Effects of butyric acid on development of intestinal mucosal barrier in lactating rats

Abstract

Objective To explore the effect of butyric acid on intestinal mucosal barrier in rats and to provide experimental rationales for preventing and treating such an intestinal disease as necrotizing enterocolitis. Methods Sprague-Dawley (SD) neonatal rats at 7 days after birth (P7) were used as experimental subjects.Three groups of experiment (12 rats), saline control (8 rats) and blank control (8 rats) were randomized by a number table.The experiment group received butyric acid while saline control group normal saline continuously administered once or twice a day.Blank control group had no treatment.After 10 days, proximal colonic tissue was harvested and transepithelial electrical resistance (TER) detected by Ussing’s chamber.The tight junction proteins ZO-1, Occludin and Claudin-1 were detected by Western blot.And the expressions of ZO-1 and Occludin in proximal colonic tissue was detected by immunohistochemistry (OD value). Results The TER values of butyric acid group at 0, 30, 60, 90 and 120 min were (70.65±5.03) Ω·cm2, (72.40±5.58) Ω·cm2, (68.84±5.02) Ω·cm2, (64.64±4.64) Ω·cm2 and (58.95±6.23) Ω·cm2, saline control group (63.56±4.28) Ω·cm2, (59.31±4.07) Ω·cm2, (51.73±4.42) Ω·cm2, (45.28±5.18) Ω·cm2 and (42.09±4.06) Ω·cm2, blank control group (59.99±4.21) Ω·cm2, (56.64±3.71) Ω·cm2, (51.53±4.00) Ω·cm2, (48.01±7.40) Ω·cm2 and (45.41±10.00) Ω·cm2.The TER values of butyric acid group were significantly different from those of saline control and blank control groups (P 0.05). The expressions of Occludin and Claudin-1 were significantly higher in butyric acid group than those in saline control group (0.74±0.08, 1.06±0.09) and blank control group (0.73±0.05, 1.04±0.06). The increases and differences were statistically significant (P 0.05). Histological immunohistochemistry showed that the expressions of ZO-1 and Occludin in intestinal epithelial cells of butyric acid group (0.22±0.04, 0.26±0.04) were significantly higher than those of saline control group (0.16±0.02, 0.21±0.02) and blank control group (0.16±0.01, 0.21±0.02). And the differences were statistically significant (P 0.05). Conclusions In lactating intestinal mucosal barrier model, butyrate up-regulates the expression of tight junction protein and promotes the development of intestinal mucosal structure and function. Key words: Butyric acid; Intestinal mucosal barrier; Tight junction; Using chamber; Transepithelial resistance