Lipids were extracted according to a previously reported procedure with slight modifications . Briefly, the tissue was homogenized for 2 min on ice in 2 ml methanol and 300 μl water with an Ultra Turrax T25 basic (IKA Labortechnik, Staufen, Germany) at 24,000 rpm in a 15 ml polypropylene vial. The homogenate was transferred into a glass vial and the polypropylene vial was rinsed two times with 500 μl methanol. Afterwards, 3 ml of chloroform (Cat.# 650498, Sigma Aldrich) were added to get a solvent mixture of chloroform/methanol/water (10:10:1, v/v/v). The extract was centrifuged for 10 min at 3,000 rpm, and the supernatant was collected in a separate glass vial. Extraction was completed by repetition of this procedure twice, one time with 3 ml chloroform/methanol/water (10:10:1, v/v/v) and the second time with a 30:60:8 (v/v/v) mixture. Every extraction step included 2 min of sonication. The pooled extracts were dried under nitrogen stream (37°C). Finally, the extract was dissolved in 100 μl chloroform/methanol/water (10:10:1, v/v/v) per 100 mg brain wet weight and stored at -20°C.