeks of TRF, respectively. Indirect calorimetric recordings were performed by the Phenomaster system at 6 weeks for 1 week, and body composition was measured by nuclear magnetic resonance spectroscopy (NMR). Substrate- and energy metabolism-related gene expressions were measured in terminal liver and subcutaneous white adipose tissues.

RESULTS

TRF increased pulsatile GH secretion in dark phase and suppressed hyperinsulinemia in MC4RKO obese mice to reach a reduced insulin/GH ratio. This was accompanied by the improvement in insulin sensitivity, metabolic flexibility, glucose tolerance, and decreased glucose fluctuation, together with appropriate modification of gene expression involved in substrate metabolism and adipose tissue browning. NMR measurement showed that TRF decreased fat mass but increased lean mass. Indirect calorimeter recording indicated that TRF decreased the respiratory exchange ratio (RER) reflecting consumption of more fatty acid in energy production in light phase and increased the oxygen consumption during activities in dark phase.

CONCLUSIONS

TRF effectively decreases hyperinsulinemia and restores pulsatile GH secretion in the overeating obese mice with significant improvement in substrate and energy metabolism and body composition without reducing total caloric intake.

Rotating Day and Night Disturb Growth Hormone Secretion Profiles, Body Energy Metabolism, and Insulin Levels in Mice

BACKGROUND

Insulin and growth hormone (GH) - 2 vital metabolic regulatory hormones - regulate glucose, lipid, and energy metabolism. These 2 hormones determine substrate and energy metabolism under different living conditions. Shift of day and night affects the clock system and metabolism probably through altered insulin and GH secretion.

METHODS

Five-week-old male mice were randomly assigned to a rotating light (RL) group (3-day normal light/dark cycle followed by 4-day reversed light/dark cycle per week) and normal light (NL) group. Body weight and food intake were recorded every week. Series of blood samples were collected for pulsatile GH analysis, glucose tolerance test, and insulin tolerance test at 9, 10, and 11 weeks from the start of intervention, respectively. Indirect calorimetric measurement was performed, and body composition was tested at 12 weeks. Expressions of energy and substrate metabolism-related genes were evaluated in pituitary and liver tissues at the end of 12-week intervention.

RESULTS

The RL group had an increased number of GH pulsatile bursts and reduced GH mass/burst. RL also disturbed the GH secretion regularity and mode. It suppressed insulin secretion, which led to a disturbed insulin/GH balance. It was accompanied by the reduced metabolic flexibility and modified gene expression involved in energy balance and substrate metabolism. Indirect calorimeter recording revealed that RL decreased the respiratory exchange ratio (RER) and oxygen consumption at the dark phase, which resulted in an increase in fat mass and free fatty acid levels in circulation.

CONCLUSION

RL disturbed pulsatile GH secretion and decreased insulin secretion in male mice with significant impairment in energy, substrate metabolism, and body composition.

The Role of Insulin-like Growth Factor-1 (IGF-1) in the Control of Neuroendocrine Regulation of Growth

In mammals, the neuroendocrine system, which includes the communication between the hypothalamus and the pituitary, plays a major role in controlling body growth and cellular metabolism. GH produced from the pituitary somatotroph is considered the master regulator of somatic development and involved, directly and indirectly, in carbohydrate and lipid metabolism via complex, yet well-defined, signaling pathways. GH production from the pituitary gland is primarily regulated by the counter-regulatory effects of the hypothalamic GHRH and SST hormones. The role of IGF-1 feedback regulation in GH production has been demonstrated by pharmacologic interventions and in genetically modified mouse models. In the present review, we discuss the role of IGF-1 in the regulation of the GH-axis as it controls somatic growth and metabolic homeostasis. We present genetically modified mouse models that maintain the integrity of the GH/GHRH-axis with the single exception of IGF-1 receptor (IGF-1R) deficiency in the hypothalamic GHRH neurons and somatotroph that reveals a novel mechanism controlling adipose tissues physiology and energy expenditure.

The GH-IGF-1 Axis in Circadian Rhythm

Organisms have developed common behavioral and physiological adaptations to the influence of the day/night cycle. The CLOCK system forms an internal circadian rhythm in the suprachiasmatic nucleus (SCN) during light/dark input. The SCN may synchronize the growth hormone (GH) secretion rhythm with the dimming cycle through somatostatin neurons, and the change of the clock system may be related to the pulsatile release of GH. The GH-insulin-like growth factor 1 (IGF-1) axis and clock system may interact further on the metabolism through regulatory pathways in peripheral organs. We have summarized the current clinical and animal evidence on the interaction of clock systems with the GH-IGF-1 axis and discussed their effects on metabolism.

Proteomic profiling of low muscle and high fat mass: a machine learning approach in the KORA S4/FF4 study

BACKGROUND

The coexistence of low muscle mass and high fat mass, two interrelated conditions strongly associated with declining health status, has been characterized by only a few protein biomarkers. High-throughput proteomics enable concurrent measurement of numerous proteins, facilitating the discovery of potentially new biomarkers.

METHODS

Data derived from the prospective population-based Cooperative Health Research in the Region of Augsburg S4/FF4 cohort study (median follow-up time: 13.5 years) included 1478 participants (756 men and 722 women) aged 55-74 years in the cross-sectional and 608 participants (315 men and 293 women) in the longitudinal analysis. Appendicular skeletal muscle mass (ASMM) and body fat mass index (BFMI) were determined through bioelectrical impedance analysis at baseline and follow-up. At baseline, 233 plasma proteins were measured using proximity extension assay. We implemented boosting with stability selection to enable false positives-controlled variable selection to identify new protein biomarkers of low muscle mass, high fat mass, and their combination. We evaluated prediction models developed based on group least absolute shrinkage and selection operator (lasso) with 100× bootstrapping by cross-validated area under the curve (AUC) to investigate if proteins increase the prediction accuracy on top of classical risk factors.

RESULTS

In the cross-sectional analysis, we identified kallikrein-6, C-C motif chemokine 28 (CCL28), and tissue factor pathway inhibitor as previously unknown biomarkers for muscle mass [association with low ASMM: odds ratio (OR) per 1-SD increase in log2 normalized protein expression values (95% confidence interval (CI)): 1.63 (1.37-1.95), 1.31 (1.14-1.51), 1.24 (1.06-1.45), respectively] and serine protease 27 for fat mass [association with high BFMI: OR (95% CI): 0.73 (0.61-0.86)]. CCL28 and metalloproteinase inhibitor 4 (TIMP4) constituted new biomarkers for the combination of low muscle and high fat mass [association with low ASMM combined with high BFMI: OR (95% CI): 1.32 (1.08-1.61), 1.28 (1.03-1.59), respectively]. Including protein biomarkers selected in ≥90% of group lasso bootstrap iterations on top of classical risk factors improved the performance of models predicting low ASMM, high BFMI, and their combination [delta AUC (95% CI): 0.16 (0.13-0.20), 0.22 (0.18-0.25), 0.12 (0.08-0.17), respectively]. In the longitudinal analysis, N-terminal prohormone brain natriuretic peptide (NT-proBNP) was the only protein selected for loss in ASMM and loss in ASMM combined with gain in BFMI over 14 years [OR (95% CI): 1.40 (1.10-1.77), 1.60 (1.15-2.24), respectively].

CONCLUSIONS

Proteomic profiling revealed CCL28 and TIMP4 as new biomarkers of low muscle mass combined with high fat mass and NT-proBNP as a key biomarker of loss in muscle mass combined with gain in fat mass. Proteomics enable us to accelerate biomarker discoveries in muscle research.

Hyperinsulinemia and Its Pivotal Role in Aging, Obesity, Type 2 Diabetes, Cardiovascular Disease and Cancer

For many years, the dogma has been that insulin resistance precedes the development of hyperinsulinemia. However, recent data suggest a reverse order and place hyperinsulinemia mechanistically upstream of insulin resistance. Genetic background, consumption of the “modern” Western diet and over-nutrition may increase insulin secretion, decrease insulin pulses and/or reduce hepatic insulin clearance, thereby causing hyperinsulinemia. Hyperinsulinemia disturbs the balance of the insulin–GH–IGF axis and shifts the insulin : GH ratio towards insulin and away from GH. This insulin–GH shift promotes energy storage and lipid synthesis and hinders lipid breakdown, resulting in obesity due to higher fat accumulation and lower energy expenditure. Hyperinsulinemia is an important etiological factor in the development of metabolic syndrome, type 2 diabetes, cardiovascular disease, cancer and premature mortality. It has been further hypothesized that nutritionally driven insulin exposure controls the rate of mammalian aging. Interventions that normalize/reduce plasma insulin concentrations might play a key role in the prevention and treatment of age-related decline, obesity, type 2 diabetes, cardiovascular disease and cancer. Caloric restriction, increasing hepatic insulin clearance and maximizing insulin sensitivity are at present the three main strategies available for managing hyperinsulinemia. This may slow down age-related physiological decline and prevent age-related diseases. Drugs that reduce insulin (hyper) secretion, normalize pulsatile insulin secretion and/or increase hepatic insulin clearance may also have the potential to prevent or delay the progression of hyperinsulinemia-mediated diseases. Future research should focus on new strategies to minimize hyperinsulinemia at an early stage, aiming at successfully preventing and treating hyperinsulinemia-mediated diseases.

T Cell Protein Tyrosine Phosphatase in Glucose Metabolism

T cell protein tyrosine phosphatase (TCPTP), a vital regulator in glucose metabolism, inflammatory responses, and tumor processes, is increasingly considered a promising target for disease treatments and illness control. This review discusses the structure, substrates and main biological functions of TCPTP, as well as its regulatory effect in glucose metabolism, as an attempt to be referenced for formulating treatment strategies of metabolic disorders. Given the complicated regulation functions in different tissues and organs of TCPTP, the development of drugs inhibiting TCPTP with a higher specificity and a better biocompatibility is recognized as a promising therapeutic strategy for diabetes or obesity. Besides, treatments targeting TCPTP in a specific tissue or organ are suggested to be considerably promising.

Stimulation of endogenous pulsatile growth hormone secretion by activation of growth hormone secretagogue receptor reduces the fat accumulation and improves the insulin sensitivity in obese mice

Obese individuals often show low growth hormone (GH) secretion, which leads to reduced lipid mobilization and further fat accumulation. Pharmacological approaches to increase GH levels in obese individuals by GH injection or GH-releasing hormone receptor agonist showed promising effects on fat reduction. However, side effects on glucose metabolism and the heavy costs on making large peptides hindered their clinical application. Here, we tested whether stimulation of endogenous GH secretion by a synthetic GH secretagogue receptor (GHSR) agonist, hexarelin, improved the metabolism in a hyperphagic obese mouse model. Male melanocortin 4 receptor knockout mice (MC4RKO) were pair-fed and received continuous hexarelin (10.56 μg/day) or vehicle infusion by an osmotic pump for 3-4 weeks. Hexarelin treatment significantly increased the pulsatile GH secretion without detectable alteration on basal GH secretion in MC4RKO mice. The treated mice showed increased lipolysis and lipid oxidation in the adipose tissue, and reduced de novo lipogenesis in the liver, leading to reduced visceral fat mass, reduced triglyceride content in liver, and unchanged circulating free fatty acid levels. Importantly, hexarelin treatment improved the whole-body insulin sensitivity but did not alter glucose tolerance, insulin levels, or insulin-like growth factor 1 (IGF-1) levels. The metabolic effects of hexarelin were likely through the direct action of GH, as indicated by the increased expression level of genes involved in GH signaling pathways in visceral adipose tissues and liver. In conclusion, hexarelin treatment stimulated the pulsatile GH secretion and reduced the fat accumulation in visceral depots and liver in obese MC4RKO mice with improved insulin sensitivity without altered levels of insulin or IGF-1. It provides evidence for managing obesity by enhancing pulsatile GH secretion through activation of GHSR in the pituitary gland.

Regulation of GH and GH Signaling by Nutrients

Growth hormone (GH) and insulin-like growth factor-1 (IGF-I) are pleiotropic hormones with important roles in lifespan. They promote growth, anabolic actions, and body maintenance, and in conditions of energy deprivation, favor catabolic feedback mechanisms switching from carbohydrate oxidation to lipolysis, with the aim to preserve protein storages and survival. IGF-I/insulin signaling was also the first one identified in the regulation of lifespan in relation to the nutrient-sensing. Indeed, nutrients are crucial modifiers of the GH/IGF-I axis, and these hormones also regulate the complex orchestration of utilization of nutrients in cell and tissues. The aim of this review is to summarize current knowledge on the reciprocal feedback among the GH/IGF-I axis, macro and micronutrients, and dietary regimens, including caloric restriction. Expanding the depth of information on this topic could open perspectives in nutrition management, prevention, and treatment of GH/IGF-I deficiency or excess during life.

Effect of long-term growth hormone replacement on glucose metabolism in adults with growth hormone deficiency: a systematic review and meta-analysis

PURPOSE

This systematic review and meta-analysis was performed to summarize the long-term (more than 6 months) effect of growth hormone (GH) replacement therapy (GHRT) on glucose metabolism among adults growth hormone deficiency (AGHD) patients.

METHODS

We searched MEDLINE, EMBASE and the Cochrane Library databases from inception till March 2020 for relevant studies evaluating the effect of GHRT on glucose metabolism in AGHD patients. Results were stratified into two periods (6-12 months and more than12 months) according to the length of follow-up.

RESULTS

Thirty-three studies including 11 randomized controlled trials (RCTs) and 22 prospective open-label studies (POLs) were included in the meta-analysis. The findings of this meta-analysis showed that GH supplementation with a duration of 6-12 months among adults with growth hormone deficiency (GHD) significantly increased fasting plasma glucose (FPG) (SMD 0.37; 95% CI 0.25 to 0.49; I² = 0%; P < 0.00001), fasting insulin (FI) (SMD 0.2; 95% CI 0.08 to 0.33; I² = 9%; P = 0.001), glycated hemoglobin (HbA1c) (SMD 0.31; 95% CI 0.17 to 0.46; I² = 10%; P < 0.0001) and homeostasis model of assessment-insulin resistance (HOMA-IR) (SMD 0.28; 95% CI 0.08 to 0.47; I² = 13%; P = 0.006). Notably, GH intervention with a duration of more than 12 months showed no significant effect on FI (SMD 0.14; 95% CI - 0.09 to 0.37; I² = 0%; P = 0.24), HbA1c (SMD - 0.02; 95% CI - 0.3 to 0.26; I² = 72%; P = 0.89) and HOMA-IR levels (SMD 0.04; 95% CI - 0.24 to 0.31; I² = 0%; P = 0.80) in adults with GHD. However, FPG levels in AGHD were still significantly increased with more than one year intervention period (SMD 0.41; 95% CI 0.29 to 0.53; I² = 0%; P < 0.00001).

CONCLUSION

Overall, the current meta-analysis demonstrated that GHRT with a shorter duration (6-12 months) led to a deterioration in glucose metabolism including FPG, FI, HbA1c and HOMA-IR in AGHD patients. However, the negative effects of GH therapy on these glucose homeostasis parameters were not seen in longer duration of GHRT, except for FPG.

Association between Growth Differentiation Factor-15 and Risk of Cardiovascular Diseases in Patients with Adult Growth Hormone Deficiency

OBJECTIVE

Patients with adult growth hormone deficiency (AGHD) confer a heightened risk of cardiovascular disease and increased mortality because of metabolic disorders. Growth differentiation factor-15 (GDF-15) plays an important role in predicting metabolic abnormalities. We sought to investigate the correlation between GDF-15 and cardiovascular risk in AGHD patients.

METHODS

The study enrolled 80 AGHD patients and 80 healthy subjects. We analyzed the association between GDF-15 and some major biochemical indicators. The potential association between GDF-15 and cardiovascular disease risk was analyzed.

RESULTS

The AGHD group exhibited increased waist-hip ratio and high-sensitivity C-reactive protein (hs-CRP) and lipid levels compared with the healthy control group. Serum GDF-15 levels in AGHD group were elevated significantly compared with the control group (P < 0.001). GDF-15 levels were negatively associated with insulin-like growth factor-1 in AGHD group (P=0.006) and positively correlated with waist-to-hip ratio (P=0.018), triglycerides (P=0.007), and hs-CRP (P=0.046). In addition, GDF-15 was positively correlated with Framingham risk score significantly after adjustment for other factors (r = 0.497, P < 0.001). Moreover, GDF-15 was an independent risk factor for cardiovascular disease in AGHD patients after adjusting for traditional cardiovascular risk factors.

CONCLUSION

Elevated GDF-15 levels were significantly associated with cardiovascular risk factors and can be considered as a predictive biomarker of cardiovascular risk in AGHD patients.

Herring Milt and Herring Milt Protein Hydrolysate Are Equally Effective in Improving Insulin Sensitivity and Pancreatic Beta-Cell Function in Diet-Induced Obese- and Insulin-Resistant Mice

Although genetic predisposition influences the onset and progression of insulin resistance and diabetes, dietary nutrients are critical. In general, protein is beneficial relative to carbohydrate and fat but dependent on protein source. Our recent study demonstrated that 70% replacement of dietary casein protein with the equivalent quantity of protein derived from herring milt protein hydrolysate (HMPH; herring milt with proteins being enzymatically hydrolyzed) significantly improved insulin resistance and glucose homeostasis in high-fat diet-induced obese mice. As production of protein hydrolysate increases the cost of the product, it is important to determine whether a simply dried and ground herring milt product possesses similar benefits. Therefore, the current study was conducted to investigate the effect of herring milt dry powder (HMDP) on glucose control and the associated metabolic phenotypes and further to compare its efficacy with HMPH. Male C57BL/6J mice on a high-fat diet for 7 weeks were randomized based on body weight and blood glucose into three groups. One group continued on the high-fat diet and was used as the insulin-resistant/diabetic control and the other two groups were given the high-fat diet modified to have 70% of casein protein being replaced with the same amount of protein from HMDP or HMPH. A group of mice on a low-fat diet all the time was used as the normal control. The results demonstrated that mice on the high-fat diet increased weight gain and showed higher blood concentrations of glucose, insulin, and leptin, as well as impaired glucose tolerance and pancreatic β-cell function relative to those on the normal control diet. In comparison with the high-fat diet, the replacement of 70% dietary casein protein with the same amount of HMDP or HMPH protein decreased weight gain and significantly improved the aforementioned biomarkers, insulin sensitivity or resistance, and β-cell function. The HMDP and HMPH showed similar effects on every parameter except blood lipids where HMDP decreased total cholesterol and non-HDL-cholesterol levels while the effect of HMPH was not significant. The results demonstrate that substituting 70% of dietary casein protein with the equivalent amount of HMDP or HMPH protein protects against obesity and diabetes, and HMDP is also beneficial to cholesterol homeostasis.