Porosomes are the universal secretory machinery in cells where membrane-bound secretory vesicles dock and transiently fuse (kiss-and-run) to release intravesicular contents to the outside of the cell during secretion. Earlier it was shown that in rat neurons 12–17 nm cup-shaped lipoprotein porosomes, possessing a central plug are present at the presynaptic membrane sometimes with 35–50 nm in diameter docked synaptic vesicles. In the current study, neuronal porosome structures following hypokinetic stress were evaluated using electron microscopy. Experiments were carried out to identify and evaluate the porosome structure at the presynaptic membrane in the rat and cat brain in control and experimentalanimals and to demonstrate the presence of porosomes in the dog brain. The results reveal for the