GHRA-88HK Sigma-AldrichHuman Ghrelin (ACTIVE) RIA

Background/Objectives:Postprandial lipaemia is an established risk factor for atherosclerosis. To investigate the acute effect of four milk-derived dietary proteins (alpha-lactalbumin, whey isolate, caseinoglycomacropeptide and whey hydrolysate) on postprandial lipaemia, we have conducted a randomized, acute, single-blinded clinical intervention study with crossover design.Subjects/Methods:A total of 11 obese non-diabetic subjects (age: 44-74, BMI: 30-41.4 kg m(-2)) were included. On 4 different days the subjects ingested a high-fat meal with the following energy distribution: 66% energy from fat (100 g of butter), 15% of energy from carbohydrate (90 g of white wheat bread) and 19% of energy from protein (45 g of pure protein). Our primary variable was plasma triglyceride measured in the 8-h postprandial period. Secondarily, retinyl palmitate, non-esterified free fatty acids, glucose, insulin, glucagon, GLP-1 and GIP, active and total grehlin and cholecystokinin were measured.Results:We observed no statistically significant (P=0.8) differences between meals on our primary variable that is, triglycerides. Whey hydrolysate was associated with a significantly (P=0.02) smaller postprandial suppression of non-esterified free fatty acids compared with the other dietary proteins.Conclusion:We did not observe significant differences in postprandial lipaemia to the four milk-derived dietary proteins. Whey hydrolysate caused less postprandial suppression of free fatty acids.European Journal of Clinical Nutrition advance online publication, 27 July 2011; doi:10.1038/ejcn.2011.142.

Ghrelin, an enteric hormone with potent appetite stimulating effects, also stimulates growth hormone release. We hypothesized that altered levels of total ghrelin (TG) or acylated ghrelin (AG) could affect growth by altering growth hormone secretion, subsequently affecting insulin-like growth factor-1 (IGF-1) generation or by altering appetite and food intake. After institutional review board approval, 52 children presenting for evaluation of chronic gastrointestinal symptoms (group 1), poor weight gain (group 2), or poor linear growth (group 3) were evaluated for fasting TG and AG levels in addition to their regular evaluation. Serum ghrelin, IGF-1, and prealbumin were compared between groups. No difference was observed for mean fasting TG between groups. However, mean fasting AG was highest in patients in group 2 (465 ± 128 pg/mL) versus group 1 (176 ± 37 pg/mL) and group 3 (190 ± 34 pg/mL). IGF-1 was lowest in patients in group 2 despite similar prealbumin levels among the three groups. We conclude that serum AG levels are highest in children with isolated poor weight gain compared with children with short stature or chronic gastrointestinal symptoms, suggesting the possibility of resistance to AG in underweight children. Additional studies are needed to further clarify ghrelin's role in growth and appetite.

Animals' attitudes to risk are profoundly influenced by metabolic state (hunger and baseline energy stores). Specifically, animals often express a preference for risky (more variable) food sources when below a metabolic reference point (hungry), and safe (less variable) food sources when sated. Circulating hormones report the status of energy reserves and acute nutrient intake to widespread targets in the central nervous system that regulate feeding behaviour, including brain regions strongly implicated in risk and reward based decision-making in humans. Despite this, physiological influences per se have not been considered previously to influence economic decisions in humans. We hypothesised that baseline metabolic reserves and alterations in metabolic state would systematically modulate decision-making and financial risk-taking in humans.

Context: Ghrelin, an endogenous ligand for the GH secretagogue receptor, is an orexigenic peptide hormone produced primarily by the stomach. Recent studies suggest significant differences in the specificity of currently available ghrelin assays. Objective: The aim of the study was to compare four ghrelin assays (two commercially available and two developed by our group) of differing specificity, each used on the same set of more than 800 plasma samples from a human study. Design: Thirteen volunteers were sampled every 20 min for 6 h after consumption of one of three isocaloric drinks consisting of either 80% fat, 80% carbohydrate, or 80% protein. The samples were assayed by RIA for total and active ghrelin, as well as by sandwich assays for acyl and des-acyl ghrelin. The ghrelin profiles for each individual were smoothed using a statistical algorithm to lessen the effects of pulsatility and noise. Results: The sandwich assays for acyl and des-acyl ghrelin yielded ghrelin values that were lower than those from the corresponding RIAs. The ghrelin profiles after nutrient ingestion were similar, yet key differences among the four assays were apparent; in particular, percentage changes were significantly greater in the sandwich assays. Conclusions: The lower levels and greater relative changes in ghrelin values reported by the sandwich assays are consistent with greater assay specificity. When applied to the nutrient study, the sandwich assays were better able to distinguish the different responses to different nutrients than were the RIAs.

BACKGROUND: Epidemiologic and clinical data indicate that nuts can be incorporated into the diet without compromising body weight. This has been attributed to strong satiety properties, increased resting energy expenditure, and limited lipid bioaccessibility. OBJECTIVE: The role of mastication was explored because of evidence that the availability of nut lipids is largely dependent on the mechanical fracture of their cell walls. DESIGN: In a randomized, 3-arm, crossover study, 13 healthy adults (body mass index, in kg/m(2): 23.1 +/- 0.4) chewed 55 g almonds 10, 25, or 40 times. Blood was collected and appetite was monitored during the following 3 h. Over the next 4 d, all foods were provided, including 55 g almonds, which were consumed under the same chewing conditions. Complete fecal samples were collected. RESULTS: Hunger was acutely suppressed below baseline (P 0.05), and fullness was elevated above baseline longer (P 0.05) after 40 chews than after 25 chews. Two hours after consumption, fullness levels were significantly lower and hunger levels were significantly higher after 25 chews than after 10 and 40 chews (P 0.05). Initial postingestive glucagon-like peptide-1 concentrations were significantly lower after 25 chews than after 40 chews (P 0.05), and insulin concentrations declined more rapidly after 25 and 40 chews than after 10 chews (both P 0.05). Fecal fat excretion was significantly higher after 10 chews than after 25 and 40 chews (both P 0.05). All participants had higher fecal energy losses after 10 and 25 chews than after 40 chews (P 0.005). CONCLUSION: The results indicate important differences in appetitive and physiologic responses to masticating nuts and likely other foods and nutrients. This trial was registered at clinicaltrials.gov as NCT00768417.

This study investigated the effect of restricting grazing time on circulating concentrations of ghrelin, nonesterified fatty acids (NEFA), and glucose before, and foraging behavior of dairy cows during, the first grazing session of the day (GS, 0800-1200 h). Forty-eight Holstein-Friesian cows (470 +/- 47 kg of BW; 35 +/- 9 d in milk) were strip-grazed on a perennial ryegrass pasture for either 4 h after each milking (2 x 4), 8 h between milkings (1 x 8), or the 24-h period excluding milking times (CTL). Cows were bled before the GS; plasma was analyzed for ghrelin and serum for glucose and NEFA. Herbage mass was measured pregrazing (0730 h), during and at the end of the GS (1200 h), and postgrazing (24 h after the first measurement). Herbage mass data were fitted to a model to estimate herbage disappearance rates. Herbage intake and bite mass were calculated using herbage mass disappearance and behavioral measurements. Bite rate, eating, searching, ruminating, and idling time were determined during the GS for each cow. No difference in glucose concentration was found between treatments. Concentrations of NEFA and ghrelin were the greatest for cows in the 1 x 8 treatment. Daily herbage intake did not differ between treatments; however, during the GS 1 x 8 had a greater herbage intake than 2 x 4 and CTL. Bite mass differed between treatments and throughout the GS. Bite mass was smallest for CTL during the first 60 min and greatest during the last 90 min, when cows in the 2 x 4 treatment had the smallest bite mass. Cows in 1 x 8 spent the longest time eating and the least time searching and ruminating. Eating time was greatest for 1 x 8 during the first 60 and last 90 min of the GS. Searching time only differed in the second 60 min, when it was the lowest for 1 x 8. Cows from all treatments did not ruminate during the first 120 min. Cows in CTL had the greatest rumination time during the last 90 min. The model fitted to represent dynamics of herbage mass disappearance presented differences in the fractional herbage disappearance rate. There was an interaction between treatment and time in herbage depletion rate. The results of this study present a fuller picture of foraging dynamics during the first 4 h of grazing and its potential relationship with physiological markers of hunger as affected by grazing management.

OBJECTIVES: The purpose of this study was to examine alterations in lipid profiles and in the serum concentrations of acylated and desacylated ghrelin, paraoxonase and arylesterase in psychiatric patients before and after treatment with 40 mg citalopram daily for 3 months. DESIGN AND METHODS: Samples were collected from 22 healthy controls and 24 psychiatric patients before and after citalopram treatment. Blood levels of acylated and desacylated ghrelin were measured by radioimmunoassay. Paraoxonase and arylesterase activities were determined spectrophotometrically. Lipid parameters were measured on the OLYMPUS-AU400. RESULTS: It was found that the levels of acylated, desacylated ghrelin, paraoxonase arylesterase, total cholesterol and triglyceride were lower in depressive patients before citalopram treatment than in the control group. Those parameters were not restored after citalopram treatment except for the arylesterase level. CONCLUSION: Decreased PON1 and ghrelin levels as well as fluctuations in lipid profiles may be involved in the etiology of depressive disorders.

The objectives of the present study were 1) to evaluate the effects of supplemental fat and ME intake on plasma concentrations of glucagon-like peptide-1 (GLP-1), cholecystokinin (CCK), glucose-dependent insulinotropic polypeptide, ghrelin, and oxyntomodulin; and 2) to determine the association of these peptides with DMI and the hypothalamic concentration of mRNA for the following neuropeptides: neuropeptide Y (NPY), agouti-related peptide (AgRP), and proopiomelanocortin (POMC). In a completely randomized block design with a 2 x 2 factorial arrangement of treatments, 32 pens with 2 wethers each were restricted-fed (2.45 Mcal/lamb per day) or offered diets ad libitum (n = 16) with or without 6% supplemental fat (n = 16) for a period of 30 d. Dry matter intake was measured daily. On d 8, 15, 22, and 29, BW was measured before feeding, and 6 h after feeding, blood samples were collected for plasma measurement of insulin, GLP-1, CCK, ghrelin, glucose-dependent insulinotropic polypeptide, oxyntomodulin, glucose, and NEFA concentrations. On d 29, blood was collected 30 min before feeding for the same hormone and metabolite analyses. At the end of the experiment, wethers were slaughtered and the hypothalami were collected to measure concentrations of NPY, AgRP, and POMC mRNA. Offering feed ad libitum (resulting in greater ME intake) increased plasma insulin and NEFA concentrations (P = 0.02 and 0.02, respectively) and decreased hypothalamic mRNA expression of NPY and AgRP (P = 0.07 and 0.02, respectively) compared with the restricted-fed wethers. There was a trend for the addition of dietary fat to decrease DMI (P = 0.12). Addition of dietary fat decreased insulin and glucose concentrations (P 0.05 and 0.01, respectively) and tended to increase hypothalamic mRNA concentrations for NPY and AgRP (P = 0.07 and 0.11, respectively). Plasma GLP-1 and CCK concentrations increased in wethers offered feed ad libitum compared with restricted-fed wethers, but the response was greater when wethers were offered feed ad libitum and had supplemental fat in the diet (fat x intake interaction, P = 0.04). The prefeeding plasma ghrelin concentration was greater in restricted-fed wethers compared with those offered feed ad libitum, but the concentrations were similar 6 h after feeding (intake x time interaction, P 0.01). Supplemental dietary fat did not affect (P = 0.22) plasma ghrelin concentration. We conclude that insulin, ghrelin, CCK, and GLP-1-05-regulate DMI in sheep by regulating the hypothalamic gene expression of NPY, AgRP, and POMC.

BACKGROUND: Salatrim is modified triacylglycerol that is rich in short-chain fatty acids and stearic acid. It is used as a lower-calorie fat replacer. In addition, it has been hypothesized that salatrim's reduced absorption in the small intestine may lead to greater amounts of fat in the gastrointestinal tract, which may decrease appetite and energy intake through the release of appetite-regulating gastrointestinal hormones. OBJECTIVE: We aimed to compare the effects of salatrim and traditional fat on appetite, ad libitum energy intake, and gastrointestinal hormones. DESIGN: Twenty-two healthy, young, normal-weight men participated in a randomized, double-blind, crossover study. Test meals were a traditional fat meal and a salatrim meal with a mixture of traditional fat and salatrim. Visual analogue scales were used to record appetite and well-being every 30 min, and blood was sampled frequently. An ad libitum lunch was served 4.5 h after the test meal. RESULTS: The salatrim meal increased fullness (P = 0.04) and decreased hunger (P = 0.06) significantly more than did the traditional fat meal. The traditional fat meal increased well-being (P = 0.02). There was no significant difference in ad libitum energy intake or overall energy intake between the 2 test days. No significant differences in blood glucose, insulin, triacylglycerol, ghrelin, cholecystokinin, glucagon-like peptide-1, or peptide YY concentrations were found. A significantly (P = 0.01) smaller increase in free fatty acids was observed after the salatrim meal than after the traditional fat meal. CONCLUSIONS: Salatrim had a modestly more suppressive effect on appetite than did a traditional fat. Gastrointestinal hormones did not seem to be involved.

OBJECTIVE: The peptide hormones ghrelin and leptin have been found in blood and breast milk. This study was undertaken to investigate whether breast milk also contains obestatin, which is derived from the same gene as ghrelin but has opposite actions, and to characterize the relations among serum and milk ghrelin, obestatin, and leptin levels in lactating mothers. METHODS: Venous blood, colostrum, and mature milk were obtained from healthy lactating women (n = 31) just before suckling. The ghrelin and obestatin concentrations were determined by radioimmunoassay. Leptin levels were measured by enzyme-amplified sensitivity immunoassay. RESULTS: Obestatin levels in colostrum (538.9 pg/mL) and mature milk (528.5 pg/mL) were more than twice the corresponding blood levels (270.3 and 289.4 pg/mL, respectively). In contrast, leptin levels in colostrum (2.01 ng/mL) and mature milk (2.04 ng/mL) were more than five-fold lower than the corresponding blood levels (11.54 ng/mL). There was no correlation between breast milk ghrelin levels and leptin (r = -0.18, P > 0.05). However, there was a positive correlation between leptin levels in breast milk and blood (r = 0.369, P 0.05). CONCLUSION: The origin of milk obestatin is not currently known, but it comes from the blood or breast and may drain through the mammary glands into the milk. Ghrelin, obestatin, and leptin in the milk may directly affect appetite and their levels may be related to the regulation of energy balance and the pathogenesis of obesity.