Extra virgin olive oil supplementation reduces inflammation in the arcuate nucleus of the hypothalamus and improves metabolic parameters in obese rats.

Objectives: Obesity is a common public health problem, affecting 2.5 billion adults. Chronic high-fat diet (HFD) exposure, an experimental obesity model, strongly impacts the hypothalamic arcuate nucleus (ARC), a structure vulnerable to dietary-induced inflammation. Extra-virgin olive oil (EVOO) supplementation can be an interesting nutritional strategy to understand and/or treat obesity: EVOO has high nutritional quality, and acts on multiple molecular targets. We investigated EVOO supplementation's impact on metabolic parameters, satiety and hypothalamic inflammation in adult rats exposed to HFD from weaning, considering sex-specific outcomes.

Methods: 21-day-old Wistar rats were allocated into groups: (1) standard chow (SC); (2) SC+EVOO; (3) HFD; (4) HFD + EVOO. EVOO was administered daily by gavage. In adulthood, the behavioral satiety sequence was evaluated. Plasma leptin and ARC inflammatory markers levels were measured by ELISA technique. The immunofluorescence intensity of Toll-like receptor-4 (TLR-4) and ionized calcium-binding adaptor molecule-1 (IBA-1) were measured in the ARC.

Results: Chronic HFD-induced obesity was evidenced in both sexes, with increased body weight, body mass index, fasting blood glucose, caloric efficiency, and plasma leptin levels. EVOO supplementation prevented HFD-induced increase in weight gain and BMI in both sexes. HFD-fed animals had altered satiety. EVOO supplementation decreased immunoreactivity of IBA-1 in the ARC, also attenuates TLR-4 immunoreactivity, interleukin (IL)-6, IL-1β, and tumor necrosis factor-α levels in the ARC of obese animals.

Conclusion: Our results demonstrate that EVOO supplementation seemed promising, improving hypothalamic inflammation in obese animals, therefore might lead to the restoration of adverse metabolic consequences.