Abstract:Objectives: The aim of this study was to investigate the effect of Lactobacillus paracasei Glory LP16 (LP16) on intestinal laxative function in mice. Methods: 100 ICR mice were randomly divided into a blank group, a model group, and three low, medium and high dose groups, 50 mice in group A and 50 mice in group B. The experiment was conducted for 15 d. In addition to the daily gavage with distilled water in the blank group and the model group, probiotic powder was given to the mice in each dose group according to the corresponding dose; at the same time, in addition to the blank group, the mice were gavaged with loperamide hydrochloride (4 mg/kg) on the 15th day to establish a constipation model. Group A was used for fecal observation, and mRNA expression of stem cell factor (SCF) and tyrosine kinase receptor (c-kit) was quantified by real-time fluorescence assay; Group B was used for intestinal propulsion test, colon HE staining, and serum neurotransmitter content was determined by using a kit. Results: Compared to the blank group, the ink propulsion rate in the model group mice was significantly reduced by 7 cm, the total black stool mass excreted within 5 h was significantly decreased by 0.28 g (P < 0.001), and the time to the first black stool was significantly prolonged by 13.7 min (P < 0.01), indicating successful modeling. Compared to the model group, the high-dose group showed a significant increase in ink propulsion rate by 7.69%, and the time to the first black stool was significantly shortened by 11 min (P < 0.05). The low, medium, and high-dose groups had an increased total black stool mass within 5 h(P < 0.05). Compared to the model group, the middle and high-dose groups showed that the arrangement of muscle cells in the colonic muscular layer was closely packed, and inflammatory cell infiltration was significantly improved; the LP16 intervention at low, medium, and high doses significantly increased the levels of GAS and SP in the serum of mice. The GAS levels increased by 9.52, 14.86, 20.53 ng/L, and SP levels increased by 5.86, 16.51, 22.76 ng/L, while VIP levels decreased (P < 0.05) by 23.46, 31.45, 41.43 ng/L, respectively. After medium and high-dose LP16 intervention, the MTL levels in the serum of mice significantly increased to 84.91, 133.33 pg/mL, while SS levels decreased (P < 0.001) to 2.30, 2.87 ng/L, respectively. It also promoted the relative expression of SCF and c-kit mRNA in colonic tissue (P < 0.001), with values of 0.34, 0.67, 0.25, 0.71, respectively. Conclusion: LP16 has a laxative effect and can improve constipation in mice. Its mechanism of action may be related to the regulation of serum neurotransmitter levels and activation of the SCF/c-kit signaling pathway.