Stimulation of Colonic Mucin Synthesis by Corticosteroids and Nicotine

1. We speculated that corticosteroids might cause beneficial stimulation of mucus synthesis, since this is a known action of carbenoxolone, itself a corticosteroid, and has also been proposed as a possible mechanism for the protective effect of smoking on ulcerative colitis. We have therefore compared the effects of corticosteroids including carbenoxolone, and nicotine on mucin synthesis, assessed by incorporation of N -[ 3 H]acetylglucosamine into mucin by colonic epithelial biopsies in culture. 2. In histologically normal biopsies from the left colon, hydrocortisone and prednisolone caused a very marked concentration-dependent increase in mucin synthesis, with maximal effect (580 and 300% of control values respectively) at 6 μmol/l [ P n = 35 biopsies (seven patients)] and 1.5 μmol/l [ P n = 35 (seven patients)] respectively. The maximal effect of hydrocortisone was significantly greater than that of prednisolone ( P P n =15 (three patients)]. In contrast, these corticosteroids caused only a small, non-significant increase in mucin synthesis in the histologically normal right colon; fludrocortisone, 2 and 20 μmol/l, and aldosterone, 0.1–10 μmol/l, had no effect. Nicotine significantly increased mucin synthesis (180–220% of control values) between 62.5 nmol/l and 6.25 μmol/l ( P 3. The marked stimulation of mucin synthesis by corticosteroids suggests that this may account, at least in part, for their therapeutic effect in ulcerative colitis.