title: An electron microscopic radioautographic identification of the APUD endocrine cells in the rat gastric pyloric glands.
abstract: The rat stomach was shown some years ago to contain numerous endocrine cells with APUD ability--cells that could take up the amino acids L-5-hydroxytryptophan (5-HTP) or L-dihydroxyphenylalanine (L-DOPA) and could decarboxylate them to their respective amines, 5-hydroxytryptamine (5-HT, serotonin) and dopamine, by means of the enzyme DOPA-decarboxylase. In a recent study, most of the APUD endocrine cells in the rat oxyntic mucosa were shown by electron microscopic radioautography to be the enterochromaffinlike cells, while the A-like cells were shown to lack APUD ability. To identify the APUD cells in the pyloric mucosa, pieces of rat pylorus were incubated in organ culture with 3H-5-HTP and were processed for light microscopic and electron microscopic radioautography. Additional specimens were incubated with 3H-5-HTP and carbidopa, an inhibitor of DOPA-decarboxylase, used to block the decarboxylation of 3H-5-HTP to 3H-5-HT, or with 3H-5-HT, used to determine where exogenous 3H-5-HT localizes in the pyloric mucosa. The 3H-5-HTP labeled all three types of endocrine cells identified within the pyloric glands--the G, enterochromaffin, and D cells. As this labeling was inhibited by carbidopa, and as exogenous 3H-5-HT labeled these cells only lightly, the labeling must have resulted from the uptake and intracellular conversion of the 3H-5-HTP of 3H-5-HT. Thus despite their morphologic differences, all rat pyloric endocrine cells possess APUD ability, a property shared by many, but not all, of the peptide- and amine-producing endocrine cells located throughout the body.
mesh_terms: D006916:5-Hydroxytryptophan / Q000378:metabolism; D001078:APUD Cells / Q000378:metabolism / Q000648:ultrastructure*; D000818:Animals; D001345:Autoradiography; D002230:Carbidopa / Q000378:metabolism; D005753:Gastric Mucosa / Q000378:metabolism / Q000648:ultrastructure; D008297:Male; D008854:Microscopy, Electron; D011708:Pylorus / Q000378:metabolism / Q000648:ultrastructure*; D051381:Rats
chemical_list: D006916:5-Hydroxytryptophan; D002230:Carbidopa