Submitted to: Journal of Dairy Science
Publication Type: Abstract Only
Publication Acceptance Date: 2/19/2008
Publication Date: 6/11/2008
Citation: Kadegowda, A.G., Connor, E.E., Teter, B.B., Sampugna, J., Piperova, L.S., Erdman, R.A. 2008. Mammary and liver lipogenic gene expression in lactating mice fed diets supplemented with trans-18:1 isomers or t10c12 CLA. Abstract. Journal of Dairy Science. 91:146.
Technical Abstract: The coordinated suppression of lipogenic pathways during milk fat depression (MFD) has suggested the involvement of a global regulator of lipogenic gene expression. Recent studies (Peterson et al., 2004; Harvatine et al., 2006) have implicated SREBP1 as the central regulator of fatty acid (FA) synthesis. The objective of this study was to examine the effects of trans-18:1 isomers or t10c12 CLA on mammary and liver lipogenic gene expression in lactating mice. Thirty lactating C57Bl6J mice were randomly assigned (n=5) to 6 diets supplemented with one of the following isomers t-7-, t-9-, t-11-18:1, t10c12-CLA (CLA) or PHVO (partially hydrogenated vegetable oil) from d6 to d10 postpartum (PP). Milk, mammary and liver samples were collected on d10 PP. Expression of genes involved in de novo FA synthesis (ACACA, FASN), desaturation (SCD1, SCD2), triacylglycerol (TG) synthesis (AGPAT), FA uptake (LPL), transcriptional regulation (SREBP1, ChREBP, INSIG1, SCAP, MLX, THRSP) and nuclear receptor signaling (PPARA, PPARG, LXRA, RXR) were tested by qPCR. Milk fat percentage was decreased by CLA (44%; P<0.001), t-7-18:1 (27%; P < 0.001) and PHVO (23%; P<0.001), compared to Control. In the mammary gland, CLA decreased (P<0.001) the genes related to de novo FA and TG synthesis and desaturation, and genes involved in transcriptional regulation including SREBP1, ChREBP, PPARA and THRSP (P<0.05). PHVO and t7-18:1 decreased the expression of AGPAT, SCD1 and THRSP (P<0.05). Similar to CLA, PHVO decreased SREBP1 and PPARA (P<0.05), while t-7 up-regulated SCAP and MLX (P<0.05). The measured genes were not altered by t-9- or t-11-18:1 in mammary gland. In liver, AGPAT was down regulated (P<0.05) with MFD, while expression of other lipogenic genes was not altered. Opposite to mammary gland, CLA up-regulated SREBP1 and PPARA (P<0.05) and decreased PPARG (P<0.05). The results showed that, in addition to SREBP1, other transcriptional regulators could be involved in milk fat synthesis.