The autonomic control of colonic mucin secretion in the mouse.

Abstract

The mucosal secretion of the mouse colon is partly sialomucin and partly sulphomucin. The former acts to protect the epithelium and the latter may act as a less viscid lubricant. The protective action of the former is so good that even full thickness trauma to the mucosa initiates no inflammatory response, presumably because it prevents the release of any pharmacologically active substances. Carbachol produces considerable epithelial shedding, resulting eventually in large mucosal deficiencies, but the mucin layer remains intact and there is no ulceration or inflammatory reaction. There is oversecretion of mucin but probably no effect on synthesis. Beta adrenergic stimulating drugs produce increased mucin synthesis and secretion, swelling of epithelial cells and inflammatory infiltration of the mucosa with retention of cellular debris and polymorphs in the crypts. Beta adrenergic blocking agents produce haemorrhage and inflammation acutely, which is probably due to ischaemia, and in the long-term shortening and thickening of the muscle coats.