Buzzell G R, Hida A, Fu S, Seyama Y
Department of Anatomy and Cell Biology, University of Alberta, Edmonton, Canada.
J Exp Zool. 1997 Feb 1;277(2):99-105.
The golden hamster Harderian gland produces a lipid secretion consisting mainly of 1-alkyl-2,3-diacylglycerol. We investigated the composition of alkyl and acyl groups in male and female hamster Harderian alkyldiacylglycerol, in animals kept in long and short photoperiods. Female hamsters in long days have alkyl groups with long saturated straight chains (C18:0 and C20:0) and methyl-branched chains (even and odd chain length iso-branched and odd chain length anteiso-branched chains). Acyl groups in females in long days are mostly long straight chains (C16:0) and methyl-branched chains. In females, short photoperiods led to reductions in the proportions of methyl-branched chains and changes in the proportions of straight chain alkyl and acyl groups; these changes were prevented by pinealectomy. Male hamsters with intact gonads, maintained in long days, had no methyl-branched chain alkyl or acyl groups; saturated straight chains were generally shorter than those of females and the odd chain length saturated C15:0 acyl group was common. Short photoperiods did not significantly alter the composition of male alkyldiacylglycerol. Castrated male hamsters in long days showed a distinctively female phenotype, with long straight chains and methyl-branched alkyl and acyl groups. Castrated males in short days showed a mixture of male and female characteristics: shorter straight chain alkyl and acyl groups, a total absence of methyl-branched alkyl groups, and the presence of methyl-branched acyl groups. These results and those of other studies suggest that testosterone controls the enzymes isovaleryl acyl-CoA dehydrogenase and 2-methyl branched-chain acyl-CoA dehydrogenase; in the absence of these enzymes, the primers for the synthesis of methyl-branched chain fatty acids are produced. Our results indicate that this control is modulated by short photoperiods (perhaps due to reduced prolactin levels). It is also suggested that characteristics of male-type alkyldiacylglycerol are better adapted to conditions of autumn and winter than are those of female-type alkyldiacylglycerol.
金黄仓鼠的哈德氏腺分泌一种脂质，主要成分是1-烷基-2,3-二酰基甘油。我们研究了处于长光照周期和短光照周期的雄性和雌性仓鼠哈德氏烷基二酰基甘油中烷基和酰基的组成。处于长日照的雌性仓鼠的烷基具有长的饱和直链（C18:0和C20:0）以及甲基支链（偶数和奇数链长的异支链和奇数链长的反异支链）。处于长日照的雌性仓鼠的酰基大多是长直链（C16:0）和甲基支链。对雌性仓鼠而言，短光照周期导致甲基支链比例降低，直链烷基和酰基比例发生变化；松果体切除可防止这些变化。处于长日照且性腺完整的雄性仓鼠没有甲基支链的烷基或酰基；饱和直链通常比雌性仓鼠的短，奇数链长的饱和C15:0酰基很常见。短光照周期并未显著改变雄性烷基二酰基甘油的组成。处于长日照的去势雄性仓鼠表现出明显的雌性表型，具有长直链以及甲基支链的烷基和酰基。处于短日照的去势雄性仓鼠表现出雄性和雌性特征的混合：直链烷基和酰基较短，完全没有甲基支链的烷基，但存在甲基支链的酰基。这些结果以及其他研究结果表明，睾酮控制异戊酰辅酶A脱氢酶和2-甲基支链酰基辅酶A脱氢酶；在缺乏这些酶的情况下，会产生甲基支链脂肪酸合成的引物。我们的结果表明，这种控制受到短光照周期的调节（可能是由于催乳素水平降低）。也有人提出，雄性型烷基二酰基甘油比雌性型烷基二酰基甘油更能适应秋冬季节的条件。
