Dietary Glyceryl Monolaurate Supplementation During Pregnancy Enhances Fetal Intrauterine Development and Antioxidant Capacity in Sows via Microbiota Modulation

Abstract

This study elucidates the mechanisms underlying the positive effect of glyceryl monolaurate (GML) on fetal intrauterine development via maternal gut-microbiota modulating effects using a sow model. Addition of GML (1000 mg/kg) improved neonatal intestinal conditions (jejunal villus height, VH/CD ratio and tight junctions) and dorsal longissimus muscle (MyoD, MyoG and MSTN) development in the GML-treated group. Furthermore, GML improved maternal gut microbiota composition by enriching short-chain fatty acid (SCFA)-producing bacteria Lactobacillus and Akkermansia. Meanwhile, SCFA concentrations in sow feces and newborn plasma, as well as their receptors (GPR41/43) in intestine and muscle were upregulated with GML, corresponding with enhanced antioxidative and anti-inflammatory capacity. Further correlation analysis revealed Akkermansia and Lactobacillus positively correlated with SCFAs, antioxidative indicators, and anti-inflammatory capacity markers. Moreover, GML inhibited the activation of the MAPK/NF-κB inflammatory signaling pathway. In summary, GML enhanced fetal intrauterine development by modulating sow intestinal SCFA-producing bacteria.

Keywords: SCFAs; antioxidative; glyceryl monolaurate; gut microbiota; intestinal; longissimus dorsi muscle.

Figure 1

Placenta and longissimus dorsi muscle development. (A) CON and GML jejunal H&E staining; villus height, crypt depth, and the ratio of VH/CD in the CON and GML groups. (B) H&E staining of the longissimus dorsi muscle; data from newborn piglets (n = 6 per group), CON: control group; GML: glyceryl monolaurate group. * p < 0.05. (n = 6 per group). Differences were determined using t-tests (p < 0.05).

Figure 2

The development of intestinal barrier function in newborn piglets. (A,B) Relative abundance of tight junction proteins (ZO-1, occludin, and claudin-1) in the jejunum; (C–F) mRNA expression of β-defensins (PBD1, PBD2, PBD3); (G) mRNA expression of mucins (MUC1, MUC2, MUC4). * p < 0.05. Data from newborn piglets (n = 6 per group). Differences were determined using t-tests (p < 0.05).

Figure 3

Development of the longissimus dorsi muscle in newborn piglets. (A,B) Effects of the GML group on the protein levels of mTOR, S6K1, and 4EBP1 in the longissimus dorsi muscle; (C) levels of muscle growth factors and growth inhibitors MSTN, MyoD, Myf5, MyoG, and MRF4 in the longissimus dorsi muscle. * p < 0.05, ** p < 0.01. Data from newborn piglets (n = 6 per group). Differences were determined using t-tests (p < 0.05).

Figure 4

Microbial structure and diversity. (A) Venn diagram of OTUs; (B) principal coordinates analysis (pCoA) score plot; (C) Shannon index, ACE index, and Chao1 index of the microbial community; (D) relative abundance at the phylum level; (E) relative abundance at the genus level. CON: control group; GML: glyceryl monolaurate group. * p < 0.05. (n = 6 per group). Differences were determined using t-tests (p < 0.05).

Figure 5

Analysis of gut microorganisms at the phylum and genus levels and KEGG functional prediction. (A–I) Analysis of microorganisms at the phylum and genus levels; microbial phylum and genus levels. (J,K) Differential prediction of KEGG metabolic pathways in fecal microbiota between the CON group and GML group. CON: control group; GML: glyceryl monolaurate group. KEGG: Kyoto Encyclopedia of Genes and Genomes. * p < 0.05; ** p < 0.01. (n = 6 per group). Differences were determined using t-tests (p < 0.05).

Figure 6

Short-chain fatty acid levels and fatty acid receptor expression. (A) Protein levels of fatty acid receptors GPR41 and GPR43 in the jejunum; (B) protein levels of fatty acid receptors GPR41 and GPR43 in the longest muscle of the back. (C,D) Levels of short-chain fatty acids in sow’s feces and plasma of piglets and their correlation with the major microorganisms. CON: control group; GML: glyceryl monolaurate group. * p < 0.05, ** p < 0.01. (n = 6 per group). Data were analyzed using Pearson correlation analysis; differences were determined using t-tests (p < 0.05).

Figure 7

Oxidative stress levels in the jejunum and longissimus dorsi muscle of neonatal piglets. (A,B) T-AOC, MDA, SOD, GSH, and GSH-PX activities in the jejunum and their correlation with major microorganisms; (C,D) T-AOC, MDA, SOD, GSH, and GSH-PX activities in the longissimus dorsi muscle and their correlation with major microorganisms. CON: control group. GML: glyceryl monolaurate group. * p < 0.05, ** p < 0.01, ***p <= 0.001. Data from newborn piglets (n = 6 per group). Data were analyzed using Pearson correlation analysis; differences were determined using t-tests (p < 0.05).

Figure 8

Inflammation levels in the jejunum and longissimus dorsi muscle of neonatal piglets (A,B) Levels of pro-inflammatory factors TNF-α, IL-1β, IL-6, and IL-12 in the jejunum and their correlation with major microorganisms; (C,D) levels of inflammatory factors TNF-α, IL-1β, IL-6, and IL-12 in the longissimus dorsi muscle and their correlation with major microorganisms. CON: control group; GML: glyceryl monolaurate group. * p < 0.05, ** p < 0.01; ***p ≤ 0.001. Data from newborn piglets (n = 6 per group). Data were analyzed using Pearson correlation analysis; differences were determined using t-tests (p < 0.05).

Figure 9

MAPK and NF-κB inflammatory signaling pathways in the jejunum and longissimus dorsi muscle of neonatal piglets. (A) Expression of MAPK (P-ERK/ERK, P-JNK/JNK, and P-P38/P38) and NF-κB signaling pathway-related proteins in the jejunum; (B) expression of MAPK (P-ERK/ERK, P-JNK/JNK, and P-P38/P38) and NF-κB signaling pathway-related proteins in the longissimus dorsi muscle. CON: control group; GML: glyceryl monolaurate group. * p < 0.05, ** p < 0.01. Red arrow: decrease. Green arrow: increase. Data from newborn piglets (n = 6 per group). Differences were determined using t-tests (p < 0.05).