We have previously demonstrated that pre- and early postnatal malnutrition in sheep induced depot- and sex-specific changes in adipose morphological features, metabolic outcomes, and transcriptome in adulthood, with perirenal (PER) as the major target followed by subcutaneous (SUB) adipose tissue. We aimed to identify coexpressed and hub genes in SUB and PER to identify the underlying molecular mechanisms contributing to the early nutritional programming of adipose-related phenotypic outcomes. Transcriptomes of SUB and PER of male and female adult sheep with different pre- and early postnatal nutrition histories were used to construct networks of coexpressed genes likely to be functionally associated with pre- and early postnatal nutrition histories and phenotypic traits using weighted gene coexpression network analysis. The modules from PER showed enrichment of cell cycle regulation, gene expression, transmembrane transport, and metabolic processes associated with both sexes' prenatal nutrition. In SUB (only males), a module of enriched adenosine diphosphate metabolism and development correlated with prenatal nutrition. Sex-specific module enrichments were found in PER, such as chromatin modification in the male network but histone modification and mitochondria- and oxidative phosphorylation-related functions in the female network. These sex-specific modules correlated with prenatal nutrition and adipocyte size distribution patterns. Our results point to PER as a primary target of prenatal malnutrition compared to SUB, which played only a minor role. The prenatal programming of gene expression and cell cycle, potentially through epigenetic modifications, might be underlying mechanisms responsible for observed changes in PER expandability and adipocyte-size distribution patterns in adulthood in both sexes.
In the present study, we investigated the effect of long-acyl chain SFA, namely palmitic acid (16:0) and stearic acid (18:0), at sn-1, 3 positions of TAG on obesity. Throughout the 15 weeks of the experimental period, C57BL/6 mice were fed diets fortified with cocoa butter, sal stearin (SAL), palm mid fraction (PMF) and high-oleic sunflower oil (HOS). The sn-1, 3 positions were varied by 16:0, 18:0 and 18:1, whilst the sn-2 position was preserved with 18:1. The HOS-enriched diet was found to lead to the highest fat deposition. This was in accordance with our previous postulation. Upon normalisation of total fat deposited with food intake to obtain the fat:feed ratio, interestingly, mice fed the SAL-enriched diet exhibited significantly lower visceral fat/feed and total fat/feed compared with those fed the PMF-enriched diet, despite their similarity in SFA-unsaturated fatty acid-SFA profile. That long-chain SFA at sn-1, 3 positions concomitantly with an unsaturated FA at the sn-2 position exert an obesity-reducing effect was further validated. The present study is the first of its kind to demonstrate that SFA of different chain lengths at sn-1, 3 positions exert profound effects on fat accretion.
The present study aimed to determine the effect of positional distribution of long-chain SFA in TAG, especially at the sn-1, 3 positions, on fat deposition using the C57BL/6 mouse model. Throughout the 15 weeks of the study, mice were fed with diets fortified with palm olein (POo), chemically interesterified POo (IPOo) and soyabean oil (SOY). Mice receiving the SOY-enriched diet gained significantly higher amounts of subcutaneous fat (P= 0·011) and total fat (P= 0·013) compared with the POo group, despite similar body mass gain being recorded. During normalisation with food consumption to obtain the fat:feed ratio, mice fed with the POo-enriched diet exhibited significantly lower visceral (P= 0·044), subcutaneous (P= 0·006) and total (P= 0·003) fat:feed than those fed with the SOY-enriched diet. It is noteworthy that mice fed with the IPOo-enriched diet gained 14·3 % more fat per food consumed when compared with the POo group (P= 0·013), despite their identical total fatty acid compositions. This was mainly attributed to the higher content of long-chain SFA at the sn-1, 3 positions of TAG in POo, which results in delayed absorption after deacylation as evidenced by the higher amounts of long-chain SFA excreted in the faeces of mice fed with the POo-enriched diet. Negative correlations were found between the subcutaneous, visceral as well as total fat accretion per food consumption and the total SFA content at the sn-1, 3 positions, while no relationships were found for MUFA and PUFA. The present results show that the positional distribution of long-chain SFA exerts a more profound effect on body fat accretion than the total SFA content.