Sr Bloom

Distribution and molecular heterogeneity of galanin in human, pig, guinea pig, and rat gastrointestinal tracts

Galanin was measured by radioimmunoassay in whole thickness extracts of the gastrointestinal wall from four species and in extracts from separate layers of human small intestine. The immunoreactivity was characterized using gel chromatography and high-pressure liquid chromatography. Two antibodies were employed, which were characterized as non-C-terminal (Gal 8) and C-terminal (Gal 9) using a C-terminal galanin 10-29 fragment. Substantial quantities of galanin immunoreactivity were found, mainly localized at the muscle layer. Both intramolecular and intermolecular heterogeneity was apparent. Two molecular forms exist in humans (Kav 0.58, 0.69). The molecular heterogeneity in humans, rats, and guinea pigs may be localized near the C-terminus of the galanin molecule. A C-terminal extension of one human galanin form is likely (Kav 0.58). These findings give radioimmunologic evidence for a neurocrine origin of galanin. The chromatographic variations suggest that extrapolation of experimental results between species should be treated with caution.

Regional distribution of bombesin and seven other regulatory peptides in the human brain

In order to compare within the same brains the quantitative distributions of a range of neuropeptides, bombesin, N- and C-terminal glucagon, cholecystokinin, neurotensin, somatostatin, substance P and vasoactive intestinal polypeptide immunoreactivities were determined by radioimmunoassay in 24 regions of 5 normal adult human brains. Each peptide showed a different distribution pattern. Of the peptides not previously mapped in detail in the human brain, bombesin-like immunoreactivity was present in all regions with the highest concentrations in particular areas of the hypothalamus, septal nuclei, nucleus accumbens, globus pallidus, amygdala, periaqueductal grey and substantia nigra. C- and N-terminal glucagon immunoreactivities were detected only in the ventromedial hypothalamus. The concentrations of the remaining 5 peptide immunoreactivities, and their molecular forms, were in good general agreement with those reported individually by others in both human brains and those of experimental animals. The quantitative mapping of the regulatory peptides in the human brain provides an essential base for further comparative study in diseased postmortem brains.

Intramural distribution of regulatory peptides in the sigmoid-recto-anal-region of the human gut

The distribution of regulatory peptides was studied in the separated mucosa, submucosa and muscularis externa taken at 10 sampling sites encompassing the whole human sigmoid colon (five sites), rectum (two sites), and anal canal (three sites). Consistently high concentrations of VIP were measured in the muscle layer at most sites (proximal sigmoid: 286 (16) pmol/g, upper rectum: 269 (17), a moderate decrease being found in the distal smooth sphincter (151 (30) pmol/g). Values are expressed as mean (SE). Conversely, substance P concentrations showed an obvious decline in the recto-anal muscle (mid sigmoid: 19 (2.0) pmol/g, distal rectum: 7.1 (1.3), upper anal canal: 1.6 (0.6)). Somatostatin was mainly present in the sigmoid mucosa and submucosa (37 (9.3) and 15 (3.5) pmol/g, respectively) and showed low, but consistent concentrations in the muscle (mid sigmoid: 2.2 (0.7) pmol/g, upper anal canal: 1.5 (0.8]. Starting in the distal sigmoid colon, a distinct peak of tissue NPY was revealed, which was most striking in the muscle (of mid sigmoid: 16 (3.9) pmol/g, upper rectum: 47 (7.8), anal sphincter: 58 (14)). Peptide YY was confined to the mucosa and showed an earlier peak (upper sigmoid: 709 (186) pmol/g, mid-distal sigmoid: 1965 (484)). A clear differential distribution of regulatory peptides was thus shown in the region studied. A possible role is suggested for NPY and VIP containing nerves in the effector control of the human internal anal sphincter.

Cell proliferation, plasma enteroglucagon and plasma gastrin levels in starved and refed rats.

SummaryThe effects of starvation and refeeding on intestinal cell proliferation at several sites of the rat gastrointestinal tract were studied and used as a model of altered cell proliferation in order to investigate the relationship between the rate of cell production and plasma gastrin and enteroglucagon.There was a marked fall in crypt cell production rate after four days starvation, with the proximal sites of the gut being most affected. The response to refeeding varied with site, suggesting that there was more than one mechanism for the control of intestinal cell proliferation.Plasma gastrin and enteroglucagon both fell to one fifth of their control level after starvation. Plasma gastrin increased slowly after refeeding, whilst plasma enteroglucagon increased rapidly to values significantly above control. Plasma gastrin was only correlated with crypt cell production in the duodenum, while plasma enteroglucagon was correlated with crypt cell production rate at several sites, indicating that enteroglucagon may be involved in the control of intestinal cell production.

Quantification of endocrine cells in whole intestinal crypts and villi.

VAN DUIJN, P. (1973) Fundamental aspects of enzyme cytochemistry. In Electron Microscopy and Cytochemistry, (edited by WISSE, E., DAEMS, W. Th., MOLENAAR, I. and VAN DUIJN, P.), pp. 3-33. Amsterdam: North Holland. VAN DUIJN, P. & VAN DER PLOEG, M. (1980) Microscopic cy tochemis t ry as matrix chemistry . In Trends in Enzyme Histochemistry and Cytochemistry, CIBA Foundation Symposium 73 (new series), pp. 209-229. Amsterdam, New York, Oxford: Excerpta Medica.

The distribution of melanin-concentrating hormone-like immunoreactivity in the central nervous system of rat, guinea-pig and man

The distribution of melanin-concentrating hormone-like immunoreactivity was investigated by radioimmunoassay in the CNS of rat, guinea-pig, pig and man. Highest concentrations of melanin-concentrating hormone-like immunoreactivity were found in the hypothalamus of all the species: rat 204.4 +/- 14.9; guinea-pig 159.5 +/- 23.3; pig 10.9 +/- 4.5 and man 80.1 +/- 19.1 pmol/g. Gel chromatographic analysis of hypothalamic extracts showed five immunoreactive peaks of melanin-concentrating hormone-like immunoreactivity in the rat and pig and six in the guinea-pig and man. High-performance liquid chromatography analysis of hypothalamic extracts showed five immunoreactive peaks in rat, guinea-pig, pig and four in man. However, these peaks appeared at different retention times from that of the single peak of salmon melanin-concentrating hormone. Examination of subcellular fractions of whole rat brain showed that most of the melanin-concentrating hormone-like immunoreactivity is found in the synaptosome fraction. Stimulation of melanin-concentrating hormone-like immunoreactivity release from rat hypothalamic slices revealed that potassium in the presence of calcium stimulated melanin-concentrating hormone-like immunoreactivity release. These findings suggest that mammalian melanin-concentrating hormone-like immunoreactivity has a different amino acid sequence from salmon melanin-concentrating hormone and may exist in multiple molecular forms. It is possible that melanin-concentrating hormone may play a role as a neurotransmitter or modulator in the mammalian CNS.