Abstract
The accumulation of some biogenic substances in the Paneth cell cytoplasmic granules of the mouse jejunum, ileum and colon and the effect of some drugs on this accumulation were studied, using the histochemical formaldehyde‐induced fluorescence method. The biogenic substances were injected i.v. and the specific catecholamine fluorescence appeared in the cytoplasmic secretory granules of the mouse Paneth cells about 10 min after I‐DOPA, dopamine, a‐methyl‐DOPA, noradrenaline, a‐methylnoradrenaline and adrenaline administration. Nia‐lamide and pargyline markedly intensified the fluorescence intensity in the Paneth cell granules after administration of the biogenic substance.Imipramine and cocaine inhibited specifically the I‐DOPA and dopamine accumulation, whereas amphetamine, amitriptyline, nortriptyline, chlorpromazin, promazine and guanethidine had no effect. After nialamide pretreatment amphetamine, nortriptyline and amitriptyline were also capable of inhibiting slightly the accumulation of these biogenic substances. 5‐Hydroxytryptamine or 5‐hydroxytryptophan were not taken up by the Peneth cell granules even after nialamide pretreatment. The apparent mechanism of the accumulation of biogenic substances by the Paneth cell secretory granules was discussed.

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