2.4. Plasma Determinations
Blood samples were taken on the day of sacrifice in heparin blood collection tubes and centrifuged for 20 min at 5000g at 4ºC. The plasma was frozen at -80ºC until further analysis. Plasma glucose, LDL (low-density lipoprotein)-cholesterol and HDL (high-density lipoprotein)-cholesterol concentrations were measured by colorimetric methods using Spinreact kits (Spinreact, S.A., Girona, Spain). Plasma insulin levels were quantified using a mouse insulin ELISA kit (Alpco Diagnosis, Salem, NH, USA). Homeostatic model assessment of insulin resistance (HOMA-IR) was computed with the formula: fasting glucose (mM) × fasting insulin (μU/mL) / 22.5.