Search results for "energy homeostasis"

Mitochondrial involvement in non-alcoholic steatohepatitis

2007

Non-alcoholic steatohepatitis (NASH) is an increasing recognized condition that may progress to end-stage liver disease. There are consistent evidences that mitochondrial dysfunction plays a central role in NASH whatever its origin. Mitochondria are the key controller of fatty acids removal and this is part of an intensive gene program that modifies hepatocytes to counteract the excessive fat storage. Mitochondrial dysfunction participates at different levels in NASH pathogenesis since it impairs fatty liver homeostasis and induces overproduction of ROS that in turn trigger lipid peroxidation, cytokines release and cell death. In this review we briefly recall the role of mitochondria in fat…

Role of polysialic acid (PSA) in the control of food intake and body weight

2013

Hypothalamus plays a major role in the regulation of energy homeostasis by the presence of neural circuits controlling food intake. These circuits are plastic and can be rewired during adulthood. We hypothesized that synaptic plasticity can occur during physiological conditions. We have shown that synaptic contact on hypothalamic anorexigen POMC neurons are rewired in mouse upon high fat diet (HFD). This synaptic process is mandatory to adjust energy intake and requires the glycan PSA (polysialic acid). PSA promotes synaptic plasticity in the brain by the weakening of cell-to-cell interaction by addition on NCAM (neural cell adhesion molecule). We hypothesized that a defect in brain synapti…

Astrocytes and hypothalamic glucose sensing: metabolic role and involvement of astroglial connexins

2012

The hypothalamus plays a pivotal role in the nervous control of glucose homeostasis. This area contains gluco-sensitive neurons. Some of them detect increases in glucose levels and regulate glucose homeostasis by stimulating insulin secretion or inhibiting food intake. It is widely accepted that astrocytes are metabolically coupled to neurons. Lactate, resulting from the metabolism of glucose by astrocytes, is transported via the monocarboxylate transporters (MCTs). In addition, gap junctions (GJ), that form networks within astrocytes, are essential to transfer glucose from the bloodstream to the active neurons. These astroglial GJ mainly consist of connexins 43 and 30 (Cxs).The aims of my …

Implication de la plasticité cérébrale hypothalamique dans la régulation de l'homéostasie énergétique chez la souris : effet d'un régime gras

2012

The hypothalamus plays a crucial role in the control of energy balance. In adult brain, this area remain plastic and the cellular network can be rapidly modified under environmental pressures. Studies show than hypothalamic remodeling are disturbed when metabolic diseases such as obesity or type II diabetes are declared. In this study we hypothesized that a high fat diet (HFD) inducing obesity could rapidly causes cell modifications in the adult hypothalamus network. To answer this question, we have established a one week HFD mouse model, and evaluated to type of hypothalamic plasticity which are synaptic plasticity and neurogenesis. Our results show that HFD leads to an increase of the exc…

Acute selective ablation of rat insulin promoter-expressing (RIP HER ) neurons defines their orexigenic nature

2012

Rat insulin promoter (RIP)-expressing neurons in the hypothalamus control body weight and energy homeostasis. However, genetic approaches to study the role of these neurons have been limited by the fact that RIP expression is predominantly found in pancreatic β-cells, which impedes selective targeting of neurons. To define the function of hypothalamic RIP-expressing neurons, we set out to acutely and selectively eliminate them via diphtheria toxin-mediated ablation. Therefore, the diphtheria toxin receptor transgene was specifically expressed upon RIP-specific Cre recombination using a RIP-Cre line first described by Herrera (RIP HER -Cre) [Herrera PL (2000) Development 127:2317–2322]. Usi…

2015

The melanocortin system is one of the most important neuronal pathways involved in the regulation of food intake and is probably the best characterized. Agouti-related peptide (AgRP) and proopiomelanocortin (POMC) expressing neurons located in the arcuate nucleus of the hypothalamus are the key elements of this system. These two neuronal populations are sensitive to circulating molecules and receive many excitatory and inhibitory inputs from various brain areas. According to sensory and metabolic information they integrate, these neurons control different aspects of feeding behavior and orchestrate autonomic responses aimed at maintaining energy homeostasis. Interestingly, composition and a…

Superfood for axons: Glial exosomes boost axonal energetics by delivery of SIRT2

2021

Axon integrity depends on support by glia facilitating axonal maintenance and energy homeostasis, but the molecular mechanisms are not well understood. In this issue of Neuron, Chamberlain et al. (2021) provide evidence that oligodendrocyte-to-axon transfer of SIRT2 via extracellular vesicles (exosomes) enables deacetylation of mitochondrial proteins, enhancing axonal energy production.

Physiological and Nutritional Roles of PPAR across Species.

2013

There has been a tremendous amount of information produced on peroxisome proliferator-activated receptors (PPARs). The interest in PPARs was originally driven largely by their role in hypolipidemia and hepatocarcinogenesis, but it soon became evident that they played important roles in the metabolic syndrome and overall health of organisms including regeneration of tissues, differentiation, insulin signaling, overall lipid metabolism, and immune response (reviewed in [1–7]). From a nutritional standpoint, the PPARs are of extreme importance because of their ability to bind and be activated by long-chain fatty acids and their metabolites. Therefore, the PPARs are recognized as ideal candidat…

Chatting Between the Brain and White Adipose Tissues

2012

Over the past decades, numerous papers have been published demonstrating the importance of the relationships between the brain and white adipose tissues in regard to body weight and metabolism regulation. Indeed the brain mainly via the sympathetic nervous system control body fat mass both by regulating adipocytes metabolism (lipolysis and lipogenesis), secretory activity (leptin and other adipokines) as well as development. In turn fat mass will send information to some brain areas via sensory nerves as well as via changes in metabolic and hormonal signals. Altogether these data are in support of a feedback loop between white adipose tissues and the brain. This crosstalk plays a major role…

Postnatal Overfeeding in Rodents by Litter Size Reduction Induces Major Short- and Long-Term Pathophysiological Consequences

2013

Numerous studies have demonstrated that the early postnatal environment can influence body weight and energy homeostasis into adulthood. Rodents raised in small litters have been shown to be a useful experimental model to study the short- and long-term consequences of early overnutrition, which can lead to modifications not only in body weight but also of several metabolic features. Postnatal overfeeding (PNOF) induces early malprogramming of the hypothalamic system, inducing acquired persisting central leptin and insulin resistance and an increase in orexigenic signals. Visceral white adipose tissue, lipogenic activity, and inflammatory status are increased in PNOF rodents, while brown adi…