PSV-6 - Impact of maternal nutrition and one-carbon metabolite supplementation during early pregnancy on glucose transporters in the bovine fetal intestine

Abstract: The aim of our study was to examine how maternal nutrition during early pregnancy affects the glucose transporter proteins (GLUT1 and GLUT3) in the fetal intestine and to determine whether supplementing with one-carbon metabolites (OCM) could alleviate any changes caused by altered maternal nutrition. We employed a 2 × 2 factorial design with two nutritional planes: control (CON; 0.45 kg/d) and restricted (RES; -0.23 kg/d), along with or without OCM supplementation (+/- OCM). Crossbred Angus heifers were synchronized for estrus and bred via artificial insemination using single-sire female-sexed semen. They were assigned to one of four nutritional treatment groups (n = 8 ± 1 per group) at breeding. Targeted weight gain and OCM supplementation were administered from day 0 to day 63 of gestation, after which all heifers were fed a common diet aimed at a 0.45 kg/d gain. OCM-supplemented treatments received daily rumen-protected methionine (7.4 g/d), choline (44.4 g/d) in a corn carrier, and weekly injections of folate (320 mg) and vitamin B₁₂ (20 mg). Non-supplemented groups received only the corn carrier and saline injections. On day 161 of gestation, heifers were harvested, and fetal jejunum samples were collected for analysis. GLUT1 and GLUT3 expressions were assessed via anti-GLUT1 and anti-GLUT3 fluorescent staining, and the images were analyzed with ImagePro-Premiere software. Maternal OCM supplementation reduced (P = 0.003) the abundance of GLUT1 in fetal villi. Maternal nutritional plane and OCM tended (P = 0.09) to interact in the crypt, with the CON+OCM group showing lower staining intensity than the CON-OCM (P = 0.0009), RES-OCM (P = 0.0003), and RES+OCM (P = 0.0072) groups for GLUT1. Total (villi and crypt combined) GLUT1 staining intensity was lower (P = 0.003) in the +OCM groups compared to -OCM groups. Fetuses from restricted dams tended (P = 0.08) to have greater GLUT3 abundance, with RES groups showing 19% greater abundance than CON groups. In crypts, the staining intensity of GLUT3 was significantly reduced by OCM (P < 0.0001), with +OCM groups showing 39% lower staining intensity compared to -OCM groups. No interaction (P = 0.43) was found between nutrition and OCM for total GLUT3. These findings demonstrate that OCM impacts the abundance of glucose transporters in the fetal intestine. The reduction in GLUT1 in +OCM groups may be due to the role of OCM in enhancing metabolic efficiency in future calves. Conversely, the upregulation of GLUT3 abundance in fetuses from restricted dams could reflect a compensatory response to ensure the readiness for sufficient glucose uptake at birth. Additional research is required to understand the long-term impact of maternal OCM on fetal development. USDA is an equal opportunity provider and employer.