Combination of palmitic and stearic acids increases the expression of lipogenic genes in mammary gland explants of lactating ewes

Abstract

The objective was to evaluate the effects of palmitic (PA) and stearic (SA) acids and their combination on gene expression of acetyl-CoA carboxylase alpha (ACACAα) PII, fatty acid synthase (FASN), stearoyl-CoA desaturase 1 (SCD1), fatty acid binding proteins (FABP3 and FABP4), and fatty acid CD36 (CD36) translocator in in vitro cultured lactating mammary tissue. Mammary gland explants of two Lacaune ewes rearing twins at 30 ± 5 days in milk, and with body weight of 70 ± 5 kg and body condition score of 3.0 ± 0.5 were used. Explants were cultured for 24 h in 6-well plates at 37 °C with 5% CO2 and saturated humidity. The treatments were a) Control: 3.5 mL of culture medium + 0.1 % bovine serum albumin; b) PA: 3.5 mL of culture medium +200 μM of palmitic acid; c) SA: 3.5 mL of culture medium +200 μM of stearic acid, and; d) PASA: 3.5 mL of culture medium +100 μM palmitic acid +100 μM stearic acid. There was no effect of treatment on FASN (P = 0.11). Compared to Control, PASA treatment increased ACACAα PII and CD36 mRNA abundance by 89 % (P = 0.001) and 44 % (P = 0.02), respectively, whereas, FABP4 mRNA was reduced by 44 % (P = 0.001). Compared to Control, SA increased ACACAα PII mRNA by 41 % (P = 0.001), whereas FABP4 mRNA was decreased in 41 %. Compared to PASA, the PA treatment, respectively, reduced the mRNA abundance of ACACAα PII, CD36 and FABP3 in 48, 40 and 24 % (P = 0.001) excepting that of FABP4 and SCD, which were increased by 131 and 39 % (P = 0.001), respectively. Compared to Control, all treatments decreased SCD mRNA abundance (P = 0.01). Therefore, PASA in mammary explants of lactating ewes increased the expression of genes involved in milk fat synthesis, FA uptake and cellular transport. The increased mRNA abundance of FA translocator CD36 by the combined FAs supports an important role for this gene in mammary explants.