Animal Products Research Division, Institute of Livestock and Grassland Science, National Agriculture and Food Research Organization (NARO), 2 Ikenodai, Tsukuba 305-0901, Japan.
Animal Breeding and Reproduction Research Division, Institute of Livestock and Grassland Science, National Agriculture and Food Research Organization (NARO), 2 Ikenodai, Tsukuba 305-0901, Japan.
Domest Anim Endocrinol. 2019 Jul;68:54-63. doi: 10.1016/j.domaniend.2019.01.002. Epub 2019 Jan 23.
Here we characterized gene expressions in subcutaneous adipose tissue and blood metabolites of pigs with genetically low backfat (Landrace) and high backfat (Meishan). As pigs aged from 1 wk-to 3-mo old, mRNA levels of adipose-specific genes increased, although their gene expressions coding for major enzymes involved in lipid metabolism (lipoprotein lipase, fatty acid synthase, and hormone-sensitive lipase) did not differ between lean and fat pigs. Instead, there were significant effects for adiponectin and its receptor AdipoR1 mRNA levels between the two breeds of which respective expressions were lower and higher in Meishan by 3 mo of age. Contrary to changes in gene expressions, the concentrations of blood glucose, triglyceride (TG), and NEFA in both breeds decreased during growth, and 3-mo-old Meishan evidenced lower glucose with higher TG than the Landrace. The homeostasis model assessment insulin resistance (HOMA-IR) index was also calculated from the measurements of fasting glucose and insulin concentration, and Meishan showed a higher value than the Landrace. We next examined these differences in Landrace and Meishan crossbreds, which were phenotypically distinguishable by the backfat thickness as the former lean type and the latter fat type. As with the purebreds, high backfat Meishan crosses showed the characteristics of lower glucose and higher TG in circulating levels and also lower adiponectin transcripts in subcutaneous adipose tissue. Collectively, our results demonstrate that levels of adiponectin and its receptor gene expressions, blood glucose, blood lipids, and HOMA-IR in pigs vary between lean and fat. These observations strongly suggest the possibility that overall metabolic differences rather than adipocyte ability itself contribute to the fatness of genetically high backfat pigs.
在这里，我们对具有低背脂（长白猪）和高背脂（梅山猪）遗传特性的猪的皮下脂肪组织和血液代谢产物中的基因表达进行了描述。随着猪从 1 周到 3 个月龄的生长，脂肪特异性基因的 mRNA 水平增加，尽管它们编码主要参与脂肪代谢的酶（脂蛋白脂肪酶、脂肪酸合酶和激素敏感脂肪酶）的基因表达在瘦肉型和脂肪型猪之间没有差异。相反，在这两个品种之间，存在脂联素及其受体 AdipoR1 mRNA 水平的显著影响，其中脂联素的表达在 3 个月龄时梅山猪更低，而 AdipoR1 的表达更高。与基因表达的变化相反，两种品种的血液葡萄糖、甘油三酯（TG）和非酯化脂肪酸（NEFA）浓度在生长过程中均降低，3 个月龄的梅山猪的葡萄糖浓度较低，而 TG 浓度较高。还从空腹血糖和胰岛素浓度的测量中计算了稳态模型评估的胰岛素抵抗（HOMA-IR）指数，结果显示梅山猪的指数高于长白猪。接下来，我们检查了长白猪和梅山猪杂交后代的这些差异，这些差异可以通过背脂厚度区分，前者为瘦肉型，后者为脂肪型。与纯种猪一样，高背脂梅山猪杂交后代表现出循环水平中葡萄糖水平较低、TG 水平较高的特征，并且皮下脂肪组织中的脂联素转录本水平也较低。总之，我们的结果表明，猪的脂联素及其受体基因表达水平、血糖、血脂和 HOMA-IR 在瘦肉型和脂肪型之间存在差异。这些观察结果强烈表明，整体代谢差异而不是脂肪细胞本身的能力可能导致具有高背脂遗传特性的猪肥胖。
