Differential distribution of somatostatin sst2 receptor splice variants in rat gastric mucosa.
The tetradecapeptide somatostatin (SRIF) has an inhibitory action on acid secretion in the stomach. It has been suggested that somatostatin may act directly on parietal cells as well as indirectly via histamine-producing cells. A family of high affinity membrane-bound receptors, which are termed sst1-sst5 receptors, mediates the physiological effects of somatostatin. On the basis of functional studies it has been suggested that somatostatin may mediate its actions in the stomach by activation of a somatostatin sst2 receptor type. Two splice variants of the rat sst2 receptor exist, sst2(a) and sst2(b), which differ in length and composition of their intracellular carboxy termini. To date, little information is available on the distribution of the somatostatin sst2(b) receptor in any peripheral tissue. Here we show for the first time the localisation of this receptor isoform in the rat oxyntic mucosa, where the receptor protein was found to be present in parietal cells. This is in contrast to sst2(a) receptor, which was localised to enterochromaffin-like cells and nerve fibres. The differential localisation of the receptor isoforms to two key cell types, parietal cells and enterochromaffin-like cells, may explain how somatostatin inhibits acid secretion by more than one mechanism.
Glaxo Institute of Applied Pharmacology, University of Cambridge, Tennis Court Road, Cambridge, CB2 1QJ, UK. mys37162@glaxowellcome.co.uk
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Schindler
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Humphrey
D017398:Alternative Splicing; D000595:Amino Acid Sequence; D000818:Animals; D000939:Epitopes / Q000737:chemistry; D005260:Female; D005753:Gastric Mucosa / Q000166:cytology* / Q000378:metabolism; D014644:Genetic Variation; D007150:Immunohistochemistry; D008969:Molecular Sequence Data; D010446:Peptide Fragments / Q000737:chemistry / Q000276:immunology; D051381:Rats; D017207:Rats, Sprague-Dawley; D017481:Receptors, Somatostatin / Q000032:analysis* / Q000737:chemistry / Q000235:genetics
D000939:Epitopes; D010446:Peptide Fragments; D017481:Receptors, Somatostatin; C115977:Sstr2 protein, rat; C106140:somatostatin receptor sst2A