Acylated Ghrelin Concentrations Research Articles

Ghrelin affects stopover decisions and food intake in a long-distance migrant

Billions of birds migrate long distances to either reach breeding areas or to spend the winter at more benign places. On migration, most passerines frequently stop over to rest and replenish their fuel reserves. To date, we know little regarding how they decide that they are ready to continue their journey. What physiological signals tell a bird's brain that its fuel reserves are sufficient to resume migration? A network of hormones regulates food intake and body mass in vertebrates, including the recently discovered peptide hormone, ghrelin. Here, we show that ghrelin reflects body condition and influences migratory behavior of wild birds. We measured ghrelin levels of wild garden warblers (Sylvia borin) captured at a stopover site. Further, we manipulated blood concentrations of ghrelin to test its effects on food intake and migratory restlessness. We found that acylated ghrelin concentrations of garden warblers with larger fat scores were higher than those of birds without fat stores. Further, injections of unacylated ghrelin decreased food intake and increased migratory restlessness. These results represent experimental evidence that appetite-regulating hormones control migratory behavior. Our study lays a milestone in migration physiology because it provides the missing link between ecologically dependent factors such as condition and timing of migration. In addition, it offers insights in the regulation of the hormonal system controlling food intake and energy stores in vertebrates, whose disruption causes eating disorders and obesity.

Acute effect of exercise intensity and duration on acylated ghrelin and hunger in men.

Acute exercise transiently suppresses the orexigenic gut hormone acylated ghrelin, but the extent to which exercise intensity and duration determine this response is not fully understood. The effects of manipulating exercise intensity and duration on acylated ghrelin concentrations and hunger were examined in two experiments. In experiment one, nine healthy males completed three, 4-h conditions (control, moderate-intensity running (MOD) and vigorous-intensity running (VIG)), with an energy expenditure of ~2.5 MJ induced in both MOD (55-min running at 52% peak oxygen uptake (V.O2peak)) and VIG (36-min running at 75% V.O2peak). In experiment two, nine healthy males completed three, 9-h conditions (control, 45-min running (EX45) and 90-min running (EX90)). Exercise was performed at 70% V.O2peak In both experiments, participants consumed standardised meals, and acylated ghrelin concentrations and hunger were quantified at predetermined intervals. In experiment one, delta acylated ghrelin concentrations were lower than control in MOD (ES = 0.44, P = 0.01) and VIG (ES = 0.98, P < 0.001); VIG was lower than MOD (ES = 0.54, P = 0.003). Hunger ratings were similar across the conditions (P = 0.35). In experiment two, delta acylated ghrelin concentrations were lower than control in EX45 (ES = 0.77, P < 0.001) and EX90 (ES = 0.68, P < 0.001); EX45 and EX90 were similar (ES = 0.09, P = 0.55). Hunger ratings were lower than control in EX45 (ES = 0.20, P = 0.01) and EX90 (ES = 0.27, P = 0.001); EX45 and EX90 were similar (ES = 0.07, P = 0.34). Hunger and delta acylated ghrelin concentrations remained suppressed at 1.5 h in EX90 but not EX45. In conclusion, exercise intensity, and to a lesser extent duration, are determinants of the acylated ghrelin response to acute exercise.

The Effect of a 20 km Run on Appetite Regulation in Long Distance Runners.

The purpose of the present study was to investigate appetite-related hormonal responses and energy intake after a 20 km run in trained long distance runners. Twenty-three male long-distance runners completed two trials: either an exercise trial consisting of a 20 km outdoor run (EX) or a control trial with an identical period of rest (CON). Blood samples were collected to determine plasma acylated ghrelin, peptide YY3-36 (PYY3-36) and other hormonal and metabolite concentrations. Energy intake during a buffet test meal was also measured 30 min after the exercise or rest periods. Although plasma acylated ghrelin concentrations were significantly decreased after the 20 km run (p < 0.05), plasma PYY3-36 did not change significantly following exercise. Absolute energy intake during the buffet test meal in EX (1325 ± 55 kcal) was significantly lower than that in CON (1529 ± 55 kcal), and there was a relatively large degree of individual variability for exercise-induced changes in energy intake (−40.2% to 12.8%). However, exercise-induced changes in energy intake were not associated with plasma acylated ghrelin or PYY3-36 responses. The results demonstrated that a 20 km run significantly decreased plasma acylated ghrelin concentrations and absolute energy intake among well-trained long distance runners.

Increased peptide YY blood concentrations, not decreased acyl-ghrelin, are associated with reduced hunger and food intake in healthy older women: Preliminary evidence

With ageing there is frequently a loss of appetite, termed anorexia of ageing, which can result in under-nutrition. We do not know how appetite control alters with ageing. The objective of this study was to investigate whether differences in the release of, and response to, gastrointestinal appetite hormones is altered in young compared to old healthy volunteers. We hypothesised that an increase in PYY and GLP-1 or a decrease ghrelin may result in a decreased appetite. A comparative experimental design, using a cross-sectional sample of ages from a healthy population, matched for sex and BMI was used. The study compared total ghrelin, acyl-ghrelin, PYY, GLP-1 and subjective appetite responses to ingestion of a standardised 2781kj (660 kcal) test meal. 31 female volunteers aged between 21 and 92yrs took part. Multiple linear regression showed that both age and sex had an independent effect on energy intake. Subjective appetite scores showed that hunger, pleasantness to eat, and prospective food intake were significantly lower in the older age groups. PYY incremental area under the curve (IAUC) was greater in the oldest old compared to younger ages f(3,27) = 2.9, p = 0.05. No differences in GLP-1, ghrelin or acyl-ghrelin were observed in the older compared to younger age groups. Our data suggest that there may be increases in postprandial PYY(3–36) levels in female octogenarians, potentially resulting in reduced appetite. There does not appear to be any change in ghrelin or acyl-ghrelin concentrations with ageing.

Changes in acyl and total ghrelin concentrations and their association with dry matter intake, average daily gain, and feed efficiency of finishing beef steers and heifers

Ghrelin is a peptide hormone produced in the gut that is implicated in signaling appetite and regulating dry matter intake (DMI). The objective of this experiment was to determine the change in acyl ghrelin, total ghrelin, and the ghrelin ratio (acyl ghrelin/total ghrelin) over an 84-d DMI and average daily BW gain (ADG) measurement period and to determine the association of those ghrelin measurements with DMI, ADG, ADG:DMI ratio (G:F), and residual feed intake in finishing beef steers and heifers. Blood samples were collected on day 0 and day 83 before feeding and between 0730 h and 1130 h. Samples were analyzed for acyl and total ghrelin using commercially available RIA. DMI in steers was greater during the last 35-d period of the experiment compared with the first 35 d (P < 0.01) and was greater than heifers regardless of period (P < 0.01). Steers had greater acyl ghrelin concentrations on day 0 than heifers, but concentrations decreased by day 83 to equal concentrations in heifers (P < 0.01). Total ghrelin concentrations were lower on day 0 in heifers but increased by day 83 and did not differ from steers on day 83 (P < 0.01). A mixed model analysis was used to determine the association of ghrelin concentrations and ratio with production traits, independent of breed and sire effects. There was an interaction of day 0 acyl ghrelin concentrations with time of sample collection for 84-d DMI (P < 0.01), ADG (P < 0.01), and G:F (P = 0.09), indicating a general positive association of acyl ghrelin with production traits, but the association weakened as time of sample collection increased. The mean ghrelin ratio tended (P = 0.08) to be positively associated with DMI in the last 35-d period. The ghrelin ratio on day 0 interacted with time of sample collection for ADG and G:F (P < 0.05), indicating an overall positive association of the ghrelin ratio with ADG and G:F. Results indicate that ghrelin is associated with DMI, ADG, and feed efficiency of finishing beef cattle, and data lend more evidence that ghrelin is involved in appetite regulation of ad libitum fed cattle.

Plasma ghrelin levels as a predictor of adverse renal events due to cisplatin-based chemotherapy in patients with esophageal cancer.

Although combination chemotherapy with docetaxel, cisplatin and 5-fluorouracil demonstrates high response rates in esophageal squamous cell carcinoma, patients treated with docetaxel, cisplatin and 5-fluorouracil frequently experience acute kidney injury. Ghrelin has shown renal protective effects in an experimental acute kidney injury model by reducing tubular apoptosis. In this prospective observational study, we evaluated the association between plasma ghrelin concentrations and docetaxel, cisplatin and 5-fluorouracil-related acute kidney injury. Forty consecutive patients with esophageal squamous cell carcinoma who received docetaxel, cisplatin and 5-fluorouracil from October 2013 to July 2014 were enrolled in this study. Serum creatinine and urinary α-1 microglobulin, a marker of renal tubular damage, were measured six times during chemotherapy. The increases of creatinine level which is defined in Common Terminology Criteria for Adverse Event were observed less frequently in patients with acyl ghrelin concentrations of ≥9.6 fmol/ml (HAG group) than in those with concentrations <9.6 fmol/ml on Day 2 (LAG group) (P= 0.024). Serum creatinine was significantly lower in the HAG group than in the LAG group (Day 8: 0.79 ± 0.16 vs. 0.97 ± 0.26, P = 0.024; Day 11: 0.85 ± 0.19 vs. 1.08 ± 0.34 mg/dl, P = 0.049). Urinary α-1 microglobulin levels were significantly lower in the HAG group than in the LAG group (Day 4: 2.48 ± 1.83 vs. 3.33 ± 1.41, P = 0.011; Day 8: 4.67 ± 5.50 vs. 5.09 ± 2.54, P = 0.011; Day 11: 11.55 ± 13.78 vs. 16.43 ± 17.84 mg/l, P = 0.020). Plasma acyl ghrelin concentrations on Day 2 of chemotherapy may be a potential predictor of docetaxel, cisplatin and 5-fluorouracil-induced acute kidney injury.

Effect of Acute High Intensity Interval Exercise on Plasma Acylated Ghrelin Concentrations

Effect of Acute High Intensity Interval Exercise on Plasma Acylated Ghrelin Concentrations

The Effect of Exercise on Plasma Ghrelin in Obesity

Background and Aim of the Work : Obesity is an important health problem worldwide. Many solutions have been proposed for this problem the most important of which is physical exercise. Exercise affects caloric expenditure signaling to ghrelin-producing cells in the stomach, thereby affecting appetite regulation. This study examined the effect of weight control programs and exercise on plasma acylated ghrelin concentration in obese subjects. Subjects and Methods : 120 obese persons were recruited and randomly assigned into two treatment groups: diet group& diet and exercise group. The first group received low caloric diet for 12 weeks, while the second group was treated with same diet and exercise program every other day for the same period. Complete clinical, laboratory investigations and ghrelin concentrations were assessed at the start and end of the study. Results : In the diet group, the body weight, the BMI, the WHR (Waist hip ratio) and waist circumference were significantly reduced. On the other hand appetite measures, the triglycerides, cholesterol, HDL and LDL serum levels did not change significantly. Acylated ghrelin was significantly increased. In the diet and exercise group, the body weight, the BMI, the WHR, waist circumference, the feeling of hunger, the desire to eat and prospective food consumption score were significantly decreased. Feeling of fullness score and Serum HDL were significantly increased. Serum triglycerides, serum cholesterol, serum LDL and acylated ghrelin were significantly reduced. Higher reduction of BMI was observed in individuals with lower serum levels of acylated ghrelin. Conclusion : Exercise training was associated with highly significant reduction of anthropometric measurements, plasma acylated ghrelin (which was associated with significant reduction of appetite measures), whereas diet intervention alone promoted opposite effects. More reduction in BMI was observed in individuals with lower plasma levels of ghrelin at the start of the study.

Appetite and Energy Intake Responses to Acute Energy Deficits in Females versus Males.

ABSTRACTPurposeTo explore whether compensatory responses to acute energy deficits induced by exercise or diet differ by sex.MethodsIn experiment one, 12 healthy women completed three 9-h trials (control, exercise-induced (Ex-Def) and food restriction–induced energy deficit (Food-Def)) with identical energy deficits being imposed in the Ex-Def (90-min run, ∼70% of V˙O2max) and Food-Def trials. In experiment two, 10 men and 10 women completed two 7-h trials (control and exercise). Sixty minutes of running (∼70% of V˙O2max) was performed at the beginning of the exercise trial. The participants rested throughout the remainder of the exercise trial and during the control trial. Appetite ratings, plasma concentrations of gut hormones, and ad libitum energy intake were assessed during main trials.ResultsIn experiment one, an energy deficit of approximately 3500 kJ induced via food restriction increased appetite and food intake. These changes corresponded with heightened concentrations of plasma acylated ghrelin and lower peptide YY3–36. None of these compensatory responses were apparent when an equivalent energy deficit was induced by exercise. In experiment two, appetite ratings and plasma acylated ghrelin concentrations were lower in exercise than in control, but energy intake did not differ between trials. The appetite, acylated ghrelin, and energy intake response to exercise did not differ between men and women.ConclusionsWomen exhibit compensatory appetite, gut hormone, and food intake responses to acute energy restriction but not in response to an acute bout of exercise. Additionally, men and women seem to exhibit similar acylated ghrelin and PYY3–36 responses to exercise-induced energy deficits. These findings advance understanding regarding the interaction between exercise and energy homeostasis in women.

Altered Appetite-Mediating Hormone Concentrations Precede Compensatory Overeating After Severe, Short-Term Energy Deprivation in Healthy Adults

Background: Adaptive responses of appetite-mediating hormones to negative energy balance are thought to contribute to a counterregulatory response that drives weight regain, but they have not been studied while controlling for reduced diet volume.Objective: In this secondary analysis, we aimed to determine the effects of short-term, severe energy deprivation (ED) on appetite and appetite-mediating hormone concentrations.Methods: Twenty-one adults with a mean ± SD age of 21 ± 3 y and body mass index of 25 ± 3 kg/m2 consumed isovolumetric diets provided over separate 48-h periods while increasing habitual energy expenditure by 1683 ± 329 kcal/d through light- and moderate-intensity exercise. Energy intake was matched to energy expenditure to maintain energy balance (EB) (−44 ± 92 kcal/d) or was <10% of energy expenditure to generate a −3696 ± 742-kcal/d energy deficit. Postprandial appetite, glucose, insulin, acyl ghrelin, peptide YY, pancreatic polypeptide (PP), and glucagon-like peptide-1 (GLP-1) responses and ad libitum energy intake were measured as secondary outcomes after both experimental periods.Results: Fasting insulin (−56% ± 42%) and acyl ghrelin (−60% ± 17%) concentrations decreased during ED but not during EB (condition-by-time interaction; P-interaction ≤ 0.01), whereas fasting leptin concentrations decreased more during ED compared with during EB (−47% ± 27% compared with −20% ± 27%; P-interaction = 0.05). Postprandial insulin (57% ± 63%; P < 0.001), GLP-1 (14% ± 28%; P = 0.04), and PP (54% ± 52%; P < 0.001) areas under the curve (AUCs) were higher, whereas the acyl ghrelin AUC was lower (−56% ± 13%; P < 0.001) after ED compared with after EB. After ED, self-rated appetite was greater, and ad libitum energy intake was 811 kcal/36 h (95% CI: 184, 1439 kcal/36 h) higher relative to after EB (P = 0.01).Conclusions: Short-term, severe ED suppressed acyl ghrelin concentrations and increased postprandial anorexigenic hormone concentrations. These effects preceded compensatory overeating, suggesting that in adults without obesity, altered sensitivity to appetite-mediating hormones may contribute to an adaptive counterregulatory response during the initial stages of negative EB. This trial was registered at clinicaltrials.gov as NCT01603550.

Impact of Exercise Timing on Appetite Regulation in Individuals with Type 2 Diabetes.

Exercise improves appetite regulation, but it is not known if premeal or postmeal exercise more effectively improves appetite regulation in individuals with type 2 diabetes. For the first time, this study compared how premeal and postmeal exercise alters appetite regulation in individuals with type 2 diabetes. Twelve obese individuals with type 2 diabetes performed 3 different trials, all in a random order, in which they consumed a dinner meal with the following: no resistance exercise (RE), premeal RE, or postmeal RE beginning 45 min after dinner. A visual analog scale was used to assess perceived hunger and fullness, and frequent blood samples were drawn for determination of acylated ghrelin, pancreatic polypeptide (PP), and peptide tyrosine tyrosine (PYY) concentrations. Premeal RE increased premeal perceived fullness, reduced perceived hunger, and reduced acylated ghrelin concentrations compared with the no RE and postmeal RE trial (P < 0.05). In the postprandial period, both premeal and postmeal RE reduced perceived hunger compared with no RE, whereas only postmeal RE reduced postprandial perceived fullness (P < 0.05) compared with no RE. Premeal or postmeal RE did not alter PYY concentrations. In both the premeal and postprandial period, RE reduced PP concentrations compared with no RE (P < 0.05), but upon cessation of RE, PP concentrations rebounded to concentrations that were similar to no RE. Both premeal and postmeal RE reduced perceived hunger and increased perceived fullness, effects that may help control food intake and aid in weight management efforts in individuals with type 2 diabetes.

Plasma concentrations of acyl-ghrelin are associated with average daily gain and feeding behavior in grow-finish pigs

The objectives of this study were to determine the effect of sex, sire line, and litter size on concentrations of acyl-ghrelin and total ghrelin in plasma of grow-finish pigs and to understand the relationship of plasma concentrations of ghrelin with feeding behavior, average daily gain (ADG), and back fat in grow-finish swine. Yorkshire-Landrace crossbred dams were inseminated with semen from Yorkshire, Landrace, or Duroc sires. Within 24 h of birth, pigs were cross-fostered into litter sizes of normal (N; >12 pigs/litter) or small (S; ≤9 pigs/litter). At 8 wk of age, pigs (n = 240) were blocked by sire breed, sex, and litter size and assigned to pens (n = 6) containing commercial feeders modified with a system to monitor feeding behavior. Total time eating, number of daily meals, and duration of meals were recorded for each individual pig. Body weight was recorded every 4 wk. Back fat and loin eye area were recorded at the conclusion of the 12-wk feeding study. A blood sample was collected at week 7 of the study to quantify concentrations of acyl- and total ghrelin in plasma. Pigs from small litters weighed more (P < 0.05) and tended (P = 0.07) to be fatter than pigs from normal litters. Postnatal litter size did not affect ADG, feeding behavior, or concentrations of ghrelin in plasma during the grow-finish phase. Barrows spent more time eating (P < 0.001) than gilts, but the number of meals and concentrations of ghrelin did not differ with sex of the pig. Pigs from Duroc and Yorkshire sires had lesser (P < 0.0001) concentrations of acyl-ghrelin than pigs from Landrace sires, but plasma concentrations of total ghrelin were not affected by sire breed. Concentrations of acyl-ghrelin were positively correlated with the number of meals and negatively correlated with meal length and ADG (P < 0.05). A larger number of short-duration meals may indicate that pigs with greater concentrations of acyl-ghrelin consumed less total feed, which likely explains why they were leaner and grew more slowly. Acyl-ghrelin is involved in regulating feeding behavior in pigs, and measuring acyl-ghrelin is important when trying to understand the role of this hormone in swine physiology.

Addition of crude glycerin to pig diets: sow and litter performance, and metabolic and feed intake regulating hormones

The continued growth in biofuel production has led to a search for alternative value-added applications of its main by-product, crude glycerin. The surplus glycerin production and a higher cost of feedstuffs have increased the emphasis on evaluating its nutritive value for animal feeding. The aim of this research was to evaluate the effect of the dietary addition of crude glycerin on sow and litter performance, and to determine the serum concentrations of hormones related to energy metabolism and feed intake in sows during gestation and lactation. A total of 63 sows were assigned randomly to one of three dietary treatments, containing 0, 3 or 6% crude glycerin (G0, G3 and G6, respectively) added to a barley-soybean meal-based diet. During gestation, none of the dietary treatments had an effect on performance, while during lactation, glycerin-fed sows consumed less feed than those fed the control diet (3.8 v. 4.2kg DM/day; P=0.007). Although lactating sows fed the G3 diet had a higher BW loss than those fed the control diet (−20.6 v. −8.7 kg; P=0.002), this difference was not reflected in litter performance. In gestation, the inclusion of glycerin did not affect blood concentrations of insulin or cortisol. However, pregnant sows fed diets supplemented with glycerin showed lower concentrations of acyl-ghrelin and higher concentrations of leptin (−55 and +68%, respectively; P<0.001). In lactating sows, there were no differences between dietary treatments for any of the hormones measured. Pre-prandial acyl-ghrelin concentrations were positively correlated with cortisol concentrations during gestation (r=0.81; P=0.001) and lactation (r=0.61; P=0.015). In conclusion, the inclusion of up to 6% crude glycerin did not affect the performance of sows during the gestation period; however it had a negative effect on the feed intake and weight loss of lactating sows. Moreover, further research is needed to elucidate the potential relationship between glycerin inclusion levels in the diet and the serum concentrations of hormones related to feed intake and energy balance control.

Short-term effects of a hypocaloric diet with low glycemic index and low glycemic load on body adiposity, metabolic variables, ghrelin, leptin, and pregnancy rate in overweight and obese infertile women: a randomized controlled trial

Obesity is related to hormonal disorders that affect the reproductive system. Low-glycemic index (LGI) diets seem to exert a positive effect on weight loss and on metabolic changes that result from obesity. We investigated the effects of a hypocaloric diet with an LGI and low glycemic load on anthropometric and metabolic variables, ghrelin and leptin concentrations, and the pregnancy rate in overweight and obese infertile women who were undergoing in vitro fertilization (IVF). The study was a randomized block-design controlled trial in which we analyzed 26 overweight or obese infertile women. Patients were assigned to a hypocaloric LGI-diet group or a control group and followed the protocol for 12 wk. Body weight, body mass index (BMI), percentage of body fat, glucose, insulin, homeostasis model assessment of insulin resistance, serum lipids, reproductive hormones, leptin, acylated ghrelin, number of oocytes retrieved in the IVF cycle, and pregnancy rate were determined. There were greater reductions in body mass, BMI, percentage of body fat, waist:hip ratio, and leptin in the LGI-diet group than in the control group (P < 0.05). Despite a change of 18% in mean values, there was no significant increase in acylated ghrelin concentrations in the LGI group compared with the control group (P = 0.215). The LGI-diet group had 85.4% more oocytes retrieved than did the control group (7.75 ± 1.44 and 4.18 ± 0.87, respectively; P = 0.039) in the IVF cycle. Three patients (21.4%) in the LGI group experienced a spontaneous pregnancy during the follow-up, which generated 3 live births. The hypocaloric LGI diet promoted a decrease in BMI, percentage of body fat, and leptin concentrations, which improved oocyte development and pregnancy rate. These results support the clinical recommendation to advise overweight and obese women to lose weight through a balanced diet before being submitted for treatment with assisted reproduction technologies. A hypocaloric diet combined with LGI foods seems to be beneficial for these patients, but additional studies are required before this treatment is recommended. This trial was registered at clinicaltrials.gov as NCT02416960.

Diagnostic accuracy of acyl-ghrelin and it association with non-alcoholic fatty liver disease in type 2 diabetic patients.

BackgroundGhrelin is a hormone produced mainly by the cells lining the fundus of the stomach, which is involved in regulation of lipid and glucose metabolism. Two major forms of ghrelin can be found in circulation: an acylated form, and non-acylated form. Serum acyl-ghrelin (AG) concentration is significantly increased in patients with visceral obesity and insulin resistance. This study was conducted to evaluate changes in serum AG levels, its diagnostic accuracy and association with NAFLD in patients with type two diabetes (T2D).MethodsIn this cross-sectional study, 91 T2D patients, age of 40–80 years, were included. All patients were divided into 3 groups. The control group included 28 T2D patients without NAFLD. The main group included 63 T2D patients with NAFLD, which was divided in 2 subgroups depending on transaminase levels: normal (n = 37) and elevated (n = 26) transaminases group. To assess the diagnostic accuracy of AG for NAFLD we used ROC-analysis.ResultsWe observed 1.5 (p = 0.016) and 2.5 (p < 0.001) fold increasing of serum AG levels in patients with NAFLD and normal or elevated transaminases compared to control groups. In multivariate logistic regression analysis high AG level was an independent, from transaminases activity, triglycerides (OR 1.791; 95 % CI 1.162–2.759; p = 0.008) and degree of IR (OR 1.599; 95 % CI 1.019–2.508; p = 0.044) predictor that associated with NAFLD. When serum AG used as non-invasive marker for NAFLD detection AUROC was 0.835 (95 % CI 0.752–0.918, p < 0.001). The cut-off value was >0.52 ng/ml, with sensitivity, specificity, PPV and NPV – 60.3 %, 92.8 %, 95.0 %, 50.9 % respectively. For distinguishing patients with NAFLD and elevated transaminases from patients with NAFLD and normal values AG was less effective.ConclusionsOur study has demonstrated that elevated AG level were associated with NAFLD. Patients with elevated transaminases had significantly higher AG levels. An increase of AG over 0.52 ng/ml can be used as a diagnostic marker for NAFLD detection in patients with T2D.

Plasma ghrelin and liquid gastric emptying in children with functional dyspepsia consistent with post-prandial distress syndrome.

Adult studies indicate a role for ghrelin in functional dyspepsia (FD) mediated through ghrelin's effect on gastric emptying (GE). This study examines the relationship between ghrelin, liquid GE, and pain in children with FD. Thirteen FD patients reporting symptoms consistent with post-prandial distress syndrome (PDS) and 17 healthy controls were enrolled. All participants received a liquid meal containing (13) C-sodium acetate. Pain severity, liquid GE utilizing exhaled (13) CO2 from the sodium acetate breath tests (ABT), plasma acyl ghrelin (AG), and des-acyl ghrelin concentrations were measured at specific intervals over 240 min following ingestion. FD-PDS patients demonstrated lower mean baseline AG (14.8 ± 9.7 vs 27.2 ± 14.0 fmol/mL; p = 0.013), AG Cmax (24.6 ± 8.2 vs 40.5 ± 16.8 fmol/mL; p = 0.007), and AG flux (18.2 ± 7.8 vs 32.7 ± 17.3 fmol/mL; p = 0.015) than controls. The time to reach maximum exhaled (13) CO2 concentration (T max ) was longer in FD patients than controls (47.5 ± 18.5 vs 35.8 ± 11.8 min; p = 0.046). Significant relationships between ghrelin analyte ratios and ABT parameters were largely confined to control participants. FD-PDS in children is associated with lower fasting and maximum AG concentrations, and dampened AG flux. These data suggest a possible role for altered ghrelin physiology in the pathogenesis of PDS.

Effect Of Post-Exercise Skimmed Milk Or Sucrose Drink Ingestion On Subsequent Appetite And Energy Intake

Ingestion of carbohydrate and protein post-exercise enhances muscle glycogen resynthesis and protein synthesis, respectively, as well as post-exercise recovery. Many exercisers do so for weight management and thus post-exercise energy intake (EI) weakens the energy deficit created by exercise and influences energy balance. PURPOSE: To investigate the effect of manipulating post-exercise recovery drink on subsequent appetite and ad-libitum EI. METHODS: After familiarisation, 10 lean males (mean (SD): age 21.3 (1.2) y, height 1.79 (0.65) m, body mass 79.2 (9.6) kg, body fat 16.5 (3.9) %) completed three randomised experimental trials. Two hours after a standard breakfast, subjects performed 30 min exercise at 60% VO2peak and five 4 min intervals at 85% VO2peak separated by 2 min rest. Post-exercise, 615 ml of a placebo (PLA: 32 kJ), skimmed milk (MILK: 912 kJ) or sucrose (CHO: 918 kJ) drink was consumed, each containing 15 ml vanilla essence and 2 g aspartame. Sixty min after drink ingestion, subjects were provided a single item ad-libitum meal and ate to satiety. Acylated ghrelin was determined in blood samples collected pre-exercise, post-exercise and pre-meal, whilst subjective appetite was measured throughout the trial and flavour characteristics of drinks were rated. RESULTS:Ad-libitum EI was lower in MILK (6746 (2035) kJ) than CHO (7762 (1921) kJ) (P<0.05) and similar in MILK and PLA (7672 (2005) kJ) (P=0.116). When energy consumed in the post-exercise drink was considered, total EI was greater in CHO than PLA or MILK (P<0.05). There were no trial differences for acylated ghrelin concentration or subjective appetite (P>0.05). MILK was rated thicker and creamier than CHO and PLA, with MILK and CHO rated sweeter than PLA (P<0.05). CONCLUSION: These results demonstrate that post-exercise consumption of skimmed milk, but not a sucrose drink suppresses subsequent EI, a finding that might be related to the thickness/creaminess of the skimmed milk. As skimmed milk ingestion has been shown to enhance post-exercise recovery and training adaptation, these findings suggest that these benefits might be possible without weakening the energy deficit induced by exercise. Skimmed milk might represent a favourable post-exercise recovery drink for exercisers undertaking weight loss or weight maintenance programmes.

Appetite and gut hormone responses to moderate-intensity continuous exercise versus high-intensity interval exercise, in normoxic and hypoxic conditions

This study investigated the effects of continuous moderate-intensity exercise (MIE) and high-intensity interval exercise (HIIE) in combination with short exposure to hypoxia on appetite and plasma concentrations of acylated ghrelin, peptide YY (PYY), and glucagon-like peptide-1 (GLP-1). Twelve healthy males completed four, 2.6 h trials in a random order: (1) MIE-normoxia, (2) MIE-hypoxia, (3) HIIE-normoxia, and (4) HIIE-hypoxia. Exercise took place in an environmental chamber. During MIE, participants ran for 50 min at 70% of altitude-specific maximal oxygen uptake (V˙O2max) and during HIIE performed 6 × 3 min running at 90% V˙O2max interspersed with 6 × 3 min active recovery at 50% V˙O2max with a 7 min warm-up and cool-down at 70% V˙O2max (50 min total). In hypoxic trials, exercise was performed at a simulated altitude of 2980 m (14.5% O2). Exercise was completed after a standardised breakfast. A second meal standardised to 30% of participants' daily energy requirements was provided 45 min after exercise. Appetite was suppressed more in hypoxia than normoxia during exercise, post-exercise, and for the full 2.6 h trial period (linear mixed modelling, p < 0.05). Plasma acylated ghrelin concentrations were lower in hypoxia than normoxia post-exercise and for the full 2.6 h trial period (p < 0.05). PYY concentrations were higher in HIIE than MIE under hypoxic conditions during exercise (p = 0.042). No differences in GLP-1 were observed between conditions (p > 0.05). These findings demonstrate that short exposure to hypoxia causes suppressions in appetite and plasma acylated ghrelin concentrations. Furthermore, appetite responses to exercise do not appear to be influenced by exercise modality.

Circulating acylghrelin levels are suppressed by insulin and increase in response to hypoglycemia in healthy adult volunteers.

Ghrelin has glucoregulatory and orexigenic actions, but its role in acute hypoglycemia remains uncertain. We aimed to investigate circulating levels of acylghrelin (AG) and unacylated ghrelin (UAG) in response to hyperinsulinemia and to hypoglycemia. A randomized, single-blind, placebo-controlled crossover study including 3 study days was performed at a university hospital clinical research center. Nine healthy men completed 3 study days: i) saline control (CTR), ii) hyperinsulinemic euglycemia (HE) (bolus insulin 0.1 IE/kg i.v. and glucose 20% i.v. for 105 min, plasma glucose ≈5 mmol/l), and iii) hyperinsulinemic hypoglycemia (HH) (bolus insulin 0.1 IE/kg i.v.). HH and HE suppressed AG concentrations at t=45-60 min as compared with CTR (P<0.05). At t=90 min, a rebound increase in AG was observed in response to HH as compared with both HE and CTR (P<0.05). UAG also decreased during HH and HE at t=45 min (P<0.05), whereas the AG-to-UAG ratio remained unaffected. This study demonstrates that AG and UAG are directly suppressed by hyperinsulinemia and that AG concentrations increase after a latency of ≈1 h in response to hypoglycemia, suggesting a potential counterregulatory role of AG.

Effects of exercise in the cold on Ghrelin, PYY, and food intake in overweight adults.

Exercise in cold water has been shown to simulate postexercise energy intake (EI) in normal-weight individuals. However, the effect of cold exercise on EI in overweight individuals has yet to be examined. The present study investigated the effect of brisk walking in a cold (8°C) and neutral (20°C) environment on postexercise EI and appetite hormone responses. Sixteen overweight participants (10 men and six women; age, 50.1 ± 11.6 yr; body mass index, 28.9 ± 4.2 kg·m) completed a 45-min treadmill walk at 8°C and 20°C in a randomized counterbalanced design. Participants were presented with an ad libitum buffet meal 45 min after exercise, and EI was covertly measured. Skin and rectal temperature were monitored throughout exercise and for 30 min after exercise, and concentrations of the appetite hormones total ghrelin, acylated ghrelin, and total peptide YY were assessed before and after exercise and before and after meal. EI was significantly greater after exercise in the cold (1299 ± 657 kcal (mean ± SD)) compared with that after exercise in the neutral environment (1172 ± 537 kcal (mean ± SD)) (P < 0.05). The change in the acylated ghrelin concentrations and the acylated ghrelin AUC values were significantly greater during walking in the cold versus those during walking in the neutral condition (P < 0.05). These findings show that in overweight individuals, exercise in the cold stimulates postexercise EI to a greater extent than exercise in a neutral environment.