scholarly journals Pancreatic signals controlling food intake; insulin, glucagon and amylin

2006 ◽  
Vol 361 (1471) ◽  
pp. 1219-1235 ◽  
Author(s):  
Stephen C Woods ◽  
Thomas A Lutz ◽  
Nori Geary ◽  
Wolfgang Langhans

The control of food intake and body weight by the brain relies upon the detection and integration of signals reflecting energy stores and fluxes, and their interaction with many different inputs related to food palatability and gastrointestinal handling as well as social, emotional, circadian, habitual and other situational factors. This review focuses upon the role of hormones secreted by the endocrine pancreas: hormones, which individually and collectively influence food intake, with an emphasis upon insulin, glucagon and amylin. Insulin and amylin are co-secreted by B-cells and provide a signal that reflects both circulating energy in the form of glucose and stored energy in the form of visceral adipose tissue. Insulin acts directly at the liver to suppress the synthesis and secretion of glucose, and some plasma insulin is transported into the brain and especially the mediobasal hypothalamus where it elicits a net catabolic response, particularly reduced food intake and loss of body weight. Amylin reduces meal size by stimulating neurons in the hindbrain, and there is evidence that amylin additionally functions as an adiposity signal controlling body weight as well as meal size. Glucagon is secreted from A-cells and increases glucose secretion from the liver. Glucagon acts in the liver to reduce meal size, the signal being relayed to the brain via the vagus nerves. To summarize, hormones of the endocrine pancreas are collectively at the crossroads of many aspects of energy homeostasis. Glucagon and amylin act in the short term to reduce meal size, and insulin sensitizes the brain to short-term meal-generated satiety signals; and insulin and perhaps amylin as well act over longer intervals to modulate the amount of fat maintained and defended by the brain. Hormones of the endocrine pancreas interact with receptors at many points along the gut–brain axis, from the liver to the sensory vagus nerve to the hindbrain to the hypothalamus; and their signals are conveyed both neurally and humorally. Finally, their actions include gastrointestinal and metabolic as well as behavioural effects.

2017 ◽  
Vol 235 (1) ◽  
pp. R13-R31 ◽  
Author(s):  
Andrea Stojakovic ◽  
Enma P Espinosa ◽  
Osman T Farhad ◽  
Kabirullah Lutfy

Chronic tobacco use leads to nicotine addiction that is characterized by exaggerated urges to use the drug despite the accompanying negative health and socioeconomic burdens. Interestingly, nicotine users are found to be leaner than the general population. Review of the existing literature revealed that nicotine affects energy homeostasis and food consumption via altering the activity of neurons containing orexigenic and anorexigenic peptides in the brain. Hypothalamus is one of the critical brain areas that regulates energy balance via the action of these neuropeptides. The equilibrium between these two groups of peptides can be shifted by nicotine leading to decreased food intake and weight loss. The aim of this article is to review the existing literature on the effect of nicotine on food intake and energy homeostasis and report on the changes that nicotine brings about in the level of these peptides and their receptors that may explain changes in food intake and body weight induced by nicotine. Furthermore, we review the effect of nicotine on the hedonic aspect of food intake. Finally, we discuss the involvement of different subtypes of nicotinic acetylcholine receptors in the regulatory action of nicotine on food intake and energy homeostasis.


2002 ◽  
Vol 80 (5) ◽  
pp. 396-406 ◽  
Author(s):  
James E Blevins ◽  
Michael W Schwartz ◽  
Denis G Baskin

The adiposity hormone leptin has been shown to decrease food intake and body weight by acting on neuropeptide circuits in the hypothalamus. However, it is not clear how this primary hypothalamic action of leptin is translated into a change in food intake. We hypothesize that the behavioral effect of leptin ultimately involves the integration of neuronal responses in the forebrain with those in the nucleus tractus solitarius in the caudal brainstem, where ingestive behavior signals are received from the gastrointestinal system and the blood. One example is the peptide cholecystokinin, which is released from the gut following ingestion of a meal and acts via vagal afferent nerve fibers to activate medial nucleus tractus solitarius neurons and thereby decrease meal size. While it is established that leptin acts in the arcuate nucleus in the hypothalamus to stimulate anorexigenic neurons that inhibit food intake while simulataneously inhibiting orexigenic neurons that increase food intake, the mechanisms linking these effects with regions of the caudal brainstem that integrate cues related to meal termination are unclear. Based on an increasing body of supportive data, we hypothesize that this integration involves a pathway comprising descending projections from neurons from the paraventricular nucleus to neurons within the nucleus tractus solitarius that are activated by meal-related satiety factors. Leptin's anorexic effect comprises primarily decreased meal size, and at subthreshold doses for eliciting an effect on food intake, leptin intensifies the satiety response to circulating cholecystokinin. The location of neurons subserving the effects of intracerebroventricular administration of leptin and intraperitoneal injection of cholecystokinin on food intake has been identified by analysis of Fos expression. These studies reveal a distribution that includes the paraventricular nucleus and regions within the caudal brainstem, with the medial nucleus tractus solitarius having the most pronounced Fos expression in response to leptin and cholecystokinin, and support the hypothesis that the long-term adiposity signal leptin and the short-term satiety signal cholecystokinin act in concert to maintain body weight homeostasis.Key words: brainstem, adiposity, satiety.


Endocrinology ◽  
2006 ◽  
Vol 147 (12) ◽  
pp. 5940-5947 ◽  
Author(s):  
Y. C. Loraine Tung ◽  
Sarah J. Piper ◽  
Debra Yeung ◽  
Stephen O’Rahilly ◽  
Anthony P. Coll

Functional disruption of either MC3R or MC4R results in obesity, implicating both in the control of energy homeostasis. The ligands for these receptors are derived from the prohormone proopiomelancortin (POMC), which is posttranslationally processed to produce a set of melanocortin peptides with a range of activities at the MC3R and MC4R. The relative importance of each of these peptides α-MSH, γ3-MSH, γ2-MSH, γ-lipotropin (γ-LPH) and, in man but not in rodents, β-MSH] in the maintenance of energy homeostasis is, as yet, unclear. To investigate this further, equimolar amounts (2 nmol) of each peptide were centrally administered to freely feeding, corticosterone-supplemented, Pomc null (Pomc−/−) mice. After a single dose at the onset of the dark cycle, α-MSH had the most potent anorexigenic effect, reducing food intake to 35% of sham-treated animals. β-MSH, γ-LPH, and γ3- and γ2-MSH all reduced food intake but to a lesser degree. The effects of peptide administration over 3 d were also assessed. Only α-MSH significantly reduced body weight, affecting both fat and lean mass. Other peptides had no significant effect on body weight. Pair-feeding of sham-treated mice to those treated with α-MSH resulted in identical changes in total weight, fat and lean mass indicating that the effects of α-MSH were primarily due to reduced food intake rather than increased energy expenditure. Although other melanocortins can reduce food intake in the short-term, only α-MSH can reduce the excess fat and lean mass found in Pomc−/− mice, mediated largely through an effect on food intake.


Endocrinology ◽  
2011 ◽  
Vol 152 (7) ◽  
pp. 2644-2654 ◽  
Author(s):  
Andrea M. Peier ◽  
Kunal Desai ◽  
James Hubert ◽  
Xiaobing Du ◽  
Liming Yang ◽  
...  

Neuromedin U (NMU) is a highly conserved peptide reported to modulate energy homeostasis. Pharmacological studies have shown that centrally administered NMU inhibits food intake, reduces body weight, and increases energy expenditure. NMU-deficient mice develop obesity, whereas transgenic mice overexpressing NMU become lean and hypophagic. Two high-affinity NMU receptors, NMUR1 and NMUR2, have been identified. NMUR1 is found primarily in the periphery and NMUR2 primarily in the brain, where it mediates the anorectic effects of centrally administered NMU. Given the broad expression pattern of NMU, we evaluated whether peripheral administration of NMU has effects on energy homeostasis. We observed that acute and chronic peripheral administration of NMU in rodents dose-dependently reduced food intake and body weight and that these effects required NMUR1. The anorectic effects of NMU appeared to be partly mediated by vagal afferents. NMU treatment also increased core body temperature and metabolic rate in mice, suggesting that peripheral NMU modulates energy expenditure. Additionally, peripheral administration of NMU significantly improved glucose excursion. Collectively, these data suggest that NMU functions as a peripheral regulator of energy and glucose homeostasis and the development of NMUR1 agonists may be an effective treatment for diabetes and obesity.


2019 ◽  
Vol 18 (7) ◽  
pp. 516-522
Author(s):  
Néstor F. Díaz ◽  
Héctor Flores-Herrera ◽  
Guadalupe García-López ◽  
Anayansi Molina-Hernández

The brain histaminergic system plays a pivotal role in energy homeostasis, through H1- receptor activation, it increases the hypothalamic release of histamine that decreases food intake and reduces body weight. One way to increase the release of hypothalamic histamine is through the use of antagonist/inverse agonist for the H3-receptor. Histamine H3-receptors are auto-receptors and heteroreceptors located on the presynaptic membranes and cell soma of neurons, where they negatively regulate the synthesis and release of histamine and other neurotransmitters in the central nervous system. Although several compounds acting as H3-receptor antagonist/inverse agonists have been developed, conflicting results have been reported and only one has been tested as anti-obesity in humans. Animal studies revealed the opposite effect in food intake, energy expeditor, and body weight, depending on the drug, spice, and route of administration, among others. The present review will explore the state of art on the effects of H3-receptor ligands on appetite and body-weight, going through the following: a brief overview of the circuit involved in the control of food intake and energy homeostasis, the participation of the histaminergic system in food intake and body weight, and the H3-receptor as a potential therapeutic target for obesity.


2018 ◽  
Vol 315 (1) ◽  
pp. E29-E37 ◽  
Author(s):  
Mariana Peduti Halah ◽  
Paula Beatriz Marangon ◽  
Jose Antunes-Rodrigues ◽  
Lucila L. K. Elias

Neonatal nutritional changes induce long-lasting effects on energy homeostasis. Adiponectin influences food intake and body weight. The aim of this study was to investigate the effects of neonatal nutritional programming on the central stimulation of adiponectin. Male Wistar rats were divided on postnatal (PN) day 3 in litters of 3 (small litter, SL), 10 (normal litter, NL), or 16 pups/dam (large litter, LL). We assessed body weight gain for 60 days, adiponectin concentration, and white adipose tissue weight. We examined the response of SL, NL, and LL rats on body weight gain, food intake, oxygen consumption (V̇o2), respiratory exchange ratio (RER), calorimetry, locomotor activity, phosphorylated-AMP-activated protein kinase (AMPK) expression in the hypothalamus, and uncoupling protein (UCP)-1 in the brown adipose tissue after central stimulus with adiponectin. After weaning, SL rats maintained higher body weight gain despite similar food intake compared with NL rats. LL rats showed lower body weight at weaning, with a catch up afterward and higher food intake. Both LL and SL groups had decreased plasma concentrations of adiponectin at PN60. SL rats had increased white adipose tissue. Central injection of adiponectin decreased body weight and food intake and increased V̇o2, RER, calorimetry, p-AMPK and UCP- 1 expression in NL rats, but it had no effect on SL and LL rats, compared with the respective vehicle groups. In conclusion, neonatal under- and overfeeding induced an increase in body weight gain in juvenile and early adult life. Unresponsiveness to central effects of adiponectin contributes to the imbalance of the energy homeostasis in adult life induced by neonatal nutritional programming.


Endocrinology ◽  
2019 ◽  
Vol 160 (10) ◽  
pp. 2441-2452 ◽  
Author(s):  
Tomokazu Hata ◽  
Noriyuki Miyata ◽  
Shu Takakura ◽  
Kazufumi Yoshihara ◽  
Yasunari Asano ◽  
...  

Abstract Anorexia nervosa (AN) results in gut dysbiosis, but whether the dysbiosis contributes to AN-specific pathologies such as poor weight gain and neuropsychiatric abnormalities remains unclear. To address this, germ-free mice were reconstituted with the microbiota of four patients with restricting-type AN (gAN mice) and four healthy control individuals (gHC mice). The effects of gut microbes on weight gain and behavioral characteristics were examined. Fecal microbial profiles in recipient gnotobiotic mice were clustered with those of the human donors. Compared with gHC mice, gAN mice showed a decrease in body weight gain, concomitant with reduced food intake. Food efficiency ratio (body weight gain/food intake) was also significantly lower in gAN mice than in gHC mice, suggesting that decreased appetite as well as the capacity to convert ingested food to unit of body substance may contribute to poor weight gain. Both anxiety-related behavior measured by open-field tests and compulsive behavior measured by a marble-burying test were increased only in gAN mice but not in gHC mice. Serotonin levels in the brain stem of gAN mice were lower than those in the brain stem of gHC mice. Moreover, the genus Bacteroides showed the highest correlation with the number of buried marbles among all genera identified. Administration of Bacteroides vulgatus reversed compulsive behavior but failed to exert any substantial effect on body weight. Collectively, these results indicate that AN-specific dysbiosis may contribute to both poor weight gain and mental disorders in patients with AN.


2015 ◽  
Vol 2015 ◽  
pp. 1-7 ◽  
Author(s):  
Alessio Molfino ◽  
Gianfranco Gioia ◽  
Filippo Rossi Fanelli ◽  
Alessandro Laviano

Inflammation characterizes the course of acute and chronic diseases and is largely responsible for the metabolic and behavioral changes occurring during the clinical journey of patients. Robust data indicate that, during cancer, functional modifications within brain areas regulating energy homeostasis contribute to the onset of anorexia, reduced food intake, and increased catabolism of muscle mass and adipose tissue. In particular, functional changes are associated with increased hypothalamic concentration of proinflammatory cytokines, which suggests that neuroinflammation may represent the adaptive response of the brain to peripheral challenges, including tumor growth. Within this conceptual framework, the vagus nerve appears to be involved in conveying alert signals to the hypothalamus, whereas hypothalamic serotonin appears to contribute to triggering catabolic signals.


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