Ultrastructural aspects of aging rat hippocampus after long-term administration of acetyl-L-carnitine.
In aged rats a decrease in axosomatic synapses of granule cells as well as a decrease in the number of synaptic vesicles of giant synapses was found. These phenomena were supposed to be correlated on the basis of a feed-back circuit existing at the level of the dentate gyrus. In fact the axosomatic synapses of the granules are inhibitory gamma-aminobutyric acid-ergic terminals of interneurons. Interneurons receive excitatory afferences from granules via the giant synapses of the mossy fibre collaterals. This results in a feed-back regulation of granule cell activity. The long-term administration of acetyl-L-carnitine to aged rats restores a synaptic pattern comparable to that of young rats. This effect on synaptic plasticity is transient.
Laschi
R
R
Institute of Clinical Electron Microscopy, University of Bologna, Italy.
Badiali de Giorgi
L
L
Bonvicini
F
F
Centurione
L
L
D000108:Acetylcarnitine / Q000494:pharmacology*; D000818:Animals; D002331:Carnitine / Q000031:analogs & derivatives*; D006624:Hippocampus / Q000187:drug effects / Q000648:ultrastructure*; D008854:Microscopy, Electron; D051381:Rats
D000108:Acetylcarnitine; D002331:Carnitine