Bilateral adrenalectomy: effect of tryptophan on protein synthesis and pepsin activity in the stomach of rats.

The effect of bilateral adrenalectomy and subsequent force-feeding of L-tryptophan on the gastric mucosal pepsin activity and [3H]leucine incorporation into total protein of the stomach (fundus) in vivo were investigated. One month after bilateral adrenalectomy the gastric mucosal pepsin activity and overall protein synthesis in the stomach were decreased by 72% and 52%, respectively. Twenty-four hours after a single tube-feeding of tryptophan (30 mg/100 g body weight) both activities returned to sham-operated control levels. In adrenalectomized rats the tryptophan-mediated stimulation of gastric mucosal pepsin activity was found to be sensitive to the RNA synthesis inhibitor, actinomycin-D. The diminution in gastric mucosal pepsin activity after adrenalectomy and its enhancement by tryptophan could not be related to the presence of an inhibitor or activator in the tissue. One month after adrenalectomy serum gastrin concentration was found to be 36% above that of the sham-operated control. In adrenalectomized rats, 24 and 48 h after tryptophan force-feeding, serum gastrin concentrations were decreased by 50% and 20%, respectively, but none of the values differed significantly from those of water-fed adrenalectomized controls.