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The effects of a simulated in vitro digestion model on the viscosity of solutions comprised of high methoxyl, low methoxyl, and low methoxyl amidated pectins were examined in conjunction with a human satiety study with healthy men (n=10) and women (n=15). Participants attended 8 morning sessions with a washout period of one week after a 12 h overnight fast. Self reported measurements were taken for the satiety parameters of hunger, fullness, satisfaction and prospective food intake using 100 mm VAS scales at predetermined time intervals over the course of 3 h. Orange juice solutions of each type of fibre were formulated to be either low viscosity (LV, 0.039±0.007 Pa•s) or high viscosity (HV, 0.14±0.035 Pa•s). The apparent viscosities of an in vitro digestion model simulating the gastric and duodenal phases in the presence of hydrolytic enzymes and bile salts were reported at 10 s-1 and 50 s-1. All pectin types showed varying apparent viscosities during the gastric phases, but showed considerable reductions in viscosity after the final phase. The low-methoxyl low and high viscosity pectin beverages were associated with the greatest effect on human subjective ratings of satiety, and high methoxyl low and high viscosity pectin beverages inconsistently exerting effects on satiety. Thus, some types of pectin are able to increase perception of satiety in humans. However, there was not a strong correlation between apparent viscosity of in vitro digestive fluids and total mean AUC for satiety related questions. Thus, fiber-induced satiety cannot be explained in full by digestate viscosity alone. / NSERC

β-D-Glucan has been proposed to suppress appetite related perceptions thus contribute favourably to the regulation of energy intake and the increasing obesity problem in North America. Due to its low concentrations in grains, the challenge has been to produce β-glucan concentrates that can be incorporated into foods without adversely affecting product attributes. Therefore in the first part of the study, a protocol for the concentration of β-glucan, based on protein-polysaccharide incompatibility, was investigated. The extract obtained was utilized in the second part, where the effect of beverages with increased β-glucan content on perceived satiety and blood glucose, at different fibre concentrations was studied. Twenty nine healthy adults participated in this study. 5 beverage pre-loads, containing between 0-2.5 g of β-glucan in 500 mL of the sample, were ingested 120 min before the given meal. Results showed a trend towards a decrease in appetite scores with increasing β-glucan content of the beverages, as well as differences in the blood glucose readings, though these were not significant, and could not solely be attributed to β-glucan content due to differences in beverage composition.

The field of food intake and satiety has received increasing interest from the research community in recent years. The mechanisms and factors that regulate satiety gains their importance from the crucial role they play in food consumption and consequently control of body weight. Leukotrienes are mediators that are released in inflammatory conditions. One of the receptors on which Leukotrienes perform their actions is Cysteinyl Leukotriene Receptor Type 2 (CysLT2Rs). Recently, our colleagues made the observation that CysLT2Rs are expressed in vagal afferent neurons. In addition, CysLT2R-/- mice appeared to be heavier than WT (Moos and Funk, unpublished observations). Based on these findings, I hypothesized that CysLT2Rs play a role in regulating food intake via vagal afferent activity. In-vivo studies were performed to characterize body weight gain and investigate whether weight gain was associated with increased food intake. I found that CysLT2R-/- mice not only have significantly higher body weight, but also eat significantly more than CysLT2R+/+ mice. Using calcium imaging techniques, I demonstrated that LTD4 and LTC4 increased calcium Ca2+ influx in nodose ganglion neuron. Moreover, the level of neuronal activation in the brainstem (NTS area) was measured in both groups of mice using immunohistochemical techniques, which suggested less postprandial neuronal activity in KO mice. These data suggest that CysLT2Rs take part in regulating body weight and food intake. In addition these results implicate vagal afferents as a possible pathway. These findings may have implications for the control of food intake in both health and disease and may lead to novel insights in the causes and treatment of disordered weight such as overweight and obesity, or even anorexia. / Thesis (Master, Physiology) -- Queen's University, 2011-02-04 10:48:47.018

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Appetite control and satiety mechanisms help animals maintain energy homeostasis; however, these mechanisms can be misregulated, leading to overweight and obesity. Caenorhabditis elegans is an excellent model system to study appetite and satiety because of its conserved behavioral aspects of satiety and conserved molecular mechanisms. ASI senses nutrition and its activity is required for the behavioral state of satiety quiescence. The purpose of this thesis project was to elucidate the function of cGMP signaling in ASI by looking at behavioral effects from the pharmacological use of sildenafil (Viagra), a PDE inhibitor, and the effects on ASI activation from mutating guanylyl cyclase DAF-11. Sildenafil treatment increases satiety quiescence and decreases fat storage in a PDE-dependent manner. The daf-11 mutation decreased overall fluorescence intensity of ASI activation and the frequency at which ASI activated by about 50% compared to wild-type worms, suggesting that DAF-11 plays an important role in ASI to promote satiety.

Desire to eat, hunger, feeling of having enough to eat, and fullness were measured in 11 eating disorder patients in treatment for less than two months, 7 eating disorder patients in treatment for more than two months, and 11 controls. The experimental group was female patients with a DSM-IV diagnosis of Anorexia Nervosa, Bulimia Nervosa, or eating disorder not-otherwise-specified. The experimental and control groups ate a test meal two hours after a preload. The groups answered four questions about desire to eat, hunger, feeling of having enough to eat, and fullness, before they ate, halfway through their meal, immediately upon finishing the meal, and 15 minutes after finishing their meal. The groups were required to eat 100% of the meal provided. The difference in data between the experimental and control groups was not statistically significant. The experimental group that had been in treatment longer than two months had means closer to the control group than the other experimental group who had been in treatment less than two months. This may suggest that the experimental group who had been in treatment more than two months was starting to regain a more normal sense of hunger and satiety. However, a repeat study with a larger sample size would be needed to prove that statement.