Trophic effects of gastrin on colorectal neoplasms in the rat.

This study was designed to determine the effect of gastrin on colorectal neoplasms in the rat. Multiple colon and rectal cancers were induced in each of 57 rats with methylazoxymethanol. Animals were randomly assigned to groups: (1) antral exclusion, (2) antrectomy, (3) sham, or (4) sham with subsequent pentagastrin injections. Resulting tumors were analyzed for concentration and synthesis of DNA, RNA, and protein. The number of tumors per rat and distribution of tumors within the colons did not vary among groups. Antrectomy did not alter the gastrin level, and tumors developing in these animals did not differ from those of sham controls. Antral exclusion markedly raised serum gastrin levels. Both chronic endogenous hypergastrinemia and administration of exogenous pentagastrin significantly increased tumor synthesis and concentration of DNA, RNA, and protein. We conclude that gastrin exerts a trophic effect on colorectal neoplasms in rats. This biological phenomenon suggests a tumor regulatory role for the hormone.