Effect of salivarectomy on the growth of gastrointestinal mucosa and urinary secretion of epidermal growth factor in rats.

The effect of salivary epidermal growth factor (EGF) on the growth and metabolism of gastrointestinal mucosa was examined by comparing DNA synthesis, DNA and RNA content, and weight of mucosa of salivarectomized and sham operated male rats. DNA synthesis of gastric mucosa was suppressed at 2 days after salivarectomy. Both weight and DNA content of oxyntic mucosa in the salivarectomized group were significantly lower than that of the sham operated group. Although salivarectomy suppressed DNA synthesis of jejunal mucosa, the difference was not significant statistically. The effect of salivarectomy on colonic mucosa was least in the gastrointestinal tract. Such a result suggested that the gradient-oriented antitrophic effect was brought about by salivarectomy. Urinary EGF excretion after salivarectomy was examined by radioreceptor assay. Although the antitrophic effect of salivarectomy on oxyntic mucosa was highest on day 2, no significant difference of urinary EGF concentration was detected on day 2. From these results it is suggested that the effect of salivarectomy on the gastrointestinal tract was not due to the change of EGF in systemic circulation but due to the change of luminal EGF.