Effect of tyramine on the compartments of the granulated vesicles in rat pineal nerve endings

DE IRALDI, AMANDA PELLEGRINO; SUBURO, ANGELA MARIÁ

EUROPEAN JOURNAL OF PHARMACOLOGY

ELSEVIER SCIENCE BV

Año: 1972 vol. 19 p. 251 - 259

0014-2999

Granulated vesicles in rat pineal nerve endings consist of 2 compartments; the core and the matrix. The core can be stained by a variety of techniques including osmium tetroxide alone and a mixture of osmium tetroxide zinciodide (ZIO), and gives histochemical reactions for catechol and indolamines. The matrix can be stained with ZIO.To determine whether the matrix ZIO-reactive material represents a store of noradrenaline, different amounts of tyramine were administered i.p. in 50 mg/kg doses at 15-min intervals. The pineal glands were then studied under the electron microscope using the above techniques. Noradrenaline was determined fluorimetrically.It was observed that after the first dose of tyramine, no significant change in the noradrenaline content occurred although the matrix ZIO-reactive material decreased by 80%,; this strongly suggests that the matrix ZIO-reactivematerial is not a noradrenaline store but represents some other component of the vesicle which is also depleted by tyramine, in contrast, the core components revealed by the techniques used disappeared gradually.