Stearoyl-coenzyme A desaturase gene expression during growth in adipose tissue from obese and crossbred pigs.
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This investigation addressed the hypothesis that, as a marker of adipocyte differentiation, stearoyl-coenzyme A desaturase (SCD) gene expression would be greater during growth in obese pigs than in crossbred, contemporary pigs. Suckled pigs from a single litter were removed from the sow for sampling at 0, 3, 10, and 17 d. The number of litters at 0, 3, 10, and 17 d of age was zero, two, three, and three (obese sows) and four, two, three, and three (crossbred sows), respectively. Postweaning pigs were removed from the sow at 14 d of age. One set of postweaning pigs was fed a high-fat, milk-based diet from d 28 to 49; pigs were killed on d 28 and 49 for sampling. The grain-fed pigs were switched to a pelleted, grain-based grower diet at d 28, and samples were obtained at 31, 35, or 49 d of age. Adipose tissue from all pigs in a litter for preweaning and postweaning pigs was pooled for the measurement of cellularity and SCD mRNA. There were significant genetic and age effects for adipocyte diameter and volume; overall, adipocytes from obese pigs were larger than those from crossbred pigs. Stearoyl-coenzyme A desaturase mRNA was barely detectable at 0 d of age and increased (P < .01) by 20-fold by 49 d of age. There was a significant genetic x age interaction (P = .026); there was more SCD mRNA in adipose tissue from obese pigs than in that from crossbred pigs during the suckling period, whereas crossbred pigs exhibited greater SCD gene expression than obese pigs during the postweaning period. The lesser SCD gene expression in postweaning obese pigs was caused by a strong depression in SCD gene expression in the grain-fed obese pigs. The data indicate that SCD gene expression provides a marker for terminal differentiation, especially in preweaning pigs. Furthermore, these results provide additional evidence that SCD gene expression is up-regulated by diets high in saturated fatty acids.
