A role for ghrelin in the central regulation of feeding

Identification of neuropeptides and neuropeptide receptor genes in Phauda flammans (Walker)

Neuropeptides and neuropeptide receptors are crucial regulators to insect physiological processes. The 21.0 Gb bases were obtained from Illumina sequencing of two libraries representing the female and male heads of Phauda flammans (Walker) (Lepidoptera: Phaudidae), which is a diurnal defoliator of ficus plants and usually outbreaks in the south and south-east Asia, to identify differentially expressed genes, neuropeptides and neuropeptide receptor whose tissue expressions were also evaluated. In total, 99,386 unigenes were obtained, in which 156 up-regulated and 61 down-regulated genes were detected. Fifteen neuropeptides (i.e., F1b, Ast, NP1, IMF, Y, BbA1, CAP2b, NPLP1, SIF, CCH2, NP28, NP3, PDP3, ARF2 and SNPF) and 66 neuropeptide receptor genes (e.g., A2-1, FRL2, A32-1, A32-2, FRL3, etc.) were identified and well-clustered with other lepidopteron. This is the first sequencing, identification neuropeptides and neuropeptide receptor genes from P. flammans which provides valuable information regarding the molecular basis of P. flammans.

Targeting appetite and satiety in diabetes and obesity, via G protein-coupled receptors

Type 2 diabetes and obesity have reached pandemic proportions throughout the world, so much so that the World Health Organisation coined the term "Globesity" to help encapsulate the magnitude of the problem. G protein-coupled receptors (GPCRs) are highly tractable drug targets due to their wide involvement in all aspects of physiology and pathophysiology, indeed, GPCRs are the targets of approximately 30% of the currently approved drugs. GPCRs are also broadly involved in key physiologies that underlie type 2 diabetes and obesity including feeding reward, appetite and satiety, regulation of blood glucose levels, energy homeostasis and adipose function. Despite this, only two GPCRs are the target of approved pharmaceuticals for treatment of type 2 diabetes and obesity. In this review we discuss the role of these, and select other candidate GPCRs, involved in various facets of type 2 diabetic or obese pathophysiology, how they might be targeted and the potential reasons why pharmaceuticals against these targets have not progressed to clinical use. Finally, we provide a perspective on the current development pipeline of anti-obesity drugs that target GPCRs.

MRAP2 inhibits β-arrestin recruitment to the ghrelin receptor by preventing GHSR1a phosphorylation

The melanocortin receptor accessory protein 2 (MRAP2) is essential for several physiological functions of the ghrelin receptor growth hormone secretagogue receptor 1a (GHSR1a), including increasing appetite and suppressing insulin secretion. In the absence of MRAP2, GHSR1a displays high constitutive activity and a weak G-protein-mediated response to ghrelin and readily recruits β-arrestin. In the presence of MRAP2, however, G-protein-mediated signaling via GHSR1a is strongly dependent on ghrelin stimulation and the recruitment of β-arrestin is significantly diminished. To better understand how MRAP2 modifies GHSR1a signaling, here we investigated the role of several phosphorylation sites within the C-terminal tail and third intracellular loop of GHSR1a, as well as the mechanism behind MRAP2-mediated inhibition of β-arrestin recruitment. We show that Ser252 and Thr261 in the third intracellular loop of GHSR1a contribute to β-arrestin recruitment, whereas the C-terminal region is not essential for β-arrestin interaction. Additionally, we found that MRAP2 inhibits GHSR1a phosphorylation by blocking the interaction of GRK2 and PKC with the receptor. Taken together, these data suggest that MRAP2 alters GHSR1a signaling by directly impacting the phosphorylation state of the receptor and that the C-terminal tail of GHSR1a prevents rather than contribute to β-arrestin recruitment.

Historical and cultural aspects of obesity: From a symbol of wealth and prosperity to the epidemic of the 21st century

World Health Organization defines obesity as abnormal or excess adipose tissue accumulation. Nowadays, this condition is a serious threat to the public health in most countries around the world. Obesity adversely affects physical, mental, and in most cultures, social well-being. However, throughout the ages-from ancient times to the 21st century-this condition has been subject to various interpretations. As a matter of fact, obesity has not always been regarded as a disease. For many decades, excessive body weight has been considered rather a symbol of health. It was a marker of wealth and prosperity, as well as a sign of high social status. The centuries that passed on the development of science and medicine have gradually changed its face, but significant progress in understanding the causes and consequences of obesity has been made in the last 30 years. This paper presents the historical outline of obesity and its treatment from ancient times to the present-from its affirmation to the epidemic in the late 20th and 21st century.

Effects of residual feed intake divergence on growth performance, carcass traits, meat quality, and blood biochemical parameters in small-sized meat ducks

Feed efficiency (FE) is a major economic trait of meat duck. This study aimed to evaluate the effects of residual feed intake (RFI) divergence on growth performance, carcass traits, meat quality, and blood biochemical parameters in small-sized meat ducks. A total of 500 healthy 21-day-old male ducks were housed in individual cages until slaughter at 63 d of age. The growth performance was determined for all the ducks. The carcass yield, meat quality, and blood biochemical parameters were determined for the selected 30 high-RFI (HRFI) and 30 low-RFI (LRFI) ducks. In terms of growth performance, the RFI, feed conversion ratio (FCR), and average daily feed intake (ADFI) were found to be significantly lower in the LRFI group (P < 0.01), whereas no differences were observed in the BW and body weight gain (P > 0.05). For slaughter performance, no differences were observed in the carcass traits between the LRFI and HRFI groups (P > 0.05). For meat quality, the shear force of breast muscle was significantly lower in the LRFI group (P < 0.05), while the other meat quality traits of breast and thigh muscles demonstrated no differences (P > 0.05). For blood biochemical parameters, the serum concentrations of triglycerides (TG) and glucose (GLU) were significantly lower in the LRFI group (P < 0.05), while the other parameters showed no differences (P > 0.05). The correlation analysis demonstrated a high positive correlation between RFI, FCR, and ADFI (P < 0.01). The RFI demonstrated a negative effect on the breast muscle and lean meat yields, but a positive effect on the shear force of breast muscle (P < 0.05). Further, the RFI demonstrated a positive effect on the TG and GLU levels (P < 0.05). These results indicate that the selection for low RFI could improve the FE of small-sized meat ducks without affecting the production performance. This study provides valuable insight into the biological processes underlying the variations in FE in small-sized meat ducks.

Antagonization of Ghrelin Suppresses Muscle Protein Deposition by Altering Gut Microbiota and Serum Amino Acid Composition in a Pig Model

Simple Summary

This study investigated the effects of the antagonization of ghrelin on muscle protein deposition, eating patterns and gut microbiota in pigs by injecting ghrelin antagonist ([D-Lys3]-GHRP-6) in a short term. We found that the antagonization of ghrelin affected the eating patterns of animals, which resulted in changes in the absorption of amino acids and gut microbiota, and it reduced protein deposition in muscles. We emphasize the important role of ghrelin in promoting muscle protein deposition and provide new clues for future research on improving muscle loss.

Abstract

Ghrelin is an appetite-stimulating hormone that can increase food intake and has been reported to prevent muscle loss; however, the mechanism is not yet fully understood. In this study, [D-Lys3]-GHRP-6 (GHRP) was used to investigate the effects of the antagonization of ghrelin on muscle protein deposition, eating patterns and gut microbiota in a pig model. We found that the growth performance and muscle fiber cross-sectional area of pigs treated with GHRP were significantly reduced compared with the control (CON) group. Moreover, the levels of serum isoleucine, methionine, arginine and tyrosine in the GHRP group were lower than that of the CON group. The abundance of acetate-producing bacteria (Oscillospiraceae UCG-005, Parabacteroides and Oscillospiraceae NK4A214 group) and acetate concentration in the colons of pigs treated with GHRP were significantly reduced. In addition, the injection of GHRP down-regulated the mRNA expression of MCT-1 and mTOR, and it up-regulated the mRNA expression of HDAC1, FOXO1 and Beclin-1. In summary, the antagonization of ghrelin reduced the concentration of important signal molecules (Arg, Met and Ile) that activate the mTOR pathway, concurrently reduce the concentration of HDAC inhibitors (acetate), promote autophagy and finally reduce protein deposition in muscles.

The Efficacy, Safety, and Pharmacology of a Ghrelin O-Acyltransferase Inhibitor for the Treatment of Prader-Willi Syndrome

CONTEXT

Acylated ghrelin (AG) stimulates appetite and is elevated compared to its unacylated (UAG) counterpart in Prader-Willi syndrome (PWS). GLWL-01 is a selective, reversible inhibitor of ghrelin O-acyltransferase (GOAT), the enzyme that converts UAG into AG.

OBJECTIVE

This work aimed to assess the efficacy, pharmacokinetics, pharmacodynamics, and safety of GLWL-01 in the treatment of PWS patients.

METHODS

A double-blind, placebo-controlled, phase 2 crossover study was conducted with 2 active treatment periods of 28 days in 19 patients (aged 16-65 years; body mass index (BMI) ≥ 28) with genetically confirmed PWS. The study took place in 7 hospital-based study centers in the United States and Canada. Patients received placebo or GLWL-01 (450 mg twice daily) orally after lead-in placebo and washout periods. The Hyperphagia Questionnaire for Clinical Trials and Caregiver Global Impression of Change were used to measure reductions in hyperphagia. Plasma concentrations of AG and UAG were evaluated as correlates.

RESULTS

Treatment resulted in statistically significant differences compared to placebo in plasma AG (P = .0002), UAG (P = .0488), and AG/UAG (P = .0003). GLWL-01 did not statistically significantly reduce hyperphagia-related behavior or bring about changes in global clinical end points, as assessed by caregivers. Anthropometric and clinical parameters correlated with obesity did not statistically significantly change in response to treatment. Less than half of patients reported a treatment-emergent adverse event (TEAE). No deaths, serious adverse events, or severe TEAEs were reported.

CONCLUSION

GLWL-01 is safe and well tolerated. Pharmacological parameters confirmed the inhibition of GOAT following administration of GLWL-01. Patients' eating behaviors, BMI, blood glucose, and total cholesterol, among other similar measures, were not modified.

Near infrared ray-guided surgery using Firefly technology of the daVinci Xi system and intraoperative upper gastrointestinal endoscopy for subtotal gastrectomy and surgery for cancer of the gastroesophageal junction

Background

In gastrectomies, especially subtotal gastrectomies and operations on the gastroesophageal junction, identifying the exact location of the tumor and establishing the appropriate resection line is very important. Accurate resection lines have a major impact on the preservation of organ function and curability. Preservation of as much as possible of the remaining stomach, including the fornix, may be an important surgical goal for maintaining an adequate postoperative quality of life. In adenocarcinoma of the gastroesophageal junction, the height of the esophageal dissection may affect reconstruction of the transhiatal approach.

Methods

We perform a new technique, near infrared ray-guided surgery, for the accurate localization of a tumor using the Firefly technology of the daVinci Xi system and intra-operative upper gastrointestinal endoscopy. We used this new technique for cases of upper gastric cancer or adenocarcinoma of the gastroesophageal junction. In this retrospective study, we examined to determine the extent (mm) of the tumor invasion of the esophagus, visualization of near infrared ray contained within endoscopic light, and distance from the proximal margin of the tumor to the surgical cut line on rapid histopathology and in the permanent preparation, including the operative videos and extracted specimens.

Results

We performed near infrared ray-guided surgery for 12 patients with gastric cancer or adenocarcinoma of the gastroesophageal junction, and the near infrared ray was clearly seen as green light with Firefly mode in all the patients. Near infrared ray-guided surgery was useful for obtaining localization of the tumor. In addition, it was possible to resect organ with adequate margins from tumor. Rapid intraoperative histopathological examinations confirmed that the resected specimens had negative margins. None of the patients required additional resection.

Conclusions

We believe that because near infrared ray-guided surgery can provide an accurate resection line, it will be useful for the resection of upper gastric cancer and adenocarcinoma of the gastroesophageal junction. It will also provide patients with a good postoperative quality of life after surgery.

GHSR controls food deprivation-induced activation of CRF neurons of the hypothalamic paraventricular nucleus in a LEAP2-dependent manner

OBJECTIVE

Prolonged fasting is a major challenge for living organisms. An appropriate metabolic response to food deprivation requires the activation of the corticotropin-releasing factor-producing neurons of the hypothalamic paraventricular nucleus (PVHCRF neurons), which are a part of the hypothalamic-pituitary-adrenal axis (HPA), as well as the growth hormone secretagogue receptor (GHSR) signaling, whose activity is up- or down-regulated, respectively, by the hormones ghrelin and the liver-expressed antimicrobial peptide 2 (LEAP2). Since ghrelin treatment potently up-regulates the HPA axis, we studied the role of GHSR in mediating food deprivation-induced activation of the PVHCRF neurons in mice.

METHODS

We estimated the activation of the PVHCRF neurons, using immuno-staining against CRF and the marker of neuronal activation c-Fos in brain sections, and assessed plasma levels of corticosterone and glucose in different pharmacologically or genetically manipulated mouse models exposed, or not, to a 2-day food deprivation protocol. In particular, we investigated ad libitum fed or food-deprived male mice that: (1) lacked GHSR gene expression, (2) had genetic deletion of the ghrelin gene, (3) displayed neurotoxic ablation of the hypothalamic arcuate nucleus, (4) were centrally treated with an anti-ghrelin antibody to block central ghrelin action, (5) were centrally treated with a GHSR ligand that blocks ghrelin-evoked and constitutive GHSR activities, or (6) received a continuous systemic infusion of LEAP2(1-12).

RESULTS

We found that food deprivation results in the activation of the PVHCRF neurons and in a rise of the ghrelin/LEAP2 molar ratio. Food deprivation-induced activation of PVHCRF neurons required the presence and the signaling of GHSR at hypothalamic level, but not of ghrelin. Finally, we found that preventing the food deprivation-induced fall of LEAP2 reverses the activation of the PVHCRF neurons in food-deprived mice, although it has no effect on body weight or blood glucose.

CONCLUSION

Food deprivation-induced activation of the PVHCRF neurons involves ghrelin-independent actions of GHSR at hypothalamic level and requires a decrease of plasma LEAP2 levels. We propose that the up-regulation of the actions of GHSR associated to the fall of plasma LEAP2 level are physiologically relevant neuroendocrine signals during a prolonged fasting.

Liver-expressed antimicrobial peptide 2 functions independently of growth hormone secretagogue receptor in calorie-restricted mice

Ghrelin is a gastric-derived peptide that stimulates feeding, blood glucose elevation, body temperature reduction, and growth hormone (GH) secretion. Liver-expressed antimicrobial peptide 2 (LEAP2) is an endogenous antagonist of the ghrelin receptor, also called growth hormone secretagogue receptor (GHSR). We studied the effects of LEAP2 administration on feeding, body weight, glycemia, body temperature, and inflammation-related genes in the liver in C57BL/6 J mice and Ghsr-knockout (Ghsr-KO) mice. We found that a single administration of LEAP2 did not abolish fasting-induced food intake in 24-h fasted C57BL/6 J mice or Ghsr-KO mice. Moreover, continuous LEAP2 administration to mice fed ad libitum for 6 days did not affect feeding, body temperature, plasma ghrelin, or blood glucose. By contrast, continuous LEAP2 administration to calorie-restricted C57BL/6 J mice and Ghsr-KO mice induced body weight loss, hypoglycemia, body temperature reduction, and upregulation of Il-6 and Il-1β mRNAs in the liver. Our findings suggest that LEAP2 functions independently of GHSR, implying that LEAP2 affects physiology beyond the ghrelin-GHSR system.

Growth hormone secretagogue receptor signaling in the supramammillary nucleus targets nitric oxide-producing neurons and controls recognition memory in mice

Ghrelin is a stomach-derived hormone that acts via the growth hormone secretagogue receptor (GHSR). Recent evidence suggests that some of ghrelin's actions may be mediated via the supramammillary nucleus (SuM). Not only does ghrelin bind to cells within the mouse SuM, but ghrelin also activates SuM cells and intra-SuM ghrelin administration induces feeding in rats. In the current study, we aimed to further characterize ghrelin action in the SuM. We first investigated a mouse model expressing enhanced green fluorescent protein (eGFP) under the promoter of GHSR (GHSR-eGFP mice). We found that the SuM of GHSR-eGFP mice contains a significant amount of eGFP cells, some of which express neuronal nitric oxide synthase. Centrally-, but not systemically-, injected ghrelin reached the SuM, where it induced c-Fos expression. Furthermore, a 5-day 40% calorie restriction protocol, but not a 2-day fast, increased c-Fos expression in non-eGFP+ cells of the SuM of GHSR-eGFP mice, whereas c-Fos induction by calorie restriction was not observed in GHSR-deficient mice. Exposure of satiated mice to a binge-like eating protocol also increased c-Fos expression in non-eGFP+ cells of the SuM of GHSR-eGFP mice in a GHSR-dependent manner. Finally, intra-SuM-injected ghrelin did not acutely affect food intake, locomotor activity, behavioral arousal or spatial memory but increased recognition memory. Thus, we provide a compelling neuroanatomical characterization of GHSR SuM neurons and its behavioral implications in mice.

Decoy bypass for appetite suppression in obese adults: role of synergistic nutrient sensing receptors GPR84 and FFAR4 on colonic endocrine cells

OBJECTIVE

Colonic enteroendocrine cells (EECs) store and release potent anorectic hormones that are key regulators of satiety. EECs express multiple nutrient sensing receptors, particularly for medium-chain fatty acids (MCFAs): GPR84 and FFAR4. Here we show a non-surgical approach with targeted colonic delivery of MCFA, which induces EEC and neuronal activation leading to anorectic effects.

DESIGN

A randomised, double-blind, placebo-controlled, cross-over study was performed in obese adults given combined GPR84 and FFAR4 agonists in colonic release capsules before meals. We measured serum hormones, energy intake and appetite perception. Cell type, activation by agonists and hormone/serotonin release were determined in human colonic explants. Mouse colonic afferent nerve responses to nutrients/mediators were recorded electrophysiologically.

RESULTS

Subjects receiving GPR84 and FFAR4 agonists had reduced overall calorific intake and increased postprandial levels of PYY versus placebo. Receptors including GPR84 and FFAR4 were coexpressed on human colonic EEC. Activation of GPR84 exclusively induced intracellular pERK, whereas FFAR4 selectively activated pCaMKII. Coactivation of GPR84 and FFAR4 induced both phosphoproteins, and superadditive release of GLP-1 and PYY. Nutrients and hormones convergently activated murine colonic afterent nerves via GLP-1, Y2 and 5-HT3 receptors.

CONCLUSIONS

Colonic GPR84 and FFAR4 agonists reduce energy intake and increase postprandial PYY in obese adults. Human colonic EECs coexpress these receptors, which activate cells via parallel intracellular pathways and synergistically evoke hormone release. Further synergism occurs in sensory nerve responses to MCFA and EEC mediators. Thus, synergistic activation of colonic endocrine cells via nutrient receptors is an important target for metabolic regulation.

TRAIL REGISTRATION NUMBER

NCT04292236.

The amount of ghrelin-immunoreactive cells in the abomasum and intestines of 13-14-week-old calves supplemented with Jerusalem artichoke flour alone or in combination with Saccharomyces cerevisiae yeast

Background and Aim: The use of antibiotics in animals for disease prevention and productivity has been banned in the European Union since 2006. Possible alternatives can be used prebiotics, probiotics, and synbiotics. These compounds can improve feed digestion and absorption in the gastrointestinal tract with identical nutrient uptake, while imparting the feeling of satiety, which reduces the activity of ghrelin-immunoreactive (IR) cells. The number of studies performed on the activity of ghrelin-IR cells in ruminants is insufficient. In particular, there are few such studies in calves during the transition period from being a relatively monogastric animal to a ruminant. The present study aimed to evaluate the effect of Jerusalem artichoke flour (containing ∼50% prebiotic inulin) and a new, commercially unavailable synbiotic (combination of Jerusalem artichoke flour and Saccharomyces cerevisiae strain 1026) on the amount of ghrelin-IR cells in the abomasum and intestines of 13-14-week-old calves. Materials and Methods: Fifteen crossbreed, Holstein Friesian and Red Holstein calves (Bos taurus) (32±4 days, 72.1±11.34 kg) were used. Calves were allocated into three groups: Control group (CoG, n=5) received the standard diet, prebiotic group (PreG, n=5) received 12 g of flour of Jerusalem artichoke (Helianthus tuberosus) per head containing 6 g of prebiotic inulin in addition to the standard diet, and synbiotic group (SynG, n=5) received a synbiotic in addition to the standard diet which consisted of two different products: 12 g of flour of Jerusalem artichoke per head containing 6 g of prebiotic inulin and probiotic 5 g of a yeast S. cerevisiae strain 1026. Feed additives were added to the concentrate once a day for 56 days. On days 1, 28, and 56, the live weight of the calves was determined. On day 56 of the experiment, three calves from each group were slaughtered. Histological samples were collected from the two parts of each calf abomasum: Pars pylorica and pars fundalis and the middle part of the duodenum and jejunum. Immunohistochemical tissue staining methods were used to detect ghrelin-IR cells. Results: The live weight of the slaughtered calves on day 56 was 115.3±21.73 kg in CoG, 130.0±17.32 kg in PreG, and 119.0±7.94 kg in SynG. Ghrelin-IR cells were more abundantly localized in the cytoplasm of the abomasum muscle gland cells in pars fundalis and pars pylorica, and to a lesser extent in the duodenum and jejunum. The number of ghrelin-IR cells in the abomasal fundic gland area was significantly higher in the CoG, than in the PreG and SynG (p=0.0001), while the difference between the PreG and SynG was not significant (p=0.700). Conclusion: The addition of Jerusalem artichoke flour and its combination with the yeast S.cerevisiae stain 1026 in calves resulted in a lower number of ghrelin-IR cells in the abomasum, duodenum, and jejunum and, although insignificantly, increased live weight (p=0.491), suggesting that calves in these groups with the same feed intake as the CoG had a better breakdown of nutrients, thus having a longer feeling of satiety.

Case Report: Prolonged Anorexia With Nausea Caused by Immune Checkpoint Inhibitors for Malignant Melanoma Treated Using Kampo Medicines Bukuryoingohangekobokuto and Ninjin’yoeito

Immune checkpoint inhibitors (ICIs) are indicated for several cancers, including malignant melanoma. Anorexia and nausea resulting in malnutrition are side effects of ICIs. In such cases, conventional drugs are used for symptom relief, but the symptoms may persist. We report a case of advanced malignant melanoma with prolonged anorexia and nausea, which occurred after nivolumab administration, and was successfully treated using Kampo medicines. A 75-year-old man with nasal bleeding visited our hospital. A nasal scope revealed an obstructive tumor in the left nasal concha. Tissue biopsy showed malignant melanoma, and computed tomography showed metastasis to the liver and bone. Thus, the patient was diagnosed with stage IV malignant melanoma. He received radiotherapy (30 Gy) and nivolumab with ipilimumab four times, followed by nivolumab administration alone. During the administration of nivolumab, he complained of severe anorexia and nausea, with a numeric rating scale (no symptoms, 0; severe symptoms, 10) score of 10. He could not consume food because of these symptoms, even after nivolumab administration was discontinued. His blood pressure was 92/59 mmHg, his performance status (PS; no fatigue, 0; bedridden or disabled, 4) was 4, and his body weight gradually decreased from 60 to 39 kg in a month. The patient showed malnutrition and dehydration and experienced anxiety and depression. Nivolumab was terminated, and conventional symptomatic drugs were prescribed, but the symptoms persisted. We then prescribed 9.0 g/day of ninjin’yoeito (TJ-108, Tsumura and Co.) to allow recovery from anorexia and subsequently added bukuryoingohangekobokuto (TJ-116, Tsumura and Co.) to treat the persistent nausea. After treatment with these two Kampo medicines, the patient’s appetite gradually recovered. Along with the recovery of nutritional status, his PS improved to 0, his anxiety and depressive state improved, and his body weight increased to 60 kg. The patient remained in good condition without cancer recurrence. The patient’s clinical course shows the usefulness of Kampo medicine as supportive care for symptom relief and maintenance of nutritional and mental status during cancer treatment.

Role of the gut-brain axis in energy and glucose metabolism

The gastrointestinal tract plays a role in the development and treatment of metabolic diseases. During a meal, the gut provides crucial information to the brain regarding incoming nutrients to allow proper maintenance of energy and glucose homeostasis. This gut-brain communication is regulated by various peptides or hormones that are secreted from the gut in response to nutrients; these signaling molecules can enter the circulation and act directly on the brain, or they can act indirectly via paracrine action on local vagal and spinal afferent neurons that innervate the gut. In addition, the enteric nervous system can act as a relay from the gut to the brain. The current review will outline the different gut-brain signaling mechanisms that contribute to metabolic homeostasis, highlighting the recent advances in understanding these complex hormonal and neural pathways. Furthermore, the impact of the gut microbiota on various components of the gut-brain axis that regulates energy and glucose homeostasis will be discussed. A better understanding of the gut-brain axis and its complex relationship with the gut microbiome is crucial for the development of successful pharmacological therapies to combat obesity and diabetes.

Energetic demands of lactation produce an increase in the expression of growth hormone secretagogue receptor in the hypothalamus and ventral tegmental area of the rat despite a reduction in circulating ghrelin

Lactating rats show changes in the secretion of hormones and brain signals that promote hyperphagia and facilitate the production of milk. Little is known, however, about the role of ghrelin in the mechanisms sustaining lactational hyperphagia. Here, we used Wistar female rats that underwent surgery to sever the galactophores to prevent milk delivery (GC rats) and decrease the energetic drain of milk delivery. We compared plasma acyl-ghrelin concentrations and growth hormone secretagogue receptor (GHSR) mRNA expression in different brain regions of GC rats with those of sham operated lactating and nonlactating rats. Additional lactating and nonlactating rats were implanted with cannulae aimed at the lateral ventricles and were used to compare feeding responses to central ghrelin or GHSR antagonist infusions to those of nonlactating rats receiving similar infusions on day 14-16 postpartum (pp). Results show lower plasma acyl-ghrelin concentrations on day 15 pp sham operated lactating rats compared to GC or nonlactating rats. These changes occur in association with increased GHSR mRNA expression in the hypothalamic arcuate nucleus (ARC) and ventral tegmental area (VTA) of sham operated lactating rats. Despite lactational hyperphagia, infusions of ghrelin (0.25 or 1 μg) resulted in similar increases in food intake in lactating and nonlactating rats. In addition, infusions of the GHSR antagonist JMV3002 (4 μg in 1 μl of vehicle) produced greater suppression of food intake in lactating rats than in nonlactating rats. These data suggest that, despite lower plasma ghrelin, the energetic drain of lactation increases sensitivity to the orexigenic effects of ghrelin in brain regions important for food intake and energy balance, and these events are associated with lactational hyperphagia.

Developmental programming of hypothalamic melanocortin circuits

The melanocortin system plays a critical role in the central regulation of food intake and energy balance. This system consists of neurons producing pro-opiomelanocortin (POMC), melanocortin receptors (MC4Rs), and the endogenous antagonist agouti-related peptide (AgRP). Pomc and Mc4r deficiency in rodents and humans causes early onset of obesity, whereas a loss of Agrp function is associated with leanness. Accumulating evidence shows that many chronic diseases, including obesity, might originate during early life. The melanocortin system develops during a relatively long period beginning during embryonic life with the birth of POMC and AgRP neurons and continuing postnatally with the assembly of their neuronal circuitry. The development of the melanocortin system requires the tight temporal regulation of molecular factors, such as transcription factors and axon guidance molecules, and cellular mechanisms, such as autophagy. It also involves a complex interplay of endocrine and nutritional factors. The disruption of one or more of these developmental factors can lead to abnormal maturation and function of the melanocortin system and has profound metabolic consequences later in life.

Effects of Corn and Broken Rice Extrusion on the Feed Intake, Nutrient Digestibility, and Gut Microbiota of Weaned Piglets

Simple Summary

Extruded cereals are largely used in newly weaned piglet diets to increase nutrient digestibility and palatability. Our findings showed that corn and broken rice extrusion diets generated negative effects on average daily feed intake (−63.5 g/day, p = 0.054) and average daily gain (−60.6 g/d, p = 0.015) in weaned piglets. Decreased feed intake was associated with increased plasma levels of the gut-derived hormones, glucagon-like peptide-1 (GLP-1) and peptide YY (PYY), which may have been attributed to increased microbiota pathogen abundance, including Sarcina, Clostridium_sensu_strictio_1, and Terrisporobacter, and decreased short-chain fatty acid-producing microbiota, such as Lactobaillaceae and Bifidobateriaceae. Our results showed that extruded cereals should be used cautiously when formulating diets for newly weaned piglets.

Abstract

In this study, we investigated the effects of corn and rice extrusion diets on feed intake, nutrient digestibility, and gut microbiota in weaned piglets. Animals were divided into four dietary groups and fed a controlled diet containing (1) 62.17% corn (CORN), 15% soybean, 10% extruded full-fat soybean, and 6% fishmeal (2) half the corn replaced by extruded corn (ECORN), (3) broken rice (RICE), and (4) extruded broken rice (ERICE) for 28 days. Rice supplementation increased dry matter total tract digestibility and gross energy. Extruded cereals generated a lower average daily feed intake (ADFI) at 15–28 and 1–28 days, decreased average daily growth (ADG) at 15–28 and 1–28 days, and a lowered body weight (BW) on day 28, regardless of cereal type. Dietary extruded cereals increased the appetite-regulating hormones glucagon-like peptide-1 (GLP-1) and peptide YY (PYY). Piglets fed extruded cereals displayed low short-chain fatty acid (SCFA) levels in plasma and low Lactobaillaceae and Bifidobateriaceae levels in feces, whereas a higher abundance of the potential pathogens Sarcina, Clostridium_sensu_strictio_1 and Terrisporobacter was observed. Piglets fed extruded cereals displayed significantly lower gas and SCFA levels during in vitro fermentation. Combined, 50% corn substituted with extruded corn or broken rice decreased piglet growth performance, possibly by altering their microbiota.

The controversial role of the vagus nerve in mediating ghrelin´s actions: gut feelings and beyond

Ghrelin is a stomach-derived peptide hormone that acts via the growth hormone secretagogue receptor (GHSR) and displays a plethora of neuroendocrine, metabolic, autonomic and behavioral actions. It has been proposed that some actions of ghrelin are exerted via the vagus nerve, which provides a bidirectional communication between the central nervous system and peripheral systems. The vagus nerve comprises sensory fibers, which originate from neurons of the nodose and jugular ganglia, and motor fibers, which originate from neurons of the medulla. Many anatomical studies have mapped GHSR expression in vagal sensory or motor neurons. Also, numerous functional studies investigated the role of the vagus nerve mediating specific actions of ghrelin. Here, we critically review the topic and discuss the available evidence supporting, or not, a role for the vagus nerve mediating some specific actions of ghrelin. We conclude that studies using rats have provided the most congruent evidence indicating that the vagus nerve mediates some actions of ghrelin on the digestive and cardiovascular systems, whereas studies in mice resulted in conflicting observations. Even considering exclusively studies performed in rats, the putative role of the vagus nerve in mediating the orexigenic and growth hormone (GH) secretagogue properties of ghrelin remains debated. In humans, studies are still insufficient to draw definitive conclusions regarding the role of the vagus nerve mediating most of the actions of ghrelin. Thus, the extent to which the vagus nerve mediates ghrelin actions, particularly in humans, is still uncertain and likely one of the most intriguing unsolved aspects of the field.

The effects of diet and chronic exercise on skeletal muscle ghrelin response

Background

Recent findings indicate that ghrelin, particularly the unacylated form (UnAG), acutely stimulates skeletal muscle fatty acid oxidation (FAO) and can preserve insulin signaling and insulin-stimulated glucose uptake in the presence of high concentrations of saturated fatty acids. However, we recently reported that the stimulatory effect of ghrelin on FAO and subsequent ability to protect insulin stimulated glucose uptake was lost following 6-weeks (6w) of chronic high fat feeding. In the current study we examined the effects of both short-term 5 day (5d) and chronic 6w high-fat diet (HFD) on muscle ghrelin response, and whether exercise training could prevent the development of muscle ghrelin resistance with 6w of HFD

Methods and Results

Soleus muscle strips were isolated from male rats to determine the direct effects of acylated (AG) and UnAG isoforms on FAO and glucose uptake. A 5d HFD did not alter the response of soleus muscle to AG or UnAG. Conversely, 6w of HFD was associated with a loss of ghrelin's ability to stimulate FAO and protect insulin stimulated glucose uptake. Muscle response to UnAG remained intact following the 6w HFD with chronic exercise training. Unexpectedly, muscle response to both AG and UnAG was also lost after 6w of low-fat diet (LFD) consumption. Protein content of the classic ghrelin receptor, GHS-R1a, was not affected by diet or training. Corticotropin-releasing hormone receptor-2 (CRF-2R) content, a putative receptor for ghrelin in muscle, was significantly decreased in soleus from 6w HFD-fed animals and increased following exercise training. This may explain the protection of UnAG response with training in HFD-fed rats but does not explain why ghrelin response was also lost in LFD-fed animals.

Conclusions

UnAG protects muscle glucose uptake during acute lipid oversupply, likely due to its ability to stimulate FAO. This effect is lost in 6w HFD-fed animals but protected with exercise training. Unexpectedly, ghrelin response was lost in 6w LFD-fed animals. The loss of ghrelin response in muscle with a LFD cannot be explained by a change in putative ghrelin receptor content. We believe that the sedentary nature of the animals is a major factor in the development of muscle ghrelin resistance and warrants further research.

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Ghrelin stimulates fatty acid oxidation in skeletal muscle.

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This stimulation is strongly associated with protection from acute fat overload.

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Prolonged sedentary behaviour and a high fat diet impair ghrelin's ability to stimulate fatty acid oxidation.

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Exercise training preserves ghrelin's positive effects on skeletal muscle.

Gut peptide regulation of food intake - evidence for the modulation of hedonic feeding

The number of people living with obesity has tripled worldwide since 1975 with serious implications for public health, as obesity is linked to a significantly higher chance of early death from associated comorbidities (metabolic syndrome, type 2 diabetes, cardiovascular disease and cancer). As obesity is a consequence of food intake exceeding the demands of energy expenditure, efforts are being made to better understand the homeostatic and hedonic mechanisms governing food intake. Gastrointestinal peptides are secreted from enteroendocrine cells in response to nutrient and energy intake, and modulate food intake either via afferent nerves, including the vagus nerve, or directly within the central nervous system, predominantly gaining access at circumventricular organs. Enteroendocrine hormones modulate homeostatic control centres at hypothalamic nuclei and the dorso-vagal complex. Additional roles of these peptides in modulating hedonic food intake and/or preference via the neural systems of reward are starting to be elucidated, with both peripheral and central peptide sources potentially contributing to central receptor activation. Pharmacological interventions and gastric bypass surgery for the treatment of type 2 diabetes and obesity elevate enteroendocrine hormone levels and also alter food preference. Hence, understanding of the hedonic mechanisms mediated by gut peptide action could advance development of potential therapeutic strategies for the treatment of obesity and its comorbidities.

Circulating acyl and des-acyl ghrelin levels in obese adults: a systematic review and meta-analysis

Ghrelin is the only known orexigenic gut hormone, and its synthesis, secretion and degradation are affected by different metabolic statuses. This meta-analysis aimed to investigate the potential differences in plasma acyl ghrelin (AG) and des-acyl ghrelin (DAG) concentrations between normal weight and obese adults. Systematic literature searches of PubMed, Embase and Web of Science through October 2021 were conducted for articles reporting AG or DAG levels in obesity and normal weight, and 34 studies with 1863 participants who met the eligibility criteria were identified. Standardized mean differences (SMDs) with 95% confidence intervals (CIs) were calculated to evaluate group differences in circulating AG and DAG levels. Pooled effect size showed significantly lower levels of baseline AG (SMD: - 0.85; 95% CI: - 1.13 to - 0.57; P_SMD < 0.001) and DAG (SMD: - 1.06; 95% CI: - 1.43 to - 0.69; P_SMD < 0.001) in obese groups compared with healthy controls, and similar results were observed when subgroup analyses were stratified by the assay technique or storage procedure. Postprandial AG levels in obese subjects were significantly lower than those in controls when stratified by different time points (SMD _30 min: - 0.85, 95% CI: - 1.18 to - 0.53, P_SMD < 0.001; SMD _60 min: - 1.00, 95% CI: - 1.37 to - 0.63, P_SMD < 0.001; SMD _120 min: - 1.21, 95% CI: - 1.59 to - 0.83, P_SMD < 0.001). In healthy subjects, a postprandial decline in AG was observed at 120 min (SMD: - 0.42; 95% CI: - 0.77 to - 0.06; P_SMD = 0.021) but not in obese subjects (SMD: - 0.28; 95% CI: - 0.60 to 0.03; P_SMD = 0.074). The mean change in AG concentration was similar in both the obese and lean health groups at each time point (ΔSMD_30min: 0.31, 95% CI: - 0.35 to 0.97, P_SMD = 0.359; ΔSMD_60min: 0.17, 95% CI: - 0.12 to 0.46, P_SMD = 0.246; ΔSMD_120min: 0.21, 95% CI: - 0.13 to 0.54, P_SMD = 0.224). This meta-analysis strengthens the clinical evidence supporting the following: lower baseline levels of circulating AG and DAG in obese individuals; declines in postprandial circulating AG levels, both for the healthy and obese individuals; a shorter duration of AG suppression in obese subjects after meal intake. These conclusions have significance for follow-up studies to elucidate the role of various ghrelin forms in energy homeostasis.

Neuronal GHS-R Differentially Modulates Feeding Patterns under Normal and Obesogenic Conditions

The orexigenic hormone ghrelin increases food intake and promotes obesity through its receptor, growth hormone secretagogue receptor (GHS-R). We previously reported two neuron-specific GHS-R knockout mouse lines, namely pan-neuronal deletion by Syn1-cre and hypothalamic deletion by AgRP-cre, exhibiting differential diet-dependent effects on body weight. GHS-R deficiency in neurons elicited less pronounced metabolic effects under regular diet (RD) than high fat diet (HFD). While there was no difference in total food intake of HFD in either mouse line, Syn1-cre; Ghsrf/f mice showed much greater anti-obesity effect than that of AgRP-cre; Ghsrf/f mice. Meal feeding pattern is known to have a major impact on energy homeostasis and obesity development. Here, we investigated the feeding behaviors of these two neuron-specific GHS-R knockout mice under RD and HFD feeding, by assessing meal number, meal size, meal duration, and feeding frequency. Under the normal diet, RD-fed Syn1-cre; Ghsrf/f mice showed a decreased meal size in dark phase, while RD-fed AgRP-cre; Ghsrf/f mice showed an increased meal duration in dark phase. Under the obesogenic diet, HFD-fed Syn1-cre; Ghsrf/f mice displayed reduced meal numbers in light phase and increased feeding in both light and dark phases, whereas HFD-fed AgRP-cre; Ghsrf/f mice showed a decreased meal duration in the light phase only. Consistently, the expression of neuropeptides (Neuropeptide Y and Orexin) was increased in the hypothalamus of RD-fed Syn1-cre; Ghsrf/f mice, whereas the expression of cannabinoid receptor type 1 (CB1) was increased in the hypothalamus of HFD fed Syn1-cre; Ghsrf/f mice. Overall, feeding pattern changes were more pronounced in Syn1-cre; Ghsrf/f mice than that in AgRP-cre; Ghsrf/f mice, and HFD elicited greater alteration than RD. While AgRP-cre; Ghsrf/f mice consumed HFD meals faster during the day (showing shorter meal duration), Syn1-cre; Ghsrf/f mice ate few HFD meals during the light phase and ate slowly throughout the day (showing longer meal duration in both phases). Our findings reveal that neuronal GHS-R regulates energy homeostasis by altering feeding patterns, and differentially modulates feeding patterns in a site- and diet-dependent manner. The distinctive data in these two mouse lines also suggest that eating slowly during the optimal feeding period (dark phase for mice) may be beneficial in combating obesity.

Effect and Mechanism of Herbal Medicines on Cisplatin-Induced Anorexia

Cisplatin is a well-known chemotherapeutic agent used to treat various types of cancers; however, it can also induce anorexia, which results in reduced food intake, loss of body weight, and lower quality of life. Although drugs such as megestrol acetate and cyproheptadine are used to decrease this severe feeding disorder, they can also induce side effects, such as diarrhea and somnolence, which limit their widespread use. Various types of herbal medicines have long been used to prevent and treat numerous gastrointestinal tract diseases; however, to date, no study has been conducted to analyze and summarize their effects on cisplatin-induced anorexia. In this paper, we analyze 12 animal studies that used either a single herbal medicine extract or mixtures thereof to decrease cisplatin-induced anorexia. Among the herbal medicines, Ginseng Radix was the most used, as it was included in seven studies, whereas both Glycyrrhizae Radix et Rhizoma and Angelicae Gigantis Radix were used in four studies. As for the mechanisms of action, the roles of serotonin and its receptors, cytokines, white blood cells, ghrelin, and leptin were investigated. Based on these results, we suggest that herbal medicines could be considered a useful treatment method for cisplatin-induced anorexia.

Circulating Liver-Enriched Antimicrobial Peptide-2 Decreases during Male Puberty

Objective

Circulating levels of liver-enriched antimicrobial peptide 2 (LEAP2), a ghrelin receptor antagonist, decrease under caloric restriction and increase in obesity. The role of LEAP2 in male puberty, a phase with accelerated energy demand, is unclear.

Methods

We determined circulating LEAP2 levels in 28 boys with constitutional delay of growth and puberty (CDGP) who participated in a randomized controlled trial (NCT01797718), and were treated with letrozole (n=15) or intramuscular low-dose testosterone (T) (n=13) for 6 months. Blood sampling and dual-energy x-ray absorptiometry-measured body composition were performed at 0, 6, and 12 month visits.

Results

Serum LEAP2 levels decreased significantly during pubertal progression (0-6 mo: mean decrease -4.3 [10.3] ng/ml, p=0.036 and 0-12mo: -3.9 [9.3] ng/ml, p=0.033). Between 0 and 6 months, the changes in serum LEAP2 levels correlated positively with changes in percentage of body fat (rs=0.48, p=0.011), and negatively with growth velocity, and estradiol levels (rs=-0.43, p=0.022, rs=-0.55, p=0.003, respectively). In the T group only, the changes in serum LEAP2 correlated negatively with changes in testosterone and estradiol levels. Between 0 and 12 months, the change in LEAP2 levels correlated negatively with the change in HDL levels (rs= -0.44, p=0.022) and positively with the change in insulin (rs=0.50, p=0.009), and HOMA-IR (rs=0.51, p=0.007) levels.

Conclusions

Circulating LEAP2 levels decreased after induction of puberty reciprocally with increased growth rate and energy demand reflecting the metabolic state of the adolescent. Further, the results suggest that estradiol levels may have a permissive role in downregulating circulating LEAP2 levels.

Status of ghrelin as an islet hormone and paracrine/autocrine regulator of insulin secretion

Ghrelin is expressed in the pancreatic islet cells as well as the stomach. In the perfused pancreas and isolated islets, GHS-R antagonism, ghrelin immunoneutralization and ghrelin-knockout (Ghr-KO) all increase glucose-induced insulin release. Thus, pharmacological, immunological and genetic blockades of ghrelin in the pancreatic islets all markedly augment glucose-induced insulin release, showing that islet-derived ghrelin physiologically restricts insulin release in rodents. In this review, we focus on the current understanding of the following key questions: 1) from which islet cells ghrelin is released, 2) on which islet cells ghrelin acts, and 3) mechanisms by which the islet-derived ghrelin inhibits insulin secretion.

The incretin/glucagon system as a target for pharmacotherapy of obesity

Obesity is a chronic, multifactorial, relapsing disease. Despite multicomponent lifestyle interventions, including pharmacotherapy, maintaining bodyweight loss is challenging for many people. The pathophysiology of obesity is complex, and currently approved pharmacotherapies only target a few of the many pathways involved; thus, single-targeting agents have limited efficacy. Proglucagon-derived peptides, glucagon, and the incretin hormones glucagon-like peptide-1 (GLP-1) and glucose-dependent insulinotropic polypeptide (GIP), represent attractive targets for managing obesity and metabolic disorders because they may have direct roles in multiple mechanisms including satiety, energy homeostasis, and lipolytic activity. Unimolecular dual and triple agonists targeting glucagon and incretin hormone receptors have been shown to promote bodyweight loss, lower glucose levels, and reduce food intake in animal models of obesity. Multiple dual receptor agonists are in clinical development for the treatment of obesity, including GLP-1/GIP and GLP-1/glucagon receptor agonists. The extent to which glucagon contributes to treatment effects remains to be understood, but it may promote bodyweight loss by reducing food intake, while concomitant GLP-1 receptor agonism ensures normal glucose control. Further research is required to fully understand the molecular mechanisms of action and metabolic effects of both dual and triple receptor agonists.

The Problem of Appetite Loss After Major Abdominal Surgery

Objective:

To systematically review the problem of appetite loss after major abdominal surgery.

Summary of Background Data:

Appetite loss is a common problem after major abdominal surgery. Understanding of etiology and treatment options is limited.

Methods:

We searched Medline, Cochrane Central Register of Controlled Trials, and Web of Science for studies describing postoperative appetite loss. Data were extracted to clarify definition, etiology, measurement, surgical influence, pharmacological, and nonpharmacological treatment. PROSPERO registration ID: CRD42021224489.

Results:

Out of 6144 articles, we included 165 studies, 121 of which were also analyzed quantitatively. A total of 19.8% were randomized, controlled trials (n = 24) and 80.2% were nonrandomized studies (n = 97). The studies included 20,506 patients undergoing the following surgeries: esophageal (n = 33 studies), gastric (n = 48), small bowel (n = 6), colon (n = 27), rectal (n = 20), hepatobiliary (n = 6), and pancreatic (n = 13). Appetite was mostly measured with the Quality of Life Questionnaire of the European Organization for Research and Treatment of Cancer (EORTC QLQ C30, n = 54). In a meta-analysis of 4 randomized controlled trials gum chewing reduced time to first hunger by 21.2 hours among patients who had bowel surgery. Other reported treatment options with positive effects on appetite but lower levels of evidence include, among others, intravenous ghrelin administration, the oral Japanese herbal medicine Rikkunshito, oral mosapride citrate, multidisciplin-ary-counseling, and watching cooking shows. No studies investigated the effect of well-known appetite stimulants such as cannabinoids, steroids, or megestrol acetate on surgical patients.

Conclusions:

Appetite loss after major abdominal surgery is common and associated with increased morbidity and reduced quality of life. Recent studies demonstrate the influence of reduced gastric volume and ghrelin secretion, and increased satiety hormone secretion. There are various treatment options available including level IA evidence for postoperative gum chewing. In the future, surgical trials should include the assessment of appetite loss as a relevant outcome measure.

Relationship Between Circulating Metabolic Hormones and Their Central Receptors During Ovariectomy-Induced Weight Gain in Rats

Although increasing research focuses on the phenomenon of body weight gain in women after menopause, the complexity of body weight regulation and the array of models used to investigate it has proven to be challenging. Here, we used ovariectomized (OVX) rats, which rapidly gain weight, to determine if receptors for ghrelin, insulin, or leptin in the dorsal vagal complex (DVC), arcuate nucleus (ARC), or paraventricular nucleus (PVN) change during post-ovariectomy weight gain. Female Sprague-Dawley rats with ad libitum access to standard laboratory chow were bilaterally OVX or sham OVX. Subgroups were weighed and then terminated on day 5, 33, or 54 post-operatively; blood and brains were collected. ELISA kits were used to measure receptors for ghrelin, insulin, and leptin in the DVC, ARC, and PVN, as well as plasma ghrelin, insulin, and leptin. As expected, body weight increased rapidly after ovariectomy. However, ghrelin receptors did not change in any of the areas for either group, nor did circulating ghrelin. Thus, the receptor:hormone ratio indicated comparable ghrelin signaling in these CNS areas for both groups. Insulin receptors in the DVC and PVN decreased in the OVX group over time, increased in the PVN of the Sham group, and were unchanged in the ARC. These changes were accompanied by elevated circulating insulin in the OVX group. Thus, the receptor:hormone ratio indicated reduced insulin signaling in the DVC and PVN of OVX rats. Leptin receptors were unchanged in the DVC and ARC, but increased over time in the PVN of the Sham group. These changes were accompanied by elevated circulating leptin in both groups that was more pronounced in the OVX group. Thus, the receptor:hormone ratio indicated reduced leptin signaling in the DVC and PVN of both groups, but only in the OVX group for the ARC. Together, these data suggest that weight gain that occurs after removal of ovarian hormones by ovariectomy is associated with selective changes in metabolic hormone signaling in the CNS. While these changes may reflect behavioral or physiological alterations, it remains to be determined whether they cause post-ovariectomy weight gain or result from it.

Ghrelin attenuates methylmercury-induced oxidative stress in neuronal cells

Methylmercury (MeHg) is a global pollutant, which can cause damage to the central nervous system at both high-acute and chronic-low exposures, especially in vulnerable populations, such as children and pregnant women. Nowadays, acute-high poisoning is rare. However, chronic exposure to low MeHg concentrations via fish consumption remains a health concern. Current therapeutic strategies for MeHg poisoning are based on the use of chelators. However, these therapies have limited efficacy. Ghrelin is a gut hormone with an important role in regulating physiologic processes. It has been reported that ghrelin plays a protective role against the toxicity of several xenobiotics. Here, we explored the role of ghrelin as a putative protector against MeHg-induced oxidative stress. Our data show that ghrelin was able to ameliorate MeHg-induced reactive oxygen species (ROS) production in primary neuronal hypothalamic and hippocampal cultures. An analogous effect was observed in mouse hypothalamic neuronal GT 1-7 cells. Using this model, our novel findings show that antioxidant protection of ghrelin against MeHg is mediated by glutathione upregulation and induction of the NRF2/NQO1 pathway.

Diet-induced Fasting Ghrelin Elevation Reflects the Recovery of Insulin Sensitivity and Visceral Adiposity Regression

CONTEXT

Lower fasting ghrelin levels (FGL) are associated with obesity and metabolic syndrome.

OBJECTIVE

We aimed to explore the dynamics of FGL during weight loss and its metabolic and adiposity-related manifestations beyond weight loss.

METHODS

This was a secondary analysis of a clinical trial that randomized participants with abdominal obesity/dyslipidemia to 1 of 3 diets: healthy dietary guidelines (HDG), Mediterranean diet (MED), or green-MED diet, all combined with physical activity (PA). Both MED diets were similarly hypocaloric and included 28 g/day walnuts. The green-MED group further consumed green tea (3-4 cups/day) and a Wolffia globosa (Mankai) plant green shake. We measured FGL and quantified body fat depots by magnetic resonance imaging at baseline and after 18 months.

RESULTS

Among 294 participants (body mass index = 31.3 kg/m2; FGL = 504 ± 208 pg/mL; retention rate = 89.8%), lower FGL was associated with unfavorable cardiometabolic parameters such as higher visceral adipose tissue (VAT), intrahepatic fat, leptin, and blood pressure (P < 0.05 for all; multivariate models). The ∆FGL18-month differed between men (+7.3 ± 26.6%) and women (-9.2% ± 21.3%; P = 0.001). After 18 months of moderate and similar weight loss among the MED groups, FGL increased by 1.3%, 5.4%, and 10.5% in HDG, MED, and green-MED groups, respectively (P = 0.03 for green-MED vs HDG); sex-stratified analysis revealed similar changes in men only. Among men, FGL18-month elevation was associated with favorable changes in insulin resistance profile and VAT regression, after adjusting for relative weight loss (HbA1c: r = -0.216; homeostatic model of insulin resistance: r = -0.154; HDL-c: r = 0.147; VAT: r = -0.221; P < 0.05 for all). Insulin resistance and VAT remained inversely related with FGL elevation beyond that explained by weight loss (residual regression analyses; P < 0.05).

CONCLUSION

Diet-induced FGL elevation may reflect insulin sensitivity recovery and VAT regression beyond weight loss, specifically among men. Green-MED diet is associated with greater FGL elevation.

Effect of dietary supplementation of lauric acid on growth performance, antioxidative capacity, intestinal development and gut microbiota on black sea bream (Acanthopagrus schlegelii)

A feeding trial of eight weeks was conducted to examine the influence of food supplementation with lauric acid (LA) on Acanthopagrus schlegelii (juvenile black sea bream). A 24 percent fish meal baseline diet was created, while the other two diets were generated with dietary supplementation of graded points of LA at 0.1 percent and 0.8 percent, respectively. Each diet was given a triplicate tank with 20 fish weighing 6.22 ± 0.19 g. In comparison with the control group, the weight gain rate, growth rate, as well as feed efficiency of fish fed of 0.1 percent diet of LA were considerably (P < 0.05) greater. The total body and dorsal muscle proximate compositions did not change significantly between groups (P > 0.05). Triglyceride (TG) content was considerably (P < 0.05) greater in the LA-supplemented meals eating group in comparison with the control group. In the group eating LA-supplemented meals, the height of villus and the number of goblet cells/villus were considerably (P < 0.05) larger. The microbial makeup of the gut was also studied. The differences in phyla, class, and family level were not statistically significant (P > 0.05). Firmicutes in the phylum, Betaproteobacteri, Gammaproteobacteria, and Clostridia in the class, and Clostridiaceae in the family were all substantially increased with higher levels of LA supplementation (P < 0.05). According to the findings of this study, an LA-supplemented diet improves fish development, antioxidative capability, gut microbiota and intestinal health.

Neuroendocrine mechanisms of reproductive dysfunctions in undernourished condition

It is well known that undernourished conditions disturb female reproductive functions in many species, including humans. These alterations are mainly caused by a reduction in gonadotrophin-releasing hormone (GnRH) secretion from the hypothalamus. Evidence from the literature suggests that some hypothalamic factors play pivotal roles in the coordination of reproductive functions and energy homeostasis in response to environmental cues and internal nutritional status. Generally, anorexigenic/satiety-related factors, such as leptin, alpha-melanocyte-stimulating hormone, and proopiomelanocortin, promote GnRH secretion, whereas orexigenic factors, such as neuropeptide Y, agouti-related protein, orexin, and ghrelin, attenuate GnRH secretion. Conversely, gonadotrophin-inhibitory hormone, which exerts anti-GnRH and gonadotrophic effects, promotes feeding behavior in many species. In addition, the activity of kisspeptin, which is a potent stimulator of GnRH, is reduced by undernourished conditions. Under normal nutritional conditions, these factors are coordinated to maintain both feeding behavior and reproductive functions. However, in undernourished conditions their activity levels are markedly altered to promote feeding behavior and temporarily suppress reproductive functions, in order to prioritize the survival of the individual over that of the species.

Ghrelin and the Control of Energy Balance in Females

Ghrelin is considered one of the most potent orexigenic peptide hormones and one that promotes homeostatic and hedonic food intake. Research on ghrelin, however, has been conducted predominantly in males and particularly in male rodents. In female mammals the control of energy metabolism is complex and it involves the interaction between ovarian hormones like estrogen and progesterone, and metabolic hormones. In females, the role that ghrelin plays in promoting feeding and how this is impacted by ovarian hormones is not well understood. Basal ghrelin levels are higher in females than in males, and ghrelin sensitivity changes across the estrus cycle. Yet, responses to ghrelin are lower in female and seem dependent on circulating levels of ovarian hormones. In this review we discuss the role that ghrelin plays in regulating homeostatic and hedonic food intake in females, and how the effects of ghrelin interact with those of ovarian hormones to regulate feeding and energy balance.

Lower ghrelin levels does not impact the metabolic benefit induced by Roux-en-Y gastric bypass

OBJECTIVE

Roux-en-Y gastric bypass is an effective intervention for metabolic disorder. We aim to elucidate whether ghrelin contributes to weight reduction, and glycemic and lipid control after Roux-en-Y gastric bypass (RYGB).

DESIGN

Four-week-old WT and Ghrl-TSC1^-/- mice were fed high fat diet for 12 weeks before surgery, and continued to be on the same diet for 3 weeks after surgery. Body weight, food intake, glycemic and lipid metabolism were analyzed before and after surgery.

RESULTS

Gastric and circulating ghrelin was significantly increased in mice with RYGB surgery. Hypoghrelinemia elicited by deletion of TSC1 to activate mTOR signaling in gastric X/A like cells demonstrated no effect on weight reduction, glycemic and lipid control induced by Roux-en-Y gastric bypass surgery.

CONCLUSION

Lower ghrelin levels does not impact the metabolic benefit induced by Roux-en-Y gastric bypass.

Insights Into the Regulation of Offspring Growth by Maternally Derived Ghrelin

The regulation of fetal development by bioactive substances such as hormones and neuropeptides derived from the gestational mother is considered to be essential for the development of the fetus. On the other hand, it has been suggested that changes in the physiological state of the pregnant mother due to various factors may alter the secretion of these bioactive substances and induce metabolic changes in the offspring, such as obesity, overeating, and inflammation, thereby affecting postnatal growth and health. However, our knowledge of how gestational maternal bioactive substances modulate offspring physiology remains fragmented and lacks a systematic understanding. In this mini-review, we focus on ghrelin, which regulates growth and energy metabolism, to advance our understanding of the mechanisms by which maternally derived ghrelin regulates the growth and health of the offspring. Understanding the regulation of offspring growth by maternally-derived ghrelin is expected to clarify the fetal onset of metabolic abnormalities and lead to a better understanding of lifelong health in the next generation of offspring.

Hypothalamic Overexpression of Neurosecretory Protein GL Leads to Obesity in Male C57BL/6J Mice

INTRODUCTION

The mechanisms underlying obesity are not fully understood, necessitating the creation of novel animal models for the investigation of metabolic disorders. We have previously found that neurosecretory protein GL (NPGL), a newly identified hypothalamic neuropeptide, is involved in feeding behavior and fat accumulation in rats. However, the impact of NPGL on obesity remains unclear in any animal model. The present investigation sought to elucidate whether NPGL causes obesity in the obesity-prone mouse strain C57BL/6J.

METHODS

We overexpressed the NPGL-precursor gene (Npgl) in the hypothalamus using adeno-associated virus in male C57BL/6J mice fed normal chow (NC) or a high-calorie diet (HCD). After 9 weeks of Npgl overexpression, we measured adipose tissues, muscle, and several organ masses in addition to food intake and body mass. To assess the effects of Npgl overexpression on peripheral tissues, we analyzed mRNA expression of lipid metabolism-related genes by quantitative RT-PCR. Whole body energy consumption was assessed using an O2/CO2 metabolism measurement before an apparent increase in body mass.

RESULTS

Npgl overexpression increased food intake, body mass, adipose tissues and liver masses, and food efficiency under both NC and HCD, resulting in obesity observable within 8 weeks. Furthermore, we observed fat accumulation in adipose tissues and liver. Additionally, mRNA expression of lipid metabolism-related factors was increased in white adipose tissue and the liver after Npgl overexpression. Npgl overexpression inhibited energy expenditure during a dark period.

CONCLUSION

Taken together, the present study suggests that NPGL can act as an obesogenic factor that acts within a short period of time in mice. As a result, this Npgl overexpression-induced obesity can be widely applied to study the etiology of obesity from genes to behavior.

Potential Role of TRPV4 in Stretch-Induced Ghrelin Secretion and Obesity

Obesity is an important health problem, which can be prevented through appetite control. Ghrelin is an appetite-stimulating hormone considered to promote obesity. Thus, we examined whether gastric stretching affects ghrelin secretion. We investigated the role of transient receptor potential vanilloid 4 (TRPV4) in gastric glands in the regulation of ghrelin secretion. TRPV4 immunostaining was performed in tissue samples from 57 patients who underwent gastrectomy. TRPV4 expression was compared between patients with (body mass index (BMI) ≥ 30) and without (BMI <30) obesity. For in vitro experiments, we used MGN3-1 cells, a ghrelin-producing cell line derived from mice. To investigate the bioactivity of TRPV4, MGN3-1 cells were treated with TRPV4 agonists and antagonists, and changes in intracellular Ca²⁺ concentration were confirmed. The concentration of ghrelin in the cell supernatant was measured using the ELISA with and without 120% stretch stimulation. TRPV4 expression was significantly higher in patients with obesity than in those without at all sites, except the fornix. Immunostaining confirmed the expression of TRPV4 in MGN3-1 cells. TRPV4 agonist administration increased intracellular Ca²⁺ concentration and ghrelin secretion in MGN3-1 cells, whereas the administration of the agonist combined with the antagonist decreased intracellular Ca²⁺ concentration and ghrelin secretion. Ghrelin secretion significantly increased in response to a 120% stretch in MGN3-1 cells. However, secretion was not increased by stretch when cells were treated with a TRPV4 antagonist. TRPV4 regulates ghrelin secretion in response to stretch in the stomach, which may affect body weight.

The PACAP Paradox: Dynamic and Surprisingly Pleiotropic Actions in the Central Regulation of Energy Homeostasis

Pituitary Adenylate Cyclase-Activating Polypeptide (PACAP), a pleiotropic neuropeptide, is widely distributed throughout the body. The abundance of PACAP expression in the central and peripheral nervous systems, and years of accompanying experimental evidence, indicates that PACAP plays crucial roles in diverse biological processes ranging from autonomic regulation to neuroprotection. In addition, PACAP is also abundantly expressed in the hypothalamic areas like the ventromedial and arcuate nuclei (VMN and ARC, respectively), as well as other brain regions such as the nucleus accumbens (NAc), bed nucleus of stria terminalis (BNST), and ventral tegmental area (VTA) - suggesting that PACAP is capable of regulating energy homeostasis via both the homeostatic and hedonic energy balance circuitries. The evidence gathered over the years has increased our appreciation for its function in controlling energy balance. Therefore, this review aims to further probe how the pleiotropic actions of PACAP in regulating energy homeostasis is influenced by sex and dynamic changes in energy status. We start with a general overview of energy homeostasis, and then introduce the integral components of the homeostatic and hedonic energy balance circuitries. Next, we discuss sex differences inherent to the regulation of energy homeostasis via these two circuitries, as well as the activational effects of sex steroid hormones that bring about these intrinsic disparities between males and females. Finally, we explore the multifaceted role of PACAP in regulating homeostatic and hedonic feeding through its actions in regions like the NAc, BNST, and in particular the ARC, VMN and VTA that occur in sex- and energy status-dependent ways.

Global relationship between parent and child obesity: a systematic review and meta-analysis

BACKGROUND

The growing prevalence of overweight and/or obese children is an important public health problem in both developed and developing countries. Although the association of obesity between parents and their children is well known, its underlying mechanisms are not well established.

PURPOSE

This meta-analysis examined parent-child (PC) relationships in obesity and identified factors such as world region and country income level that may influence this relationship.

METHODS

We identified all related studies published between January 1, 2015 and May 31, 2020 by conducting a literature search using the MeSH terms "obesity," "overweight," "body mass index," "parent," "child," "associate," and "relate" in the PubMed database in English.

RESULTS

The meta-analysis of 23 studies that reported an odds ratio (OR) for parent and child obesity associations found a significant association between parents and children who were overweight or obese (pooled OR, 1.97; 95% confidence interval, 1.85-2.10). A meta-regression analysis was used to examine the sources of interstudy heterogeneity. The association between parent and child obesity was higher in Asia than in Europe and the Middle East and higher in high-income countries than in middle-or low-income countries. In addition, a higher association between parent and child obesity was found when both parents were obese than when only the father or mother was obese. This study from multiple countries indicates a significant PC relationship in weight status that varies according to PC pair type, parent and child weight statuses, world region, and country income level.

CONCLUSION

These results demonstrate that the risk of childhood obesity is greatly influenced by parental weight status and indicate that parents could play an important role in preventing child obesity.

Effects of low energy availability on female reproductive function

Background

It is known that metabolic and nutritional disturbances induce reproductive dysfunction in females. The main cause of these alterations is reduced gonadotrophin‐releasing hormone (GnRH) secretion from the hypothalamus, and the underlying mechanisms have gradually been elucidated.

Methods

The present review summarizes current knowledge about the effects of nutrition/metabolism on reproductive functions, especially focusing on the GnRH regulation system.

Main findings

Various central and peripheral factors are involved in the regulation of GnRH secretion, and alterations in their activity combine to affect GnRH neurons. Satiety‐related factors, i.e., leptin, insulin, and alpha‐melanocyte‐stimulating hormone, directly and indirectly stimulate GnRH secretion, whereas orexigenic factors, i.e., neuropeptide Y, Agouti‐related protein, orexin, and ghrelin, attenuate GnRH secretion. In addition, kisspeptin, which is a potent positive regulator of GnRH, expression is reduced by metabolic and nutritional disturbances.

Conclusion

These neuroendocrine systems may be defensive mechanisms, which help organisms to survive adverse conditions by temporarily suppressing reproduction.

GHS-R1a deficiency mitigates lipopolysaccharide-induced lung injury in mice via the downregulation of macrophage activity

Acute respiratory distress syndrome (ARDS) is a critical illness syndrome characterized by dysregulated pulmonary inflammation. Currently, effective pharmacological treatments for ARDS are unavailable. Ghrelin, an endogenous ligand for the growth hormone secretagogue receptor type 1a (GHS-R1a), has a pivotal role in regulating energy metabolism and immunomodulation. The role of endogenous ghrelin in ARDS remains unresolved. Herein, we investigated the role of endogenous ghrelin signaling by using GHS-R1a-null (ghsr^-/-) mice and lipopolysaccharide (LPS)-induced ARDS model. Ghsr^-/- mice survived longer than controls after LPS-induced lung injury. Ghsr^-/- mice showed lower levels of pro-inflammatory cytokines and higher oxygenation levels after lung injury. The peritoneal macrophages isolated from ghsr^-/- mice exhibited lower levels of cytokines production and oxygen consumption rate after LPS stimulation. Our results indicated that endogenous ghrelin plays a pivotal role in initiation and continuation in acute inflammatory response in LPS-induced ARDS model by modulating macrophage activity, and highlighted endogenous GHS-R1a signaling in macrophage as a potential therapeutic target in this relentless disease.

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

Background

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

Materials and methods

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

Results

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

Conclusion

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

Ghrelin is a signal to facilitate the utilization of fatty acids and save glucose by the liver, skeletal muscle, and adipose tissues in chicks

Ghrelin, classically known as a central appetite-stimulating hormone, has recently been recognized to play an important role in peripheral tissue energy metabolism. In chicken, contrary to mammal, ghrelin acts as an anorexia signal, increased by fasting and further elevated after refed. In the present study, the effect of ghrelin on glucose/lipid utilization by peripheral tissues was investigated. Injection of exogenous acyl ghrelin reduced plasma triglyceride and glucose levels of chickens at both fasting and fed status. In the in vitro cultured chicken primary hepatocytes, adipocytes, and myoblasts, ghrelin suppressed glucose uptake, stimulated fatty acids uptake and oxidation, and decreased TG content. In hepatocyte, ghrelin increased the activities of LPL and HL, and upregulated the expression levels of gene ACC, CPT1, and PPARα. Ghrelin treatment markedly increased the protein level of p-ACC, PPARγ, PGC1α, and CPT1 in hepatocytes, adipocytes and myoblasts. Inhibition of AMPK activity by Compound C had no influence on glucose uptake by hepatocyte, adipocyte, and myoblast, but further amplified the stimulated fatty acid uptake of adipocyte by ghrelin. The present result demonstrates that ghrelin facilitates the uptake and oxidation of fatty acid and cut down the utilization of glucose by the liver, muscle, and adipose tissues. The result suggests that ghrelin functions as a signal of fatty acid oxidation. The study provides a vital framework for understanding the intrinsic role of ghrelin as a crucial factor in the concerted regulation of metabolic substrate of hepatocytes, adipocytes, and myoblasts.

Insulin signalling in tanycytes gates hypothalamic insulin uptake and regulation of AgRP neuron activity

Insulin acts on neurons and glial cells to regulate systemic glucose metabolism and feeding. However, the mechanisms of insulin access in discrete brain regions are incompletely defined. Here we show that insulin receptors in tanycytes, but not in brain endothelial cells, are required to regulate insulin access to the hypothalamic arcuate nucleus. Mice lacking insulin receptors in tanycytes (IR^∆Tan mice) exhibit systemic insulin resistance, while displaying normal food intake and energy expenditure. Tanycytic insulin receptors are also necessary for the orexigenic effects of ghrelin, but not for the anorexic effects of leptin. IR^∆Tan mice exhibit increased agouti-related peptide (AgRP) neuronal activity, while displaying blunted AgRP neuronal adaptations to feeding-related stimuli. Lastly, a highly palatable food decreases tanycytic and arcuate nucleus insulin signalling to levels comparable to those seen in IR^∆Tan mice. These changes are rooted in modifications of cellular stress responses and of mitochondrial protein quality control in tanycytes. Conclusively, we reveal a critical role of tanycyte insulin receptors in gating feeding-state-dependent regulation of AgRP neurons and systemic insulin sensitivity, and show that insulin resistance in tanycytes contributes to the pleiotropic manifestations of obesity-associated insulin resistance.

Changes in urinary glucose concentration and body weight in patients treated with the selective SGLT2 inhibitor luseogliflozin

AIMS

We investigated the effects of the SGLT2 inhibitor luseogliflozin on blood and urinary glucose and body weight.

METHODS

Luseogliflozin 2.5 mg was administered once daily for 24 weeks to 30 outpatients with type 2 diabetes. Urinary glucose concentration, continuous glucose monitoring values, HbA1c, fasting glucose, and body weight were evaluated. Correlations with urinary glucose, subcutaneous/visceral fat mass, insulin, EPA/AA ratio, plasma free fatty acids, ghrelin, blood ketones, plasma 1,5-anhydro-D-glucitol were evaluated.

RESULTS

Urinary glucose significantly increased from 11.1 ± 11.8 g at Week -4 to 84.5 ± 46.8 g at Week 24. HbA1c significantly declined from 7.88 ± 0.88% to 7.36 ± 1.13% at Week 24. Mean blood glucose significantly decreased from 149.6 ± 41.8 to 131.6 ± 31.1 mg/dL at Week 24. Subcutaneous and visceral fat mass was also significantly decreased, as were AST and ALT (P < 0.01). Blood urea nitrogen was significantly increased, and urate significantly decreased from 5.04 ± 1.07 to 4.53 ± 0.94 mg/dL. The homeostasis model assessment ratio remained significantly improved throughout the treatment period. Acyl ghrelin levels remained constant but des-acyl ghrelin increased significantly.

CONCLUSIONS

Luseogliflozin monotherapy resulted in an improvement in blood glucose, a decrease in body weight, and decreased insulin resistance. Luseogliflozin appears to be an effective therapy for obese diabetics.

Chronodisruption by chronic jetlag impacts metabolic and gastrointestinal homeostasis in male mice

AIM

Chronodisruption desynchronizes peripheral clocks and leads to metabolic diseases. Feeding cues are important synchronizers of peripheral clocks and influence rhythmic oscillations in intestinal microbiota and their metabolites. We investigated whether chronic jetlag, mimicking frequent time zone travelling, affected the diurnal fluctuations in faecal short-chain fatty acid (SCFA) levels, that feed back to the gut clock to regulate rhythmicity in gut function.

METHODS

Rhythms in faecal SCFAs levels and in the expression of clock genes and epithelial markers were measured in the colonic mucosa of control and jetlagged mice. The entraining effect of SCFAs on the rhythm in clock gene mRNA expression was studied in primary colonic crypts. The role of the circadian clock in epithelial marker expression was studied in Arntl^-/- mice.

RESULTS

Chronic jetlag increased body weight gain and abolished the day/night food intake pattern which resulted in a phase-delay in the rhythm of faecal SCFAs that paralleled the shift in the expression of mucosal clock genes. This effect was mimicked by stimulation of primary colonic crypts from control mice with SCFAs. Jetlag abolished the rhythm in Tnfα, proglucagon and ghrelin expression but not in the expression of tight junction markers. Only a dampening in plasma glucagon-like peptide-1 but not in ghrelin levels was observed. Rhythms in ghrelin but not proglucagon mRNA expression were abolished in Arntl^-/- mice.

CONCLUSION

The altered food intake pattern during chronodisruption corresponds with the changes in rhythmicity of SCFA levels that entrain clock genes to affect rhythms in mRNA expression of gut epithelial markers.

Effect of Essential Oils on the Oxyntopeptic Cells and Somatostatin and Ghrelin Immunoreactive Cells in the European Sea Bass (Dicentrarchus labrax) Gastric Mucosa

The current work was designed to assess the effect of feed supplemented with essential oils (EOs) on the histological features in sea bass's gastric mucosa. Fish were fed three diets: control diet (CTR), HERBAL MIX® made with natural EOs (N-EOs), or HERBAL MIX® made with artificial EOs obtained by synthesis (S-EOs) during a 117-day feeding trial. Thereafter, the oxyntopeptic cells (OPs) and the ghrelin (GHR) and somatostatin (SOM) enteroendocrine cells (EECs) in the gastric mucosa were evaluated. The Na+K+-ATPase antibody was used to label OPs, while, for the EECs, anti-SOM and anti-GHR antibody were used. The highest density of OP immunoreactive (IR) area was in the CTR group (0.66 mm2 ± 0.1). The OP-IR area was reduced in the N-EO diet group (0.22 mm2 ± 1; CTR vs. N-EOs, p < 0.005), while in the S-EO diet group (0.39 mm2 ± 1) a trend was observed. We observed an increase of the number of SOM-IR cells in the N-EO diet (15.6 ± 4.2) compared to that in the CTR (11.8 ± 3.7) (N-EOs vs. CTR; p < 0.05), but not in the S-EOs diet. These observations will provide a basis to advance current knowledge on the anatomy and digestive physiology of this species in relation to pro-heath feeds.

Naturally occurring mutations in G protein-coupled receptors associated with obesity and type 2 diabetes mellitus

G protein-coupled receptors (GPCRs) are the largest family of membrane receptors involved in the regulation of almost all known physiological processes. Dysfunctions of GPCR-mediated signaling have been shown to cause various diseases. The prevalence of obesity and type 2 diabetes mellitus (T2DM), two strongly associated disorders, is increasing worldwide, with tremendous economical and health burden. New safer and more efficacious drugs are required for successful weight reduction and T2DM treatment. Multiple GPCRs are involved in the regulation of energy and glucose homeostasis. Mutations in these GPCRs contribute to the development and progression of obesity and T2DM. Therefore, these receptors can be therapeutic targets for obesity and T2DM. Indeed some of these receptors, such as melanocortin-4 receptor and glucagon-like peptide 1 receptor, have provided important new drugs for treating obesity and T2DM. This review will focus on the naturally occurring mutations of several GPCRs associated with obesity and T2DM, especially incorporating recent large genomic data and insights from structure-function studies, providing leads for future investigations.