Halls Leah S, Son Yura, Lorenz W Walter, Shockey Jay, Heo Junwon, Call Jarrod A, Paton Chad M
Department of Nutritional Sciences, University of Georgia, Athens, GA, USA.
Georgia Genomics and Bioinformatics Core, University of Georgia, Athens, GA, USA.
J Physiol. 2025 Aug 22. doi: 10.1113/JP287121.
Cottonseed oil (CSO) is a seed oil with a unique fatty acid composition and the ability to reduce lipid levels in humans and mice. The present study aimed to characterize the effects of dihydrosterculic acid (DHSA), a cyclopropyl fatty acid found in CSO, on lipid metabolism. First, male wild-type mice were fed CSO- or isocaloric oil-enriched diets (lacking DHSA) for 6 weeks. Tissues were analyzed via RNA-sequencing which identified 45 differentially expressed genes within the CSO group, the majority of which are associated with lipid metabolic processes. Despite being a moderate-fat diet, no changes in hepatic or plasma triglyceride were observed in the CSO group. Confirmational tissue analysis showed an increase in hepatic peroxisome proliferator-activated receptor alpha (PPARα) and PPARα target gene expression in the CSO group compared to control groups, suggesting that DHSA effects may be mediated through increased PPARα transcriptional activity and fatty acid oxidation (FAO). To test this hypothesis, female PPARα knockout mice were fed a CSO-enriched diet. In the absence of PPARα, the lipid-lowering effect of the CSO diet was lost. Next, FAO was assessed in DHSA-treated HepG2 cells by measuring mitochondrial respiration with long-chain fatty acids and adenosine diphosphate substrates. Compared to the control, DHSA-treated cells demonstrated a higher capacity to utilize FAO for energy production. Lastly, CSO-fed mice exhibited significantly lower respiratory exchange ratio with an elevated energy expenditure (EE) compared to SFO-fed mice. In total, these data suggest that the effects of CSO are the result of a DHSA-dependent increase in EE via PPARα induction of FAO pathways. KEY POINTS: Previous studies with cottonseed oil- (CSO) enriched diets showed reductions in hepatic and plasma lipids; however, it is unclear whether linoleic acid or dihydrosterculic acid (DHSA), a cyclopropyl fatty acid found in CSO, is responsible for these phenotypic changes. This study utilized a unique diet design in which mice were fed either a CSO-enriched diet (DHSA + linoleic acid) or an isocaloric oil-enriched diet (containing linoleic acid but lacking DHSA). RNA-sequencing analysis indicated CSO-fed mice demonstrated increased expression of genes associated with fatty acid oxidation (FAO) in addition to increases in the transcription factor and FAO regulator peroxisome proliferator-activated receptor alpha (PPARα) and its oxidative target genes. Knockout of PPARα confirmed this transcription factor is required for the lipid-lowering phenotype seen following CSO-enriched diets. CSO-fed mice demonstrated significantly lower respiratory exchange ratio and higher energy expenditure compared to chow- and SFO-fed mice, indicative of elevated FAO exclusive to the CSO group.
棉籽油（CSO）是一种具有独特脂肪酸组成且能够降低人和小鼠血脂水平的种子油。本研究旨在表征二氢硬脂酸（DHSA）（一种存在于CSO中的环丙基脂肪酸）对脂质代谢的影响。首先，雄性野生型小鼠被喂食富含CSO或等热量油（不含DHSA）的饮食6周。通过RNA测序分析组织，该分析在CSO组中鉴定出45个差异表达基因，其中大多数与脂质代谢过程相关。尽管是中等脂肪饮食，但在CSO组中未观察到肝脏或血浆甘油三酯的变化。验证性组织分析显示，与对照组相比，CSO组肝脏过氧化物酶体增殖物激活受体α（PPARα）及其靶基因表达增加，这表明DHSA的作用可能是通过增加PPARα转录活性和脂肪酸氧化（FAO）介导的。为了验证这一假设，给雌性PPARα基因敲除小鼠喂食富含CSO的饮食。在缺乏PPARα的情况下，CSO饮食的降脂作用消失。接下来，通过测量长链脂肪酸和二磷酸腺苷底物的线粒体呼吸来评估DHSA处理的HepG2细胞中的FAO。与对照组相比，经DHSA处理的细胞表现出更高的利用FAO产生能量的能力。最后，与喂食大豆油（SFO）的小鼠相比，喂食CSO的小鼠呼吸交换率显著降低，能量消耗（EE）升高。总体而言，这些数据表明CSO的作用是通过PPARα诱导FAO途径使EE依赖于DHSA增加的结果。
先前关于富含棉籽油（CSO）饮食的研究表明肝脏和血浆脂质减少；然而，尚不清楚亚油酸或二氢硬脂酸（DHSA）（一种存在于CSO中的环丙基脂肪酸）是否是这些表型变化的原因。本研究采用了独特的饮食设计，即给小鼠喂食富含CSO的饮食（DHSA + 亚油酸）或等热量富含油的饮食（含有亚油酸但不含DHSA）。RNA测序分析表明，喂食CSO的小鼠除了转录因子和FAO调节因子过氧化物酶体增殖物激活受体α（PPARα）及其氧化靶基因增加外，还表现出与脂肪酸氧化（FAO）相关基因的表达增加。敲除PPARα证实该转录因子是富含CSO饮食后出现的降脂表型所必需的。与喂食普通饲料和SFO的小鼠相比，喂食CSO的小鼠呼吸交换率显著降低，能量消耗更高，这表明CSO组FAO升高。
