The effect of cathartics on prostaglandin synthesis by rat gastro-intestinal tract

Rats were dosed with the cathartics cascara, phenolphthalein, senna or ricinoleic acid with or without a 3 day pretreatment with indomethacin. Jejunum, proximal and distal ileum and colon were assayed for prostaglandin E (PGE) content by RIA. While indomethacin significantly reduced the PGE content of all tissue in all treatment groups it did not completely prevent the increase in PGE content induced by phenolphthalein, senna and ricinoleic acid. It is concluded that the contact cathartics increase PGE synthesis by the gastro-intestinal tract and this could in part explain their action. Ricinoleic acid did not appear to act as a PG precursor.