Localisation of gastrins to neuro- and adenohypophysis

Abstract

SEVERAL peptides including substance P^1,2, somatostatin^3,4, the enkephalins^5,6 and cholecystokinin (CCK)^7–10 have been found both in nerve cells of the brain and in endocrine cells of the gut. CCK was first demonstrated in brain tissue by a gastrin radioimmunoassay as a peptide different from and smaller than heptadecapeptide gastrin⁷. Using six different gastrin antisera, Dockray provided strong evidence that the reported gastrin immunoreactivity⁷ corresponded to the COOH-terminal octa-peptide of CCK⁸, which reacts with certain gastrin antisera because of the identical COOH-terminal pentapeptide sequences of gastrin and CCK. Studies using antisera specific for CCK without cross-reaction with gastrin have now confirmed that CCK is present in large quantities in the brain^9,10 and that the peptide originally demonstrated by gastrin antisera⁷ indeed corresponded to the COOH-terminal octapeptide of CCK. In contrast, no peptides similar to any of the known molecular forms of gastrin have so far been found in brain tissue. We have used various sequence-specific antisera to distinguish between gastrin and CCK, and we report here that true gastrin also is present in the central nervous system. The only region of the brain containing significant amounts of gastrin was the hypophysis cerebri. Both pituitary lobes contained molecular forms of gastrin closely resembling those found in antrum¹¹.