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Without homeostatic control of feeding behavior, energy balance will be disturbed towards either energy surfeit or deficit, respectively, leading to obesity or wasting. Anorexia Nervosa (AN) is a disorder characterized with food restriction and weight loss1,2 due to intense fear of gaining weight and a distorted perception of body weight. The individuals with anorexia believe they are fat and seek to prevent weight gain by restricting the amount of energy intake even when they are starvation. Anorexia and its associated disorders impose a huge burden to our society, so treating and reversing anorexia are of paramount importance. However, the underlying mechanisms of anorexia are poorly understood, and there is a lack of effective treatments.
Keywords: underlying; paramount; anorexia
NEURO Short Astrocyte: A Potential Target for the Communication Treatment of Anorexia Nervosa * *Corresponding author Yunlei Yang, PhD, MD * Yunlei Yang Principal Investigator Department of Neuroscience and Physiology Department of Neuroscience and Physiology, SUNY Upstate Medical University, Syracuse, SUNY Upstate Medical University NY 13210, USA Syracuse, NY 13210, USA Tel. 315-464-7733 Fax: 315-464-7712 E-mail: yangyun@upstate.edu Without homeostatic control of feeding behavior, energy balance will be disturbed towards either energy surfeit or deficit, respectively, leading to obesity or wasting. Anorexia 1,2 Volume 2 : Issue 1 Nervosa (AN) is a disorder characterized with food restriction and weight loss1,2 due to intense Article Ref. #: 1000NOJ2110 fear of gaining weight and a distorted perception of body weight. The individuals with anorexia believe they are fat and seek to prevent weight gain by restricting the amount of energy in- take even when they are starvation. Anorexia and its associated disorders impose a huge burden Article History th to our society, so treating and reversing anorexia are of paramount importance. However, the Received: June 26 , 2015 th underlying mechanisms of anorexia are poorly understood, and there is a lack of effective treat- Accepted: July 30 , 2015 th ments.
Published: July 30 , 2015 The nervous system consists of two classes of cells, neurons and glia. Thus, it is Citation important to define the integrative processes of neurons and glial cells in the brain regions that Yang Y. Astrocyte: a potential target control food intake. It is well recognized that neurons play critical roles in controlling feed- for the treatment of anorexia nervo- ing behavior and appetite, while little is known about glial influences on feeding. Astrocytes, sa. Neuro Open J. 2015; 2(1): 42-44.
the most abundant glial cells in the brain, are closely associated with neuronal synapses to doi: 10.17140/NOJ-2-110 3-9 scale synaptic strength and modulate neural circuits, as well as with cerebral blood vessels 10,11 to adjust blood supply. Emerging evidence demonstrates the functional role of astrocytes in 12,13 complex behaviors. Interestingly, in response to high-fat diet (HFD) feeding, astrocytes in the ARC proliferate and express functional receptors for leptin,14 adipocyte-derived anorexi- 15,16 genic peptide. These studies strongly suggest the involvement of astrocytes in the regulation of appetite.
In the hypothalamic arcuate nucleus, AgRP (Agouti-related peptide) neurons are nec- essary and sufficient to rapidly evoke food intake while POMC (Pro-opiomelanocortin) neu- 17,18 rons inhibit feeding. The electrical activities of the neurons are critical for them to regulate 17,18 food intake. Prior studies demonstrate that both of the two types of neurons in the ARC 19,20 receive synaptic inputs, and glutamatergic excitatory synaptic inputs are crucial for neu- ronal firing.19 We thus propose that astrocytes in the ARC could serve as surveyors of hunger states and in turn modulate feeding by rewiring the appetite control circuits in the ARC. In anorexic mice, astrocytes may negatively regulate feeding by reducing synaptic strength at and the firing rate of orexigenic AgRP neuron through release of the inhibitory gliotransmitter(s), such as adenosine. Adenosine in turn inhibits synapse transmission and neuron firing rate 21-24 by acting on A1 receptors in both pre- and post-synaptic neurons. Collectively, we propose that glial cells may actively participate in regulating energy balance by modulating appetite control circuits. It is well recognized that hypothalamic arcuate nucleus is a key brain 25-27 region that control energy intake and energy expenditure. In our recent studies, we find that Copyright food intake is also under the control of astrocytes. For instance, we find that the food intake is ©2015 Yang Y. This is an open ac- reduced by selective chemogenetic activation of astrocytes localized in the mediobasal hypo- cess article distributed under the Creative Commons Attribution 4.0 thalamus in mice.28 International License (CC BY 4.0), which permits unrestricted use, Collectively, these results indicate that glial cells may also, at least in part, con- distribution, and reproduction in any medium, provided the original tribute to the development of anorexia nervosa. Furthermore, emerging evidence indicates that work is properly cited. appetite is also under the control of “higher level” brain structures, such as cortex and hip- NEURO pocampus, well- recognized brain regions implicated in emotion 12. Gourine AV, Kasymov V, Marina N, et al. Astrocytes control and cognition.29 For instance, lesion of ventral hippocampus re- breathing through pH-dependent release of ATP. Science. 2010; duces appetite, indicating that ventral hippocampus exerts tonic 329: 571-575. doi: 10.1126/science.1190721 inhibition on food intake. To fully understand the control of food intake and seek effective clinical therapeutics to treat ap- 13. Oliet SH, Piet R, Poulain DA. Control of glutamate clear- petite disorders, such as anorexia nervosa, it is of importance to ance and synaptic efficacy by glial coverage pf neurons. Sci- consider both neuronal and glial processes localized in multiple ence. 2001; 292: 923-926. doi: 10.1126/science.1059162 (http:// brain regions.