Factors affecting the distribution of ingested propionic acid in the rat forestomach.

Propionic acid (PA) when incorporated into food pellets and fed to male Wistar rats for 20 wk had no effect on the forestomach mucosa; however, in powdered diet PA led to pronounced hyperplasia and severe inflammatory lesions in the forestomach mucosa near the limiting ridge. Since this discrepancy in the effect of PA may have been caused by the type of diet in which PA was administered, the distribution of total PA (including the corresponding acid-soluble CoA ester) in different parts of the stomach and certain variables affecting this distribution were investigated. In the forestomachs of rats fed 4% PA in powdered diet, the amount of PA in hyperplasias (1553 +/- 508 micrograms PA/g tissue) was three times higher than that in the remainder of the tissue (479 +/- 247 micrograms PA/g tissue). The PA content decreased progressively towards the glandular parts. There was a slight, but not significant, decrease in the PA content of the forestomach and a slight increase in the PA content of the glandular stomach in rats fed pelleted food compared with those fed powdered diet. Supplementation of 1% L-carnitine to PA powdered diet for 12 wk led to a significant decrease (P < 0.02) in PA accumulation in hyperplastic tissues compared with hyperplasias induced by PA alone, although L-carnitine had no influence on the severity of hyperplastic changes in the forestomachs of rats. The present study shows that the type of diet in which PA was administered to male Wistar rats is of great importance for the development of hyperplasia, PA or the corresponding CoA ester can accumulate in the forestomach and is preferably accumulated in hyperplasias, and PA accumulation does not appear to be directly related to the severity of hyperplastic changes.