Role of prostaglandin E 2 in cholinergic-mediated glycoprotein synthesis in canine antrum

Abstract

We studied the mechanism of cholinergic stimulation of mucin synthesis in canine antral explants, including the role of PGE 2 as an intermediate messenger. Isolated antral mucosa was incubated with 10 −5 M carbachol (Cb), 10 −5 M indomethacin (IND), 10 −5 M pirenzepine (PZ), 10 −5 M Cb+10 −5 M PZ, 10 −5 M Cb+10 −5 M IND, and 10 −5 M IND +PGE 2 (10 −8 , 10 −7 and 10 −6 M) in the presence or absence of [ 3 H]glucosamine. After 24 hr, total glycoprotein synthesis was quantitated by Sepharose-4B chromatography and by 10% TCA/1%PTA precipitation with lipid extraction. PGE 2 released into the media was measured by radioimmunoassay (RIA). Cb significantly increased total glycoprotein synthesis and produced a significant increase in PGE 2 release. The increase in glycoprotein synthesis and the release of PGE 2 was blocked by the addition of muscarinic antagonist PZ. The addition of IND significantly inhibited glycoprotein synthesis and almost entirely suppressed PGE 2 secretion. IND also inhibited the effect of Cb on glycoprotein synthesis and PGE 2 release. Moreover, PGE 2 (10 −6 and 10 −7 M) significantly increased the glycoprotein synthesis in the canine stomach. This suggests the coordinate participation of PGE 2 -releasing cell population in modulation of glycoprotein synthesis in gastric mucosa.