Obesity has become a worldwide health problem. Therefore, its treatment has become a priority for public health systems and a challenge for science. Leptin has emerged as a major regulator of energy balance through its actions in the hypothalamus. Furthermore, this adipokine seems to be involved in the dysregulation of sensorial and reward brain systems occurring during obesity, such us sweet taste and preference. Some of the most realistic treatments for obesity pathology is the administration of low-caloric diets and the use of specific bioactive compounds.
The aim of our study was to develop an intervention based on a caloric-restricted diet and to analyse the effects of the supplementation with a natural bioactive compound named Oleuropein (OLE) on that restricted diet. Oleuropein is a polyphenolic compound obtained from green olives and it has been previously described to have significant effects on body weight loss and adipose tissue mass.
We used male Sprague-Dawley rats aged 21 days at the start of the experiment. The animals were divided in two diet groups for 8 weeks: a standard (STD) group (n=10) fed with standard chow ad libitum and a cafeteria diet (CAF) group (n=30) fed with cafeteria diet (bacon, carrots, muffins, cookies, pâté, cheese and sugared milk) ad libitum in order to induce obesity. After 8 weeks, the CAF group was divided into three groups (n=10 per group) until the end of the experiment (week 22): the CAF group remained with the same diet; a cafeteria restricted-diet group (CAFr), fed a 30% of caloric-restricted diet; and the oleuropein group (CAFrO), fed the restricted diet supplemented with 25mg OLE/kg·day. Several biometric parameters were measured in order to characterize the effects of the dietary intervention. Moreover, a set of plasmatic parameters are being performed to determine the concentrations of glucose, triacylglycerides, total cholesterol, non-esterified fatty acids, insulin-resistance, leptin and adiponectin.
As expected, CAF diet induced a significant increase of body weight and body weight gain compared to STD diet. Also, both CAFr and CAFrO interventions induced a soft increase of body weight. Adiposity levels were higher due to the CAF diet, whereas in the restricted-diet groups they were intermediate between those in CAF and STD groups. Regarding food intakes, both CAF and CAFr diets induced a significantly higher caloric intake compared with the STD diet. CAF diets induced a higher interscapular brown adipose tissue mass and also higher subcutaneous and visceral white adipose tissues. The CAFr diet reduced the visceral fat compared to the CAF diet. Lastly, Oleuropein supplementation did not exert any additional effect over caloric restriction alone on those parameters. The analysis of all the parameters obtained during the experiment is expected to provide us a deeper insight on the mechanisms underlying obesity and dietary intervention.