Abstract: In this study, the therapeutic effect of Lactobacillus paracasei N1115 fermented milk on constipation was examined by using a mouse model of constipation induced by loperamide hydrochloride. After 15 days of feeding with the fermented milk at low (1 × 107 CFU/mL), middle (1 × 108 CFU/mL) and high (1 × 109 CFU/mL) dosages, the constipated mice had a significant increase in defecation and fecal moisture content (P < 0.05) as well as increased intestinal propulsion rates of 57.3%, 67.3% and 71.3%, respectively, when compared with the control group (P < 0.05). Analysis of short chain fatty acids in feces by gas chromatography-mass spectrometry showed significantly increased contents of acetic acid, propionic acid, butyric acid and valeric acid in the treated mice (P < 0.05) along with more diverse short chain fatty acids than compared with the control mice. Histological analysis of distal colon tissue showed that the colon mucosa of the treated mice remained intact with orderly cell arrangement, while that of the model control mice was reduced in thickness with shallower pits. Furthermore, immunohistochemical analysis of interstitial cells of Cajal (ICC) in colon tissue using c-kit antibody showed that feeding constipated mice with the fermented milk significantly increased colonic ICC, indicating increased ICC activity and intestinal movement. These results showed that L. paracasei N1115 fermented milk had a positive therapeutic effect on constipation.

Key words: Lactobacillus paracasei, fermented milk, constipation, short chain fatty acids