Heptadecapeptide gastrin in the vagal nerve.

Abstract

Immunoreactive gastrin was present in vagal nerves from cats, dogs, and human beings. The In cats electrical vagal stimulation causes a release of gastrin heptadecapeptide, which is atropin resistant (1-4). Recently a large number of peptides have been found to possess a dual localization to endocrine cells and neurons. Such peptides include substance P, vasoactive intestinal polypeptide (VIP), somatostatin, neurotensin, and cholecystokinin (5-12). Previous findings of gastrin immunoreactivity in the central nervous system (13) have recently been shown to be due to a crossreacting cholecystokinin octapeptide (14). Since no innervation of the G cells has been demonstrated, it occurred to us that vagal stimulation might cause a release of gastrin from gastrinergic nerves extending from the vagi. In the present communication we present evidence for the occurrence of heptadecapeptide gastrin in the trunk and branches of the vagal nerve. MATERIALS AND METHODSSpecimens from the main trunks of the cervical, thoracic, and abdominal vagi were obtained from anesthetized cats and dogs. From human beings, specimens from the abdominal vagus were obtained at surgery. Immediately after sampling, the tissue was frozen on dry ice. While frozen the tissue was cut into pieces weighing a few milligrams, which were boiled for 20 min at pH 6.4 (10 ml of water per g of tissue) and homogenized. After centrifugation, the supernatant was assayed in dilutions from 1:10 to 1:10,000.In addition, tissue specimens from the gastrointestinal tract, stomach to proximal colon, of cats were either immediately frozen in melting Freon-22, freeze-dried, vapor-fixed with diethylpyrocarbonate and embedded in paraffin or fixed in a 4% paraformaldehyde solution (pH 7.3) for 1-4 hr, washed in phosphate buffer (pH 7.3) containing 20% sucrose overnight, and subsequently frozen in melting Freon-22 for cryostat sectioning.Chromatography. Extracts (1.0-1.5 ml) were applied to Sephadex G-50 superfine columns (10 X 1000 mm) and eluted with 20 mM veronal (pH 8.4) containing 0.1% bovine serum albumin at 40 with a flow of 5 ml/hr. Fractions of 1.0 ml were collected and assayed with region-specific radioimmunoassays for gastrin and cholecystokinin. The columns were calibrated with 125I-labeled albumin (to indicate the void volume, V0) and 22NaCl (to indicate the total volume, Vt). Moreover, the columns were calibrated with different molecular forms of gastrin and cholecystokinin: highly purified human triacontatetrapeptide gastrin (component II or gastrin-34) (generous gift from R. A. Gregory, Liverpool, England), synthetic human heptadecapeptide gastrin (component III or gastrin-17), synthetic human NH2-terminal tridecapeptide gastrin (generous gift from J. S. Morley, I. C. I., Alderley Park, Cheshire, England), highly purified porcine triacontatriapeptide cholecystokinin CCK-33, and the corresponding COOH-terminal octapeptide (generous gifts from V. Mutt, The Karolinska Institute, Stockholm).Radioimmunoassays. The tissue extracts and the chromatography f...

Molecular structure and genetic mapping of the mouse gastrin gene

“…In adult vertebrates, the primary site of gastrin synthesis is the antral G-cells in the stomach. However, gastrin peptides have also been detected in the small and large intestine [2], vagal nerve [3], ovary [4], testis [5], hypothalamus and pituitary gland [6]. Moreover, during fetal life, gastrin is expressed in the pancreas [7], and colorectal tissues [8].…”

Expression and localization of gastrin messenger RNA and peptide in spermatogenic cells.

“…The gastrin gene is expressed mainly in the antroduodenal G cells, and to a minor extent in the neonatal pancreas (12), vagal neurons (13), pituitary cells (14), and bronchial mucosal cells (15). In addition to I cells of the small intestine, the CCK gene is expressed in multiple central (16)(17)(18)(19) and peripheral neurons (20), in pituitary corticotrophs (21) and, as recently reported, in spermatogenic cells of several mammalian species (22,23).…”

Molecular cloning of human gastrin cDNA: evidence for evolution of gastrin by gene duplication.

“…Available, although indirect, evidence suggests that these forms reflect different steps in the posttranslational processing (7,8). Recently, gastrins have also been found in extraantral endocrine cells and neurons, in which, however, the processing differs from that of the antral cells (9)(10)(11)(12). In (3,200 Ci/mmol) were obtained from New England Nuclear.…”