Propionate Modulates Spontaneous Contractions via Enteric Nerves and Pprostaglandin Release in the Rat Distal Colon

Abstract

Short-chain fatty acids, such as propionate and acetate, are produced by bacterial fermentation of carbohydrates in the colonic lumen. We examined effects of propionate on the frequency and the mean amplitude of spontaneous giant contractions (GCs) in circular muscle strips of the rat distal colon with the mucosa attached. Addition of propionate increased the frequency of GCs for about 20 min (≥1 mM) while the mean amplitude was decreased (≥0.1 mM). The propionate-induced increase in the frequency of GCs was blocked by the muscarinic acetylcholine receptor antagonist, atropine. In contrast, the nicotinic receptor antagonist, hexamethonium augmented the response. The propionate-induced decrease in the mean amplitude of GCs was prevented by the cyclo-oxygenase inhibitor, piroxicam. Pretreatment of the tissues with acetate prevented the propionate-induced modulations of the frequency and amplitude of GCs. These results suggest that propionate increases the frequency of GCs by activation of cholinergic motor neurons and decreases the mean amplitude by prostaglandin release. Propionate as well as acetate may be involved in regulation of the spontaneous circular muscle activity in the rat distal colon.