Dietary effects of Raphanus sativus cv Sango on lipid and oxysterols accumulation in rat brain: A lipidomic study on a non-genetic obesity model

The present study aimed to evaluate the impact of Raphanus sativus cv Sango sprout juice (SSJ) administration (75 mg/kg b.w. SSJ/day) on the brain lipidomic profile (fatty acid, sterols, cholesterol oxidation) of rats (non-genetic model) subjected to a high-fat (34% crude fat) dietary regimen. The SSJ did not affect the lipid infiltration (7.7-9.3%) and the fatty acid composition of the rat brain, which was mainly composed by unsaturated fatty acids (∼ 58%); however, the high-fat diet regimen significantly halved linoleic acid (LA). The high-fat diet also decreased (21.13 mg/g) the level of brain cholesterol with respect to the regular diet (4.5% crude fat) (23.83 mg/g); however, when the diet was shifted from high-fat to a regular regimen with or without SSJ supplementation, the levels of cholesterol significantly (p < 0.05) increased up to 30.46 mg/g of brain. The main oxysterols were 24(S)-hydroxycholesterol (24(S)-HC) and β-epoxycholesterol (β-EC). The high-fat diet led to the highest cholesterol oxidation (63.1 μg/g), increasing 27-hydroxycholesterol (27-HC) infiltration (0.24 μg/g rat brain) through the blood-brain barrier (BBB) compared to the regular diet (0.13 μg/g rat brain). On the other hand, when the diet was switched from high-fat to a regular regimen with SSJ supplementation, a significant reduction of 27-HC in the rat brain was found. Although 24-HC did not significantly change (p = 0.054), an increasing trend was observed when high-fat diet was supplied. The principal component analysis (PCA) revealed that SSJ was more active in counteracting cholesterol oxidation when supplied with the high-fat diet, due to inverse correlation with 24(S)-HC and 27-HC; however, further studies are needed to better understand which is the relationship between LA and cholesterol homeostasis in rat brain.