Hida A, Uchijima Y, Seyama Y
Department of Physiological Chemistry and Metabolism, Graduate School of Medicine, The University of Tokyo, Bunkyo-ku, Tokyo, 113-0033, Japan.
J Biochem. 1998 Sep;124(3):648-53. doi: 10.1093/oxfordjournals.jbchem.a022161.
The Harderian gland of golden hamster (Mesocricetus auratus) secretes copious lipids, most of which is 1-alkyl-2,3-diacylglycerol (ADG). We previously reported that the composition of ADG shows marked sexual dimorphism [Seyama et al. (1995) J. Biochem. 117, 661-670]. Male ADG contains only straight chain alkyl and acyl groups, but female ADG contains a lot of branched chain ones too. In this study, we investigated the metabolism of branched chain amino acids (BCAAs) and analyzed the incorporation of the metabolites into lipids in the Harderian gland. Golden hamsters were injected intraperitoneally with [U-14C]BCAAs, and Harderian glands were obtained at 3, 6, 9, and 24 h after injection. Lipids were then extracted from the glands and analyzed. Thin layer chromatography revealed that the ADG was labeled in both sexes, but the profile depended on the sex. The cholesterol fraction was labeled only in the male gland. The alkyl and acyl groups of ADG were subjected to radio-gas liquid chromatography. As for the alkyl groups, radioactivity was detected in straight-C16 and -C18 chains in males, while branched-C17 and -C19 chains were labeled in females. As for the acyl groups, straight-C14, -C15, and -C16 chains were labeled in males, while in females, branched-C17 and -C19 chains were labeled as well as a straight-C16 chain. These results suggest that the BCAA metabolism should be regulated as to the sex at the step of branched chain acyl-CoA degradation in the Harderian gland of golden hamster, which causes the sexual dimorphism in the lipid composition in this gland.
金黄仓鼠（Mesocricetus auratus）的哈德氏腺分泌大量脂质，其中大部分是1-烷基-2,3-二酰基甘油（ADG）。我们之前报道过ADG的组成存在明显的性别差异[Seyama等人（1995年），《生物化学杂志》117卷，661 - 670页]。雄性ADG仅含有直链烷基和酰基，但雌性ADG也含有大量支链烷基和酰基。在本研究中，我们研究了支链氨基酸（BCAAs）的代谢，并分析了这些代谢产物在哈德氏腺脂质中的掺入情况。给金黄仓鼠腹腔注射[U - 14C]BCAAs，并在注射后3、6、9和24小时获取哈德氏腺。然后从腺体中提取脂质并进行分析。薄层色谱显示，两性的ADG均被标记，但图谱取决于性别。胆固醇部分仅在雄性腺体中被标记。对ADG的烷基和酰基进行放射性气液色谱分析。关于烷基，在雄性的直链C16和C18链中检测到放射性，而在雌性中，支链C17和C19链被标记。关于酰基，雄性的直链C14、C15和C16链被标记，而在雌性中，支链C17和C19链以及直链C16链被标记。这些结果表明，在金黄仓鼠哈德氏腺中，BCAA代谢在支链酰基辅酶A降解步骤应按性别进行调节，这导致了该腺体脂质组成的性别差异。
