Diets exceeded in n6 polyunsaturated fatty acids affect vitality and fetal growth due to alterations in the placental vascularization in a murine model

Abstract

Abstract: 

Excess dietary n6 polyunsaturated fatty acids (PUFA) affects various reproductive parameters. Objective: to evaluate the effect of diets exceeded in linoleic acid (LA)-n6 on placental vascularization, vitality and fetal growth.

Albino swiss mice were fed from gestation day 0.5 (GD 0.5) with diets: control (C, commercial diet, LA=1.6%, n=25) or C with 10% of soybean or sunflower oils (SOD, LA=6.68%, n=24 and SFOD, LA=7.68%, n=26). At GD 16.5, mothers were sacrificed, and the following parameters were assessed: placental and fetal weights, fetal vitality. Placental areas and placental necrosis areas were measured in histological sections with H/E. Immunohistochemistry for nitric oxide synthase III (eNOS) in placental labyrinth was performed. For vascular endothelial delineation and natural killers (NK) cell labelling, histochemical analysis was performed with lectins: BSA-I and DBA, respectively. The labelled area and staining intensity were quantified through reciprocal intensity and number of NK cells, using FIJI software. Statistics: ANOVA, Kruskall-Wallis and Chi-square, p≤0.05.

SFOD placentas were significantly lighter than SOD and C (SFOD=0.13±0.02 vs SOD=0.14±0.02 and C=0.15±0.02, p≤0.005). Significantly lower fetal weights in treated females (SOD=0.59±0.01, n=84 and SFOD=0.68±0.01, n=115 vs C=0.72±0.02, n=52; p≤0.005). Lower foetal vitality in treated females: SFOD= 69.59% and SOD=73.95% vs C=92.86%; p≤0.05. No significant differences in placental areas. Greater area of necrosis in decidua of SFOD placentas (SFOD=122.05µm2±32.38 vs SOD=52.39µm2±28.59 and C=35.78µm2±11.91; p≤0.05). No significant differences in eNOS-labelled area. However, staining intensity was lower in SFOD (SFOD=78.44±3.80 vs SOD=110.61±9.07 and C=100.21±4.76; p≤0.05). The labelled area with BSA-I was significantly greater in the treated females (SFOD=87.37µm2±0.88 and SOD=88.47µm2±2.07 vs C=80.01µm2±2.47; p≤0.05); however, the staining intensity was higher in the control group (C=98.33±2.4 vs SFOD=67.43±3.6 and SOD=73.83±7.69; p≤0.05). No significant differences in NK quantification.

The lower staining intensity of eNOS and BSA-I staining demonstrates alterations in vascularization in group SFOD, which contains more n6. These changes would reduce nutrients supply to the foetus, affecting its growth and vitality. Further determinations will be made in order to study NK cells involved in placental angiogenesis and trophoblast development.