scholarly journals Evidence for hypothalamic ketone body sensing: impact on food intake and peripheral metabolic responses in mice

2016 ◽  
Vol 310 (2) ◽  
pp. E103-E115 ◽  
Author(s):  
Lionel Carneiro ◽  
Sarah Geller ◽  
Xavier Fioramonti ◽  
Audrey Hébert ◽  
Cendrine Repond ◽  
...  
Keyword(s):  
Food Intake ◽  
Ketone Body ◽  
Energy Homeostasis ◽  
Ketone Bodies ◽  
Glucose Production ◽  
Body Level ◽  
Homeostasis Regulation ◽  
The Impact ◽  
Body Concentration

Monocarboxylates have been implicated in the control of energy homeostasis. Among them, the putative role of ketone bodies produced notably during high-fat diet (HFD) has not been thoroughly explored. In this study, we aimed to determine the impact of a specific rise in cerebral ketone bodies on food intake and energy homeostasis regulation. A carotid infusion of ketone bodies was performed on mice to stimulate sensitive brain areas for 6 or 12 h. At each time point, food intake and different markers of energy homeostasis were analyzed to reveal the consequences of cerebral increase in ketone body level detection. First, an increase in food intake appeared over a 12-h period of brain ketone body perfusion. This stimulated food intake was associated with an increased expression of the hypothalamic neuropeptides NPY and AgRP as well as phosphorylated AMPK and is due to ketone bodies sensed by the brain, as blood ketone body levels did not change at that time. In parallel, gluconeogenesis and insulin sensitivity were transiently altered. Indeed, a dysregulation of glucose production and insulin secretion was observed after 6 h of ketone body perfusion, which reversed to normal at 12 h of perfusion. Altogether, these results suggest that an increase in brain ketone body concentration leads to hyperphagia and a transient perturbation of peripheral metabolic homeostasis.

Role of fat-derived substrates in the regulation of gluconeogenesis during fasting

1996 ◽  
Vol 270 (5) ◽  
pp. E822-E830 ◽  
Author(s):  
F. Fery ◽  
L. Plat ◽  
C. Melot ◽  
E. O. Balasse
Keyword(s):  
Ketone Body ◽  
Ketone Bodies ◽  
Glucose Turnover ◽  
Oxidation Rates ◽  
Relative Contribution ◽  
Beta Hydroxybutyrate ◽  
Hormonal Milieu ◽  
Body Concentration

To determine the role of fat-derived substrates in the regulation of glucose metabolism during fasting, glucose turnover, urea nitrogen production, alanine conversion to glucose, and substrate oxidation rates were measured in 34 normal 4-day-fasted volunteers treated with the antilipolytic drug acipimox or placebo for 8 h. The approximately 50% inhibition of lipolysis induced by acipimox increased glucose concentration and production, respectively, by approximately 35 and approximately 30%, whereas the protein breakdown and the amount of alanine converted to glucose were increased, respectively, by approximately 70 and approximately 85%. Insulin levels were reduced by approximately 40%, cortisol levels doubled, and growth hormone concentration increased sevenfold. The relative contribution of free fatty acid (FFA) and ketone body lowering to the observed response was evaluated in nine acipimox-treated subjects in whom ketone body concentration was clamped with an intravenous beta-hydroxybutyrate infusion. The results of these experiments suggest that, during fasting, both FFA and ketone bodies tend to suppress gluconceogenesis and to protect the protein stores. FFA seem to exert their effects mainly through their ability to modulate the hormonal milieu (especially insulin), whereas ketone bodies seem to act mainly by other mechanisms. Thus the widespread view according to which FFA exert a stimulatory role on gluconeogenesis does not apply to the fasting state in vivo.

Glutamatergic plasticity within neurocircuits of the dorsal vagal complex and the regulation of gastric functions

2021 ◽  
Author(s):  
Courtney Clyburn ◽  
Kirsteen N Browning
Keyword(s):  
Food Intake ◽  
Energy Homeostasis ◽  
Intestinal Secretion ◽  
Motor Nucleus ◽  
Glutamatergic Transmission ◽  
Gi Tract ◽  
Dorsal Motor Nucleus ◽  
Efferent Neurons ◽  
Rapid Transmission

The meticulous regulation of the gastrointestinal (GI) tract is required for the co-ordination of gastric motility and emptying, intestinal secretion, absorption, and transit as well as for the overarching management of food intake and energy homeostasis. Disruption of GI functions is associated with the development of severe GI disorders as well as the alteration of food intake and caloric balance. Functional GI disorders as well as the dysregulation of energy balance and food intake are frequently associated with, or result from, alterations in the central regulation of GI control. The faithful and rapid transmission of information from the stomach and upper GI tract to second order neurons of the nucleus of the tractus solitarius (NTS) relies on the delicate modulation of excitatory glutamatergic transmission, as does the relay of integrated signals from the NTS to parasympathetic efferent neurons of the dorsal motor nucleus of the vagus (DMV). Many studies have focused on understanding the physiological and pathophysiological modulation of these glutamatergic synapses, although their role in the control and regulation of GI functions has lagged behind that of cardiovascular and respiratory functions. The purpose of this review is to examine the current literature exploring the role of glutamatergic transmission in the DVC in the regulation of Gl functions.

scholarly journals The Antiobesity Effects of Centrally Administered Neuromedin U and Neuromedin S Are Mediated Predominantly by the Neuromedin U Receptor 2 (NMUR2)

Endocrinology ◽  
2009 ◽  
Vol 150 (7) ◽  
pp. 3101-3109 ◽  
Author(s):  
Andrea Peier ◽  
Jennifer Kosinski ◽  
Kimberly Cox-York ◽  
Ying Qian ◽  
Kunal Desai ◽  
...  
Keyword(s):  
Food Intake ◽  
Energy Homeostasis ◽  
Central Administration ◽  
Diet Induced Obesity ◽  
Inhibit Food Intake ◽  
Selective Agonists ◽  
Treatment Of Obesity ◽  
The Brain ◽  
Deficient Mice

Neuromedin U (NMU) and neuromedin S (NMS) are structurally related neuropeptides that have been reported to modulate energy homeostasis. Pharmacological data have shown that NMU and NMS inhibit food intake when administered centrally and that NMU increases energy expenditure. Additionally, NMU-deficient mice develop obesity, whereas transgenic mice overexpressing NMU are lean and hypophagic. Two high-affinity NMU/NMS receptors, NMUR1 and NMUR2, have been identified. NMUR1 is predominantly expressed in the periphery, whereas NMUR2 is predominantly expressed in the brain, suggesting that the effects of centrally administered NMU and NMS are mediated by NMUR2. To evaluate the role of NMUR2 in the regulation of energy homeostasis, we characterized NMUR2-deficient (Nmur2−/−) mice. Nmur2−/− mice exhibited a modest resistance to diet-induced obesity that was at least in part due to reduced food intake. Acute central administration of NMU and NMS reduced food intake in wild-type but not in Nmur2−/− mice. The effects on activity and core temperature induced by centrally administered NMU were also absent in Nmur2−/− mice. Moreover, chronic central administration of NMU and NMS evoked significant reductions in body weight and sustained reductions in food intake in mice. In contrast, Nmur2−/− mice were largely resistant to these effects. Collectively, these data demonstrate that the anorectic and weight-reducing actions of centrally administered NMU and NMS are mediated predominantly by NMUR2, suggesting that NMUR2-selective agonists may be useful for the treatment of obesity.

scholarly journals STAT3 but Not ERK2 Is a Crucial Mediator Against Diet-Induced Obesity via VMH Neurons

2021 ◽  
Author(s):  
Gabriel Henrique Marques Gonçalves ◽  
Sabrina Mara Tristão ◽  
Rafaella Eduarda Volpi ◽  
Gislaine Almeida-Pereira ◽  
Beatriz de Carvalho Borges ◽  
...  
Keyword(s):  
Body Weight ◽  
Food Intake ◽  
Energy Expenditure ◽  
Energy Homeostasis ◽  
Specific Pattern ◽  
Conditional Knockout ◽  
Steroidogenic Factor 1 ◽  
Diet Induced Obesity ◽  
Affect Body Weight

Leptin plays an important role in the protection against diet-induced obesity (DIO) by its actions in ventromedial hypothalamic (VMH) neurons. However, little is known about the intracellular mechanisms involved in these effects. To assess the role of the STAT3 and ERK2 signaling in neurons that express the steroidogenic factor 1 (SF1) in the VMH on energy homeostasis, we used cre-lox technology to generate male and female mice with specific disruption of STAT3 or ERK2 in SF1 neurons of the VMH. We demonstrated that the conditional knockout of STAT3 in SF1 neurons of the VMH did not affect body weight, food intake, energy expenditure and glucose homeostasis in animals on regular chow. However, when challenged with high-fat diet (HFD), loss of STAT3 in SF1 neurons caused a significant increase in body weight, food intake and energy efficiency that was more remarkable in females which also showed a decrease in energy expenditure. In contrast, deletion of ERK2 in SF1 neurons of VMH did not have any impact on energy homeostasis in both regular diet and HFD conditions. In conclusion, STAT3 but not ERK2 signaling in SF1 neurons of VMH plays a crucial role to protect against DIO in a sex-specific pattern.

scholarly journals The PACAP/PAC1 Receptor System and Feeding

2021 ◽  
Author(s):  
Keerthana Sureshkumar ◽  
Andrea Saenz ◽  
Syed Muzzammil Ahmad ◽  
Kabirullah Lutfy
Keyword(s):  
Food Intake ◽  
Energy Homeostasis ◽  
Brain Regions ◽  
Regulatory Action ◽  
Laboratory Animals ◽  
Pac1 Receptor ◽  
Receptor System ◽  
Nervous Systems ◽  
Peripheral Nervous Systems

Pituitary adenylyl cyclase activating polypeptide (PACAP) belongs to the vasoactive intestinal polypeptide (VIP)/secretin/glucagon superfamily. PACAP is present in two forms, PACAP-38 and PACAP-27, and binds to three guanine-regulatory (G) protein-coupled receptors (PAC1, VPAC1, and VPAC2). PACAP is expressed in the central and peripheral nervous systems with high PACAP levels found in the hypothalamus, a brain region involved in feeding and energy homeostasis. PAC1 receptors are high-affinity and PACAP-selective receptors, while VPAC1 and VPAC2 receptors show a comparable affinity to PACAP and VIP. PACAP and its receptors are expressed in the central and peripheral nervous systems, with moderate to high expression in the hypothalamus, amygdala, and other limbic structures. Consistent with their expression, PACAP is involved in several physiological responses and pathological states. A growing body of literature suggests that PACAP regulates food intake in laboratory animals. However, there is no comprehensive review of the literature on this topic. Thus, the purpose of this article is to review the literature regarding the role of PACAP and its receptors in food intake regulation and to synthesize how PACAP exerts its anorexic effects in different brain regions. To achieve this goal, we searched PubMed and reviewed 68 articles regarding the regulatory action of PACAP on food intake. Here, we present the literature regarding the effect of exogenous PACAP on feeding and the role of endogenous PACAP in this process. We also provide evidence regarding the effect of PACAP on the homeostatic and hedonic aspects of food intake, the neuroanatomical sites where PACAP exerts its regulatory action, which PACAP receptors may be involved, and the role of various signaling pathways and neurotransmitters in hypophagic effects of PACAP.

scholarly journals Pyruvate and ketone-body transport across the mitochondrial membrane. Exchange properties, pH-dependence and mechanism of the carrier

1978 ◽  
Vol 172 (3) ◽  
pp. 377-387 ◽  
Author(s):  
A P Halestrap
Keyword(s):  
Mitochondrial Membrane ◽  
Ketone Body ◽  
Ketone Bodies ◽  
Ph Dependence ◽  
Physiological Regulation ◽  
First Order Kinetics ◽  
Sh Group ◽  
Km Value ◽  
The Difference

The effects of exchangeable ions and pH on the efflux of pyruvate from preloaded mitochondria are reported. Efflux obeys first-order kinetics, and the stimulation of efflux by exchangeable ions such as acetoacetate and lactate obeys Michaelis–Menten kinetics. The apparent Km value +/- S.E. for acetoacetate was 0.56 +/- 0.14 mM (n = 5) and that for lactate 12.3 +/- 2.3 mM (n = 6). The Vmax. values +/- S.E. at 0 degrees C were 16.2 +/- 2.0 and 21.9 +/- 2.7 nmol/min per mg of protein. The exchange of a variety of other substituted monocarboxylates was also studied. Efflux was also stimulated by increasing the external pH. The data gave a pK for the transport process of 8.35 and a Vmax. of 3.31 +/- 0.14 nmol/min per mg. The similarity of the Vmax. values for various exchangeable ions but the difference of this from the Vmax. in the absence of exchangeable ions may indicate that transport of pyruvate occurs with H+ and not in exchange for an OH- ion. The inhibition of transport by alpha-cyano-4-hydroxycinnamate took several seconds to reach completion at 0 degrees C. It is proposed that inhibition occurs by binding to the substrate site and subsequent reaction with an -SH group on the inside of the membrane. The inhibitor can be displaced by substrates that can also enter the mitochondria independently of the carrier and so compete with the inhibitor for the substrate-binding site on the inside of the membrane. A mechanism for transport is proposed that invokes a transition state of pyruvate involving addition of an -SH group to the 2-carbon of pyruvate. Evidence is presented that suggests that ketone bodies may cross the mitochondrial membrane either on the carrier or by free diffusion. The physiological involvement of the carrier in ketone-body metabolism is discussed. The role of ketone bodies and pH in the physiological regulation of pyruvate transport is considered.

scholarly journals The Role of Peptide Hormones Discovered in the 21st Century in the Regulation of Adipose Tissue Functions

Genes ◽  
2021 ◽  
Vol 12 (5) ◽  
pp. 756
Author(s):  
Paweł A. Kołodziejski ◽  
Ewa Pruszyńska-Oszmałek ◽  
Tatiana Wojciechowicz ◽  
Maciej Sassek ◽  
Natalia Leciejewska ◽  
...  
Keyword(s):  
Adipose Tissue ◽  
Energy Expenditure ◽  
21St Century ◽  
Energy Homeostasis ◽  
Peptide Hormones ◽  
Brown Adipose ◽  
Homeostasis Regulation

Peptide hormones play a prominent role in controlling energy homeostasis and metabolism. They have been implicated in controlling appetite, the function of the gastrointestinal and cardiovascular systems, energy expenditure, and reproduction. Furthermore, there is growing evidence indicating that peptide hormones and their receptors contribute to energy homeostasis regulation by interacting with white and brown adipose tissue. In this article, we review and discuss the literature addressing the role of selected peptide hormones discovered in the 21st century (adropin, apelin, elabela, irisin, kisspeptin, MOTS-c, phoenixin, spexin, and neuropeptides B and W) in controlling white and brown adipogenesis. Furthermore, we elaborate how these hormones control adipose tissue functions in vitro and in vivo.

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