Chronic administration of pentagastrin: effect on gastric mucosal protein synthesis in rats

Groups of adult rats were injected with either saline or pentagastrin (500 microgramg/kg) for 14 days. The capacity of the gastric mucosal ribosomes to synthesize endogenous and exogenous mRNA-directed protein in a cell-free system was then investigated. Polyribosomal profiles were also analysed on sucrose gradients. The endogenous mRNA-directed incorporation of 14C-labelled amino acids into protein by the gastric mucosal ribosomes from the pentagrastrin-injected rats was found to be considerably greater than that of the control. In the presence of exogenous mRNA (poly-U) the polyribosomes as well as the endogenous mRNA-free ribosomes (run-off ribosomes) from the pentagastrin-treated group showed 86% and 136% increment in [14C]-phenylalanie incorporation as compared to the corresponding control preparation. The ribosomal ribonuclease activity between the groups was found to be the same. The results of the present investigation indicate that an enhancement in the translational capacity of the ribosomes is in part responsible for stimulation of gastric mucosal protein synthesis after chronic administration of pentagastrin.