The endometrial expression of prostaglandin cascade components in lactating dairy cows fed different polyunsaturated fatty acids

Feeding n-6 polyunsaturated fatty acids (PUFA) increases the endometrial percentages of linoleic and arachidonic acids (AA), enhances the synthesis of prostaglandin F2α (PGF2α), and improves uterine health. In contrary, the n-3 PUFA, eicosapentaenoic acid, and docosahexaenoic acid may play pivotal roles by suppressing the synthesis of uterine PGF2α, a component being centrally involved in the control of the bovine estrous cycle and in early embryo survival. The objectives of the present study were to determine the effect of feeding a diet enriched in either α-linolenic acid (n-3) or linolenic acid (n-6) on the uterine expression of genes related to prostaglandin cascade and uterine release of PGF2α (measured as 13, 14-dihydro-15-keto PGF2α [PGFM]). From calving to 60 days in milk, cows (n = 24) were fed isonitrogenous, isocaloric, and isolipidic diets that differed in the ratio of n-3/n-6 PUFA. Treatments including palm oil ([PLM]; saturated FA, n = 8), soybean whole roast ([SOY]; n-6, n = 8), and linseed extruded ([LIN]; n-3, n = 8). At 30 days in milk, the ovulatory cycles of cows were synchronized using 2 injections of PGF2α with a 14-day interval. On day 15 postovulation, cows were injected with oxytocin and blood samples were collected to monitor the uterine release of PGF2α (measured as PGFM) and uterine endometrial biopsies were prepared to evaluate the expression of genes related to prostaglandin cascade (prostaglandin F synthase [PGFS], prostaglandin E synthase [PGES], prostaglandin endoperoxide synthase-2 [PGHS-2]), phospholipase A2 (PLA2), peroxisome proliferator-activated receptors [PPAR]). Results showed that uterine endometrial PPAR-δ genes were higher in cows fed LIN (3.17-fold) compared with cows fed PLM or SOY (P < 0.05). The messenger RNA (mRNA) level of PGES in the LIN group was threefold as high as those found in SOY and PLM diets (P < 0.05). The mean relative gene expression of PLA2 and PGFS was increased in animals fed the SOY diet (2.4- and 1.7-fold, respectively) compared with LIN and PLM diets (P < 0.05). The expression of mRNA for the PGHS-2, PPAR-α, and PPAR-γ was not influenced by the diet effect. Dietary inclusion of soy FAs was associated with an increase in the PGFM concentration, possibly through an increase in the expression of genes involved in prostaglandin cascade. The uterine concentration of PGFM, however, was decreased in cows fed diets containing n-3 FAs.