ENDOCRINE-LIKE CELLS IN RAT STOMACH: EFFECTS OF 6-HYDROXYDOPA ON AMINE STORES AND AMINO ACID DECARBOXYLASE ACTIVITIES. A CHEMICAL, FLUORESCENCE HISTOCHEMICAL AND ELECTRON MICROSCOPIC STUDY

R. Hkanson ¹, L. -I. Larsson ¹, and F. Sundler ¹

¹ Departments of Pharmacology and Histology, University of Lund, Lund, Sweden

The mucosa of the oxyntic gland area in the stomach of the rat contains two types of endocrine-like cells, belonging to a cell system referred to as enterochromaffin-like. It has previously been shown that both cell types produce and store histamine and that, if supplied with dopa, they are capable of producing and storing dopamine. Treatment with 6-hydroxydopa for 3 days caused marked activation of the histamine-forming enzyme, histidine decarboxylase, without affecting the histamine concentration. At the same time, 6-hydroxydopa treatment reduced the amount of dopamine appearing in the enterochromaffin-like cells after injection of L-dopa. Electron microscopic examination of the two types of endocrine-like cells revealed markedly swollen granules in one of the two cell types. No such effects were seen after treatment with 6-hydroxydopamine. It is suggested that the primary effect of 6-hydroxydopa is reflected in granular damage and that other cytochemical changes are secondary.