Use of the ZDF rat to model dietary fat induced hypercoagulability is limited by progressive and fatal nephropathy

Introduction: Zucker diabetic fatty (ZDF) rats are used widely as an animal model of metabolic syndrome and insulin resistance. Our study focused on the effects of high versus low dietary fat on the development of Type 2 diabetes in obese male ZDF rats (fa/fa), including biomarkers to detect early signs of hypercoagulability and vascular injury in the absence of overt thrombosis.

Methods: In this study, male (5/group) 10-week-old CRL:ZDF370(obese) rats were fed low (LFD, 16.7% fat) or high fat (HFD, 60% fat) diet for 12 or 15 weeks. Cohorts of 5 rats within diet groups were scheduled for sample collection after weeks 12 and 15.

Results: HFD-fed ZDF rats had oily coats, lower rates of food consumption, more accelerated weight gain and increased serum cholesterol (+15%) and triglyceride concentrations (+75%) vs. LFD-fed ZDF rats. Urinary ketones were observed only in HFD-fed ZDF rats and greater urine glucose and protein concentrations in HFD-fed ZDF vs. LFD-fed ZDF rats were seen. Hemostasis testing showed ~2-fold greater fibrinogen concentration, increased von Willebrand factor concentration, and high thrombin generation in HFD-fed ZDF vs LFD-fed ZDF rats. Increased mortality in the HFD-fed ZDF rat was attributed to exacerbations of altered carbohydrate metabolism as evidenced by ketonuria and nephropathy leading to renal failure.

Discussion: This characterization shows that the ZDF rat at the age, sex and weight used in this study is highly sensitive to dietary fat content that can exacerbate prothrombotic, metabolic and renal disturbances and increase mortality.