The Effects of Extra Virgin Olive Oil Supplementation and Aerobic Exercise Training on Inflammation and Hormones in Rats Fed an Atherogenic Diet

Westernized diet and sedentary lifestyle may exacerbate systemic inflammation and provoke hormonal changes. Extra virgin olive oil (EVOO) derived phytochemicals oleocanthal (OLEO) and oleacein (OLEA) demonstrate anti-inflammatory and antioxidant effects. PURPOSE: The purpose of the study is to evaluate the effects of OLEO/OLEA supplementation and aerobic exercise training (T) on plasma inflammatory cytokines and hormones in rats fed high fat atherogenic diet (A). METHODS: Forty-eight female Sprague-Dawley rats were fed an atherogenic diet consisting of 1.25% cholesterol and 0.5% cholic acid for 12 weeks. Half of the rats were supplemented with 20% EVOO containing high OLEO/OLEA (1000 mg/kg, HO, n=24) or low OLEO/OLEA (100 mg/kg, LO, n=24). In each dietary group, half group was trained (T) on treadmill for 12 weeks (25m/min, 10% grade for 60 min/day, 5 days/week), while the other half remained sedentary. Additionally, another two separate groups of rats were fed a chow diet (C, n=6) and atherogenic diet (A, n=12), respectively without OLEO/OLEA or aerobic exercise training , to confirm the atherogenic model. Inflammatory cytokines (interleukin (IL)- 1β, monocyte chemoattractant protein (MCP)-1 and tumor necrosis factor (TNF)-α) and hormones (leptin and insulin) were measured in plasma using Bioplex 200 Multiplex  immunoassay. RESULTS: The atherogenic group showed a significant increase on plasma IL1b and TNF-a levels when compared to the control group (P<0.01). LO showed a trend to increase IL-1b compared to A (P=0.060). Aerobic exercise training showed a significant main effect to lower TNF-α (P<0.05) and LO+T showed a trend to decrease TNF-α levels compared to A (P=0.059). LO decreased plasma insulin levels compared to A (P<0.05), and aerobic exercise training further decreased insulin concentrations in LO+T vs. A (P<0.001). HO+T showed lower insulin levels compared to A (P<0.05). HO increased plasma insulin levels compared to LO (P<0.05), while abolished by aerobic exercise training (P<0.05, HO+T vs. HO). CONCLUSIONS: An atherogenic diet significantly increased pro-inflammatory cytokines IL-1b and TNF-a compared to control diet. Low OLEO/OLEA supplementation decreased insulin levels but was reversed by high OLEO/OLEA supplementation. Aerobic exercise training decreased insulin and TNF-a levels in atherogenic rats fed OLEO/OLEA.