scholarly journals Obesity and Appetite Control

2012 ◽  
Vol 2012 ◽  
pp. 1-19 ◽  
Author(s):  
Keisuke Suzuki ◽  
Channa N. Jayasena ◽  
Stephen R. Bloom

Obesity is one of the major challenges to human health worldwide; however, there are currently no effective pharmacological interventions for obesity. Recent studies have improved our understanding of energy homeostasis by identifying sophisticated neurohumoral networks which convey signals between the brain and gut in order to control food intake. The hypothalamus is a key region which possesses reciprocal connections between the higher cortical centres such as reward-related limbic pathways, and the brainstem. Furthermore, the hypothalamus integrates a number of peripheral signals which modulate food intake and energy expenditure. Gut hormones, such as peptide YY, pancreatic polypeptide, glucagon-like peptide-1, oxyntomodulin, and ghrelin, are modulated by acute food ingestion. In contrast, adiposity signals such as leptin and insulin are implicated in both short- and long-term energy homeostasis. In this paper, we focus on the role of gut hormones and their related neuronal networks (the gut-brain axis) in appetite control, and their potentials as novel therapies for obesity.

2005 ◽  
Vol 64 (2) ◽  
pp. 213-216 ◽  
Author(s):  
C. W. le Roux ◽  
S. R. Bloom

Obesity is taking on pandemic proportions. The laws of thermodynamics, however, remain unchanged, as energy will be stored if less energy is expended than consumed; the storage is usually in the form of adipose tissue. Several neural, humeral and psychological factors control the complex process known as appetite. Recently, a close evolutionary relationship between the gut and brain has become apparent. The gut hormones regulate important gastrointestinal functions such as motility, secretion, absorption, provide feedback to the central nervous system on availability of nutrients and may play a part in regulating food intake. Peptide YY (PYY) is a thirty-six amino acid peptide related to neuropeptide Y (NPY) and is co-secreted with glucagon-like peptide 1. Produced by the intestinal L-cells, the highest tissue concentrations of PYY are found in distal segments of the gastrointestinal tract, although it is present throughout the gut. Following food intake PYY is released into the circulation. PYY concentrations are proportional to meal energy content and peak plasma levels appear postprandially after 1 h. PYY3-36 is a major form of PYY in both the gut mucosal endocrine cells and the circulation. Peripheral administration of PYY3-36 inhibits food intake for several hours in both rodents and man. The binding of PYY3-36 to the Y2 receptor leads to an inhibition of the NPY neurones and a possible reciprocal stimulation of the pro-opiomelanocortin neurones. Thus, PYY3-36 appears to control food intake by providing a powerful feedback on the hypothalamic circuits. The effect on food intake has been demonstrated at physiological concentrations and, therefore, PYY3-36 may be important in the everyday regulation of food intake.


2005 ◽  
Vol 289 (4) ◽  
pp. R1042-R1047 ◽  
Author(s):  
Sibylle Oesch ◽  
Lukas Degen ◽  
Christoph Beglinger

The control of food intake and satiety requires a coordinated interplay. Oral protein and duodenal fat inhibit food intake and induce satiety, but their interactive potential is unclear. Our aim was therefore to investigate the interactions between an oral protein preload and intraduodenal (ID) fat on food intake and satiety feelings. Twenty healthy male volunteers were studied in a randomized, double-blind, four-period crossover design. On each study day, subjects underwent one of the following treatments: 1) water preload plus ID saline perfusion, 2) water preload plus ID fat perfusion, 3) protein preload plus ID saline perfusion, or 4) protein preload plus ID fat perfusion. Subjects were free to eat and drink as much as they wished. An oral protein preload significantly reduced caloric intake (19%, P < 0.01). Simultaneous administration of an oral protein preload and ID fat did not result in a positive synergistic effect with respect to caloric consumption, rejecting the initial hypothesis that the two nutrients exert a positive synergistic effect on food intake. An oral protein preload but not ID fat altered the feelings of hunger and fullness. These data indicate that the satiety effect of an oral protein preload is not amplified by ID fat; indeed, the effect of a protein preload does not seem to be mediated by cholecystokinin, glucagon-like peptide-1, or peptide YY. Much more information is necessary to understand the basic physiological mechanisms that control food intake and satiety.


2017 ◽  
Vol 51 (1) ◽  
pp. 52-70 ◽  
Author(s):  
M. M. I. Abdalla

Abstract The maintenance of the body weight at a stable level is a major determinant in keeping the higher animals and mammals survive. Th e body weight depends on the balance between the energy intake and energy expenditure. Increased food intake over the energy expenditure of prolonged time period results in an obesity. Th e obesity has become an important worldwide health problem, even at low levels. The obesity has an evil effect on the health and is associated with a shorter life expectancy. A complex of central and peripheral physiological signals is involved in the control of the food intake. Centrally, the food intake is controlled by the hypothalamus, the brainstem, and endocannabinoids and peripherally by the satiety and adiposity signals. Comprehension of the signals that control food intake and energy balance may open a new therapeutic approaches directed against the obesity and its associated complications, as is the insulin resistance and others. In conclusion, the present review summarizes the current knowledge about the complex system of the peripheral and central regulatory mechanisms of food intake and their potential therapeutic implications in the treatment of obesity.


2012 ◽  
Vol 108 (5) ◽  
pp. 778-793 ◽  
Author(s):  
F. A. Duca ◽  
M. Covasa

The gastrointestinal peptides are classically known as short-term signals, primarily inducing satiation and/or satiety. However, accumulating evidence has broadened this view, and their role in long-term energy homeostasis and the development of obesity has been increasingly recognised. In the present review, the recent research involving the role of satiation signals, especially ghrelin, cholecystokinin, glucagon-like peptide 1 and peptide YY, in the development and treatment of obesity will be discussed. Their activity, interactions and release profile vary constantly with changes in dietary and energy influences, intestinal luminal environment, body weight and metabolic status. Manipulation of gut peptides and nutrient sensors in the oral and postoral compartments through diet and/or changes in gut microflora or using multi-hormone ‘cocktail’ therapy are among promising approaches aimed at reducing excess food consumption and body-weight gain.


2017 ◽  
Vol 102 (7) ◽  
pp. 2364-2372 ◽  
Author(s):  
Tricia Tan ◽  
Preeshila Behary ◽  
George Tharakan ◽  
James Minnion ◽  
Werd Al-Najim ◽  
...  

Abstract Background: Roux-en-Y gastric bypass (RYGB) surgery is currently the most effective treatment of obesity, although limited by availability and operative risk. The gut hormones Glucagon-like peptide-1 (GLP-1), Peptide YY (PYY), and Oxyntomodulin (OXM) are elevated postprandially after RYGB, which has been postulated to contribute to its metabolic benefits. Objective: We hypothesized that infusion of the three gut hormones to achieve levels similar to those encountered postprandially in RYGB patients might be effective in suppressing appetite. The aim of this study was to investigate the effect of a continuous infusion of GLP-1, OXM, and PYY (GOP) on energy intake and expenditure in obese volunteers. Methods: Obese volunteers were randomized to receive an infusion of GOP or placebo in a single-blinded, randomized, placebo-controlled crossover study for 10.5 hours a day. This was delivered subcutaneously using a pump device, allowing volunteers to remain ambulatory. Ad libitum food intake studies were performed during the infusion, and energy expenditure was measured using a ventilated hood calorimeter. Results: Postprandial levels of GLP-1, OXM, and PYY seen post RYGB were successfully matched using 4 pmol/kg/min, 4 pmol/kg/min, and 0.4 pmol/kg/min, respectively. This dose led to a mean reduction of 32% in food intake. No significant effects on resting energy expenditure were observed. Conclusion: This is, to our knowledge, the first time that an acute continuous subcutaneous infusion of GOP, replicating the postprandial levels observed after RYGB, is shown to be safe and effective in reducing food intake. This data suggests that triple hormone therapy might be a useful tool against obesity.


2011 ◽  
Vol 2011 ◽  
pp. 1-10 ◽  
Author(s):  
Keisuke Suzuki ◽  
Channa N. Jayasena ◽  
Stephen R. Bloom

Obesity has received much attention worldwide in association with an increased risk of cardiovascular diseases, diabetes, and cancer. At present, bariatric surgery is the only effective treatment for obesity in which long-term weight loss is achieved in patients. By contrast, pharmacological interventions for obesity are usually followed by weight regain. Although the exact mechanisms of long-term weight loss following bariatric surgery are yet to be fully elucidated, several gut hormones have been implicated. Gut hormones play a critical role in relaying signals of nutritional and energy status from the gut to the central nervous system, in order to regulate food intake. Cholecystokinin, peptide YY, pancreatic polypeptide, glucagon-like peptide-1, and oxyntomodulin act through distinct yet synergistic mechanisms to suppress appetite, whereas ghrelin stimulates food intake. Here, we discuss the role of gut hormones in the regulation of food intake and body weight.


2008 ◽  
Vol 8 (2_suppl) ◽  
pp. S34-S41 ◽  
Author(s):  
Philip J Larsen

Endogenous glucagon-like peptide-1 (GLP-1) is an incretin hormone that plays an important role in maintaining pancreatic function as well as caloric intake. Since the advent of GLP-1 receptor agonists resistant to dipeptidyl peptidase-4 (DPP-4) (degradation, it has become clear that their chronic use promotes negative energy balance. With regard to their effects on body weight, the principal action of GLP-1 agonists is mediated via their inhibition of eating. In searching for the underlying mechanism of GLP-1 receptor agonist-induced anorexic effect, scientists have discovered pathways in the central nervous system, as well as in the periphery. This review describes emerging knowledge of a peripheral endocrine GLP-1 system mediating its activity through a central ascending GLP-1 pathway and targeting hypothalamic sites involved in the regulation of energy homeostasis. Thus peripheral and central GLP-1 sensitive pathways appear to be organised to co-operatively help control food intake and body weight.Br J Diabetes Vasc Dis 2008;8 (Suppl 2): S34—S41


2019 ◽  
Vol 316 (4) ◽  
pp. R406-R416
Author(s):  
Nathaneal J. Huston ◽  
Lynne A. Brenner ◽  
Zachary C. Taylor ◽  
Robert C. Ritter

Neuropeptide Y (NPY), peptide YY (PYY), and their cognate receptors (YR) are expressed by subpopulations of central and peripheral nervous system neurons. Intracerebroventricular injections of NPY or PYY increase food intake, and intrahypothalamic NPY1 or NPY5 receptor agonist injections also increase food intake. In contrast, injection of PYY in the periphery reduces food intake, apparently by activating peripheral Y2R. The dorsal vagal complex (DVC) of the hindbrain is the site where vagal afferents relay gut satiation signals to the brain. While contributions of the DVC are increasingly investigated, a role for DVC YR in control of food intake has not been examined systematically. We used in situ hybridization to confirm expression of Y1R and Y2R, but not Y5R, in the DVC and vagal afferent neurons. We found that nanoinjections of a Y2R agonist, PYY-(3–36), into the DVC significantly increased food intake over a 4-h period in satiated male rats. PYY-(3–36)-evoked food intake was prevented by injection of a selective Y2R antagonist. Injection of a Y1R/Y5R-preferring agonist into the DVC failed to increase food intake at doses reported to increase food intake following hypothalamic injection. Finally, injection of PYY-(3–36) into the DVC prevented reduction of 30-min food intake following intraperitoneal injection of cholecystokinin (CCK). Our results indicate that activation of DVC Y2R, unlike hypothalamic or peripheral Y2R, increases food intake. Furthermore, in the context of available electrophysiological observations, our results are consistent with the hypothesis that DVC Y2R control food intake by dampening vagally mediated satiation signals in the DVC.


2008 ◽  
Vol 294 (4) ◽  
pp. E698-E708 ◽  
Author(s):  
James R. C. Parkinson ◽  
Waljit S. Dhillo ◽  
Caroline J. Small ◽  
Owais B. Chaudhri ◽  
Gavin A. Bewick ◽  
...  

Peptide YY (PYY) is secreted postprandially from the endocrine L cells of the gastrointestinal tract. PYY3-36, the major circulating form of the peptide, is thought to reduce food intake in humans and rodents via high-affinity binding to the autoinhibitory neuropeptide Y (NPY) receptor within the arcuate nucleus. We studied the effect of early light-phase injection of PYY3-36 on food intake in mice fasted for 0, 6, 12, 18, 24, and 30 h and show that PYY3-36 produces an acute anorexigenic effect regardless of the duration of fasting. We also show evidence of a delayed orexigenic effect in ad libitum-fed mice injected with PYY3-36 in the early light phase. This delayed orexigenic effect also occurs in mice administered a potent analog of PYY3-36, d-Allo Ile3 PYY3-36, but not following injection of other anorectic agents (glucagon-like-peptide 1, oxyntomodulin, and lithium chloride). Early light-phase injection of PYY3-36 to ad libitum-fed mice resulted in a trend toward increased levels of hypothalamic NPY and agouti-related peptide mRNA and a decrease in proopiomelanocortin mRNA at the beginning of the dark phase. Furthermore, plasma levels of ghrelin were increased significantly, and there was a trend toward decreased plasma PYY3-36 levels at the beginning of the dark phase. These data indicate that PYY3-36 injection results in an acute anorexigenic effect followed by a delayed orexigenic effect.


2014 ◽  
Vol 307 (8) ◽  
pp. E619-E629 ◽  
Author(s):  
Roger Reidelberger ◽  
Alvin Haver ◽  
Krista Anders ◽  
Bettye Apenteng

Cholecystokinin (CCK)-induced suppression of feeding is mediated by vagal sensory neurons that are destroyed by the neurotoxin capsaicin (CAP). Here we determined whether CAP-sensitive neurons mediate anorexic responses to intravenous infusions of gut hormones peptide YY-(3–36) [PYY-(3–36)] and glucagon-like peptide-1 (GLP-1). Rats received three intraperitoneal injections of CAP or vehicle (VEH) in 24 h. After recovery, non-food-deprived rats received at dark onset a 3-h intravenous infusion of CCK-8 (5, 17 pmol·kg−1·min−1), PYY-(3–36) (5, 17, 50 pmol·kg−1·min−1), or GLP-1 (17, 50 pmol·kg−1·min−1). CCK-8 was much less effective in reducing food intake in CAP vs. VEH rats. CCK-8 at 5 and 17 pmol·kg−1·min−1 reduced food intake during the 3-h infusion period by 39 and 71% in VEH rats and 7 and 18% in CAP rats. In contrast, PYY-(3–36) and GLP-1 were similarly effective in reducing food intake in VEH and CAP rats. PYY-(3–36) at 5, 17, and 50 pmol·kg−1·min−1 reduced food intake during the 3-h infusion period by 15, 33, and 70% in VEH rats and 13, 30, and 33% in CAP rats. GLP-1 at 17 and 50 pmol·kg−1·min−1 reduced food intake during the 3-h infusion period by 48 and 60% in VEH rats and 30 and 52% in CAP rats. These results suggest that anorexic responses to PYY-(3–36) and GLP-1 are not primarily mediated by the CAP-sensitive peripheral sensory neurons (presumably vagal) that mediate CCK-8-induced anorexia.


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