Background/ObjectivesExpanding visceral adiposity is associated with increased inflammation and increased risk for developing obesity-related comorbidities. The goal of this study was to examine high fat diet (HFD)-induced differences in adipocyte size and cytokine/chemokine expression in visceral and subcutaneous adipose depots in obesity-prone (OP) and obesity-resistant (OR) rats.MethodsOP and OR rats were fed either a low fat diet (LFD, 10% kilocalories from fat) or HFD (60% kilocalories from fat) for 7 weeks. Adipocyte size and the presence of crown-like structures in epididymal and inguinal adipose tissue were determined. A multiplex cytokine/chemokine panel was used to assess the expression of inflammatory markers in epididymal and inguinal adipose tissues.ResultsA higher percentage of large adipocytes (> 5000 μm2) was detected in the epididymal and inguinal adipose tissues of OP rats and a higher percentage of small adipocytes (< 4000 μm2) was detected in the epididymal and inguinal adipose tissues of OR rats. More crown-like structures were identified in epididymal adipose tissue of OP rats fed a LFD, compared to OR rats. Consumption of a HFD increased the number of crown-like structures in OR, but not OP rats. Epididymal expression of pro-inflammatory cytokines (IL-1β, TNF-α) was higher in OP rats, compared to OR rats fed LFD. HFD consumption increased epididymal expression of GM-CSF, IL-1α, IL-1β, IL-6, MIP-2, and TNF-α in OP and OR rats. Inguinal expression of pro-inflammatory cytokines (IL-1α, IL-1β, TNF-α) was higher in OP rats, compared to OR rats.ConclusionsOverall, these data suggest that a higher susceptibility to developing obesity is characterized by large adipocytes and increased visceral adipose inflammation. Interestingly, in OR rats, the detrimental effects of HFD consumption on visceral adipose inflammation are evident with only small increases in weight and adiposity, suggesting that HFD also increases the risk for obesity-related comorbidities in OR rats.

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Aims: Individual susceptibility to develop obesity may impact the development of cardiometabolic risk factors that lead to obesity-related comorbid conditions. Obesity-prone Osborne-Mendel (OM) rats expressed higher levels of visceral adipose inflammation than obesity-resistant, S5B/PI (S5B) rats. However, the consumption of a high fat diet (HFD) differentially affected OM and S5B rats and induced an increase in visceral adipose inflammation in S5B rats. The current study examined the effects of HFD consumption on cardio-metabolic risk factors in OM and S5B rats.Materials & Methods: Glucose regulation and circulating levels of lipids, adiponectin and Creactive protein were assessed following 8 weeks of HFD or low fat diet (LFD) consumption. Left ventricle hypertrophy and mRNA expression of cardiovascular disease biomarkers were also quantified in OM and S5B rats. Key Findings: Circulating levels of triglycerides were higher, while HDL cholesterol, adiponectin and glycemic control were lower in OM rats, compared to S5B rats. In the left ventricle, BNP and CTGF mRNA expression were higher in OM rats and IL-6, IL-1β, VEGF, and iNOS mRNA expression were higher in S5B rats.Significance: These findings support the hypothesis that cardio-metabolic risk factors are increased in obesity-prone individuals, which may increase the risk for the development of

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