![]() Four to six-week-old mice ( n=34) were randomly divided into four groups: the control 1 (C1) group ( n=7), the HFD group ( n=10), the control 2 (C2) group ( n=7) and the lipopolysaccharide (LPS) group ( n=10). Animals had ad libitum access to water and food and were weighed at weekly intervals. Mice were bred and maintained at regular housing temperatures (23 ☌) and 12-h light/dark cycle starting at 0700 hours. Studies were conducted in male mice on C56BL/6J background. We hypothesise that such a comparison can shed new insight on the effects of these two opposite states of energy balance on appetite regulation. The aim of this study was to compare the global proteomic profile of the hypothalamus in mice exposed to a HFD or with anorexia of acute illness. Provided that nutritional intervention protocols are likely to interfere with multiple pathways inside the cell, a system-wide interrogation of the host response using non-targeted quantitative proteomics was warranted. 4 Deciphering the molecular events of these two contradictory observations in a global and directly comparative way allows for a more causal understanding on the relations between diet, inflammatory signals and appetite regulation. 3 Conversely, emerging evidence suggests that hypothalamic ‘inflammatory’ activation as a result of a high-fat diet (HFD) and obesity can disturb anorexigenic and thermogenic signals and promote abnormal body weight control. 2 Systemic acute inflammatory signals can cause profound anorexia by disrupting the physiological regulation of appetite in the hypothalamus. Under physiological conditions, a variety of peripheral signals regulate appetite and adjust energy intake to match energy consumption requirements. 1 The hypothalamus is the key brain site for the regulation of food intake and energy balance in mammals. Overweight and obesity as a result of positive energy balance constitute major public health burdens with significant economic and social implications. The GlyR protein may constitute a novel treatment target for the reduction of central orexigenic signals in obesity. Conversely, under chronic inflammation in the hypothalamus as a response to HFD, mechanisms mediating a sustained ‘perpetual cycle’ of appetite enhancement were observed. High-precision quantitative proteomics revealed that under acute systemic inflammation in the hypothalamus as a response to LPS, homeostatic mechanisms mediating loss of appetite take effect. In mice with obesity, nuclear factor-κB, glycine receptor subunit alpha-4 (GlyR) and neuropeptide Y levels were elevated, whereas serotonin receptor 1B levels decreased. In the LPS groups, the anorexigen pro-opiomelanocortin was downregulated. Furthermore, the study identified potential pharmacologic targets. Literature research with in silico bioinformatics interpretation of the differentiated proteome identified key biological relevant proteins and implicated pathways. Hierachical clustering of the differentiated proteome revealed distinct proteomic signatures for the hypothalamus under the HFD and LPS nutritional conditions. Of these, 7718 protein groups were profiled with a minimum of two unique peptides for each. Quantitative proteomics of the hypothalamous regions profiled a total of 9249 protein groups ( q<0.05). Key proteins were validated with quantitative PCR. Hypothalamic regions were analysed using a quantitative proteomics method based on a combination of techniques including iTRAQ stable isotope labeling, orthogonal two-dimensional liquid chromatography hyphenated with nanospray ionization and high-resolution mass spectrometry. The control 2 ( n=7) and lipopolysaccharide (LPS) groups ( n=10) were fed a normal diet for 8 weeks before receiving an injection of saline and LPS, respectively. Methods:įour to six-week-old male C56BL/6J mice were fed a normal (control 1 group n=7) or a HFD (HFD group n=10) for 8 weeks. This comparison could provide insight on the effects of these two opposite states of energy balance on appetite regulation. This study examined the proteomic profile of the hypothalamus in mice exposed to a high-fat diet (HFD) or with the anorexia of acute illness. ![]()
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