Meta-analysis of the relationship between obestatin and ghrelin levels and the ghrelin/obestatin ratio with respect to obesity

Unlocking the Potential of Obestatin: A Novel Peptide Intervention for Skeletal Muscle Regeneration and Prevention of Atrophy

Obestatin is derived from the same gene as that of ghrelin and their functions were perceived to be antagonistic. Recent developments have shown that although they are known to have contradictory functions, effect of obestatin on skeletal muscle regeneration is similar to that of ghrelin. Obestatin works through a receptor called GPR39, a ghrelin and motilin family receptor and transduces signals in skeletal muscle similar to that of ghrelin. Not only there is a similarity in the receptor family, but also obestatin targets similar proteins and transcription factors as that of ghrelin (for example, FoxO family members) for salvaging skeletal muscle atrophy. Moreover, like ghrelin, obestatin also works by inducing the transcription of Pax7 which is required for muscle stem cell mobilisation. Hence, there are quite some evidences which points to the fact that obestatin can be purposed as a peptide intervention to prevent skeletal muscle wasting and induce myogenesis. This review elaborates these aspects of obestatin which can be further exploited and addressed to bring obestatin as a clinical intervention towards preventing skeletal muscle atrophy and sarcopenia.

Understanding the Immunological Quality of Breast Milk in Maternal Overweight and Obesity

Maternal obesity, affecting many pregnant women globally, not only poses immediate health risks but also modulates breast milk composition. Obesity is linked to inflammation and oxidative stress, impacting breast milk's immune properties. This paper explores the intricate relationship between maternal metabolic disorders, such as obesity, and breast milk's immunological components. We conducted a thorough search for original and review articles published until 17 October 2023 in the PUBMED/Scopus database. This search included several terms related to human breast milk, immunological properties, and obesity. Articles were selected with the consensus of all authors. Maternal metabolic disorders have discernible effects on the composition of immune-related components in breast milk, such as immunoglobulins, lactoferrin, leptin, ghrelin, adiponectin, C-reactive protein, growth factors, extracellular vesicles, and lymphocytes. These changes in breast milk composition can significantly impact the newborn's immune system, with potential long-term health implications beyond the immediate postnatal period. Maternal metabolic health is a critical factor in shaping the health trajectory of the neonate through breastfeeding, although the full advantages of breastfeeding for children of mothers with obesity remain uncertain. Ongoing research aims to understand and unravel these links.

The association of a body shape index and visceral adiposity index with neurotrophic, hormonal and metabolic factors among apparently healthy women: a cross-sectional analysis

Purpose

A body shape index (ABSI) and visceral; adiposity index (VAI) can reflect some cardio-metabolic risk factors in the population. To the best of our knowledge, there are no previous studies conducted on the assessment of the association between neurotrophic factors, Ghrelin and Obestatin with ABSI and VAI. We aimed to investigate this association among apparently healthy women.

Methods

Ninety apparently healthy women were recruited in the present study. All participants were in need of dietary intervention for weight loss and participated in the study before receiving any intervention. Dietary, anthropometric, physical activity, stress level and biochemical assessments, as well as blood pressure measurements were done for all participants.

Results

Women in the highest tertile of ABSI had significantly lower SBP compared to the lowest ABSI tertile. Women who were in the highest tertile of VAI had significantly lower serum Obestatin levels compared to the first and second tertiles in both crude and adjusted comparisons. Serum NGF, Obestatin and Ghrelin levels were significantly lower in the highest tertile of VAI compared to the lowest tertile in both crude and adjusted comparisons. HOMA-IR, serum insulin, LDL-C, TG and TC were significantly higher in the highest tertile of VAI compared to the lowest tertile. QUICKI in the highest tertiles were significantly lower than the first tertile in adjusted model.

Conclusion

This evidence can be useful for researchers in applying appropriate anthropometric indices regarding different populations with multifactorial metabolic complications. The current findings need approving by prospective population study and also clinical trial researches.

Diverse and Complementary Effects of Ghrelin and Obestatin

Ghrelin and obestatin are two “sibling proteins” encoded by the same preproghrelin gene but possess an array of diverse and complex functions. While there are ample literature documenting ghrelin’s functions, the roles of obestatin are less clear and controversial. Ghrelin and obestatin have been perceived to be antagonistic initially; however, recent studies challenge this dogma. While they have opposing effects in some systems, they function synergistically in other systems, with many functions remaining debatable. In this review, we discuss their functional relationship under three “C” categories, namely complex, complementary, and contradictory. Their functions in food intake, weight regulation, hydration, gastrointestinal motility, inflammation, and insulin secretion are complex. Their functions in pancreatic beta cells, cardiovascular, muscle, neuroprotection, cancer, and digestive system are complementary. Their functions in white adipose tissue, thermogenesis, and sleep regulation are contradictory. Overall, this review accumulates the multifaceted functions of ghrelin and obestatin under both physiological and pathological conditions, with the intent of contributing to a better understanding of these two important gut hormones.

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

Background Ghrelin and obestatin are two gastric hormones encoded by the same preproghrelin gene that convey information concerning nutritional status to the central nervous system. Ghrelin has been considered as an appetite stimulating peptide that has a role in the regulation of energy homeostasis. Obestatin has been described for its appetite suppressing effects opposing ghrelin's effect on food intake. The study aimed to evaluate ghrelin, obestatin and the ghrelin/obestatin ratio in obese children compared to non-obese and correlate them to food macronutrients intake. Methods This study is a cross-sectional case control study comprising 60 obese children, in addition to 31 age- and sex-matched controls. All children were subjected to clinical examination, anthropometric assessment, and a 3-day 24-h dietary recall. Fasting serum ghrelin and obestatin levels were evaluated, the ghrelin/obestatin ratio was calculated and they were correlated to macronutrients intake. Results Obese children had significantly lower serum fasting levels of ghrelin, obestatin and the ghrelin/obestatin ratio than the control group. The mean intake of total energy and macronutrients was significantly higher in obese children. Ghrelin showed positive correlation with total energy and fat intake in the obese group. Obestatin had positive correlations with total energy and fat intake while the ghrelin/obestatin ratio had a negative correlation with the total energy intake in the control group. Conclusions Ghrelin, obestatin and the ghrelin/obestatin ratio were significantly lower in obese children and significantly associated with their total energy intake. Disturbed ghrelin to obestatin balance may have a role in the etiology and pathophysiology of obesity.

The Function and Alteration of Immunological Properties in Human Milk of Obese Mothers

Maternal obesity is associated with metabolic changes in mothers and higher risk of obesity in the offspring. Obesity in breastfeeding mothers appears to influence human milk production as well as the quality of human milk. Maternal obesity is associated with alteration of immunological factors concentrations in the human milk, such as C-reactive protein (CRP), leptin, IL-6, insulin, TNF-Alpha, ghrelin, adiponectin, and obestatin. Human milk is considered a first choice for infant nutrition due to the complete profile of macro nutrients, micro nutrients, and immunological properties. It is essential to understand how maternal obesity influences immunological properties of human milk because alterations could impact the nutrition status and health of the infant. This review summarizes the literature regarding the impact of maternal obesity on the concentration of particular immunological properties in the human milk.

The effect of orlistat and weight loss diet on plasma ghrelin and obestatin

BACKGROUND

The objective of this study was to evaluate the effect of weight loss with hypocaloric diet and orlistat treatment in addition to hypocaloric diet on gut-derived hormones ghrelin and obestatin.

MATERIALS AND METHODS

A total of 52, euglycemic and euthyroid, obese female patients were involved in the study. The patients were assigned to two groups: Group 1 (n = 26) received hypocaloric diet alone and Group 2 (n = 26) received orlistat in addition to hypocaloric diet for 12 weeks. Anthropometric measurements, serum lipid, insulin levels, and obestatin and ghrelin values were assessed at the beginning of the study and after 12 weeks of therapy.

RESULTS

Baseline clinical characteristics and laboratory parameters including serum ghrelin and obestatin concentrations and ghrelin/obestatin ratio were similar between the two groups. After 12 weeks, mean change in BMI, fat mass, and fat-free mass (FFM) were -1.97 ± 1.56 kg/m2 (P = 0.003), -2.63% ±2.11% (P = 0.003), and -1.06 ± 0.82 kg (P = 0.003), respectively, in Group 1. In Group 2, mean change in BMI was -2.11 ± 1.24 kg/m2 (P = 0.001), fat mass was -3.09% ±2.28% (P = 0.002), and FFM was -1.26 ± 0.54 kg (P = 0.001). However, fasting glucose, lipid, and insulin levels did not change in Group 1. Furthermore, except serum high-density lipoprotein cholesterol and triglyceride levels, no significant change was observed in Group 2. Although serum ghrelin and obestatin concentrations increased significantly in both groups (Group 1: pGhrelin: 0.047, pobestatin: 0.001 and Group 2: pGhrelin: 0.028, pobestatin: 0.006), ghrelin/obestatin ratio did not change significantly. When the changes in anthropometric assessments and laboratory parameters were compared, no significant difference was observed between the two groups. Furthermore, no correlation was observed between ghrelin or obestatin and any other hormonal and metabolic parameters.

CONCLUSION

Weight loss with diet and diet plus orlistat is both associated with increased ghrelin and obestatin concentrations.

Treatment with Obestatin-A Ghrelin Gene-Encoded Peptide-Reduces the Severity of Experimental Colitis Evoked by Trinitrobenzene Sulfonic Acid

Obestatin is a 23-amino acid peptide derived from proghrelin, a common prohormone for ghrelin and obestatin. Previous studies showed that obestatin exhibited some protective and therapeutic effects in the gut. The aim of our presented study was to examine the effect of treatment with obestatin on trinitrobenzene sulfonic acid (TNBS)-induced colitis. In rats anesthetized with ketamine, colitis was induced through intrarectal administration of 25 mg of 2,4,6-trinitrobenzene sulfonic acid (TNBS). Obestatin was administered intraperitoneally at doses of 4, 8, or 16 nmol/kg, twice per day for four consecutive days. The first dose of obestatin was given one day before the induction of colitis, and the last one was given two days after administration of TNBS. Fourteen days after the induction of colitis, rats were anesthetized again with ketamine, and the severity of colitis was determined. The administration of obestatin had no effect on the parameters tested in rats without the induction of colitis. In rats with colitis, administration of obestatin at doses of 8 or 16 nmol/kg reduced the area of colonic damage, and improved mucosal blood flow in the colon. These effects were accompanied by a reduction in the colitis-evoked increase in the level of blood leukocytes, and mucosal concentration of pro-inflammatory interleukin-1β. Moreover, obestatin administered at doses of 8 or 16 nmol/kg reduced histological signs of colonic damage. The administration of obestatin at a dose of 4 nmol/kg failed to significantly affect the parameters tested. Overall, treatment with obestatin reduced the severity of TNBS-induced colitis in rats. This effect was associated with an improvement in mucosal blood flow in the colon, and a decrease in local and systemic inflammatory processes.

Serum obestatin level strongly correlates with lipoprotein subfractions in non-diabetic obese patients

BACKGROUND

Obestatin is a ghrelin-associated peptide, derived from preproghrelin. Although many of its effects are unclear, accumulating evidence supports positive actions on both metabolism and cardiovascular function. To date, level of obestatin and its correlations to the lipid subfractions in non-diabetic obese (NDO) patients have not been investigated.

METHODS

Fifty NDO patients (BMI: 41.96 ± 8.6 kg/m²) and thirty-two normal-weight, age- and gender-matched healthy controls (BMI: 24.16 ± 3.3 kg/m²) were enrolled into our study. Obestatin level was measured by ELISA. Low-density lipoprotein (LDL) and high-density lipoprotein (HDL) subfractions, intermediate density lipoprotein (IDL) and very low-density lipoprotein (VLDL) levels and mean LDL size were detected by nongradient polyacrylamide gel electrophoresis (Lipoprint).

RESULTS

Serum level of obestatin was significantly lower in NDO patients compared to controls (3.01 ± 0.5 vs. 3.29 ± 0.6 μg/ml, p < 0.05). We found significant negative correlations between the level of obestatin and BMI (r = - 0.33; p < 0.001), level of serum glucose (r = - 0.27, p < 0.05), HbA1c (r = - 0.38; p < 0.001) and insulin (r = - 0.34; p < 0.05). Significant positive correlation was found between obestatin level and the levels of ApoA1 (r = 0.25; p < 0.05), large HDL subfraction ratio and level (r = 0.23; p < 0.05 and r = 0.24; p < 0.05), IDL (r = 0.25 p < 0.05) and mean LDL size (r = 0.25; p < 0.05). Serum VLDL ratio and level negatively correlated with obestatin (r = - 0.32; p < 0.01 and r = - 0.21; p = 0.05). In multiple regression analysis obestatin was predicted only by VLDL level.

CONCLUSIONS

Based on our data, measurement of obestatin level in obesity may contribute to understand the interplay between gastrointestinal hormone secretion and metabolic alterations in obesity.

Ghrelin Axis Reveals the Interacting Influence of Central Obesity and Hypertension

Objective: This study aimed to investigate how central obesity and hypertension modulate unacylated ghrelin (UnAG), acylated ghrelin (AG), obestatin, growth hormone (GH), and the ratios of UnAG/obestatin, AG/obestatin, and total ghrelin/obestatin. Methods: Circulatory abundances of UnAG, AG, obestatin and GH were determined in 387 Hong Kong Chinese female adults with age between 24 to 86 years based on a 2 × 2 factorial design of hypertension (blood pressure ≥140/90 mmHg) and central obesity (waist circumference or WC ≥80 cm). Participants were categorized as neither hypertensive nor centrally obese (NHNO; n = 105), hypertensive but not centrally obese (HNO; n = 102), centrally obese but not hypertensive (NHO; n = 74) and hypertensive and centrally obese (NO; n = 106). Pearson's correlation analyses were performed to detect the association between the peptides examined with WC and blood pressure. The main and interaction effects of hypertension and central obesity were examined by generalized estimating equations analyses. Results: Correlation analyses revealed that systolic blood pressure was negatively correlated with AG/obestatin, UnAG/obestatin and total ghrelin/obestatin ratios, AG, total ghrelin, and GH, while diastolic blood pressure was negatively correlated with UnAG/obestatin, total ghrelin/obestatin ratios, and GH. WC was negatively correlated with AG/obestatin, UnAG/obestatin, and total ghrelin/obestatin ratios, UnAG, AG, total ghrelin, GH, and obestatin. Interaction effects of hypertension and central obesity were observed on UnAG/obestatin, AG/obestatin and total ghrelin/obestatin ratios, and obestatin. Obestatin in NHO group was significantly higher compared to NHNO and HO groups. UnAG/obestatin, AG/obestatin, and total ghrelin/obestatin ratios were higher in NHNO group compared to HNO and HO groups. Main effects of central obesity and hypertension were observed in UnAG, total ghrelin and GH. The HO group manifested the lowest level of UnAG, total ghrelin and GH among all the groups studied. Main effect of hypertension was observed on AG, suggesting that hypertensive individuals exhibited lower levels of AG regardless of central obesity. Conclusion: Circulatory ghrelin gene products and GH exhibit different modes of modulation in response to the co-manifestation of multiple cardiovascular risk factors compared with a single risk factor alone.

Sex-related differences in the association of ghrelin levels with obesity in adolescents

BACKGROUND

The utility of ghrelin as a biomarker may be different depending on gender. The aim of this study was to assess ghrelin levels in a population-based sample of adolescents, and to evaluate their association with obesity and obesity-related parameters depending on sex.

METHODS

The studied population included 601 randomly selected 14-to 16-year-old children. Anthropometrical data were measured and body mass index (BMI) and waist to hip ratio calculated. Body composition was assessed using an impedance body composition analyzer. Total serum ghrelin levels were determined using a multiplexed bead immunoassay. Serum leptin and adiponectin levels were determined by ELISA and insulin by RIA.

RESULTS

Ghrelin levels were significantly higher in girls than in boys. Serum ghrelin concentrations were significantly lower (p<0.01) in obese than in normal weight (NW) girls, but showed no differences by weight category in boys. Ghrelin showed a significant negative relationship with waist circumference (WC), waist to hip ratio and fat mass (p<0.05) in both genders, and with weight and BMI (p<0.01) in girls, and insulin (p<0.01) and HOMA (p<0.05) in boys. Ghrelin also correlated negatively with leptin levels in girls (p<0.01).

CONCLUSIONS

Our study describes serum ghrelin levels in adolescents, showing a sexual dimorphism in ghrelin levels in these 14-to 16-year-old children, and a different association of ghrelin levels with obesity by gender that suggests a different appetite and energy expenditure control depending on sex at this age.

Comprehensive Map of Molecules Implicated in Obesity

Obesity is a global epidemic affecting over 1.5 billion people and is one of the risk factors for several diseases such as type 2 diabetes mellitus and hypertension. We have constructed a comprehensive map of the molecules reported to be implicated in obesity. A deep curation strategy was complemented by a novel semi-automated text mining system in order to screen 1,000 full-length research articles and over 90,000 abstracts that are relevant to obesity. We obtain a scale free network of 804 nodes and 971 edges, composed of 510 proteins, 115 genes, 62 complexes, 23 RNA molecules, 83 simple molecules, 3 phenotype and 3 drugs in "bow-tie" architecture. We classify this network into 5 modules and identify new links between the recently discovered fat mass and obesity associated FTO gene with well studied examples such as insulin and leptin. We further built an automated docking pipeline to dock orlistat as well as other drugs against the 24,000 proteins in the human structural proteome to explain the therapeutics and side effects at a network level. Based upon our experiments, we propose that therapeutic effect comes through the binding of one drug with several molecules in target network, and the binding propensity is both statistically significant and different in comparison with any other part of human structural proteome.

Effect of enalapril maleate on ghrelin levels in metabolic syndrome in rats

We have explored how enalapril affects ghrelin levels in serum and renal tissues of rats with fructose-induced MetS, using 5-week-old Wistar albino male rats weighing 220 ± 20 g. They divided into 5 groups: (i) control (CT), no fructose supplement fed on standard rat pellet and tap water for 60 days, (ii) metabolic syndrome (MetS) fed with 10% fructose for 60 days, (iii) rats after metabolic syndrome developed treated with enalapril over 30 days (MetS+E30), (iv) rats in which only enalapril was administered for 60 days (E60), and (v) MetS-treated with enalapril for 60 days (MetS+E60). Enalapril maleate was given at 20mg/kg per day by gavage. Fasting serum insulin, uric acid, triglyceride, low-density lipoprotein cholesterol and total cholesterol levels were significantly higher, and the amount of high density lipoprotein cholesterol, and acylated and desacyl ghrelin levels was significantly lower in the MetS groups. Ghrelins were significantly lower in all 3 groups, which were administered enalapril than that of MetS and the control group. Immunohistochemical staining showed that the density of ghrelin was parallel to the serum levels of the peptide. Ghrelin immunoreactivity in the kidneys was of moderate density in the distal and collecting tubules, mild density in the proximal tubule and glomeruli, whereas the density decreased in the MetS group and other enalapril-treated groups. In conclusion, ghrelin levels in MetS groups were significantly lower than control group, and thus Enalapril treatment improves components of MetS and has direct effects on serum ghrelin levels that are independent of MetS.

Circulating levels of obestatin and copeptin in obese and nonobese women with polycystic ovary syndrome

OBJECTIVE

Polycystic ovary syndrome (PCOS) is one of the most common endocrinopathies, affecting 5-8% of reproductive-age women. It is associated with insulin resistance, central obesity, type 2 diabetes mellitus, dyslipidemia, and cardiovascular diseases. The current study was undertaken to evaluate serum copeptin and obestatin levels, carotid artery intima-media thickness, and brachial artery flow mediated dilatation in obese and nonobese women with PCOS and age-matched healthy controls and to investigate their relationship with each other and with clinical, metabolic, and hormonal parameters and cardiovascular risk factors.

METHOD

In the study population, we analyzed 60 patients with PCOS and 30 age-matched healthy women as controls. The patients with PCOS were divided into two groups based on body mass index (BMI): obese group (BMI>30kg/m(2), n=30) or nonobese group (BMI<30kg/m(2), n=30). History was obtained and a physical examination, peripheral venous blood sampling, and carotid and brachial artery ultrasonography were performed. Serum copeptin and obestatin levels, total testosterone, C-reactive protein (CRP), glucose, total cholesterol, low-density lipoprotein (LDL) cholesterol, high-density lipoprotein (HDL) cholesterol, triglycerides, homeostasis model assessment for insulin resistance (HOMA-IR), carotid artery intima-media thickness (CIMT), and brachial artery flow-mediated vasodilation (FMD) were determined and compared among the groups.

RESULTS

Women with PCOS, especially obese ones, had higher triglycerides, HOMA-IR, total testosterone, CRP, systolic and diastolic blood pressure, and waist-to-hip ratio (WHR), and lower HDL. Serum obestatin levels were significantly lower in the obese PCOS group than they were in the nonobese and control groups (p<0.001). Serum copeptin levels were significantly higher in the obese PCOS group than they were in the nonobese PCOS and control groups (p<0.001). CIMT values were similar among the groups (p>0.05). Brachial artery FMD was lower in the PCOS groups than it was in the control group (p<0.001). Obestatin and FMD values were negatively correlated with cardiovascular risk factors, whereas copeptin was positively correlated. A significant positive correlation was found between copeptin, BMI, WHR, hirsutism score, total testosterone, and HOMA-IR. There was no correlation between CIMT, copeptin, obestatin, and FMD. A positive correlation was seen between CIMT, BMI, triglycerides, and HOMA-IR.

CONCLUSION

Copeptin and obestatin may provide useful information regarding future cardiovascular risk in PCOS patients as copeptin was positively correlated and obestatin was negatively correlated with cardiovascular risk factors.

Effect of maternal body mass index on hormones in breast milk: a systematic review

Background

Maternal Body Mass Index (BMI) is positively associated with infant obesity risk. Breast milk contains a number of hormones that may influence infant metabolism during the neonatal period; these may have additional downstream effects on infant appetite regulatory pathways, thereby influencing propensity towards obesity in later life.

Objective

To conduct a systematic review of studies examining the association between maternal BMI and the concentration of appetite-regulating hormones in breast milk.

Method

Pubmed was searched for studies reporting the association between maternal BMI and leptin, adiponectin, insulin, ghrelin, resistin, obestatin, Peptide YY and Glucagon-Like Peptide 1 in breast milk.

Results

Twenty six studies were identified and included in the systematic review. There was a high degree of variability between studies with regard to collection, preparation and analysis of breast milk samples. Eleven of fifteen studies reporting breast milk leptin found a positive association between maternal BMI and milk leptin concentration. Two of nine studies investigating adiponectin found an association between maternal BMI and breast milk adiponectin concentration; however significance was lost in one study following adjustment for time post-partum. No association was seen between maternal BMI and milk adiponectin in the other seven studies identified. Evidence for an association between other appetite regulating hormones and maternal BMI was either inconclusive, or lacking.

Conclusions

A positive association between maternal BMI and breast milk leptin concentration is consistently found in most studies, despite variable methodology. Evidence for such an association with breast milk adiponectin concentration, however, is lacking with additional research needed for other hormones including insulin, ghrelin, resistin, obestatin, peptide YY and glucagon-like peptide-1. As most current studies have been conducted with small sample sizes, future studies should ensure adequate sample sizes and standardized methodology.

Gastrointestinal morbidity in obesity

Obesity is a complex disease that results from increased energy intake and decreased energy expenditure. The gastrointestinal system plays a key role in the pathogenesis of obesity and facilitates caloric imbalance. Changes in gastrointestinal hormones and the inhibition of mechanisms that curtail caloric intake result in weight gain. It is not clear if the gastrointestinal role in obesity is a cause or an effect of this disease. Obesity is often associated with type 2 diabetes mellitus (T2DM) and cardiovascular disease (CVD). Obesity is also associated with gastrointestinal disorders, which are more frequent and present earlier than T2DM and CVD. Diseases such as gastroesophageal reflux disease (GERD), cholelithiasis, or nonalcoholic steatohepatitis are directly related to body weight and abdominal adiposity. Our objective is to assess the role of each gastrointestinal organ in obesity and the gastrointestinal morbidity resulting in those organs from the effects of obesity.

Is association between thyroid hormones and gut peptides, ghrelin and obestatin, able to suggest new regulatory relation between the HPT axis and gut?

BACKGROUND

Ghrelin and obestatin are important appetite- and energy-regulating peptides, secreted by the stomach. These gut peptides and thyroid hormones are involved in metabolism regulation. Although subclinical thyroidism is common, to date, very few studies have been reported about gut hormones in thyroid dysfunction, and their results are controversial. The purpose of this study was to investigate ghrelin and obestatin in patients with subclinical hypo- and hyperthyroidism. Moreover, is association between thyroid hormones and gut peptides able to suggest new regulatory relation between the HPT axis and gut?

MATERIALS AND METHODS

The study group included 70 subclinical hypo- and hyperthyroid subjects (in equal groups) and 35 healthy euthyroid controls. Serum values of ghrelin, obestatin, free T3, free T4, thyroid-stimulating hormone and the ratio of ghrelin to obestatin were measured in all participants.

RESULTS

Ghrelin and obestatin both decreased in subclinical hypothyroid subjects (320±81ng/l and 44.3±11.7ng/l, respectively) compared to the control group (487±110ng/l and 58.5±10.3ng/l, respectively). On the other hand, ghrelin and obestatin both increased in subclinical hyperthyroid subjects (750±289ng/l and 71.1±27.3ng/l, respectively) compared to the control group. In addition, ghrelin and obestatin showed strong correlations with TSH, FT3 and FT4.

CONCLUSION

This study shows that gut hormones are significantly associated with thyroid hormones. Thus, there may be a cross talk between the HPT axis and gut. We would like to consider new regulatory relation for description of the found data.

Structure and physiological actions of ghrelin

Ghrelin is a gastric peptide hormone, discovered as being the endogenous ligand of growth hormone secretagogue receptor. Ghrelin is a 28 amino acid peptide presenting a unique n-octanoylation modification on its serine in position 3, catalyzed by ghrelin O-acyl transferase. Ghrelin is mainly produced by a subset of stomach cells and also by the hypothalamus, the pituitary, and other tissues. Transcriptional, translational, and posttranslational processes generate ghrelin and ghrelin-related peptides. Homo- and heterodimers of growth hormone secretagogue receptor, and as yet unidentified receptors, are assumed to mediate the biological effects of acyl ghrelin and desacyl ghrelin, respectively. Ghrelin exerts wide physiological actions throughout the body, including growth hormone secretion, appetite and food intake, gastric secretion and gastrointestinal motility, glucose homeostasis, cardiovascular functions, anti-inflammatory functions, reproductive functions, and bone formation. This review focuses on presenting the current understanding of ghrelin and growth hormone secretagogue receptor biology, as well as the main physiological effects of ghrelin.

Role of ghrelin in the pathophysiology of gastrointestinal disease

Ghrelin is a 28-amino-acid peptide that plays multiple roles in humans and other mammals. The functions of ghrelin include food intake regulation, gastrointestinal (GI) motility, and acid secretion by the GI tract. Many GI disorders involving infection, inflammation, and malignancy are also correlated with altered ghrelin production and secretion. Although suppressed ghrelin responses have already been observed in various GI disorders, such as chronic gastritis, Helicobacter pylori infection, irritable bowel syndrome, functional dyspepsia, and cachexia, elevated ghrelin responses have also been reported in celiac disease and inflammatory bowel disease. Moreover, we recently reported that decreased fasting and postprandial ghrelin levels were observed in female patients with functional dyspepsia compared with healthy subjects. These alterations of ghrelin responses were significantly correlated with meal-related symptoms (bloating and early satiation) in female functional dyspepsia patients. We therefore support the notion that abnormal ghrelin responses may play important roles in various GI disorders. Furthermore, human clinical trials and animal studies involving the administration of ghrelin or its receptor agonists have shown promising improvements in gastroparesis, anorexia, and cancer. This review summarizes the impact of ghrelin, its family of peptides, and its receptors on GI diseases and proposes ghrelin modulation as a potential therapy.

Overeating makes the gut grow fonder; new insights in gastrointestinal satiety signaling in obesity

PURPOSE OF REVIEW

As the prevalence of overweight and obesity increases, there is a growing need to develop effective treatment strategies in addition to bariatric surgery. Research has focused on understanding the pathophysiologic mechanisms that contribute to the occurrence and maintenance of obesity and overweight, and on how bariatric surgery is able to overcome these obstacles. In this review, new insights in the gastrointestinal regulatory mechanisms in obesity and bariatric surgery will be discussed.

RECENT FINDINGS

Diet-induced obesity (DIO) leads to changes in gut peptide secretion and other gastrointestinal responses to nutrients. These changes reduce satiety signaling and therefore complicate loss of body weight. Weight loss by dietary restriction does not restore gastrointestinal responses to nutrients to normal, but alters these responses to further complicate weight loss. Only bariatric surgery is able to overcome these changes by mechanisms that are hitherto unclear but may involve altered gut peptide secretion or changes in bile acid metabolism.

SUMMARY

DIO alters nutrient-induced gastrointestinal signaling in a way that facilitates further weight gain and complicates weight loss. A better understanding of these mechanisms and the way bariatric surgery can overcome these changes is crucial in developing effective treatment strategies.

Obestatin receptor in energy homeostasis and obesity pathogenesis

Based on the bioinformatic prediction, Zhang and colleagues discovered obestatin, a new 23-amino acid hormone from rat stomach extract encoded by the ghrelin gene. Obestatin is present not only in the gastrointestinal tract, but also in the spleen, mammary gland, breast milk, and plasma. Obestatin appears to function as part of a complex gut-brain network whereby hormones and substances from the stomach, intestine and the brain about satiety or hunger. Given the current research regarding the effects of obestatin and its possible cognate receptor(s), this chapter provides the latest review of the physiological and pathological characteristics of this hormone and its possible receptor(s) in energy homeostasis and obesity.

Hormonal mechanisms underlying the relationship between obesity and breast cancer

Given the worldwide epidemic of obesity, it is inevitably an increasingly common comorbidity for women who develop breast cancer; therefore, it is critical to understand its impact on this disease. This review focuses on the influence of obesity on breast cancer development and progression and describes the hormonal factors that may underlie the observations, with particular emphasis on the roles of estrogen, insulin/insulin-like growth factor axis, and adipokines.

The expanding roles of the ghrelin-gene derived peptide obestatin in health and disease

Obestatin is a 23 amino acid, ghrelin gene-derived peptide hormone produced in the stomach and a range of other tissues throughout the body. While it was initially reported that obestatin opposed the actions of ghrelin with regards to appetite and food intake, it is now clear that obestatin is not an endogenous ghrelin antagonist, but it is a multi-functional peptide hormone in its own right. In this review we will discuss the controversies associated with the discovery of obestatin and explore emerging central and peripheral roles of obestatin, which includes adipogenesis, pancreatic homeostasis and cancer.