Synergistic effect of fermented rice extracts on the probiotic and laxative properties of yoghurt in rats with loperamide-induced constipation

Abstract

Aim. The objective was to evaluate the synergistic effects of fermented rice extracts (FRe) on the laxative and probiotic properties of yoghurt in rats with loperamide-induced constipation. Methods. After constipation induction, yoghurt containing FRe (BFRe; 0.05%, 0.1%, or 1%) was administered orally once per day for 6 days. Results. Loperamide treatment caused marked decreases in fecal pellet numbers and water content discharged, as well as in the surface mucosal thickness of the colonic lumen, intestinal charcoal transit ratio, thickness, and number of mucous-producing goblet cells in the colonic mucosa, whereas it increased the remnant fecal pellet number and the mean diameter of the colonic lumen. However, this loperamide-induced constipation was ameliorated by treatment with FRe, yoghurt single formula, or 0.05%, 0.1%, or 1% BFRe (10 mL/kg). Additionally, the viable numbers of Lactobacillus in the cecal contents and feces were markedly higher than those in constipated rats. Moreover, greater probiotic and laxative effects were detected in BFRe-treated rats than in rats treated with equivalent doses of yoghurt or FRe single formula. Conclusion. The results suggest that addition of FRe to liquid yoghurt will enhance the probiotic and beneficial laxative effects of yoghurt in the digestive tract, without causing side effects.

Figure 1

((a), (b)). Lactobacillus numbers in the cecal contents and feces of loperamide-induced constipated rats after oral treatment of the test agents. Significant increases in viable Lactobacillus numbers were detected in cecal contents and feces 6 days after continuous oral treatment of 10 mg/kg FRe, liquid yoghurt single formula, or the three concentrations of BFRe, as compared with the loperamide control. In addition, greater increases in Lactobacillus numbers were detected with all three BFRe concentrations compared with equivalent doses of liquid yoghurt or FRe single formula. Values are expressed as means ± SD of five independent culture plates. The test agents, diluted 10-fold, were incubated at 37°C for 96 h under anaerobic conditions using candle jars, and all were administered in a 10 mL/kg volume. All solutions were administered as 10 mL/kg doses. ^a P < 0.01 and ^b P < 0.05 compared with the vehicle control by the LSD test. ^c P < 0.01 and ^d P < 0.05 compared with the loperamide control by the LSD test. ^e P < 0.01 and ^f P < 0.05 compared with the vehicle control by the MW test. ^g P < 0.01 and ^h P < 0.05 compared with the loperamide control by the MW test.

Figure 2

Histological profiles of the fecal pellet-containing colons of loperamide-induced constipated rats treated with the vehicle control ((a), (b)), loperamide control ((c), (d)), 5 mg/kg FRe ((e), (f)), 10 mg/kg FRe ((g), (h)), yoghurt ((i), (j)), and BFRe 0.05% ((k), (l)), 0.1% ((m), (n)), and 1% ((o), (p)) (10 mL/kg). Note the marked decreases in the surface mucosal thickness of remnant fecal pellets in the colonic lumen, mucosal thickness. And mucous-producing cell numbers were detected in the loperamide control, as compared with the vehicle control. However, dramatic increases in these same parameters were detected after 6 days of continuous oral treatment of all test agents, as compared with the loperamide control. In addition, more favorable histopathological changes in the colonic mucosa and the surface mucous of remnant fecal pellets in the colon were detected with all three BFRe concentrations compared with equivalent doses of liquid yoghurt or FRe single formula. Yoghurt: Bulgaris, a brand of commercial yoghurt (Namyang, Korea). FRe: fermented rice extracts. BFRe: mixed formula consisting of yoghurt and the appropriate percentages (0.05, 0.1, and 1%) of FRe. Values are expressed mean ± SD of five rats. The arrow indicates the measured surface mucosal thickness. M, colonic mucosa; F, fecal pellets. All stained with Alcian Blue. Scale bars = 150 μm.