Prostaglandin E2-mediated Stimulation of Mucus Synthesis and Secretion by Rhein Anthrone, the Active Metabolite of Sennosides A and B, in the Mouse Colon

Abstract

Rhein anthrone, the active metabolite of sennosides A and B, stimulated PGE2 release into the mouse colonic lumen. At 6.24 mg kg-1, it decreased net water and Na+ absorption significantly in the case of water, but could not reverse the net absorption in mouse ligated colon, although it enhanced net K+ secretion. Pretreatment with indomethacin diminished the effects of rhein anthrone except on K+ net secretion. Rhein anthrone or PGE2 markedly stimulated mucus secretion and synthesis in mouse ligated colon. The enhanced mucus secretion and synthesis induced by rhein anthrone were significantly suppressed by pretreatment with indomethacin. Our results have shown that the colonic secretion of water and electrolytes mediated by PGE2 is partly involved in the rhein anthrone-induced diarrhoea but that in mice, the mucoid diarrhoea induced by rhein anthrone results mainly from PGE2-mediated mucus synthesis and secretion in the colon.

Effect of a direct-fed microbial (Primalac) on structure and ultrastructure of small intestine in turkey poults

“…Caballero-Franco et al (2007) reported a 60% increase in basal luminal mucin content with a probiotic treatment. The mucus layer acts as a barrier between the luminal contents and intestinal nutrient transporters and it protects the mucosal surface from exogenous and endogenous irritants such as bile salts (Yagi et al, 1990). The increase in size and number of intestinal glands and villi could result in increased enzyme pro- duction, resulting in better digestion and absorption of nutrients.…”

Secretory Phospholipases A 2 Are Secreted From Ciliated Cells and Increase Mucin and Eicosanoid Secretion From Goblet Cells

“…Prostaglandins also stimulate mucus secretion in the airways, 48 stomach, 49 colon, 50 and uterus. 51 We show that indomethacin, a cyclooxygenase inhibitor, decreased sPLA 2 -induced mucus secretion, suggesting that cyclooxygenase pathway products may play a role in sPLA 2 -induced mucus secretion.…”

Suppression of the Purgative Action of Rhein Anthrone, the Active Metabolite of Sennosides A and B, by Calcium Channel Blockers, Calmodulin Antagonists and Indometacin

“…The colon was removed and the total colonic fluid was withdrawn and centrifuged at 100,000 g for 20 min at 5°C. According to the modified method of Beubler and Kollar [8], net water flux and electrolyte transport were estimated and expressed as ml water/g tissue and pmol/g tissue, respectively [3], A negative value denotes net absorp tion and a positive value net secretion. Calcium channel blockers were given 30 min before rhein anthrone, except for nicardipine which was given 60 min before.…”

“…The mucus was precipitated using 10% trichloroacetic acid from the colonic tluid and the precipitate was washed with 95% ethanol. The TPBH content was determined photo metrically using galactose as a standard at 540 nm and expressed as mg TPBH/g tissue, according to the meth od of Yagi et al [3].…”

“…In rats, pretreatment with the PG biosynthesis inhibitor indometacin, only delayed and did not completely block the onset of the diarrhoea. Thus, we concluded that other mechanisms in addition to the PGdependent mechanism are also involved in the purgative action of rhein anthrone [2][3][4]. Donowitz et al [5] showed that the changes in active electrolyte transport with senna were dependent on Ca2+ in the serosal but not the mucosal bathing solution in vitro.…”