Gastric motor and sensory functions in obesity

Deficits in gastrointestinal responses controlling food intake and body weight

The gastrointestinal tract serves as a portal sensing incoming nutrients and relays mechanical and chemosensory signals of a meal to higher brain centers. Prolonged consumption of dietary fat causes adaptive changes within the alimentary, metabolic, and humoral systems that promote a more efficient process for energy metabolism from this rich source, leading to storage of energy in the form of adipose tissue. Furthermore, prolonged ingestion of dietary fats exerts profound effects on responses to signals involved in termination of a meal. This article reviews the effects of ingested fat on gastrointestinal motility, hormone release, and neuronal substrates. It focuses on changes in sensitivity to satiation signals resulting from chronic ingestion of high-fat diet, which may lead to disordered appetite and dysregulation of body weight.

Potato protease inhibitors inhibit food intake and increase circulating cholecystokinin levels by a trypsin-dependent mechanism

Objective

To investigate the mechanisms underlying the satiety-promoting effects of a novel protease inhibitors concentrate derived from potato (PPIC).

Methods

Acute and prolonged effects of oral PPIC administration (100 mg/kg per day) on food intake, body weight, and gastric emptying were evaluated in healthy rats. Parameters of body weight, food intake, plasma glucose, insulin, and cholecystokinin (CCK) were measured. Duodenal proteolytic activity and CCK expression were determined in tissue extracts. Intestinal STC-1 cell culture model was used to investigate the direct effect of PPIC on CCK transcript level and secretion.

Results

Acute oral administration of PPIC reduced immediate food intake during the first two hours following the treatment, delayed gastric emptying, and decreased proteolytic activity in the duodenum. Repeated oral ingestion of PPIC reduced weight gain in male rats and significantly elevated the plasma CCK levels. Although duodenal mucosal CCK mRNA levels increased in response to PPIC administration, the concentrate failed to elevate CCK expression or release in STC-1 cells. The 14-day ascending dose range study (33 to 266 mg/kg PPIC per day) showed no adverse side effects associated with PPIC administration.

Conclusion

These findings provided evidence that PPIC is effective in reducing food intake and body weight gain in healthy rats when administered orally by increasing circulating CCK levels through a trypsin-dependent mechanism.

Paired comparison between water and nutrient drink tests in healthy volunteers

CONTEXT: Drink tests constitute an inexpensive and non-invasive tool, which has been proposed to discriminate individuals with altered fluid intake, as dyspeptics. However, their use in everyday clinical practice is still limited as standardization still lacks. OBJECTIVE: To perform a direct, paired comparison between the water and the nutrient drink test in normal volunteers. METHODS: Thirty eight normal volunteers (19 males, 19 females, mean age 24.4 ± 0.4 years) underwent drink test with water and nutrient (Nutridrink) within 7-10 days. Both tests included a loading (consumption of 100 mL/min for water and 15 mL/min for Nutridrink for the longest possible period of time) and a recuperation phase (observation after cessation of fluid intake), being separated by the maximal saturation point. During phases, satiety, fullness, discomfort, bloating, belching, nausea, pain and burning sensation (epigastric and thoracic) were recorded using a 0-100 visual analogue scale score (VAS). For the purpose of configuration, four variables were considered: time (t), VAS score (V), VAS slope (S) for a given time period, and probability of participation (Q) at a given timepoint. RESULTS: The loading phase lasted for 11.6 ± 1.7 min in water (total VAS: 879 ± 123, total VAS slope 72.6 ± 10.9 min-1) and 93.3 ± 18.4 min in Nutridrink test (total VAS: 1462 ± 411, total VAS slope 15.9 ± 3.2 min-1); P<0.001. The mean ingested volume recorded was 1155 ± 164 mL for water and 1399 ± 276 mL for nutrient; P = 0.076. Cessation of fluid intake was mainly attributed to fullness (76.3%) in water and satiety (69.2%) in Nutridrink test. Nausea was recorded only in Nutridrink test (15.4%). No volunteer reported substantial, persistent pain or burning sensation. The recuperation phase lasted 63.6 ± 7.8 min in water (total VAS: 278 ± 75, total VAS slope 3.97 ± 0.95 min-1) and 123.2 ± 17.5 min in Nutridrink test (total VAS: 841 ± 126, total VAS slope 6.81 ± 1.63 min-1); P<0.001. Concerning total VAS scores for both phases of the two tests, fullness and satiety represented a mere four fifths of the total (43% and 36%, respectively). Belching (8%), bloating (6%), nausea (4%), and discomfort (3%) followed, while pain and burning sensation represented <1% of the whole. However, intra- and intertest correlations concerning total and symptom-specific VAS scores revealed statistically significant variations underlying differences in physiology of liquid intake. A multiple regression model considering body mass index, gender and age as dependent variables, and total and symptom-specific VAS scores and slopes for both phases of the two tests as independent variables, did not reveal any primary correlation. The function linking the expected probability of participation Q and symptom-specific VAS score V with time t is approached by the formulas Q(t)=1/[1+(t/c)^k] and V(t)=V0*e^(-t/c), respectively; V0 is the mean symptom-specific VAS score, c, and k are phase- and test- related constants, and e = 2.718 is the base of natural logarithms. CONCLUSION: The comparative standardization of both drink tests in normal individuals might provide a tool for clinical application, targeting the diagnosis and treatment of relevant functional disorders.

Long-term administration of an aqueous extract of dried, immature fruit of Poncirus trifoliata (L.) Raf. suppresses body weight gain in rats

AIM OF STUDY

The purpose of the present study was to examine the effects of daily administration of an aqueous extract of the dried, immature fruit of Poncirus trifoliata Raf. (Rutaceae) (PF-W) on body weight in rats.

MATERIALS AND METHODS

PF-W was used in following experiments: 10-week-long measurement of body weight and food intake, in vitro pancreatic lipase activity assay, in vivo triglyceride concentration study, and measurement of intestinal transit rate.

RESULTS

A high dose of PF-W (200 mg/2 mL/animal/day, in aqueous solution) was administered intragastrically to rats for 10 weeks. PF-W suppressed body weight gain by 6%. However, administration of PF-W at a lower dose (20 mg/animal/day) did not reduce weight gain. Administration of low- or high-dose PF-W had no effect on food intake throughout the experimental period. Additional experiments revealed that the suppressive effect of PF-W on body weight gain was not related to pancreatic lipase activity. Moreover, co-administration of PF-W with a lipid emulsion did not reduce plasma triglyceride concentration. Of interest, the high dose of PF-W significantly increased the rate of intestinal transit, whereas oral administration of the lower dose did not. Control and PF-W-treated groups did not differ in hematological and serum biochemical parameters, or in relative organ weights after 10 weeks of high-dose PF-W administration.

CONCLUSION

PF-W does not suppress body weight gain by interfering with fat absorption in a pancreatic lipase-dependent manner. The suppressive effect of PF-W on weight gain is likely due to the increased rate of intestinal transit, and the consequent reduction in nutrient absorption. Moreover, it appears that PF-W is relatively safe for long-term use. Taken together, the results of the present study suggest that long-term, daily administration of PF-W successfully suppressed body weight gain-apparently due to accelerated intestinal transit and not to interference with pancreatic lipase activity. Due to its apparent long-term safety, PF-W is a potential therapeutic agent for reduction of body weight in humans.

Peripheral mechanisms in the control of appetite and related experimental therapies in obesity

The function of the stomach and the gut hormonal responses to food ingestion constitute highly integrated homeostatic responses that maintain euglycemia and normal digestion. This intrinsic feedback involves vagal and hormonal mechanisms. Important signals such as GLP-1 and PYY that arise peripherally induce satiation and also delay gastric emptying or increase insulin secretion. Novel therapies are being developed to mimic or enhance these feedback mechanisms and to control appetite as a means to treat obesity.

Proximal gastric function in volunteers with different types of simple obesity: an analysis of 67 cases

AIM: To analyze the characteristics of changes in proximal gastric function in volunteers with different types of simple obesity.

METHODS: Sixty-seven volunteers with simple obesity were divided into three groups, namely, group A (volunteers with binge eating), group B (volunteers with normal diet) and group C (volunteers with functional dyspepsia). Thirty-two non-obese healthy volunteers formed the control group (group D). Gastric barostat studies were then performed to record the changes in gastric capacity, intragastric pressure and gastric compliance in response to mechanical distension.

RESULTS: The initial volume (IV) and maximal tolerance volume (MV) in group A were significantly larger than those in group D (t = -6.63 and -5.20, respectively; both P < 0.01), whereas these two parameters in group C were significantly lower than those in group D (t = 3.48 and 2.11, respectively; both P < 0.01). The initial intragastric pressure (IP) and the maximal tolerance pressure (MP) in group C were significantly lower than those in group D (t = 2.09 and 2.08, respectively; both P < 0.05). The initial gastric compliance (IC) and the maximal tolerance compliance (MC) in group A were significantly higher than those in group D (t = 2.44 and -5.56, respectively; both P < 0.01), whereas these two parameters in group C were significantly than those in group D (t = 2.44 and 2.32, respectively; both P < 0.05).

CONCLUSION: The main reason for the development of obesity in binge eaters is due to an increase in gastric capacity, compliance and accommodation as well as a delay in satiety.

Characteristics of gastric emptying rate in simple obesity accompanied by bulimia

AIM: To observe gastric emptying rates in simple obesity accompanied by bulimia, simple obesity with normal diet and normal weight people, and to investigate the characteristics of gastric emptying.

METHODS: Forty two subjects with simple obesity accompanied by bulimia, 32 subjects with simple obesity and normal food intake and 40 people with normal weight were studied with SPECT. After subjects eating test meal marked 99mTc-DTPA, picture of stomach was collected, and gastric emptying rate was calculated according to a fixed formula.

RESULTS: Gastric emptying halftime of simple obesity accompanied by bulimia was shorter than that of normal control (71.21 ± 19.2 min vs 81.25 ± 14.08 min, P < 0.01). Gastric emptying halftime of normal food intake group was similar to that of normal control group. Gastric emptying rate of simple obesity with bulimia was quicker than normal control (30 min: 22.35% ± 4.53% vs 15.82% ± 4.72%; 60 min: 55.13% ± 9.21% vs 47.25% ± 8.18%; 90 min: 76.35% ± 5.76% vs 69.29% ± 8.85%; 120 min: 92.22% ± 7.41% vs 84.92% ± 6.53%, all P < 0.01). Gastric emptying rate of normal food intake group was similar to that of normal control group.

CONCLUSION: The gastric emptying rate in simple obesity with bulimia become is quicker, which may partly account for obesity.

Effect of a cellulose-containing weight-loss supplement on gastric emptying and sensory functions

CM3, a highly cross-linked cellulose in capsule form, expands in the stomach to a size several fold of its original volume. It is purported to induce a prolonged feeling of satiation and a delay in gastric emptying, thus promoting weight loss. We examined whether CM3 delays gastric emptying (using the stable isotope (13)C-octanoic breath test) and whether it influences subjective feelings of appetite sensations (using visual analog scales, VASs). We performed a double-blind randomized placebo-controlled crossover trial in 19 moderately obese but otherwise healthy subjects (mean age 55 +/- 9 years, BMI 31.1 +/- 4.6 kg/m(2)). The subjects were treated with six capsules of CM3 or matching placebo 30 min before a standardized solid meal. Breath collection and VASs were performed over 4 h every 15 min and 30 min, respectively. Half-excretion time of (13)CO(2) in breath, indicating gastric emptying half time, was the primary outcome parameter. The study was powered to detect a change in gastric emptying of 20-30 min. Mean (13)CO(2) half-excretion time changed from 2.3 +/- 0.4 to 2.4 +/- 0.33 h (mean difference +6 min, 95% confidence interval (CI) -3 to +15 min; P = 0.17). Appetite sensations (hunger, satiation, fullness, prospective food consumption, desire to eat something sweet, salty, savory, or fatty) changed over time during the course of the postprandial phase but were not influenced by CM3 (repeated measures ANOVA). In obese subjects, acute administration of the weight-loss supplement CM3 does not delay gastric emptying and does not influence subjective appetite sensations.

Gastrointestinal regulation of food intake: general aspects and focus on anandamide and oleoylethanolamide

The gastrointestinal tract plays a pivotal role in the regulation of food intake and energy balance. Signals from the gastrointestinal tract generally function to limit ingestion in the interest of efficient digestion. These signals may be released into the bloodstream or may activate afferent neurones that carry information to the brain and its cognitive centres, which regulates food intake. The rate at which nutrients become systemically available is also influenced by gastrointestinal motility: a delay in gastric emptying may evoke a satiety effect. Recent evidence suggests that the endocannabinoid anandamide and the related acylethanolamide oleoylethanolamide are produced in the intestine and might regulate feeding behaviour by engaging sensory afferent neurones that converge information to specific areas of the brain. The intestinal levels of these acylethanolamides are inversely correlated to feeding, as food deprivation increases intestinal levels of anandamide (which acts in the gut as a 'hunger signal'), while it decreases the levels of oleoylethanolamide (which acts in the gut as a 'satiety signal'). Additionally, these acylethanolamides, whose gastric levels change in response to diet-induced obesity, alter gastrointestinal motility, which might contribute to their effect on food intake and nutrient absorption.

Inhibitory effect of the anorexic compound oleoylethanolamide on gastric emptying in control and overweight mice

Gastric emptying regulates food intake. Oleoylethanolamide (OEA), an endogenous acylethanolamide chemically related to the endocannabinoid anandamide, inhibits food intake, but its effect on gastric emptying is unknown. Here, we investigated the effect and the role of OEA on gastric emptying in mice fed either a standard (STD) or a high-fat diet (HFD) for 14 weeks. Gastric emptying was reduced by OEA, but not by its saturated analog, palmitoylethanolamide. The effect of OEA was unaffected by rimonabant (cannabinoid CB1 receptor antagonist), SR144528 (cannabinoid CB2 receptor antagonist), 5'-iodoresiniferatoxin (transient receptor potential vanilloid type 1 antagonist), or MK886 (peroxisome proliferator-activated receptor-alpha) antagonist. Compared to STD mice, HFD mice showed delayed gastric emptying and higher levels of gastric OEA. HFD-induced increase in OEA levels was accompanied by increased expression of the OEA-synthesizing enzyme N-acyl-phosphatidylethanolamine-selective phospholipase D and decreased expression of the OEA-degrading enzyme fatty acid amide hydrolase. These results might suggest that elevation of gastric OEA could possibly contribute to the delayed gastric emptying observed in HFD-fed animals. HFD regulates OEA levels in the stomach through an increase of its biosynthesis and a decrease of its enzymatic degradation. The inhibitory effect of OEA on gastric emptying here observed might underlie part of the anorexic effects of this compound previously reported.

Gastric tube volume after duodenal switch and its correlation to short-term weight loss

BACKGROUND

Bariatric operations may have a restrictive and a malabsorptive component. The restrictive component is considered key for short-term weight loss. However, there are important volume discrepancies between gastric reservoirs in different bariatric surgical techniques, which questions the real meaning of the restrictive part of the operation. We have investigated the relationship between residual gastric volume after sleeve gastrectomy in duodenal switch (DS) and weight loss over the first postoperative year.

METHODS

14 patients submitted to a modified DS and one patient submitted to a sleeve gastrectomy were studied. All patients had an abdominal CT performed between the third and the ninth postoperative month to measure residual gastric volume. Gastric tube volume was correlated to early postoperative weight loss.

RESULTS

Mean excess BMI loss was 75% at 12 months. Mean gastric tube volume was 208 cc. Gastric volume was not related to preoperative weight or BMI; instead, it was directly related to patient's height. There was no statistical relation between gastric volume and weight loss at 3, 6, 9 or 12 months after the operation.

CONCLUSION

After DS, gastric tube volume is not directly related to weight changes. Other factors could have influence on intake restriction, such as gastric tube compliance or different mechanisms of satiety induction, because no differences in weight loss were observed between narrow tubes and wider ones, despite important variations in volume.

The role of endocannabinoids in the regulation of gastric emptying: alterations in mice fed a high-fat diet

BACKGROUND AND PURPOSE

Endocannabinoids (via cannabinoid CB(1) receptor activation) are physiological regulators of intestinal motility and food intake. However, their role in the regulation of gastric emptying is largely unexplored. The purpose of the present study was to investigate the involvement of the endocannabinoid system in the regulation of gastric emptying in mice fed either a standard diet (STD) or a high-fat diet (HFD) for 14 weeks.

EXPERIMENTAL APPROACH

Gastric emptying was evaluated by measuring the amount of phenol red recovered in the stomach after oral challenge; CB(1) expression was analysed by quantitative reverse transcription-PCR; endocannabinoid (anandamide and 2-arachidonoyl glycerol) levels were measured by liquid chromatography-mass spectrometry.

KEY RESULTS

Gastric emptying was reduced by anandamide, an effect counteracted by the CB(1) receptor antagonist rimonabant, but not by the CB(2) receptor antagonist SR144528 or by the transient receptor potential vanilloid type 1 (TRPV1) antagonist 5'-iodoresiniferatoxin. The fatty acid amide hydrolase (FAAH) inhibitor N-arachidonoyl-5-hydroxytryptamine (but not the anandamide uptake inhibitor OMDM-2) reduced gastric emptying in a way partly reduced by rimonabant. Compared to STD mice, HFD mice exhibited significantly higher body weight and fasting glucose levels, delayed gastric emptying and lower anandamide and CB(1) mRNA levels. N-arachidonoylserotonin (but not rimonabant) affected gastric emptying more efficaciously in HFD than STD mice.

CONCLUSIONS AND IMPLICATIONS

Gastric emptying is physiologically regulated by the endocannabinoid system, which is downregulated following a HFD leading to overweight.

Adjustable totally implantable intragastric prosthesis (ATIIP)-Endogast for treatment of morbid obesity: one-year follow-up of a multicenter prospective clinical survey

BACKGROUND

The Adjustable Totally Implantable Intragastric Prosthesis (ATIIP)-Endogas is a new mini-invasive technique for the treatment of morbid obesity. The ATIIP is conducted using a surgical and endoscopic procedure. The permanent presence of an air-inflated prosthesis inside the gastric corpus-fundus area and the fixation of the stomach to the abdominal wall are the two main principles in the technique. The prosthesis is connected to a subcutaneous totally implantable system. The aim of the ATIIP is to induce early satiety and reduction of meal intake. This study presents the preliminary results of 1-year follow-up of a multicenter prospective clinical survey.

METHODS

From November 2004 to March 2007, 57 patients underwent ATIIP: 28 males (49%) and 29 females (51%), with mean age 43.6 years (18-69) and mean BMI 48.9 (33.7-81.2). Follow-up was 1-28 months.

RESULTS

Feasibility was 100%, reproducibility 100%, and acceptability found no vomitting. Mean volume of the prosthesis was 210 ml of air (first 3 months, 40 patients). Mean %EWL was 22.3% (3 mos, 40 pts), 28.7% (6 mos, 38 pts), and 39.2% (12 mos, 20 pts). Early postoperative complication was local subcutaneous infection in 7 pts (12.2%). In 16 pts who had a subcutaneous drain and empirical antibiotic therapy until the 4th postoperative day, local infection occurred in 1 patient (6.2%). Late postoperative complications occurred in 3 pts (5.2%) who developed port erosion.

CONCLUSIONS

Preliminary results indicate that the ATIIP is feasible, reproducible, safe with low risk of complications and has encouraging results in weight loss. Morbidly obese patients >60 years old and the super-obese (BMI>50) are specific indications.

Laparoscopic adjustable pyloric band with fundoplication in bariatric surgery: technique and preliminary results

BACKGROUND

Laparoscopic biliopancreatic diversion according to Scopinaro is an extremely effective operation for weight loss, but carries significant morbidity in terms of metabolic deficiencies.

METHODS

A study was conducted as to the feasibility, safety and efficiency of a novel procedure, accomplishing a 'reversible Scopinaro BPD', performed in two stages: first the placement of an adjustable band in a juxtapyloric position, aiming at maintaining postprandial satiety, and second, the construction of a transmesocolic Roux-en-Y gastro-enterostomy with a 2.5-m long distal jejunal limb, reanastomosed 50 cm proximal to the ileocecal valve.

RESULTS

15 patients, mean BMI 38.9, 8 males and 7 females, underwent the first stage of pyloric adjustable banding. All benefited at the same time from a Nissen fundoplication, to avoid gastroesophageal reflux. 1 patient was withdrawn from the study at this stage because of peritonitis of unknown cause and removal of the band. 3 patients benefited from the second stage of the operation because of insufficient weight loss, and/or symptoms of gastric stasis. 1 patient developed diarrhea and was treated by peroral cholestyramine. Weight loss was similar to the regular BPD figures.

CONCLUSION

The placement of an adjustable gastric band in a juxtapyloric position, combined with a Nissen fundoplication, appears to be a safe and efficient satiety-inducing operation. In case of insufficient weight loss, and/or exaggerated gastric stasis, a Scopinaro BPD construction can be added to the otherwise unharmed stomach, hereby constituting an instantly reversible malabsorptive component.

Gastric emptying of solids and semi-solids in morbidly obese and non-obese subjects: an assessment using the 13C-octanoic acid and 13C-acetic acid breath tests

BACKGROUND

It has been suggested that obesity is associated with an altered rate of gastric emptying. The objective of the present study was to determine whether the rates of solid and semi-solid gastric emptying differ between morbidly obese patients and lean subjects.

METHODS

The Gastric-emptying time (GET) of solid and semi-solid meals were compared between lean healthy subjects and morbidly obese patients enrolled in two previously published studies. GET of solid and semi-solid meals was measured using the 13C-octanoic acid breath test and 13C-acetic acid breath test, respectively, in 24 lean and 14 morbidly obese individuals of both sexes. Student t-test was used to compare the mean data between the lean and morbidly obese groups. The influence of sex, gender, BMI and morbid obesity on the GET of solid meals was verified by linear regression analysis.

RESULTS

Mean t(1/2) values of solid GET (+/- standard deviation) were 203.6 +/- 76.0 min and 143.5 +/- 19.1 min for lean and obese subjects, respectively (P = 0.0010). Mean t(lag) values of solid GET were 127.3 +/- 42.7 min and 98.4 +/- 13.0 min for lean and obese subjects, respectively (P = -0.0044). No significant difference in semi-solid GET was observed between the lean and morbidly obese groups.

CONCLUSION

The present study demonstrated a significantly enhanced gastric emptying of the solid meal test in morbidly obese patients when compared to lean subjects. This finding is compatible with the hypothesis that rapid gastric emptying in morbidly obese subjects increases caloric intake due to a more rapid loss of satiety.

Appetite and obesity: a gastroenterologist's perspective

This review focuses on the gastrointestinal tract's control of appetite and interventions directed to the gut that are effective in the treatment of obesity. It examines the evidence linking gut hormones to the control of both appetite and upper gastrointestinal motility, the evidence that stomach function is altered and contributes to satiation in obesity and outlines the principles of therapy for obesity which are directed at the gastrointestinal tract. These therapies impair fat absorption or alter stomach functions through pharmacological, device, endoscopic, or surgical approaches. Gastroenterologists need to understand the role of factors controlling appetite in order to effectively manage the increasing number of obese patients and the ways the gut function may be altered as a result of the treatments and their complications.

Effects of a combination fiber system on appetite and energy intake in overweight humans

Appetite management may aid energy balance through moderation of the size (satiation) and/or frequency (satiety) of eating occasions. This double-blind, randomized, cross-over design study explored the effects of the addition of alginate and guar gum to a breakfast bar on appetite and food intake. Following baseline evaluations of health, appetite and diet, participants were randomized to receive the fiber containing bar or control bar. They reported to the laboratory after an overnight fast, rated their appetite and consumed the relevant 55 g bar within 10 min in place of their normal breakfast meal. Appetite ratings were again made immediately after consuming the bar and at 30 minute intervals for 5 h. This was repeated for 5 consecutive days (Monday-Friday) followed by a 9-day washout period and a similar 5-day treatment period with the alternate bar. Gastrointestinal tolerance was rated daily. Sensory ratings of the bars were obtained on the first and fifth study days. Twenty-four-hour diet recalls were conducted on three random days during baseline and each intervention period. No significant treatment effects were observed in self-reported appetitive sensations over each 5-hour post-loading period. There also was no evidence of a cumulative effect over the five treatment days. Daily energy intake was not different on the two treatments. Although these data do not support the efficacy of including guar and an alginate fiber combination in a solid food matrix for moderation of appetite and acute food intake, further testing of the concept under different conditions and with different forms of guar and alginate may prove worthwhile.

Inhibitory effects of intestinal electrical stimulation on food intake, weight loss and gastric emptying in rats

The aim was to investigate the effects of intestinal electrical stimulation (IES) on food intake, body weight, and gastric emptying in rats. An experiment on food intake and weight change was performed in 22 rats on a control diet and 10 diet-induced obese (DIO) rats for 4 wk with IES or sham IES. The effect of IES on gastric emptying was performed in another 20 rats in the control group. We found that 1) in control rats, 4-wk IES resulted in a reduction of 18.2% in the total amount of food intake compared with sham-IES (P = 0.02); the rats treated with IES had a weight change of -1 +/- 7.8g (P = 0.03), which was equivalent to a weight loss of 6.2% due to IES when adjusted for normal growing. 2) Acute IES delayed gastric emptying by 20% in the control rats (P < 0.01). 3) In the DIO rats, 1-wk IES with the same parameters as those used in the control rats resulted in a significant reduction in the total amount of food intake (126.6 +/- 6.3 g vs. 116.9 +/- 3.2 g, P < 0.01). More reduction in food intake was noted, and a significant weight change was also observed when stimulation energy was increased. 4) No adverse events were observed in any of the experiments. In conclusion, IES delays gastric emptying, reduces food intake, and decreases weight gain in control growing rats. These data suggest that it is worthy to explore therapeutic potentials of IES for obesity.

The role of peptide YY in integrative gut physiology and potential role in obesity

PURPOSE OF REVIEW

Obesity is an increasing global epidemic. Several central and peripheral hormones and neurotransmitters are involved in appetite control. Peptide YY (PYY) - one of the major anorexigenic (satiation-causing) gastrointestinal peptides - when administered peripherally, leads to decreased food intake and hunger scores.

RECENT FINDINGS

The vagus nerve, brainstem, and hypothalamus play an important role in PYY-mediated appetite control. In some studies, fasting and postprandial PYY levels are decreased in obese subjects. In others, levels are no different between obese and nonobese subjects. One study showed that obese subjects must consume more calories to increase PYY to levels seen in nonobese subjects. Surgical weight-loss procedures lead to increased fasting and postprandial PYY levels that are thought to contribute to weight loss achieved with these procedures.

SUMMARY

These findings lend some support for the association between PYY and obesity that could lead to possible new therapeutic options in obesity. PYY exerts anorexigenic effects; it is possible that surgical weight-loss procedures work synergistically with PYY to promote weight loss. Further investigation is needed to clarify whether PYY actually causes reduced calorie intake or whether the rate of food delivery to the ileo-colonic segment influences PYY levels, thus affecting satiation.

Proximal gastric motility in critically ill patients with type 2 diabetes mellitus

AIM: To investigate the proximal gastric motor response to duodenal nutrients in critically ill patients with long-standing type 2 diabetes mellitus.

METHODS: Proximal gastric motility was assessed (using a barostat) in 10 critically ill patients with type 2 diabetes mellitus (59 ± 3 years) during two 60-min duodenal infusions of Ensure^® (1 and 2 kcal/min), in random order, separated by 2 h fasting. Data were compared with 15 non-diabetic critically ill patients (48 ± 5 years) and 10 healthy volunteers (28 ± 3 years).

RESULTS: Baseline proximal gastric volumes were similar between the three groups. In diabetic patients, proximal gastric relaxation during 1 kcal/min nutrient infusion was similar to non-diabetic patients and healthy controls. In contrast, relaxation during 2 kcal/min infusion was initially reduced in diabetic patients (p < 0.05) but increased to a level similar to healthy humans, unlike non-diabetic patients where relaxation was impaired throughout the infusion. Duodenal nutrient stimulation reduced the fundic wave frequency in a dose-dependent fashion in both the critically ill diabetic patients and healthy subjects, but not in critically ill patients without diabetes. Fundic wave frequency in diabetic patients and healthy subjects was greater than in non-diabetic patients.

CONCLUSION: In patients with diabetes mellitus, proximal gastric motility is less disturbed than non-diabetic patients during critical illness, suggesting that these patients may not be at greater risk of delayed gastric emptying.

Feed intolerance in critical illness is associated with increased basal and nutrient-stimulated plasma cholecystokinin concentrations

OBJECTIVE

Delayed gastric emptying and intolerance to gastric feeding occur frequently in the critically ill. In these patients, gastric motor responses to nutrients are disturbed. Cholecystokinin (CCK) slows gastric emptying. The aim of this study was to determine plasma CCK concentrations during fasting and in response to small-intestine nutrient infusion in critically ill patients.

DESIGN

Randomized, controlled trial.

SETTING

Level 3, mixed medical and surgical intensive care unit.

SUBJECTS

A total of 31 mechanically ventilated, critically ill patients (23 men, 51 +/- 3 yrs) and 28 healthy subjects (21 men, 43 +/- 2 yrs).

INTERVENTIONS

Subjects received two 60-min duodenal infusions of Ensure (complete balanced nutrition), at 1 and 2 kcal/min, in a randomized, single-blind fashion. The nutrient infusions were separated by a 2-hr "washout" period. Blood samples for measurement of plasma CCK concentrations were obtained immediately before and every 20 mins during nutrient infusion.

MEASUREMENTS AND MAIN RESULTS

Baseline and nutrient-stimulated plasma CCK concentrations were higher in critically ill patients compared with healthy subjects (p < .001). The magnitude of the rise in plasma CCK in response to nutrients was also greater in the critically ill (p < .01). Of the 23 patients who received enteral nutrition before the study, nine were intolerant of gastric feeding. In these patients, both the baseline plasma CCK concentration and the magnitude of CCK increase during nutrient infusions were greater than in patients with feed tolerance (p < .002). Impaired renal function was associated with an increased baseline CCK concentration but had no effect on the CCK response to nutrients.

CONCLUSIONS

Both fasting and nutrient-stimulated plasma CCK concentrations are increased in critically ill patients, particularly in those with feed intolerance. This may provide a humoral mechanism for delayed gastric emptying seen in critical illness.

Gastric sensorimotor functions and hormone profile in normal weight, overweight, and obese people

BACKGROUND & AIMS

Peptide YY (PYY) levels are reported to be decreased in obesity. The relation between gastric functions, satiation, and gut hormones in obesity is incompletely understood. The aim of this study was to compare gastric volumes, emptying, maximum tolerated volumes, postchallenge symptoms, and selected gut hormones in normal, overweight, or obese healthy volunteers.

METHODS

In 73 nonbulimic normal, overweight, or obese participants weighing less than 137 kg, we measured gastric emptying of solids and liquids by scintigraphy (gastric emptying half-time [GE t(1/2)]); gastric volumes by single-photon emission computed tomography; maximum tolerated volumes and symptoms by satiation test; and plasma leptin, ghrelin, insulin, glucagon-like peptide 1, and PYY levels. Groups were compared using 1-way analysis of covariance adjusted for sex. Univariate associations among measured responses were assessed using Spearman correlations. Multiple linear regression models, adjusting for weight and sex, assessed the independent ability of gastric functions and hormones to predict satiation volume.

RESULTS

Obese and overweight subjects had significantly lower postprandial gastric volumes, higher fasting and postprandial insulin and leptin levels, and lower fasting ghrelin and lower postprandial reduction in ghrelin levels. PYY levels were not different in obese or overweight subjects compared with controls. The GE t(1/2) was correlated inversely with postprandial PYY; increased body weight was associated with faster GE t(1/2) of solids (r(s) = 0.33, P = .005) and liquids (r(s) = 0.24, P = .04). Postprandial changes in gastric volume and PYY were independent predictors of satiation (both P = .01).

CONCLUSIONS

Overweight or obesity are associated with lower postprandial gastric volumes and normal PYY levels. Gastric emptying influences postprandial PYY levels. Postprandial PYY and gastric volume independently predict satiation volume in nonbulimic people across a wide body mass index range.

Obesity does not increase effects of synthetic ghrelin on human gastric motor functions

BACKGROUND & AIMS

Ghrelin is secreted by the stomach and stimulates food intake. Obese individuals have lower fasting plasma ghrelin levels but increased appetite, suggesting greater responses to endogenous ghrelin in obesity. The aim of this study was to compare effects of exogenous ghrelin (at a dose that stimulates growth hormone [GH] release in the physiologic range) versus placebo on gastric emptying, gastric volume, and postprandial symptoms and determine whether body mass (ranging from normal weight to obesity) influences responses to ghrelin.

METHODS

After intravenous bolus synthetic human ghrelin (0.33 mug/kg) or saline, we measured plasma GH, gastric volume, and gastric emptying by combined (99m)Tc-single-photon emission computed tomography and scintigraphy ((111)In egg meal, 300 kcal) and postprandial symptoms using visual analogue scales.

RESULTS

In 25 obese subjects (5 men and 20 women; body mass index [BMI], 36 +/- 4 kg/m(2)) and 13 female normal-weight (BMI, 22 +/- 2 kg/m(2)) subjects of similar ages, ghrelin increased GH levels (15.0 +/- 2.4 ng/mL) at 40 minutes postinjection and tended to decrease fasting gastric volumes compared with placebo (P = .059). There were no effects of BMI on treatment response and no differences between ghrelin and saline on postprandial (P = .09) or change in (postprandial minus fasting) gastric volumes, gastric emptying, or aggregate postprandial symptoms. Effects of ghrelin did not differ between obese and normal-weight participants.

CONCLUSIONS

At doses that stimulate physiologic GH plasma levels, synthetic ghrelin tended to decrease fasting gastric volumes without altering postprandial volumes or gastric emptying in a predominantly female cohort. The data are not consistent with the hypothesis that higher body mass is associated with increased gastric responsiveness to ghrelin.

Peripheral mechanisms of sibutramine involving proximal gastric motility in dogs

OBJECTIVE

Sibutramine, a serotonin-norepinephrine uptake inhibitor, has been used for treating obesity. However, its possible mechanisms involving gastric motility have not been reported. The aim of this study was to evaluate the effects of sibutramine on gastric accommodation and antral motility.

RESEARCH METHODS AND PROCEDURES

The study was performed in seven dogs with a stomach cannula and composed of two separate experiments: antral contractions and gastric tone. Each experiment included two sessions on 2 separate days in a randomized order: a control session and a treatment session with sibutramine (5 mg/kg per os) administrated 2 hours before the study.

RESULTS

Sibutramine significantly increased fasting gastric tone; the gastric volume in the fasting state at baseline was 103.8 +/- 12.3 mL and significantly decreased to 35.3 +/- 16.0 mL with sibutramine (p = 0.0075). Sibutramine also impaired gastric accommodation. The average postprandial gastric volume was 472.1 +/- 16.7 mL in the control session and reduced to 302.2 +/- 53.6 mL with sibutramine (p = 0.013). The average postprandial increase in gastric volume during the 60-minute postprandial period with sibutramine was significantly lower than the corresponding values in the control session: 266.8 +/- 46.1 vs. 393.9 +/- 15.3 mL (p = 0.03). Sibutramine had no effects on postprandial antral contractions.

DISCUSSION

Sibutramine increases gastric tone and impairs gastric accommodation to an orally ingested meal. The inhibitory effect of sibutramine on gastric accommodation may partially explain the reduced food intake with sibutramine in patients with obesity.