GRF (somatocrinin) stimulates release of neurotensin, calcitonin and cAMP by a rat C cell line

We reported previously that GRF stimulates release of neurotensin (NT) by a clonal line of rat C cells (44-2 C). We report here that GRF stimulates calcitonin (CT) and cAMP release in these cells. For release experiments, replicate cultures are incubated for 5–180 min in serum-free defined medium. CT, NT and cAMP are measured by RIA. At a maximally effective concentration of GRF (.1–1.0 nM), there is a 2–3 fold stimulation of CT release at 60–90 min with peak release at 180 min. In contrast, GRF causes a rapid 4–6 fold increase of NT release within 5–15 min. In 44–2 C cells there is a 4–40 fold stimulation of cAMP release by GRF. We conclude that in 44–2 C cells GRF stimulates release of NT and cAMP and show for the first time the effect of this peptide on release of CT.