Fig. 6

Exploration of the underlying mechanism by which 3-IAld and PGD2 promote rumen epithelial and muscular development. a Schematic of cell culture experimental design. Primary ruminal epithelia cells and smooth muscle cells were isolated from the rumen epithelia and muscular layer of Hu lambs (42 days of age). Primary ruminal epithelia cells were divided into control (n = 5), 3-IAld (n = 5), 3-IAld + AhR inhibitor (n = 5), and 3-IAld + β-catenin inhibitor (n = 5) group. To identify the effect of PGD2 on primary ruminal smooth muscle cell proliferation, the cells were treated with DMSO (n = 5), PGD2 without (n = 5) or with CAMK2 inhibitor (n = 5). b, c 3-IAld increased the proliferation of primary rumen epithelia cells in a AhR-Wnt/β-catenin pathway-dependent manner. d 3-IAld accelerated the cell cycle process of primary rumen epithelia cells via AhR-Wnt/β-catenin pathway-dependent manner. e–g 3-IAld enhanced the relative mRNA (f) and protein (e and g) levels of AhR, CYP1A1, and β-catenin in the primary rumen epithelia cells. h, i PGD2 accelerated proliferation of primary smooth muscle cells in a Ca²⁺ pathway-dependent manner. j PGD2 accelerated the cell cycle process of primary rumen smooth muscle cells in a Ca²⁺ pathway-dependent manner. k, l PGD2 enhanced the relative mRNA and protein expression of CASQ1 in the primary rumen smooth muscle cells. m PGD2 enhanced intracellular Ca²⁺ level and protein levels of CAMK2 in the primary rumen smooth muscle cells. Data represented the mean ± SEM, n = 5 per group. *P < 0.05 compared with the control group; # P < 0.05 compared with the 3-IAld or PGD2 group via independent sample t-test