Ethanol Toxicity During Brain Development: Alterations of Excitatory Synaptic Transmission in Immature Organotypic Hippocampal Slice Cultures.
BACKGROUND
The developing brain is particularly vulnerable to alcohol: Drinking during pregnancy can lead to a number of physical, learning, and behavioral disorders in the newborn. It has been demonstrated that immature and mature brain tissues display a differential sensitivity to ethanol (EtOH) toxicity and that cerebral structure and function are diversely impaired according to the stage of synaptic maturation.


METHODS
Rat organotypic hippocampal slice cultures were exposed for 7 days to EtOH (100 to 300 mM) after 2 days (immature) or 10 days (mature) of culture in vitro; EtOH was then removed from the medium, and 24 hours later, slices were analyzed by fluorescence microscopy, Western blotting, electrophysiology, and electron microscopy to explore the molecular mechanisms of EtOH toxicity in the developing hippocampus.


RESULTS
EtOH withdrawal elicited a selective CA1 pyramidal cell injury in mature slices, but not in immature slices. A significant increase in the expression of pre- and postsynaptic proteins in mature slices revealed that slice maturation is presumably associated with the development of new synapses. Incubation with chronic EtOH for 7 days and its removal from the medium induced a significant decrease in GluA1 and GluA2 expression levels; a significant reduction in the expression of synaptophysin and GluN2A was observed only after EtOH withdrawal. Whole-cell patch-clamp recordings showed that incubation with EtOH for 7 days induced a significant decrease in spontaneous excitatory postsynaptic current (sEPSC) frequency in CA1 pyramidal cells of immature slices and a trend toward a decrease in sEPSC amplitude. Electron microscopy revealed a disorganization of neurotubuli in immature slices after chronic exposure to EtOH.


CONCLUSIONS
These results indicate that prolonged incubation with EtOH and its subsequent withdrawal from the medium induce an impairment of excitatory synaptic transmission and possibly an incorrect formation of neuronal circuits in developing hippocampus in vitro, which is suggestive of mechanisms that may lead to mental retardation in fetal alcohol spectrum disorders.
['Gerace|Elisabetta|E|', 'Landucci|Elisa|E|', 'Totti|Arianna|A|', 'Bani|Daniele|D|', 'Guasti|Daniele|D|', 'Baronti|Roberto|R|', 'Moroni|Flavio|F|', 'Mannaioni|Guido|G|', 'Pellegrini-Giampietro|Domenico E|DE|']
D000428:Alcohol Drinking D000818:Animals D000831:Animals, Newborn D000431:Ethanol D006624:Hippocampus D009924:Organ Culture Techniques D051381:Rats D017208:Rats, Wistar D009435:Synaptic Transmission
Ethanol Organotypic Hippocampal Slices Neurotubuli Fetal Alcohol Spectrum Disorders Glutamate Receptors