The potential of the marine microalga Diacronema lutheri in the prevention of obesity and metabolic syndrome in high-fat fed Wistar rats

Long-chain polyunsaturated fatty acids n-3 series (n-3 LC-PUFA) and especially eicosa- 18 pentaenoic and docosahexaenoic acids are known to exert preventive effects on obesity and meta- 19 bolic syndrome. Mainly consumed in the form of fish oil, LC-PUFA n-3 are also found in significant 20 quantities in other sources such as certain microalgae. The aim of this study was to evaluate the 21 effects of Diacronema lutheri (Dia), a microalga rich in n-3 LC-PUFA on metabolic disorders associ- 22 ated to obesity. Three groups of male Wistar rats (n = 6 per group) were submitted for eight weeks 23 to a standard diet or high-fat and high fructose diet (HF), supplemented or not with 12% of Dia (HF- 24 Dia). Compared to HF rats, HF-Dia rats showed a 41% decrease in plasma triacylglycerol (TAG), an 25 increase of plasma cholesterol (+35%) as well as high density lipoprotein-cholesterol (+51%) without 26 change low density lipoprotein-cholesterol levels. Although fasting glycemia did not change, glu- 27 cose and insulin tolerance tests highlighted an improvement of glucose and insulin homeostasis. 28 Dia supplementation restored body weight and fat mass, and decreased levels of liver TAG (-75%) 29 and cholesterol (-84%). In HF-Dia rats, leptin was decreased (-30%) below the control level corre- 30 sponding to a reduction of 68% compared to HF rats. Similarly, the anti-inflammatory cytokines 31 interleukin 4 (IL-4) and IL-10 were restored up to control levels, corresponding to a 74% and 58% 32 increase with respect to HF rats, respectively. In contrast, the level of IL-6 remained similar in the 33 HF and HF-Dia groups and about twice that of the control. In conclusion, these results indicated 34 that the D. lutheri microalga may be beneficial for the prevention of weight gain and improvement 35 of lipid and glucose homeostasis.