Changes in protein and nucleic acid synthesis in rat gastric mucosa after pentagastrin.

The trophic effects of gastrin on gastrointestinal tissues have been shown to be physiologically important. This study was designed to investigate the sequence of changes in macromolecular synthesis in the rat gastric mucosa following a single dose of pentagastrin. The earliest response was an increase at 1-2 h of poly (A) messenger RNA (mRNA). This increase dropped after 4 h but remained slightly elevated even 12 h after pentagastrin. By 6 h there was a large increase in protein synthesis that lasted until 12 h. Accompanying this rise in protein synthesis was a large increase in ribosomal (rRNA) and transfer RNA (tRNA), which peaked at 12 h. The changes in both fractions of RNA and protein were over by 18 h. No significant increase in secreted protein was noted, but there was a slight, transient decrease at 1 h. Pentagastrin stimulated all forms of RNA, but the largest increase was seen in the rRNA fraction. After multiple doses, parallel increases in rRNA and tRNA were seen. The stimulation of protein synthesis could be abolished by actinomycin D, and was, therefore, RNA dependent.