Measurement of Ghrelin as a Marker of Appetite Dysregulation in Cats with and without Chronic Kidney Disease

Appetite abnormalities and weight loss are important comorbidities in the treatment of chronic kidney disease (CKD) in cats. Ghrelin, a key hormone involved in the regulation of appetite and metabolism, is a potential marker of appetite dysregulation in cats with CKD. The aim of this study was to compare the plasma concentrations of acylated, desacyl, and total ghrelin in normal cats and cats with CKD. Storage methodology was investigated prior to evaluating ghrelin concentrations in normal and CKD cats to facilitate clinical sample collection. Twelve normal cats and twelve cats with CKD were enrolled. Plasma acylated and total ghrelin concentrations were measured using radioimmunoassay. Desacyl ghrelin was calculated (total ghrelin minus acylated ghrelin). Cats with CKD had significantly increased total ghrelin and calculated desacyl ghrelin concentrations in comparison to normal cats (p < 0.0001 and p = 0.0001). There was no significant difference in active ghrelin concentrations between groups. Both total ghrelin and calculated desacyl ghrelin were significantly correlated with serum creatinine concentrations (p < 0.0001, r = 0.70 and p < 0.0001, r = 0.73). Elevated plasma desacyl ghrelin concentrations in cats with CKD provides evidence for dysregulation of appetite in feline CKD.

Toward a consensus nomenclature for ghrelin, its non-acylated form, liver expressed antimicrobial peptide 2 and growth hormone secretagogue receptor

The stomach-derived octanoylated peptide ghrelin was discovered in 1999 and recognized as an endogenous agonist of the growth hormone secretagogue receptor (GHSR). Subsequently, ghrelin has been shown to play key roles in controlling not only growth hormone secretion, but also a variety of other physiological functions including, but not limited to, food intake, reward-related behaviors, glucose homeostasis and gastrointestinal tract motility. Importantly, a non-acylated form of ghrelin, desacyl-ghrelin, can also be detected in biological samples. Desacyl-ghrelin, however, does not bind to GHSR at physiological levels, and its physiological role has remained less well-characterized than that of ghrelin. Ghrelin and desacyl-ghrelin are currently referred to in the literature using many different terms, highlighting the need for a consistent nomenclature. The variability of terms used to designate ghrelin can lead not only to confusion, but also to miscommunication, especially for those who are less familiar with the ghrelin literature. Thus, we conducted a survey among experts who have contributed to the ghrelin literature aiming to identify whether a consensus may be reached. Based on the results of this consensus, we propose using the terms "ghrelin" and "desacyl-ghrelin" to refer to the hormone itself and its non-acylated form, respectively. Based on the results of this consensus, we further propose using the terms "GHSR" for the receptor, and "LEAP2" for liver-expressed antimicrobial peptide 2, a recently recognized endogenous GHSR antagonist/inverse agonist.

A Systematic Review and Meta-Analysis Finds Increased Blood Levels of All Forms of Ghrelin in Both Restricting and Binge-Eating/Purging Subtypes of Anorexia Nervosa

Anorexia nervosa (AN) is a severe psychiatric condition associated with high mortality and chronicity. The hunt for state, trait, subtyping, and prognostic biomarkers is ongoing and the orexigenic hormone ghrelin and its different forms, acyl ghrelin and desacyl ghrelin, have been proposed to be increased in AN, especially in the restrictive subtype. A systematic literature search was performed using established databases up to 30 November 2020. Forty-nine studies met inclusion criteria for cross-sectional and longitudinal meta-analyses on total ghrelin, acyl ghrelin, and desacyl ghrelin. All forms of ghrelin were increased in the acute stage of anorexia nervosa during fasting compared to healthy controls. Previous notions on differences in ghrelin levels between AN subtypes were not supported by current data. In addition, a significant decrease in total ghrelin was observed pre-treatment to follow-up. However, total ghrelin levels at follow-up were still marginally elevated compared to healthy controls, whereas for acyl ghrelin, no overall effect of treatment was observed. Due to heterogeneity in follow-up designs and only few data on long-term recovered patients, longitudinal results should be interpreted with caution. While the first steps towards a biomarker in acute AN have been completed, the value of ghrelin as a potential indicator of treatment success or recovery status or its use in subtype differentiation are yet to be established.

Dietary macronutrient regulation of acyl and desacyl ghrelin concentrations in children with Prader-Willi syndrome (PWS)

BACKGROUND

The effects of dietary macronutrients on orexigenic and anorexigenic hormones in children are poorly understood.

OBJECTIVE

To explore effects of varying dietary macronutrients on appetite-regulating hormones [acyl ghrelin (AG) and desacyl ghrelin (DAG), glucagon-like peptide 1 (GLP-1), peptide tyrosine tyrosine (PYY) and insulin] in children with PWS and healthy children (HC).

DESIGN

Randomized, cross-over experiments compared two test diets [high protein-low carbohydrate (HP-LC) and high protein-low fat (HP-LF)] to a STANDARD meal (55% carbohydrate, 30% fat, 15% protein). Experiment 1 included ten children with PWS (median age 6.63 years; BMI z 1.05); experiment 2 had seven HC (median age 12.54 years; BMI z 0.95). Blood samples were collected at baseline and at 60-minute intervals for 4 hours. Independent linear mixed models were adjusted for age, sex and BMI z-score.

RESULTS

Fasting and post-prandial AG and DAG concentrations are elevated in PWS children; the ratio of AG/DAG is normal. Food consumption reduced AG and DAG concentrations in both PWS and HC. GLP-1 levels were higher in PWS after the HP-LC and HP-LF meals than the STANDARD meal (P = .02-0.04). The fasting proinsulin to insulin ratio (0.08 vs 0.05) was higher in children with PWS (P = .05) than in HC. Average appetite scores in HC declined after all three meals (P = .02) but were lower after the HP-LC and HP-LF meals than the STANDARD meal.

CONCLUSION

Altered processing of proinsulin and increased GLP-1 secretion in children with PWS after a high protein meal intake might enhance satiety and reduce energy intake.

Plasma desacyl ghrelin-to-acyl ghrelin ratio is a predictor of postoperative complications and prognosis after pancreaticoduodenectomy

The current study aimed to clarify the significance of the preoperative desacyl ghrelin (DG)-to-acyl ghrelin (AG) ratio in patients undergoing pancreaticoduodenectomy (PD). Ghrelin, a peptide hormone mainly produced in the stomach, possesses unique functions. Recently, studies have determined the involvement of plasma gherlin in certain postoperative outcomes, particularly in surgical resections of the stomach. Although PD involves gastric resection, few reports have determined the involvement of ghrelin following PD. From April 2003 to December 2011, 195 patients underwent PD for tumors of the pancreatic head, bile duct and ampulla of Vater at the Division of Hepato-Biliary-Pancreatic Surgery, Department of Surgery, University of Miyazaki Faculty of Medicine (Miyazaki, Japan). Of these, 83 patients were enrolled into the present study as their plasma gherlin levels were measured. AG, DG, total ghrelin (TG) and the DG-to-AG ratio (D/A) were subsequently assessed. Furthermore, the prognostic nutritional index (PNI) and high-sensitivity modified Glasgow Prognostic Score (HS-mGPS) were determined. Morbidity was examined in all 83 patients, but mortality was only determined in 69 individuals after 14 patients were excluded due to the presence of benign disease. The results revealed that the TG of patients undergoing standard PD (SPD) was significantly lower than that of patients undergoing pylorus-preserving PD or subtotal stomach-preserving PD. It was also determined that TG levels declined significantly in SPD patients at 2 weeks after surgery. Negative associations were identified between plasma ghrelin levels and PNI, and between serum albumin and HS-mGPS. Patient morbidity was determined to be 31.3% and the severe complications exhibited by patients included pancreatic fistula (14.5%), intra-abdominal abscess (15.7%), intra-abdominal bleeding (6.0%) and liver abscess (1.2%). Multivariate analysis revealed that disease location and low D/A were independent risk factors for severe complications. The 5-year overall survival (OS) rate was 41.5%. Multivariate analysis also demonstrated that diabetes mellitus, long postoperative hospital stay and low D/A were independent risk factors for OS. The present study revealed the D/A may serve as a useful predictive factor for postoperative complications and prognosis after PD.

Fasting and postprandial acyl and desacyl ghrelin and the acyl/desacyl ratio in obese patients before and after different types of bariatric surgery

Introduction

The mechanism underlying beneficial outcomes of bariatric surgery still remains unclear. Especially little is known about hormonal and metabolic changes induced by the novel bariatric procedure mini gastric bypass (MGB).

Aim

To evaluate pre- and post-prandial changes in both ghrelin isoforms in obese patients without diabetes and cardiovascular complications treated with MGB, sleeve gastrectomy (SG) or Roux-en-Y gastric bypass (RYGB) surgery.

Material and methods

From 45 patients initially enrolled in the study, 23 persons completed a one-year follow-up period. Venous blood for acyl and desacyl ghrelin (AG and DAG) as well as other metabolic assays was collected 3 months before and 6 and 12 months after bariatric surgery (MGB, RYGB, SG) – in the fasting state and 2 h after the consumption of a standard 300 kcal-mixed meal (Nutridrink standard, Nutricia).

Results

AG and DAG levels (both fasting and prandial) as well as AG/DAG ratio did not change after 6 and 12 months in MGB and RYGB groups. In the SG group we observed a significant decrease in fasting and postprandial DAG levels and consecutively an increase in the fasting AG/DAG ratio after 6 and 12 months. Six months after surgery we observed some differences between carbohydrate metabolism measures in the MGB group (lower HbA_1c, HOMA-IR and fasting insulinaemia) in comparison to the rest of the participants, but 12 months after each type of surgery body mass index and indices of carbohydrate and lipid metabolism did not differ.

Conclusions

The results of our study demonstrate that all studied bariatric procedures can successfully reduce overall body weight and suggest also that the mechanisms of weight loss and improvement in carbohydrate and lipid metabolism after all three types of surgery are independent of ghrelin and the acyl/desacyl ghrelin ratio.

Combination of Selective Immunoassays and Mass Spectrometry to Characterize Preproghrelin-Derived Peptides in Mouse Tissues

Preproghrelin is a prohormone producing several preproghrelin-derived peptides with structural and functional heterogeneity: acyl ghrelin (AG), desacyl ghrelin (DAG), and obestatin. The absence of selective and reliable assays to measure these peptides simultaneously in biological samples has been a limitation to assess their real proportions in tissues and plasma in physiological and pathological conditions. We aimed at reliably measure the ratio between the different preproghrelin-derived peptides in murine tissues using selective immunoassays combined with a highly sensitive mass spectrometry method. AG-, DAG-, and obestatin-immunopositive fractions from the gastrointestinal tract of adult wild-type and ghrelin-deficient mice were processed for analysis by mass spectrometry (MS) with a Triple Quadrupole mass spectrometer. We found that DAG was predominant in mouse plasma, however it only represented 50% of total ghrelin (AG+DAG) production in the stomach and duodenum. Obestatin plasma levels accounted for about 30% of all circulating preproghrelin-derived peptides, however, it represented <1% of total preproghrelin-derived peptides production (AG+DAG+Obestatin) in the stomach. Assays were validated in ghrelin-deficient mice since neither ghrelin nor obestatin immunoreactivities were detected in their stomach, duodenum nor plasma. MS analyses confirmed that obestatin-immunoreactivity in stomach corresponded to the C-terminal amidated form of the peptide but not to des(1-10)-obestatin, nor to obestatin-Gly. In conclusion, specificity of ghrelin and obestatin immunoreactivities in gastrointestinal tissues using selective immunoassays was validated by MS. Obestatin was less abundant than AG or DAG in these tissues. Whether this is due to inefficient processing rate of preproghrelin into mature obestatin in gastrointestinal mouse tissues remains elusive.

Among Metabolic Factors, Significance of Fasting and Postprandial Increases in Acyl and Desacyl Ghrelin and the Acyl/Desacyl Ratio in Obstructive Sleep Apnea before and after Treatment

STUDY OBJECTIVES

There are reports suggesting that obstructive sleep apnea (OSA) may itself cause weight gain. However, recent reports showed increases in body mass index (BMI) following continuous positive airway pressure (CPAP) treatments. When considering weight changes, changes in humoral factors that have significant effects on appetite such as acyl (AG) and desacyl ghrelin (DAG), leptin, insulin, and glucose and their interactions, examples of which are AG/DAG and AG/insulin, are important. The aim of this study was to test the hypothesis that some appetite-related factors had a specific profile before and after CPAP treatment.

METHODS

Metabolic parameters were measured cross-sectionally while fasting and 30, 60, 90, and 120 min following breakfast in no or mild OSA (apnea-hypopnea index < 15, n = 15) and moderate-to-severe OSA (apnea-hypopnea index ≥ 15, n = 39) participants in a single institute. There were no differences in age, sex, BMI, or visceral fat accumulation between the two groups. Twenty-one patients with moderate-to-severe OSA who received CPAP treatment also prospectively underwent the same testing following 3 months of CPAP treatment.

RESULTS

Although fasting and postprandial glucose, insulin, and leptin levels did not differ between no or mild OSA and moderate-to-severe OSA participants, AG and DAG, including AG/DAG and AG/insulin, under fasting and postprandial conditions were significantly increased in the moderate-to-severe OSA patients (p < 0.01). After 3 months of CPAP treatment in 21 of the moderate-to-severe OSA participants, AG/DAG did not change significantly, but other ghrelin-related parameters including AG/insulin significantly decreased compared with values before treatment but remained higher than in no or mild OSA.

CONCLUSION

Among several important metabolic factors, ghrelin-related factors had the strongest associations with moderate-to-severe OSA. These results indicate that continuous changes in ghrelin secretion in OSA patients existed at least within 3 months of CPAP treatment. Methods to prevent OSA as well as treatment in its early stage may be recommended.

Serum levels of desacyl ghrelin in patients with schizophrenia on clozapine monotherapy

AIM

Desacyl ghrelin is a hormone that might be a functional inhibitor of ghrelin, a potent hunger-stimulating peptide.

METHODS

We determined fasting serum desacyl ghrelin levels in 24 subjects with schizophrenia on clozapine monotherapy and 24 healthy, age- and sex-matched controls. Biochemical and anthropometric measurements were combined with body composition determined using bioelectric impedance analysis.

RESULTS

There were no differences in desacyl ghrelin levels between patients taking clozapine and the control group (272.09 ± 137.96 vs 259.62 ± 140.91 pg/mL, z = 0.17, P = 0.87). In the clozapine group, there were no differences between men and women for ghrelin levels (246.66 ± 123.17 vs 295.39 ± 151.77 pg/mL, z = -0.98, P = 0.32). In the clozapine group, fasting serum levels of ghrelin negatively correlated with waist-to-hip ratio (WHR) (r = -0.45, P = 0.03) and ionized calcium (r = -0.45, P = 0.03). Levels of ghrelin were lower in patients with WHR above World Health Organization-defined cut-off points (246.84 ± 114.34 [Q1 = 152.18, Q2 = 220.92, Q3 = 327.85] vs 400.30 ± 123.36 [Q1 = 283.73, Q2 = 414.03, Q3 = 485.8] pg/mL, z = 2.52, P = 0.01). In the clozapine group, there were no correlation with age, height, weight, body mass index, abdominal circumference, waist circumference, hip circumference, WHR, blood pressure, total cholesterol, high-density lipoproteins, low-density lipoproteins, triglycerides, uric acid, homocysteine, glucose, insulin, clozapine dose, duration of treatment with antipsychotics, duration of treatment with clozapine, total fat, target fat, basal metabolic rate, target weight, lean weight, body water, homoeostasis model assessment of insulin resistance (HOMA) 1-IR, HOMA2-IR and quantitative insulin sensitivity check index.

CONCLUSION

Based on our results, we cannot conclude that treatment with clozapine affects levels of desacyl ghrelin. Also, in our study population we did not confirm previously described associations between desacyl ghrelin and various metabolic parameters.

Cold ambient temperature reverses abdominal surgery-induced delayed gastric emptying and decreased plasma ghrelin levels in rats

We investigated whether acute cold-induced vagal activation through brainstem thyrotropin-releasing hormone (TRH) signaling influences abdominal surgery-induced delayed gastric emptying (GE) in fasted rats. Laparotomy and cecal palpation or sham (short anesthesia alone) was performed 10 min before or 30 min after cold exposure (4-6°C) lasting 90 min. Non-nutrient GE was assessed during 70-90 min of cold exposure. Control groups remained at room temperature (RT). The stable TRH analog, RX-77368 (50 ng/rat) was injected intracisternally immediately before surgery and GE monitored 30-50 min postsurgery in rats maintained at RT. Plasma acyl (AG) and total ghrelin levels were assessed using the new RAPID blood processing method and radioimmunoassays. Desacyl ghrelin (DAG) was derived from total minus AG. In rats maintained at RT, abdominal surgery decreased GE by 60% compared to sham. Cold before or after surgery or RX-77368 normalized the delayed GE. In non-fasted rats, cold exposure increased plasma AG and DAG levels at 2 h (2.4- and 2.7-times, respectively) and 4 h (2.2- and 2.0-times, respectively) compared to values in rats maintained at RT. In fasted rats, abdominal surgery decreased AG and DAG levels by 2.4- and 2.1-times, respectively, at 90 min. Cold for 90 min after surgery normalized AG and DAG levels to those observed in sham-treated animals kept at RT. These data indicate that endogenous (cold exposure) and exogenous (TRH analog) activation of medullary TRH vagal signaling prevent abdominal surgery-induced delayed GE. The restoration of circulating AG levels inhibited by abdominal surgery may contribute to alleviate postoperative gastric ileus.

Lipopolysaccharide differentially decreases plasma acyl and desacyl ghrelin levels in rats: potential role of the circulating ghrelin-acylating enzyme GOAT

Bacterial lipopolysaccharide (LPS) in rodents is an established model for studying innate immune responses to gram-negative bacteria and mimicking symptoms of infections including reduced food intake associated with decreased circulating total ghrelin levels. The ghrelin-acylating enzyme, ghrelin-O-acyltransferase (GOAT) involved in the formation of acyl ghrelin (AG) was recently identified. We investigated changes in circulating AG, desacyl ghrelin (DG) and GOAT induced by intraperitoneal LPS (100 microg/kg) and associated changes in food intake. Plasma AG and total ghrelin were assessed by radioimmunoassay, GOAT protein by Western blot and mRNA by RT-qPCR. DG was derived from total minus AG. Plasma AG and DG were decreased at 2, 5 and 7 h (p<0.01) post-injection compared to vehicle and recovered at 24 h. At 2 h there was a significantly greater decrease of AG (-53%) than DG (-28%) resulting in a decreased AG/DG ratio (1:5, p<0.01), which thereafter returned to pre-injection values (1:3). This altered ratio was associated with a 38% decrease in plasma GOAT protein compared to vehicle (p<0.001), whereas gastric GOAT protein was slightly increased by 10% (p<0.05). GOAT mRNA expression was unchanged. Food intake was reduced by 58% measured during the 1.5-2 h period post-LPS injection. Decreased plasma AG and DG preceded the rise in rectal temperature and blood glucose that peaked at 7 h. These data indicate that LPS induces a long-lasting reduction of AG and DG levels that may have a bearing with the decrease in food intake. The faster drop in AG than DG within 2 h is associated with reduced circulating GOAT.

Effects of glucose and insulin on acyl ghrelin and desacyl ghrelin, leptin, and adiponectin in pregnant women with diabetes

The aim of the study was to compare the regulation of ghrelin, leptin, and adiponectin by insulin and glucose during the second and third trimesters of pregnancy in women with diabetes. We studied 9 pregnant women with diabetes. All women were treated with insulin and omitted the morning dose on the day of the test. After collection of baseline fasting samples, we performed 3 successive glucose clamps: 2 euglycemic clamps (glucose, 5 mmol/L; insulin infusion at 20 and 40 mU m(-2) min(-1)) and 1 hyperglycemic clamp (glucose, 10 mmol/L; insulin infusion at 40 mU m(-2) min(-1)). We determined concentrations of acyl and desacyl ghrelin (using a double-antibody sandwich assay that recognizes the full-length molecule), leptin, and adiponectin. Fasting desacyl ghrelin concentrations decreased, whereas insulin and leptin concentrations increased, between the second and third trimesters of pregnancy (P < or = .011). During the clamp studies, desacyl ghrelin concentrations decreased by 33% (second trimester, P = .004) and 27% (third trimester, P = .09) with increasing glucose and insulin concentrations, whereas acyl ghrelin, leptin, and adiponectin concentrations were unaffected. Glucose and insulin regulate desacyl ghrelin concentrations in pregnant women with diabetes. Impaired desacyl ghrelin regulation may affect energy metabolism in pregnant women with poorly controlled diabetes.

Centrally administered ghrelin potently inhibits water intake induced by angiotensin II and hypovolemia in rats

Ghrelin is a potent, centrally acting orexigenic hormone. Recently, we showed that centrally administered ghrelin is a potent antidipsogenic hormone in 24-h water deprived rats. In this study, we examined the effect of intracerebroventricular (icv) injection of ghrelin on angiotensin II (AII)-induced water intake in rats. We also examined the effects of icv injection of ghrelin on drinking induced by intraperitoneal injection of an isotonic polyethylene glycol (PEG) solution that causes isotonic hypovolemia. Water intake induced by the icv injection of AII or ip injection of PEG was significantly reduced after icv injection of ghrelin, although food intake was stimulated by the hormone. The drinking induced by AII was also inhibited by the icv administration of 4alpha-phorbol 12, 13-didecanoate, an agonist of the osmosensitive TRPV4 channel. This study showed that ghrelin is a potent antidipsogenic peptide by antagonizing general dipsogenic mechanisms including those activated by AII and hypovolemia in rats.

Acylated ghrelin concentrations are markedly decreased during pregnancy in mothers with and without gestational diabetes: relationship with cholinesterase

Acylated (octanoylated) ghrelin stimulates food intake and growth hormone secretion and is deacylated into desacyl ghrelin by butyrylcholinesterase. Acylated and desacyl ghrelin both promote adipogenesis. Ghrelin concentrations decrease with hyperglycemia and hyperinsulinism. We hypothesized that 1) acylated ghrelin increases during pregnancy, contributing positively to energy balance, but is lower in women with gestational diabetes and 2) butyrylcholinesterase activity is inversely correlated with acylated ghrelin concentrations. In a first group of subjects, using two-site sandwich ghrelin assays that specifically detect full-length forms, we investigated women with and without gestational diabetes (n = 14/group) during pregnancy and after delivery. We examined whether changes in ghrelin during a test meal were correlated with changes in pituitary growth hormone [assessed through calculation of the area under the curve (AUC) during the test meal]. In postpartum subjects, the percent of total ghrelin that is acylated was four to five times higher than previously observed using single antibody assays. During pregnancy, acylated ghrelin concentrations (mean +/- SE) were lower compared with the postpartum period throughout the meal (AUC 1.2 +/- 0.2 vs. 10.2 +/- 1.9 ng.ml(-1).90 min(-1), P < 0.001). In the postpartum, acylated ghrelin and growth hormone were positively correlated (r = 0.50, P = 0.007). Desacyl (but not acylated) ghrelin was increased in subjects with gestational diabetes during and after pregnancy (AUC 15.4 +/- 1.9 vs. 8.6 +/- 1.2 ng.ml(-1).90 min(-1), P = 0.005). In a second group of subjects (n = 13), acylated ghrelin was similarly suppressed during pregnancy. Circulating octanoate concentrations (3.1 +/- 0.5 vs. 4.5 +/- 0.6 microg/ml, P = 0.029) and cholinesterase activity (705 +/- 33 vs. 1,013 +/- 56 U/ml, P < 0.001) were lower during pregnancy compared with the postpartum period. In conclusion, acylated ghrelin markedly decreases during pregnancy, likely because of a decrease in the acylation process. Desacyl ghrelin increases in gestational diabetes, possibly reflecting resistance to the inhibitory effect of insulin on ghrelin secretion.

Dose-dependent effects of barley cooked with white rice on postprandial glucose and desacyl ghrelin levels

White rice is an indispensable staple food in Japan, although it is a high glycemic index food. The objective of this study was to estimate how barley cooked with white rice might affect postprandial glucose, insulin and desacyl ghrelin concentrations as well as fullness. The study was conducted in randomized crossover design with nine healthy subjects. Blood glucose, insulin, free fatty acid and desacyl ghrelin concentrations and subjective levels of fullness and hunger were measured for 240 min after intake of glucose, white rice, 30% rolled barley (30BAR), 50% rolled barley (50BAR) and 100% rolled barley (100BAR) containing 75 g of available carbohydrate. Postprandial glucose and insulin levels were suppressed by intake of 30BAR, 50BAR and 100BAR comparing with those of white rice. Area under the curves of plasma glucose and insulin concentrations was reduced by barley intake in a dose-dependent manner. Although plasma desacyl ghrelin levels decreased postprandially, the degree of reduction was suppressed by barley intake in a dose-dependent manner. Postprandial desacyl ghrelin levels can be a sensitive biomarker of carbohydrate metabolism. The combination of white rice with barley plays a beneficial role in preventing and treating type 2 diabetes, obesity and other metabolic diseases.

Desacyl ghrelin inhibits the orexigenic effect of peripherally injected ghrelin in rats

Studies showed that the metabolic unlike the neuroendocrine effects of ghrelin could be abrogated by co-administered unacylated ghrelin. The aim was to investigate the interaction between ghrelin and desacyl ghrelin administered intraperitoneally on food intake and neuronal activity (c-Fos) in the arcuate nucleus in non-fasted rats. Ghrelin (13 microg/kg) significantly increased food intake within the first 30 min post-injection. Desacyl ghrelin at 64 and 127 microg/kg injected simultaneously with ghrelin abolished the stimulatory effect of ghrelin on food intake. Desacyl ghrelin alone at both doses did not alter food intake. Both doses of desacyl ghrelin injected separately in the light phase had no effects on food intake when rats were fasted for 12h. Ghrelin and desacyl ghrelin (64 microg/kg) injected alone increased the number of Fos positive neurons in the arcuate nucleus compared to vehicle. The effect on neuronal activity induced by ghrelin was significantly reduced when injected simultaneously with desacyl ghrelin. Double labeling revealed that nesfatin-1 immunoreactive neurons in the arcuate nucleus are activated by simultaneous injection of ghrelin and desacyl ghrelin. These results suggest that desacyl ghrelin suppresses ghrelin-induced food intake by curbing ghrelin-induced increased neuronal activity in the arcuate nucleus and recruiting nesfatin-1 immunopositive neurons.