The best known action of glucagon is to increase hepatic glucose production by stimulating glycogenolysis and gluconeogenesis
The best known action of glucagon is to increase hepatic glucose production by stimulating glycogenolysis and gluconeogenesis. the degree of homeostatic regulation that cessation of eating is. There are now drugs available that act through receptors for satiation factors and which cause weight loss, demonstrating that this system is amenable to manipulation for therapeutic goals. Conclusions:Although progress on effective medical therapies for obesity has been relatively slow in coming, advances in understanding the central regulation of food intake may ultimately be turned into useful treatment options. Hormonal and neural signals arising within the gastrointestinal tract and other organs interact in the brain to determine meal size and body weight. The past decade has seen an increasing recognition that a complex interplay exists between the central nervous system (CNS) and the activity of numerous organs involved Hoechst 33258 in energy homeostasis. This requires the transmission of key information to the brain, and control of food intake is one component of energy balance where endocrine signaling from the periphery to the CNS has a particularly important role. Considered broadly, energy homeostasis consists of the interrelated processes integrated by the brain to maintain energy stores at appropriate levels Hoechst 33258 for given environmental conditions. Energy homeostasis thus includes the regulation of nutrient levels in key storage organs (e.g.fat in adipose tissue and glycogen in the liver and elsewhere) as well as in the blood (e.g.blood glucose). To accomplish this, the brain receives continuous information about energy stores and fluxes in critical organs, about food that is being eaten and absorbed, and about basal and situational energy needs by tissues. The brain in turn controls tissues that have important roles in energy homeostasis, like the liver and musculoskeletal system, as well Hoechst 33258 as the secretion of key metabolically active hormones, primarily through the autonomic nervous system. The brain is thus able to respond to ongoing as well as unanticipated demands via well-coordinated responses to prevent shortfalls in energy stores while maintaining biochemical homeostasis. This review focuses on hormonal and related signals that inform the brain of energy levels, thereby influencing energy intake and ultimately body weight. As a general rule, signals arising in the periphery that influence food intake and energy expenditure can be partitioned into two broad categories (Fig. 1) (1,2,3). One comprises the signals generated during meals that cause satiation (i.e.feelings of fullness that contribute to the decision to stop eating) and/or satiety (i.e.prolongation of the interval until hunger or a drive to eat reappears). The prototypical satiation signal is the duodenal peptide cholecystokinin (CCK), which is secreted in response to dietary lipid or protein and which activates receptors on local sensory nerves in the duodenum, sending a message to the brain via the vagus nerve that contributes to satiation. The second category includes hormones such as insulin and leptin that are secreted in proportion Sox2 Hoechst 33258 to the amount of fat in the body. These adiposity hormones enter the brain by transport through the blood-brain barrier and interact with specific neuronal receptors primarily in the hypothalamus to affect energy balance. Satiation and adiposity signals interact with other factors in the hypothalamus and elsewhere in the brain to control appetite and body weight, and they are the topic of this review. == Figure 1. == Model summarizing different levels of control over energy homeostasis. During meals, signals such as CCK, GLP-1, and distension of the stomach that arise from the gut (stomach and intestine) trigger nerve impulses in sensory nerves traveling to the hindbrain. These satiation signals synapse with neurons in the nucleus of.