Measuring IP3 Generation in Real-Time Using a NanoBiT Luminescence Biosensor.

G protein-coupled receptors that activate Gq/11 regulate a range of physiological processes including neurotransmission, energy homeostasis, blood pressure regulation, and calcium homeostasis. Activation of Gq/11-coupled receptors stimulates the generation of inositol 1,4,5-trisphosphate (IP3), which mobilizes intracellular calcium release from the endoplasmic reticulum. This chapter describes an assay that uses a NanoBiT-IP3 luminescent biosensor to detect increases in IP3 in live cells. It describes how to perform these assays to assess signaling by the ghrelin receptor and the calcium-sensing receptor in HEK293 cells.

Effect of Hyperinsulinemia on Leptin and Ghrelin Levels in Polycystic Ovarian Syndrome: A Meta-Analysis.

Polycystic ovarian syndrome (PCOS) is the most common endocrine disorder in women of reproductive age. Leptin and ghrelin are important markers in PCOS due to their correlation with obesity, insulin resistance, and fertility. There is currently a debate in the literature about whether altered leptin and ghrelin levels in women with PCOS are a result of the disease itself or if they are due to factors such as the hyperinsulinemic state characteristic of PCOS. This meta-analysis aims to assess if insulin levels impact leptin and ghrelin levels in PCOS.  Eight case-control studies assessing the relationship between insulin and leptin, as well as five case-control studies assessing the relationship between insulin and ghrelin, were identified in PubMed. Pearson's correlation coefficient (PCC) and the sample size were extracted, and two meta-analyses were conducted using a random-effects model. Total heterogeneity (I2) with a confidence interval of 95% was then determined. "Leave-one out" diagnostics were calculated for each case. If a study was identified as being significantly influential, the study was removed from the data set, and the trim and fill procedure was applied. Publication bias was assessed using Egger's regression test and rank correlation test.  Our results showed a moderate positive relationship (r=0.56, 95% confidence interval (CI) (0.42, 0.71), with substantial heterogeneity I2=81.35%, 95% CI (25.2799, 88.2451)) between insulin and leptin levels, and a moderate negative relationship (r=-0.33, 95% CI (-0.43, -0.24)), with low heterogeneity (I2=0.00%, 95% CI (0.0000, 80.8159)) between insulin and ghrelin levels. Therefore, there is a significant relationship between insulin and higher leptin and lower ghrelin levels in women with PCOS. Better insulin control may have a positive effect on fertility, appetite, weight, body image, and quality of life in these women. This correlation is likely multifactorial, and further studies are needed to isolate factors influencing these hormones.

Gut Hormones: Possible Mediators of Addictive Disorders?

BACKGROUND: Alcohol and drug dependence are major health and economic burdens to society. One of the major challenges to reducing this burden will be to develop more effective and better tolerated medications that target alternative mechanisms in the brain. While the dopamine system has been well characterized for mediating the reward value of drugs, there is evidence that the endocrine system also conveys signals to the same neural systems using gut hormones. SUMMARY: These gut hormones, produced in the stomach and intestine and that regulate food intake, have also been shown to control the use of other substances, such as alcohol and drugs of abuse. Examples of such hormones are ghrelin and glucagon-like peptide-1, which exert their effects on dopamine transmission in parts of the brain known to be involved in some of the core features of addiction, such as reward sensitivity. KEY MESSAGES: This raises the possibility that gut hormone systems may play a pivotal role in addictive disorders. This review will briefly outline emerging evidence that the ghrelin and glucagon-like peptide-1 hormones are contrasting mediators of alcohol and drug use and may present a promising alternative target for treatment intervention in addictive disorders.

The Impact of Gastrointestinal Hormones on Human Adipose Tissue Function.

BACKGROUND: Obesity is a global issue, the development of which depends on many interacting factors. Among these, hormones secreted in the gastrointestinal tract play an important role. The aim of this review was to assess the impact of these hormones on the functions of adipose tissue. METHODS: The analysis was based on the latest research concerning both adipose tissue and gastrointestinal hormones. RESULTS: It was found that these hormones can significantly affect adipose tissue, both directly and indirectly. Some hormones, when secreted in excess, can stimulate adipose tissue formation processes, while others can inhibit them. The impact of hormones depends on the location and type of adipose tissue as well as the physiological state of the body. It should also be noted that no hormone acts in isolation but in close cooperation with other factors. CONCLUSIONS: The relationship between gastrointestinal hormones and adipose tissue, and their role in obesity, is a complex and evolving field of study. Further research is necessary, particularly into the interactions between hormones and other factors, as well as their mutual interactions.

Physiologically relevant lactate accumulation from exercise or peripheral injection does not alter central or peripheral appetite signaling in mice.

Lactate has been implicated in exercise-induced appetite suppression though little work has explored the mechanisms underpinning its role. Recent work suggests lactate accumulation via exercise and intracerebroventricular injection can alter central appetite regulating pathways, though a supraphysiological dose of lactate was administered centrally and there was no assessment of peripheral appetite markers. Therefore, we examined how physiologically relevant lactate accumulation via exercise or intraperitoneal injection altered central and peripheral appetite signaling pathways and whether the lactate dehydrogenase inhibitor oxamate could blunt any exercise effect. Forty 10-week-old C57BL/6 J male mice (n = 10/group) were assigned to either: 1) sedentary (SED + SAL; saline); 2) exercise (EX+SAL; saline); 3) exercise with oxamate (EX+OX; 750 mg‧kg-1 body mass); or 4) lactate (SED + LAC; 1.0 g‧kg-1 body mass). Blood, stomach, and hypothalamus samples were collected ∼2 h post-exercise/injection. Though oxamate blunted exercise-induced lactate accumulation compared to the EX+SAL condition (P = 0.044, d = 0.73), there were no differences in circulating acylated ghrelin or stomach ghrelin O-acyltransferase content between groups (P > 0.213, ηp2<0.125). There were also no differences in hypothalamic content for neuropeptide Y, proopiomelanocortin, agouti-related peptide, and alpha melanocyte-stimulating hormone (P > 0.150, ηp2<0.170). Exercise did increase phosphorylated-total signal transducer and activator of transcription 3 (pSTAT3) compared to EX+OX (p = 0.065, d = 1.23) but there were no differences in other markers of lactate signaling: phosphorylated-total adenosine monophosphate activated protein kinase, and protein kinase b (P > 0.121, ηp2<0.160). Our results suggest that lactate accumulation due to exercise or peripheral injection does not alter central or peripheral appetite signaling when measured 2 h post-exercise/injection, though pSTAT3 was blunted with oxamate.

Unacylated Ghrelin Protects Against Age-Related Loss of Muscle Mass and Contractile Dysfunction in Skeletal Muscle.

Sarcopenia, the progressive loss of muscle mass and function, universally affects older adults and is closely associated with frailty and reduced quality of life. Despite the inevitable consequences of sarcopenia and its relevance to healthspan, no pharmacological therapies are currently available. Ghrelin is a gut-released hormone that increases appetite and body weight through acylation. Acylated ghrelin activates its receptor, growth hormone secretagogue receptor 1a (GHSR1a), in the brain by binding to it. Studies have demonstrated that acyl and unacylated ghrelin (UnAG) both have protective effects against acute pathological conditions independent of receptor activation. Here, we investigated the long-term effects of UnAG in age-associated muscle atrophy and contractile dysfunction in mice. Four-month-old and 18-month-old mice were subjected to either UnAG or control treatment for 10 months. UnAG did not affect food consumption or body weight. Gastrocnemius and quadriceps muscle weights were reduced by 20%-30% with age, which was partially protected against by UnAG. Specific force, force per cross-sectional area, measured in isolated extensor digitorum longus muscle was diminished by 30% in old mice; however, UnAG prevented the loss of specific force. UnAG also protected from decreases in mitochondrial respiration and increases in hydrogen peroxide generation of skeletal muscle of old mice. Results of bulk mRNA-seq analysis and our contractile function data show that UnAG reversed neuromuscular junction impairment that occurs with age. Collectively, our data revealed the direct role of UnAG in mitigating sarcopenia in mice, independent of food consumption or body weight, implicating UnAG treatment as a potential therapy against sarcopenia.

Design, Synthesis, and Preclinical Evaluation of a High-Affinity 18F-Labeled Radioligand for Myocardial Growth Hormone Secretagogue Receptor Before and After Myocardial Infarction.

The peptide hormone ghrelin is produced in cardiomyocytes and acts through the myocardial growth hormone secretagogue receptor (GHSR) to promote cardiomyocyte survival. Administration of ghrelin may have therapeutic effects on post-myocardial infarction (MI) outcomes. Therefore, there is a need to develop molecular imaging probes that can track the dynamics of GHSR in health and disease to better predict the effectiveness of ghrelin-based therapeutics. We designed a high-affinity GHSR ligand labeled with 18F for imaging by PET and characterized its in vivo properties in a canine model of MI. Methods: We rationally designed and radiolabeled with 18F a quinazolinone derivative ([18F]LCE470) with subnanomolar binding affinity to GHSR. We determined the sensitivity and in vivo and ex vivo specificity of [18F]LCE470 in a canine model of surgically induced MI using PET/MRI, which allowed for anatomic localization of tracer uptake and simultaneous determination of global cardiac function. Uptake of [18F]LCE470 was determined by time-activity curve and SUV analysis in 3 regions of the left ventricle-area of infarct, territory served by the left circumflex coronary artery, and remote myocardium-over a period of 1.5 y. Changes in cardiac perfusion were tracked by [13N]NH3 PET. Results: The receptor binding affinity of LCE470 was measured at 0.33 nM, the highest known receptor binding affinity for a radiolabeled GHSR ligand. In vivo blocking studies in healthy hounds and ex vivo blocking studies in myocardial tissue showed the specificity of [18F]LCE470, and sensitivity was demonstrated by a positive correlation between tracer uptake and GHSR abundance. Post-MI changes in [18F]LCE470 uptake occurred independently of perfusion tracer distributions and changes in global cardiac function. We found that the regional distribution of [18F]LCE470 within the left ventricle diverged significantly within 1 d after MI and remained that way throughout the 1.5-y duration of the study. Conclusion: [18F]LCE470 is a high-affinity PET tracer that can detect changes in the regional distribution of myocardial GHSR after MI. In vivo PET molecular imaging of the global dynamics of GHSR may lead to improved GHSR-based therapeutics in the treatment of post-MI remodeling.

The LEAP2 Response to Cancer-Related Anorexia-Cachexia Syndrome in Male Mice and Patients.

The hormone ghrelin serves a protective role in cancer-related anorexia-cachexia syndrome (CACS)-a condition in which plasma levels of ghrelin rise, its administration lessens CACS severity, and experimentally reduced signaling by its receptor (GHSR) worsens fat loss and anorexia and accelerates death. Yet, actions for the related hormone liver-expressed antimicrobial peptide-2 (LEAP2), which is an endogenous GHSR antagonist, are unexplored in CACS. Here, we found that plasma LEAP2 and LEAP2/ghrelin ratio were lower in Lewis lung carcinoma (LLC) and RM-9 prostate cancer CACS mouse models. Ghrelin deletion exaggerated losses of tumor-free body weight and fat mass, reduced food intake, reduced soleus muscle weight, and/or lowered grip strength in LLC or RM-9 tumor-bearing mice. LEAP2 deletion lessened reductions in tumor-free body weight and fat mass and increased food intake in LLC or RM-9 tumor-bearing mice. In a 55-subject cohort of patients with CACS or weight-stable cancer, the plasma LEAP2/total ghrelin ratio was negatively correlated with 6-month weight change preceding blood collection. These data demonstrate that ghrelin deletion exacerbates CACS in the LLC and RM-9 tumor-bearing mouse models while contrastingly, LEAP2 deletion reduces measures of CACS in these tumor-bearing mouse models. Further, they suggest that lower plasma LEAP2/ghrelin ratio protects against worsened CACS.

Protective role of ghrelin against 6PPD-quinone-induced neurotoxicity in zebrafish larvae (Danio rerio) via the GHSR pathway.

The toxicity mechanisms of N-(1,3-dimethylbutyl)-N'-phenyl-p-phenylenediamine quinone (6PPD-Q), an antioxidant derivative of 6PPD via ozone reaction commonly used in rubber and tire industries, were investigated in zebrafish larvae with concentrations ranging from 0 to 50 µg/L. Despite normal hatchability, 6PPD-Q exposure led to reduced body length and swimming distance in 120 hours post-fertilization (hpf) larvae. At the highest concentration (50 µg/L), 6PPD-Q significantly impaired dopaminergic neuron development and neurotransmitter levels, including dopamine, 5-hydroxytryptamine, and glutamate. Transcriptome profiling unveiled perturbations in growth and developmental gene expression, such as upregulation of runx2a, runx2b, and ghrl (ghrelin and obestatin prepropeptide), and downregulation of stat1b, auto1, and cidea. Notably, anamorelin, a growth hormone secretagogue receptor (GHSR) agonist, recovered the behavioral deficits induced by 6PPD-Q, implying a neuroprotective role of ghrelin possibly mediated via the ghrelin/GHSR pathway. Collectively, our findings indicate that ghrelin upregulation may counteract 6PPD-Q toxicity in zebrafish larvae, shedding light on potential therapeutic avenues for mitigating the adverse effects of this antioxidant byproduct.

Transcription repression of estrogen receptor alpha by ghrelin/Gq/11/YAP signaling in granulosa cells promotes polycystic ovary syndrome.

Polycystic ovarian syndrome (PCOS) is a prevalent endocrinological disorder affected by ghrelin. This study aimed to investigate the molecular mechanisms underlying the effects of ghrelin on PCOS manifestations in mice and to assess the therapeutic potential of ghrelin. Female C57BL/6 mice were subcutaneously injected with 6 mg/100 g dehydroepiandrosterone (DHEA) for 20 days to induce PCOS. Alterations in reproductive cycles, ovarian morphology, serum sex hormone levels, and related signaling markers were examined. Furthermore, ghrelin-induced effects on granulosa cells and the role of ghrelin/Gq/11/ Yes-associated protein (YAP) signaling were studied by silencing Gαq/11 or YAP using si-RNAs. Finally, we evaluated the therapeutic potential of anti-ghrelin antibodies in DHEA-induced PCOS mice. DHEA administration led to significant PCOS-associated changes including weight gain, disrupted estrous cycles, ovarian morphological alterations, and hormonal imbalances in mice, with elevated Gαq/11 and acylated ghrelin expression, which was also noted in PCOS patients. However, treatment with anti-ghrelin antibodies effectively managed DHEA-induced damage in PCOS mice. In vitro, ghrelin exposure resulted in granulosa cell injury and modulated estrogen receptors alpha (ERα) and YAP protein levels, whereas silencing YAP and Gαq/11 reversed ghrelin-induced detrimental effects and up-regulated ERα expression. This study revealed that DHEA-induced PCOS traits in mice could be improved by anti-ghrelin antibodies, with the ghrelin/Gq/11/YAP signaling pathway identified as a crucial mediator in granulosa cells, affecting ERα transcription to regulate PCOS. These findings suggest a potential therapeutic strategy for the treatment of PCOS.

Hunger signalling in the olfactory bulb primes exploration, food-seeking and peripheral metabolism.

OBJECTIVE: Although the metabolic state of an organism affects olfactory function, the precise mechanisms and their impact on behavior and metabolism remain unknown. Here, we assess whether ghrelin receptors (GHSRs) in the olfactory bulb (OB) increase olfactory function and influence foraging behaviors and metabolism. METHODS: We performed a detailed behavioural and metabolic analysis in mice lacking GHSRs in the OB (OBGHSR deletion). We also analsyed OB scRNA-seq and spatial transcriptomic datasets to assess GHSR+ cells in the main and accessory olfactory bulbs, as well as the anterior olfactory nucleus. RESULTS: OBGHSR deletion affected olfactory discrimination and habituation to both food and non-food odors. Anxiety-like and depression-like behaviors were significantly greater after OBGHSR deletion, whereas exploratory behavior was reduced, with the greatest effect under fasted conditions. OBGHSR deletion impacted feeding behavior as evidenced by altered bout number and duration, as well as buried food-seeking. OBGHSR deletion increased body weight and fat mass, spared fat utilisation on a chow diet and impaired glucose metabolism indicating metabolic dysfunction. Cross referenced analysis of OB scRNA-seq and spatial transcriptomic datasets revealed GHSR+ glutamate neurons in the main and accessory olfactory bulbs, as well as the anterior olfactory nucleus. Ablation of glutamate neurons in the OB reduced ghrelin-induced food finding and phenocopied results seen after OBGHSR deletion. CONCLUSIONS: OBGHSRs help to maintain olfactory function, particularly during hunger, and facilitate behavioral adaptations that optimise food-seeking in anxiogenic environments, priming metabolic pathways in preparation for food consumption.

Intragastric botulinum toxin injection directly regulates ghrelin expression via reactive oxygen species and NF-κB signaling.

AIMS: One effective clinical strategy to combat obesity is intragastric botulinum toxin (BTX) injection, which increases gastric emptying time and regulates appetite. However, it remains unknown if and how BTX affects ghrelin levels. MATERIALS AND METHODS: An obese animal model was established by feeding male mice with high-fat diet (HFD). BTX was administered by subserosal injection in the antrum via an upper midline laparotomy. The mice were monitored in terms of body weight and blood biochemical parameters. Glucose utility and insulin sensitivity were measured by intraperitoneal glucose and insulin tolerance tests. Additionally, stomach and liver were histologically examined after BTX treatment. AGS gastric adenocarcinoma cells were used to investigate the molecular mechanism by which BTX affects ghrelin expression. KEY FINDINGS: In HFD-fed mice, BTX injection significantly decreased both food intake and body weight over a 3-week monitoring period. Moreover, HFD-induced hyperglycemia, hyperinsulinemia, dyslipidemia and obesity readouts were improved after BTX injection. Importantly, mice also exhibited decreased plasma and gastric ghrelin levels after BTX injection. In cultured AGS cells, BTX significantly increased reactive oxygen species (ROS) levels and activated nuclear factor-κB (NF-κB), which led to decreased ghrelin expression. Pre-treatment with inhibitors of either ROS or NF-κB reversed the effects of BTX on ghrelin expression in the cultured cells. SIGNIFICANCE: BTX decreases ghrelin expression in HFD-fed animals and in AGS cells through an ROS/NF-κB-dependent pathway. This mechanism may contribute to decreased food intake in obese subjects receiving intragastric BTX injection for weight control.

Leptin, ghrelin and high-molecular-weight adiponectin in relation to anxiety in older adults.

BACKGROUND: Leptin and ghrelin have been linked to depressive symptoms in older adults. There is a large overlap between depression and anxiety in this group. It is unclear whether the same associations exist with anxiety. Adiponectin has an inverse association with anxiety in older adults. However, the association between the most biologically active isoform - high-molecular-weight (HMW) adiponectin - and anxiety has not been previously reported. METHODS: We analyzed the association between leptin, ghrelin and HMW adiponectin and general symptoms of anxiety (HADS-A score ≥ 7) at baseline and after three years of follow-up in a population based cohort of older adults in the Netherlands (n = 898) using multivariable logistic regression analyses. RESULTS: For leptin there was significant effect modification by sex. We found a positive association between leptin and general symptoms of anxiety in men at baseline and after three years of follow-up after adjusting for depressive symptoms, when comparing the third to the first leptin tertile (T3 vs T1 OR 3.40, 95 % CI 1.08 - 10.78). We found no significant associations for ghrelin. HMW adiponectin was associated with general symptoms of anxiety at follow up. We found a positive association both before and after adjustment for depressive symptoms (T3 vs T1 OR 3.26, 95 % CI 1.36 - 7.83). CONCLUSIONS: Our results showed significant associations in men only between leptin and HMW adiponectin and general symptoms of anxiety after three years of follow up. Our findings contribute to further insight into the pathophysiology of anxiety in older adults. However, further research is necessary as we show associations.

Adipokines in Neuroendocrine Tumors: An Evaluation of the Serum Levels of Ghrelin and Leptin.

Neuroendocrine tumors (NETs) are a heterogeneous group of tumors that are characteristically different from other malignancies. The difference is not only in the prognosis, which is usually more favorable in such patients, but also in the high clinical progression of the disease, where NET patients do not experience the cachexia typical of other malignancies. The purposes of this study were to evaluate the ghrelin and leptin levels in a group of patients diagnosed with gastroenteropancreatic neuroendocrine tumors (GEP-NETs) and bronchopulmonary neuroendocrine tumors (BP-NETs) and to analyze the relationship between the body mass index (BMI), cachexia and selected NET markers. The study group comprised 52 patients with GEP-NETs and BP-NETs, while the controls comprised 67 healthy volunteers. The ghrelin and leptin concentrations were determined in both groups. The concentrations of chromogranin A, serotonin, 5-hydroxyindoleacetic acid (5-HIAA), total cholesterol, triglycerides and glucose were determined in the study group. Characteristics of the study group and of the controls were defined by age, sex and BMI, and the effects of these factors on the ghrelin and leptin concentrations were assessed. The data obtained were subject to statistical analysis. The study cohort showed higher levels of ghrelin as compared to the controls (142.31 ± 26.00 vs. 121.49 ± 35.45, p = 0.016), and no statistical difference in the levels of leptin (11.15 ± 9.6 vs. 12.94 ± 20.30, p = 0.439) were observed. Significantly lower levels of leptin were found in patients with the small intestine primary location, as compared to individuals with primary locations in the lungs and the pancreas (4.9 ± 6.49 vs. 16.97 ± 15.76, p = 0.045, and 4.9 ± 6.49 vs. 12.89 ± 8.56, p = 0.016, respectively). A positive correlation was observed between the leptin levels and the BMIs in both the study group (rS = 0.33, p = 0.016) and the controls (rS = 0.41, p = 0.001). The study group showed a negative correlation between the leptin levels and 5-HIAA (rS = -0.32, p = 0.026) and a negative correlation between the leptin levels and Ki-67 (rS = -0.33, p = 0.018). The control group showed negative correlations between the ghrelin and the volunteer age (rS = -0.41, p = 0.008), the leptin and the volunteer age (rS = -0.44, p < 0.001), the leptin and total cholesterol (rS = -0.24, p < 0.049) as well as the leptin and triglycerides (rS = -0.33, p < 0.006). The current study emphasized the importance of the markers' determination, where ghrelin appears as a valuable diagnostic biomarker in NETs, probably responsible for maintaining a normal BMI, despite the progression of the disease.

The protective effect of Ghrelin peptide on doxorubicin hydrochloride induced heart failure in rats.

BACKGROUND: To investigate the protective effect and mechanism of Ghrelin on Doxorubicin (Dox) hydrochloride induced heart failure (HF) and myocardial injury in rats. METHODS: 45 rats were randomly divided into control group, HF group and Ghrelin group. Dox hydrochloride was injected intraperitoneally to establish the model of HF in rats of HF group and Ghrelin group. Rats in the Ghrelin group were given intraperitoneal injection of Ghrelin twice a day, and rats in the HF group and control group were given equal volume of normal saline for a total of 6 weeks. The changes of echocardiography, cardiac hemodynamics, myocardial histology and plasma inflammatory factors were observed. RESULTS: After the Ghrelin intervention, compared with the HF group, the left ventricular end-diastolic diameter (LVDD) and left ventricular end-systolic diameter (LVSD) in the Ghrelin group was markedly reduced (P < 0.05), and left ventricular ejection fraction (LVEF) was significantly increased (P < 0.05). Compared with HF group, the left ventricular systolic pressure (LVSP), maximum rate of increase in left ventricular pressure (+ dP/dtmax) and maximum rate of decrease in left ventricular pressure (- dP/dtmax) of Ghrelin group was remarkedly increased (P < 0.05), left ventricular diastolic pressure (LVDP) decreased (P < 0.05). In the Ghrelin group, the degree and extent of cardiomyocyte degeneration and necrosis were remarkedly reduced compared with the HF group. The levels of TNF-α and iNOS in Ghrelin group were notably lower than those in HF group (P < 0.05), the IL-10 level increased markedly (P < 0.05). CONCLUSION: Ghrelin may reduce Dox-induced myocardial injury and improve cardiac function in rats by regulating inflammation and oxidative stress.

Therapeutic potential of ghrelin/GOAT/GHSR system in gastrointestinal disorders.

Ghrelin, a peptide primarily secreted in the stomach, acts via the growth hormone secretagogue receptor (GHSR). It regulates several physiological processes, such as feeding behavior, energy homeostasis, glucose and lipid metabolism, cardiovascular function, bone formation, stress response, and learning. GHSR exhibits significant expression within the central nervous system. However, numerous murine studies indicate that ghrelin is limited in its ability to enter the brain from the bloodstream and is primarily confined to specific regions, such as arcuate nucleus (ARC) and median eminence (ME). Nevertheless, the central ghrelin system plays an essential role in regulating feeding behavior. Furthermore, the role of vagal afferent fibers in regulating the functions of ghrelin remains a major topic of discussion among researchers. In recent times, numerous studies have elucidated the substantial therapeutic potential of ghrelin in most gastrointestinal (GI) diseases. This has led to the development of numerous pharmaceutical agents that target the ghrelin system, some of which are currently under examination in clinical trials. Furthermore, ghrelin is speculated to serve as a promising biomarker for GI tumors, which indicates its potential use in tumor grade and stage evaluation. This review presents a summary of recent findings in research conducted on both animals and humans, highlighting the therapeutic properties of ghrelin system in GI disorders.

Intermittent protein restriction elevates food intake and plasma ghrelin in male mice.

Low-protein diets affect body weight, body composition, food intake, and food preferences in mice. Furthermore, single periods of protein restriction can have lasting effects on these parameters. We sought to examine the effect of multiple, short, bouts of protein restriction, relative to long-term maintenance on either a control (NR) or protein-restricted (PR) diet. We found that male mice experiencing intermittent protein restriction (IPR) were indistinguishable from NR mice in terms of body weight and composition, but had food intake and plasma ghrelin as high as mice on PR diet, even when they were returned to control diet. This was not found in female mice. The results of this experiment highlight the importance of diet history on food intake and ghrelin levels in male mice, and the difference in how PR diet might affect male and female mice.

Changes in lipid profile parameters depending on the a1166c polymorphism of the angiotensin II type I receptor gene as a predictor of arterial hypertension.

OBJECTIVE: Aim: To investigate lipid profile parameters depending the polymorphism of the A1166C I type gene receptor of the angiotensin II as a predictor of arterial hypertension. PATIENTS AND METHODS: Materials and Methods: The study involved 86 patients with arterial hypertension. The control group consisted of 30 practically healthy individuals. Indicators of lipid metabolism in the blood serum of patients were determined using "Lachema" kits on an analyzer. The the polymorphism of the A1166C I type gene receptor of the angiotensin II was studied by polymerase chain reaction with electrophoretic detection of the results. RESULTS: Results: Higher levels of total cholesterol were found in patients with CC genotype compared to AA genotype carriers ((8.94±0.09) vs (5.18±0.02) mmol/L). The level of low-density lipoprotein in CC-genotype carriers was (7.43±0.03) versus (3.66±0.02) mmol/L in A-allele homozygotes. Triglycerides and very low density lipoproteins were also significantly higher in CC genotype carriers compared to patients with AA genotype. The level of high-density lipoprotein was lower in homozygotes with C-allele than in patients with the AA genotype, and was (0.59±0.12) versus (0.99±0.03) mmol/L. CONCLUSION: Conclusions: The presence in the CC genotype the I type gene receptor of the angiotensin II type is a predictor of dyslipidemia. In patients with arterial hypertension, the presence in the C-allele of the I type gene of the angiotensin II type contributes to a significant increase in serum adipokines and a decrease in ghrelin levels.

The adipose tissue melanocortin 3 receptor is targeted by ghrelin and leptin and may be a therapeutic target in obesity.

OBJECTIVE: Obesity is linked to perturbations in energy balance mechanisms, including ghrelin and leptin actions at the hypothalamic circuitry of neuropeptide Y (NPY) and melanocortin. However, information about the regulation of this system in the periphery is still scarce. Our objective was to study the regulation of the NPY/melanocortin system in the adipose tissue (AT) and evaluate its therapeutic potential for obesity and type 2 diabetes. METHODS: The expression of the NPY/melanocortin receptors' levels was assessed in the visceral AT of individuals with obesity and altered metabolism. Protein levels of these receptors were evaluated in cultured adipocytes incubated with ghrelin (30 and 100 ng/mL) and leptin (1 and 10 nM) and in the AT of an animal model with a mutation in the leptin receptor (ZSF1 rat), to understand their regulation by leptin and ghrelin. The vertical sleeve gastrectomy animal model was used to evaluate the putative therapeutic potential of the NPY/melanocortin system. RESULTS: In this study, we unravelled that leptin (1 nM and 10 nM) selectively reduced the levels of NPY5R and MC3R but no other NPYR/MCRs in cultured adipocytes. In turn, acylated ghrelin (100 ng/mL) significantly increased NPY1R, but the inhibition of its receptor also abrogates MC3R levels. However, in the Lepr-deficient ZSF1 rat, both NPY5R and MC3R levels were reduced, along with other NPYRs and MCRs, suggesting that leptin resistance negatively affects NPY and melanocortin signalling. In human adipose tissue, we found a downregulation of genes encoding the NPY and melanocortin receptors in the visceral AT of individuals with obesity and insulin resistance, being correlated with genes regulating metabolic activity. Additionally, diabetic obese rats submitted to vertical sleeve gastrectomy showed increased levels of NPY, melanocortin, ghrelin, and leptin receptors in the AT, including MC3R, suggesting it may constitute a therapeutic target in obesity. CONCLUSIONS: Our results suggest that the AT NPY/melanocortin system, particularly the MC3R, may be involved in the neuroendocrine regulation of adipocyte metabolism. Altogether, our work shows MC3R is under the control of the ghrelin/leptin duo, is reduced in patients with obesity and prediabetes, and may constitute a therapeutic target in obesity.

Therapeutic effects of alpha lipoic acid and/or caffeine-loaded chitosan nanoparticles on memory impairment and neurochemical changes in high-fat diet-induced obese rats.

The therapeutic effects of alpha lipoic acid (LA) and/or caffeine-loaded chitosan nanoparticles (CCNPs) on obesity-induced memory impairment were evaluated in the present study. Rats were divided into control rats, obese rats induced by high fat diet (HFD) and obese rats treated with LA and/or CCNPs. Obesity was confirmed by measuring the body mass index (BMI). Memory and cognitive functions were evaluated by novel object recognition test (NORT). The levels of serotonin (5-HT), dopamine (DA), norepinephrine (NE), lipid peroxidation (MDA), nitric oxide (NO), reduced glutathione (GSH), interleukin-1ß (IL-1ß), tumor necrosis factor-α (TNF-α), leptin (LEP) and ghrelin (GHR) and the activities of monoamine oxidase (MAO), acetylcholinesterase (AchE) and Na+,K+,ATPase were determined in the cortex and hippocampus. The cerebral histopathological alterations were examined in obese rats. Obese rats showed impaired memory and exhibited significant neurochemical changes, including decreased levels of 5-HT, DA, GSH, GHR, and Na+,K+-ATPase activity, as well as an increase in AchE, MAO, MDA, NO, IL-1ß, TNF-α, and LEP. LA and/or CCNPs treatment reduced BMI and improved memory. LA or CCNPs alleviated the cortical and hippocampal neurochemical changes and histopathological changes induced by obesity. Furthermore, LA and CCNPs exhibited antioxidant and anti-inflammatory properties, which likely contributed to their effects. However, no synergistic effect was observed between LA and CCNPs. These findings suggest that LA or CCNPs may be a potential therapy against obesity and its adverse effects on memory, mediated by their ability to restore monoamine levels and exhibit antioxidant and anti-inflammatory properties.