There is evidence that the menstrual cycle affects appetite, such that energy intake is lower during the follicular compared with the luteal phase. Gastric emptying influences energy intake, glycemia, and plasma glucagon-like peptide-1 (GLP-1), insulin, and cholecystokinin (CCK) release. We hypothesized that 1) gastric emptying of a glucose drink is slower, and glycemia, plasma hormones, hunger, and energy intake are less, during the follicular compared with the luteal phase; 2) the reduction in the latter parameters during the follicular phase are related to slower gastric emptying; and 3) these parameters are reproducible when assessed twice within a particular phase of the menstrual cycle. Nine healthy, lean women were studied on three separate occasions: twice during the follicular phase (days 6-12) and once during the luteal phase (days 18-24). Following consumption of a 300-ml glucose drink (0.17 g/ml), gastric emptying, blood glucose, plasma hormone concentrations, and hunger were measured for 90 min, after which energy intake at a buffet meal was quantified. During the follicular phase, gastric emptying was slower (P < 0.05), and blood glucose (P < 0.01), plasma GLP-1 and insulin (P < 0.05), hunger (P < 0.01), and energy intake (P < 0.05) were lower compared with the luteal phase, with no differences for CCK or between the two follicular phase visits. There were inverse relationships between energy intake, blood glucose, and plasma GLP-1 and insulin concentrations with the amount of glucose drink remaining in the stomach at t = 90 min (r < -0.6, P < 0.05). In conclusion, in healthy women 1) gastric emptying of glucose is slower, and glycemia, plasma GLP-1 and insulin, hunger, and energy intake are less during the follicular compared with the luteal phase; 2) energy intake, glycemia, and plasma GLP-1 and insulin are related to gastric emptying; and 3) these parameters are reproducible when assessed twice during the follicular phase.

Gastric emptying, as well as intragastric meal distribution, and gastrointestinal hormones, including cholecystokinin (CCK), play an important role in appetite regulation. The evaluation of gastrointestinal factors regulating food intake is commonly performed in healthy, lean, young male participants. It has, however, been suggested that there is a marked interindividual variability in the effects of nutrient 'preloads' on energy intake in this group. Whether there is significant intraindividual variation in acute energy intake after a nutrient preload, and, if so, how this relates to day-to-day differences in gastric emptying and gastrointestinal hormone release, is unclear. The purpose of the present paper is to evaluate the hypothesis that energy intake after a nutrient preload would be reproducible and associated with reproducible patterns of gastric emptying, intragastric distribution and gastrointestinal hormone release. Fifteen healthy men (age 25 (SEM 5) years) consumed a glucose preload (50 g glucose in 300 ml water; 815 kJ) on three occasions. Gastric emptying and intragastric meal distribution (using three-dimensional ultrasound), blood glucose, plasma insulin and CCK concentrations and appetite perceptions were evaluated over 90 min, and energy intake from a cold buffetstyle meal was then quantified. Energy intake was highly reproducible within individuals between visits (intraclass correlation coefficient, r i ¼ 0·9). Gastric emptying, intragastric meal distribution, blood glucose, plasma insulin and CCK concentrations and appetite perceptions did not differ between visits (r i . 0·7 for all). In healthy males, energy intake is highly reproducible, at least in the short term, and is associated with reproducible patterns of gastric emptying, glycaemia, insulinaemia and CCK release.Day-to-day energy intake: Gastric emptying: Cholecystokinin: Three-dimensional ultrasound Studies evaluating appetite and energy intake in a laboratory setting have frequently utilised 'preload' paradigms (1 -7) , in which subjects receive a standardised amount of a test meal that can vary in macronutrient composition, physical state, volume and energy density, either orally or infused directly into the stomach or small intestine, and subsequent energy intake is assessed. Healthy, lean, young male subjects are frequently used in such studies, as they have been reported to have a greater capacity to adjust energy intake in response to a energy preload (i.e. by decreasing the amount of energy consumed at a subsequent meal), when compared with elderly men, healthy females or obese individuals (8,9) . Nevertheless, within this group, there appears to be substantial interindividual variability in both the total amount of food consumed and the magnitude of the reduction in their energy intake in response to energy manipulation (10) . For example, while a significant overall (mean) reduction in energy intake was evident in response to an intraduodenal lipid infusion, when compared with a control infusion of saline, the magnitude ...

Gentilcore D, Nair NS, Vanis L, Rayner CK, Meyer JH, Hausken T, Horowitz M, Jones KL. Comparative effects of oral and intraduodenal glucose on blood pressure, heart rate, and splanchnic blood flow in healthy older subjects. Am J Physiol Regul Integr Comp Physiol 297: R716 -R722, 2009. First published June 24, 2009 doi:10.1152/ajpregu.00215.2009.-Postprandial hypotension occurs frequently, particularly in the elderly. The magnitude of the fall in blood pressure (BP) and rise in heart rate (HR) in response to enteral glucose are greater when gastric emptying (GE) or small intestinal infusion are more rapid. Meal ingestion is associated with an increase in splanchnic blood flow. In contrast, gastric distension may attenuate the postprandial fall in BP. The aims of this study were to evaluate, in older subjects, the comparative effects of intraduodenal glucose infusion, at a rate similar to GE of oral glucose, on BP, HR, superior mesenteric artery (SMA) flow, and blood glucose. Eight healthy subjects (5 men, 3 women, age 66 -75 yr) were studied on two occasions. On day 1, each subject ingested 300 ml of water containing 75 g glucose. GE was quantified by three-dimensional ultrasonography between time t ϭ 0 -120 min, and the rate of emptying (kcal/min) was calculated. On day 2, glucose was infused intraduodenally at the same rate as that on day 1. On both days, BP, HR, SMA flow, and blood glucose were measured. The mean GE of oral glucose was 1.3 Ϯ 0.1 kcal/min. Systolic BP (P Ͻ 0.01), SMA flow (P Ͻ 0.05), and blood glucose (P Ͻ 0.01) were greater and HR less (P Ͻ 0.01) after oral, compared with intraduodenal, glucose. There were comparable falls in diastolic BP during the study days (P Ͻ 0.01 for both). We conclude that the magnitude of the fall in systolic BP and rise in HR are less after oral, compared with intraduodenal, glucose, presumably reflecting the "protective" effect of gastric distension. postprandial hypotension; gastric emptying; three-dimensional and Doppler ultrasound POSTPRANDIAL HYPOTENSION, defined as a decrease in systolic blood pressure Ն20 mmHg, occurring within 2 h of the end of a meal (23,25,38,39), is an important clinical problem, most commonly affecting the elderly and patients with autonomic dysfunction, the latter often secondary to diabetes (23,25,38,39). Postprandial hypotension is associated with significant complications, including syncope and falls (25) and, in some cases, stroke and angina (1,25,51).The stomach is likely to modulate the hypotensive response to a high-carbohydrate meal in two ways, first, by controlling the rate at which glucose enters the small intestine. Our laboratory's studies in healthy older subjects (26, 42) and patients with type 2 diabetes (28, 46) have established that there is a direct relationship between the magnitude of the fall in systolic blood pressure with the rate of small intestinal delivery of glucose (26,28,41,42), a response that depends on the total load of glucose entering the duodenum independent of glucose concentration (11,27). When glu...

The aim of this study was to determine whether the nitric oxide (NO) synthase inhibitor, N(g)-nitro-L-arginine-methyl-ester (L-NAME), reverses the effects of acute hyperglycaemia on gastric emptying and antropyloroduodenal (APD) motility. The study had a four-way randomized crossover (hyperglycaemia vs euglycaemia; L-NAME vs placebo) design in a clinical laboratory setting. Seven healthy volunteers [four males; age 30.3 +/- 3.8 years; body mass index (BMI) 23.6 +/- 1.2 kg m(-2)] were the study subjects. After positioning a transnasal manometry catheter across the pylorus, the blood glucose concentration was maintained at either 15 or 5 mmol L(-1) using a glucose/insulin clamp. An intravenous infusion of L-NAME (180 microg kg(-1 )h(-1)) or placebo (0.9% saline) was commenced (T = -30 min) and continued for 150 min. At T = -2 min, subjects ingested a drink containing 50 g of glucose made up to 300 mL with water. Gastric emptying was measured using 3D ultrasound, and APD motility using manometry. Hyperglycaemia slowed gastric emptying (P < 0.05), and this effect was abolished by L-NAME. L-NAME had no effect on gastric emptying during euglycaemia. Hyperglycaemia suppressed fasting antral motility [motility index: 3.9 +/- 0.8 (hyperglycaemia) vs 6.5 +/- 0.6 (euglycaemia); P < 0.01]; l-NAME suppressed postprandial antral motility [motility index: 3.6 +/- 0.2 (L-NAME) vs 5.1 +/- 0.2 (placebo); P < 0.001]. Postprandial basal pyloric pressure was higher during hyperglycaemia (P < 0.001), and lower after administration of L-NAME (P < 0.001). Slowing of gastric emptying induced by hyperglycaemia is mediated by NO, and may involve the modulation of tonic pyloric activity.

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