Thiazolidinedione-induced alterations in lipid and protein-related gene expression in lactating sows

Context Thiazolidinedione (TZD) is a chemical agonist of transcription factor peroxisome proliferator-activated receptor gamma (PPARG) that can stimulate insulin cellular signaling by increasing protein synthesis and altering lipogenesis in the mammary gland and adipose tissue. Aims The objective was to evaluate the effect of TZD on insulin and mammalian target of rapamycin (mTOR) activity, lipogenic, protein and lactose gene expression, and milk composition of lactating sows. Methods Forty lactating multiparous sows were randomly assigned to one of two treatments for 15 days (from Day 13 to Day 28 of lactation): (1) control (no TZD added); or (2) 8 mg/kg BW of TZD mixed with feed. Plasma insulin, glucose, and non-esterified fatty acids (NEFA) concentrations, milk composition and fatty acid profile, and gene expression in mammary gland and adipose tissue were analyzed. Key results TZD did not affect insulin, glucose and NEFA in plasma. There was no effect on milk composition; however, TZD reduced saturated fatty acids (SFA; P = 0.02) and increased monounsaturated fatty acids (MUFA; P = 0.03) by 11.3% and 13.7% in the milk fatty acid profile, respectively. In addition, there was an increase of 20.1% in the expression of AGPAT6 (P = 0.001) and trends of DGAT1 (P = 0.08) and SCD (P = 0.06) in the mammary gland of TZD-treated sows. Lipogenic genes in adipose tissue were not affected. Among the genes related to protein synthesis in mammary gland tissue, CSN3 increased by 42.7% (P = 0.02) in TZD compared to the control. Conclusion In summary, TZD increases the expression of genes related to lipid and protein synthesis in the mammary gland and alters SFA and MUFA in the milk profile of lactating sows. Implications The findings suggest that PPARG activation by TZD may be a promising strategy to modulate mammary gland metabolism and enhance milk quality in lactating sows.