Hypothalamic expression of inflammatory mediators in an animal model of binge eating

Binge eating episodes are characterized by uncontrollable, distressing eating of a large amount of highly palatable food and represent a central feature of bingeing related eating disorders. Research suggests that inflammation plays a role in the onset and maintenance of eating-related maladaptive behavior. Markers of inflammation can be selectively altered in discrete brain region where they can directly or indirectly regulate food intake. In the present study we measured expression levels of different components of cytokine systems (IL-1, IL-6, IL-18, TNF-\uf061 and IFN-&3) and related molecules (iNOS and COX2) in the preoptic and anterior-tuberal parts of the hypothalamus of a validated animal model of binge eating. In this animal model, based on the exposure to both food restriction and frustration stress, binge-like eating behavior for highly palatable food is not shown when animals are exposed to the frustration stress during the estrus phase. We found a characteristic down-regulation of the IL-18/ IL-18 receptor system (with increased expression of the inhibitor of the pro-inflammatory cytokine IL18, IL-18BP, together with a decreased expression of the binding chain of the IL-18 receptor) and a three-fold increase in the expression of iNOS specifically in the anterior- tuberal region of the hypothalamus of animals that develop a binge-like eating behavior. Differently, when food restricted animals were stressed during the estrus phase IL-18 expression increased while iNOS expression was not significantly affected. Considering the role of this region of the hypothalamus in controlling feeding related behavior, this can be relevant in eating disorders and obesity. Our data suggest that by targeting centrally selected inflammatory markers, we may prevent that disordered eating turns into a full blown eating disorder

Hypothalamic CRF1 receptor mechanisms are not sufficient to account for binge‐like palatable food consumption in female rats

OBJECTIVE: The present study evaluated the effect of systemic injection of the CRF1 receptor antagonist R121919, the corticosterone synthesis inhibitor metyrapone and central amygdala (CeA) injections of the nonselective CRF antagonist D-Phe-CRF(12-41) in rats in which binge eating was evoked by stress and cycles of food restriction. METHOD: Female rats were subjected or not to repeated cycles of regular chow food restriction/ad libitum feeding during which they were also given limited access (2 h) to palatable food. On the test day, rats were either exposed or not to the sight of the palatable food for 15 min without allowing access, before assessing food consumption. RESULTS: Systemic injections of R121919, but not of the metyrapone, blocked binge-like eating behavior. Restricted and stressed rats showed up-regulation of crh1 receptor mRNA signal in the bed nucleus of the stria terminalis and CeA but not in basolateral amygdala (BLA) or in the paraventricular nucleus. Injection D-Phe-CRF(12-41) in CeA but not in the BLA-blocked binge-like eating behavior. DISCUSSION: These findings demonstrate that extra-hypothalamic CRF1 receptors, rather than those involved in endocrine functions, are involved in binge eating and the crucial role of CRF receptors in CeA. CRF1 receptor antagonism may represent a novel pharmacological treatment for binge-related eating disorders

Brain Alterations in High Fat Diet Induced Obesity: Effects of Tart Cherry Seeds and Juice

Evidence suggests that obesity adversely affects brain function. High body mass index, hypertension, dyslipidemia, insulin resistance, and diabetes are risk factors for increasing cognitive decline. Tart cherries (Prunus Cerasus L.) are rich in anthocyanins and components that modify lipid metabolism. This study evaluated the effects of tart cherries on the brain in diet-induced obese (DIO) rats. DIO rats were fed with a high-fat diet alone or in association with a tart cherry seeds powder (DS) and juice (DJS). DIO rats were compared to rats fed with a standard diet (CHOW). Food intake, body weight, fasting glycemia, insulin, cholesterol, and triglycerides were measured. Immunochemical and immunohistochemical techniques were performed. Results showed that body weight did not differ among the groups. Blood pressure and glycemia were decreased in both DS and DJS groups when compared to DIO rats. Immunochemical and immunohistochemical techniques demonstrated that in supplemented DIO rats, the glial fibrillary acid protein expression and microglial activation were reduced in both the hippocampus and in the frontal cortex, while the neurofilament was increased. Tart cherry intake modified aquaporin 4 and endothelial inflammatory markers. These findings indicate the potential role of this nutritional supplement in preventing obesity-related risk factors, especially neuroinflammation

A multidisciplinary approach to study the brain injury in Diet-Induced Obesity (DIO) rats

Obesity represents an independent risk factor for the development of cerebrovascular disease and cognitive impairment. The systemic effects, such as increased fat mass, hypertension, insulin resistance and general metabolic dysfunction, have been identified as factors that may lead to impaired cognitive function. To clarify the possible relationships between obesity and nervous system changes, high-caloric Diet-Induced Obesity (DIO) rats 7 weeks-old, were studied after 17 weeks of hypercaloric diet compared to control rats with not fat diet (Chow) or to rats not developing obesity (DIO-resistant DR). Food consumption, fat mass content, blood pressure and blood parameters were assessed. Different behavioural tests were used to estimate cognitive performance. RT-qPCR, immunochemical and immunohistochemical analysis were performed to evaluate neuronal, glial and vascular markers. The obese phenotype developd after 5 weeks of high fat diet exposure and body weight values remained higher in DIO rats compared to the control group and DR rats during the treatment. Systolic blood pressure, glycaemia and insulin were higher in DIO rats only after 17 weeks. No differences in values of total cholesterol and triglycerides were observed. Furthermore increase of thiobarbituric reactive substances and increase of oxidated proteins, was observed in the serum of DIO rats compared to Chow rats. The open-field test revealed, in the older DIO rats, a decrease of cumulative distance travelled and in the number of rearings and an increase of total immobility time. Older DIO rats only, showed a reduction of retention latency time in the passive avoidance test. RT-qPCR, immunochemical and immunohistochemical analysis showed an increased expression of the glial-fibrillary acid protein in the frontal cortex and hippocampus of older DIO rats compared to age-matched Chow and DR rats. A decrease of neurofilament expression was found in the hippocampus of older DIO rats without changes in the number of neurons. A modulation in the Transient Receptor Potential (TRP) channels and synaptic components was highlighted in cerebral areas. These results indicate that obesity in rats, in addition to the development of correlate cerebrovascular risk factors, causes brain injury characterized by astrogliosis, neurodegeneration and impaired learning and memory tasks. The identification of neurodegenerative changes in DIO rats may represent the first step to better characterize the neuronal modifications occurring in the obesity and propose pharmacological treatments or food strategies to counter them

Obesity-related nervous system injury: preliminary evidences in diet induced obesity (DIO) rats.

Increased food intake, reduced physical activity and altered metabolic processes are the variables that affect energy balance inducing obesity. Obesity is now considered an increas-ingly medical challenge. Actually, the prevalence of obesity has increased dramatically worldwide over the last decades and has now reached epidemic proportions. On the other hand, obesity is associated with the development of chronic diseases such as cerebrovascu-lar disease promoting the cognitive decline. Caloric-dense diet induced obesity (DIO), provides a useful animal model sharing several common features with human obesity. DIO rats of 7 weeks of age are expose to high fat (45 %) diet ad libitum and after 5 weeks the obese phenotype starts to be develop. To clarify the possible relationships between obesity and nervous system changes, DIO rats were studied after 5 weeks and 17 weeks of hypercaloric diet compared to the control rats with not fat diet (Chow). Memory performance were measured using different cognitive tests. Moreover, ultrasonographic (US) and computed tomography (CT) evaluations were per-formed to detect adipose tissue changes. Magnetic resonance imaging (MRI) to highlight brain morphological alterations was used. Morphological changes of brain areas (frontal cor-tex, hippocampus) were evaluated by immunohistochemical analysis. The results confirmed the developed of obesity after 5 weeks of fat diet. At long-term (17 weeks) high fat diet exposure, rats increased significantly their body weight in comparison to the control group and the youngest DIO rats. The US and CT analysis indicated an increase of deposition of both visceral and subcutaneous adipose tissue and evidences a decrease of hepatic attenuation in the older DIO rats.MRI images did not show vascular and morphologi-cal alterations in brain. Instead, immuhistochemical and immunochemical analysis, revealed an increase expression of glial-fibrillary acidic protein (GFAP) in the older DIO rats compared to the age- matched Chow rats both in frontal cortex and in hippocampus. DIO rats showed a reduction of retention latency time in the emotional learning task. These preliminary findings indicate that the development of obesity, does not determined gross anatomy alteration in brain, but the occurrence of injury characterized by astrogliosis. The identification of neurodegenerative changes in DIO may represent the first insight to better characterize the neuronal involvement in obesity

Obesity affects central nervous system: a multidisciplinary study in Diet-Induced Obesity (DIO) rats

Obesity has doubled worldwide in the last thirty years, becoming pandemic [1]. Overconsumption of energy-dense food is advanced as the major explanation for the current increase of overweight and obesity, including for children and adolescents [2]. Obesity represents also an independent risk factor for the development of cerebrovascular disease and cognitive impairment. The systemic effects, such as increased fat mass, hypertension, insulin resistance and general metabolic dysfunction, have been identified as factors that may lead to im-paired cognitive function [3]. In humans, obesity is associated with cognitive deficits, especially de-clarative memory which depends on the hippocampus [4]. To clarify the possible relationships between obesity and nervous system changes, high-caloric Diet-Induced Obesity (DIO) rats were studied after 5 weeks and 17 weeks of hypercaloric diet com-pared to the control rats with not fat diet (Chow) or to rats not developing obesity (DIO-resistant DR). DIO rats of 7 weeks of age were exposed to specific diet ad libitum and after 5 weeks the ob-ese phenotype starts to develop. Food consumption, fat mass content, blood pressure, fasting insulin and glucose levels were moni-tored. The behavioral analysis included locomotor activity and anxiety-like behavior test, novel ob-ject recognition test, spatial learning, and memory test were performed. Magnetic resonance imaging (MRI) in the brain was performed to investigate possible gross anatomical changes. RT-PCR, immunochemical and immunohistochemical analysis were performed to evaluate neuronal and glial alterations. After long-term high fat diet exposure, body weight was remarkably increased in DIO rats com-pared to the control group and DR rats. Glycaemia was higher in DIO rats only after 17 weeks of the high fat diet. No differences in values of total cholesterol and triglycerides were observed. Sys-tolic blood pressure was higher in DIO rats only after 17 weeks of high-fat diet compared to age-matched Chow rats and DR rats. Furthermore increased oxidative stress was observed in the serum of DIO rats compared to Chow rats. The open-field test revealed, in the older DIO rats, a decrease of cumulative distance traveled, their number of rearings and increasing the total immobility time. Only older DIO rats showed a reduc-tion of retention latency time in the passive avoidance test. MRI did not show significant morpho-logical and vascular brain changes. Immunohistochemical and immunochemical analysis showed an increased expression of the glial-fibrillary acid protein in the frontal cortex and hippocampus of older DIO rats compared to age-matched Chow and DR rats. A decrease of neurofilament expression was found in the hippocampus of older DIO rats without decrease of the number of neurons. RT-qPCR analysis revealed a modula-tion in the Transient Receptor Potential (TRP) channels and synaptic components. These results indicate that obesity in rats, in addition to the development of correlate cerebrovascu-lar risk factors, causes brain injury characterized by astrogliosis, neurodegeneration and impaired learning and memory tasks. The identification of neurodegenerative changes in DIO rats may represent the first step to better characterize the neuronal modifications occurring in the obesity and propose pharmacological treatments or food strategies to counteract them. [1] WHO, World health Organisation, 2013. http://www.who.int/mediacentre/factsheets/fs311/en/ [2] R.B. Ervin, C.L. Ogden. Trends in intake of energy and macronutrients in children and adoles-cents from 1999–2000 through 2009–2010. NCHS Data Brief 2013, 113, 1 [3] R.M. Uranga, A.J. Bruce-Keller, C.D. Morrison, S.O. Fernandez-Kim, P.J. Ebenezer, et al.. In-tersection between metabolic dysfunction, high fat diet consumption, and brain aging. J Neurochem 2010, 114, 344 [4] H. Francis, R. Stevenson. The longer-term impacts of Western diet on human cognition and the brain. Appetite 2013, 63, 11

Epigenetic regulation of nociceptin/orphanin FQ and corticotropin-releasing factor system genes in frustration stress-induced binge-like palatable food consumption

Evidence suggests that binge eating may be caused by a unique interaction between dieting and stress. We developed a binge-eating model in which female rats with a history of intermittent food restriction show binge-like palatable food consumption after 15 min exposure to the sight of the palatable food (frustration stress). Aim of the present study was to investigate the regulation of the stress neurohormone corticotropin releasing factor (CRF) system and of the nociceptin/orphanin FQ (N/OFQ) system genes in selective rat brain regions, using our animal model. Food restriction by itself might be responsible in the hypothalamus for the downregulation on mRNA levels of CRF-1 receptor (CRF-1R), N/OFQ as well as its receptor NOP. For the latter, this alteration might be due to selective histone modification changes. Instead, CRF gene appears to be upregulated in the hypothalamus and in the ventral tegmental area only when rats are food restricted and exposed to frustration stress and, of relevance, these changes appear to be due to a reduction in DNA methylation at gene promoters. Moreover, CRF-1R mRNA resulted also to be differentially regulated in these two brain regions. Our data add information on altered N/OFQ and CRF signalling in food restriction and under stressful conditions, and provide insight on the use of this model of binge eating for the study of epigenetic modifications in controlled genetic and environmental backgrounds. ACKNOWLEDGMENTS: The work was supported by the Italian Ministry of University and Research under grant FIRB-RBFR12DELS to CC and CDA. The authors declare no competing financial interests

EXTRA-HYPOTHALAMIC CRF-1 RECEPTOR MECHANISMS IN FRUSTRATION STRESS-INDUCED BINGE-LIKE PALATABLE FOOD CONSUMPTION IN FEMALE RATS

The interaction between dieting and stress is a key factor for triggering binge episodes on palatable food in human binge eaters. Corticotropin releasing factor (CRF) mechanisms are known to play a pivotal role in the regulation of this maladaptive behavior. The present study evaluated the effect of the CRF1 receptor antagonist R121919 and the corticosterone synthesis inhibitor metyrapone in female rats in which binge eating was evoked by stress and cycles of food restrictions. Rats were first subjected or not to repeated cycles of regular chow food restriction/refeeding during which they were also given limited access (2 h) to palatable food. On the test day, rats were either exposed or not to the sight of the palatable food for 15 minutes without allowing access (frustration stress), before assessing food consumption for 2 h. Systemic injections of the CRF1 receptor antagonist R121919, but not of the metyrapone, blocked binge-like eating behavior. Moreover, corticosterone injection did not induce binge eating in non-stressed rats. Restricted and stressed rats showed upregulation of crh1 receptor mRNA signal in the bed nucleus of the stria terminalis (BNST) and central amygdala (CeA) but not in basolateral amygdala (BLA) or in the paraventricular nucleus. Injection of CRF receptor antagonist D-Phe-CRF(12e 41) in CeA but not in the BLA blocked binge-like eating behavior. These findings demonstrate that extra-hypothalamic CRF1 receptors, rather than those involved in endocrine functions, are involved in binge eating. CRF1 receptor antagonism may represent a novel pharmacological treatment for binge-related eating disorder

Epigenetic regulation of Adenosine A2A receptor gene transcription on compulsive food consumption

Satisfactory treatments for eating disorders, such as binge eating disorder and bulimia nervosa, are not available at present. Using a well-characterized animal model of binge eating, we investigated the epigenetic regulation of the adenosine A2A Receptor (A2AAR) gene. Gene expression analysis carried out on the amygdala complex of restricted and stressed rats revealed a significant increase of A2AAR mRNA when compared to non-stressed and non-restricted rats. Administration of the A2AAR agonist (VT 7) induced in restricted and stressed rats a significant increase of A2AAR mRNA levels when compared to vehicle group, whereas a significant decrease in rats pre-treated with the A2AAR antagonist (ANR 94) was observed.Pyrosequencing analysis revealed a significant reduction of the % of DNA methylation at A2AAR promoter region in restricted and stressed compared to the non-stressed and non-restricted animals. Significant changes in the DNA methylation status of A2AAR promoter were found in restricted and stressed rats after administration of VT 7 or ANR 94. We observed a decrease of DNA methylation in VT 7 treated rats and a hypermethylation in ANR 94 rats with respect to the vehicle group.The increase in A2AAR mRNA observed in restricted and stressed rats could be due to a compensatory mechanism to counteract the effect of binge eating, suggesting that the A2AAR activation, inducing receptor gene up-regulation, could be relevant to reduce food consumption. We here demonstrated for the first time the epigenetic regulation of A2AAR in an animal model of binge eating

Epigenetic regulation of nociceptin/orphanin FQ and corticotropin-releasing factor system genes in frustration stress-induced binge-like palatable food consumption

Evidence suggests that binge eating may be caused by a unique interaction between dieting and stress. We developed a binge-eating model in which female rats with a history of intermittent food restriction show binge-like palatable food consumption after a 15-minute exposure to the sight of the palatable food (frustration stress). The aim of the present study was to investigate the regulation of the stress neurohormone corticotropin-releasing factor (CRF) system and of the nociceptin/orphanin FQ (N/OFQ) system genes in selective rat brain regions, using our animal model. Food restriction by itself seems to be responsible in the hypothalamus for the downregulation on messenger RNA levels of CRF-1 receptor, N/OFQ and its receptor (NOP). For the latter, this alteration might be due to selective histone modification changes. Instead, CRF gene appears to be upregulated in the hypothalamus as well as in the ventral tegmental area only when rats are food restricted and exposed to frustration stress, and, of relevance, these changes appear to be due to a reduction in DNA methylation at gene promoters. Moreover, also CRF-1 receptor gene resulted to be differentially regulated in these two brain regions. Epigenetic changes may be viewed as adaptive mechanisms to environmental perturbations concurring to facilitate food consumption in adverse conditions, that is, in this study, under food restriction and stressful conditions. Our data on N/OFQ and CRF signaling provide insight on the use of this binge-eating model for the study of epigenetic modifications in controlled genetic and environmental backgrounds