[Changes in the processes of vesicular recycling in the hippocampal presynapses during the modelling of glutamate neurotoxicity].

In order to test directly morphofunctional changes in presynaptic terminals (PTs) of hippocampal slice preparations (28 day-old rats, Ca 1 neurons), their ultrastructure was studied electron-microscopically under 0.5 h exposure of 500 mumol/l. glutamate added into the incubation medium. The morphometrical and statistical stereological approach has demonstrated a sufficient rise in the mean number of exo/endocytosis caveolae per a PT (up to 13), an increase of PTs surface area (from 2.23 to 3.15 microns, on the average), whereas the mean PTs volume was practically unchanged as compared to the controls. These quantitative data have allowed estimating changes in physical and chemical presynaptic membrane parameters, correlating with the observed plastic alterations under increased extracellular glutamate concentration. It has been shown that the studied effects can take place during earlier stages of the long-term potentiation development.