Altered Levels of Phospholipids and Lysophospholipids in Adipose Tissues of Bilaterally Adrenalectomized Rats...

Rat adipose tissues were shown to exhibit a high level of autotaxin having lysophospholipase D activity. Previously, we reported that an elevated level of lysophosphatidic acid (LPA) in rat plasma was due to a decreased lysophosphatidylcholine concentration, increased plasma lysophospholipase D activity, and decreased lipid phosphate phosphatase activity toward LPA in adrenalectomized (ADL) rats. We hypothesized that the profiles of LPA, its precursor lysophospholipids (LPLs), and parent phospholipids (PLs) also may be altered in adipose tissues of ADL rats. To examine this possibility, we determined the tissue levels of molecular species of PLs and LPLs, including LPA, by LC-tandem MS. The levels of six LPLs in rat brown adipose tissue (BAT) were increased in ADL rats. In rat epididymal white adipose tissue (EpiWAT), the levels of LPLs except for LPA were increased. In rat inguinal WAT, the level of phosphatidylglycerol was increased. These results suggest that tissue levels of LPLs were upregulated by adrenal hormones in BAT and EpiWAT by different mechanisms.