Long-term maintenance of mature hippocampal slices in vitro

Cultures of primary neurons or thin brain slices are typicality prepared fr om immature animals. We introduce a method to prepare hippocampal slice cul tures from mature rats aged 20-31 days. Mature slice cultures retain hippoc ampal cytoarchitecture and synaptic connections up to 3 months in vitro. Sp ontaneous epileptiform activity is rarely observed suggesting long-term ret ention of normal neuronal excitability and of excitatory and inhibitory syn aptic networks. Picrotoxin, a GABAergic Cl(-)channel antagonist, induced ch aracteristic interictal-like bursts that originated in the CA3 region, but not in the CA1 region. These data suggest that;mature slice cultures displa yed long-term retention of GABAergic inhibitory synapses that effectively s uppressed synchronized burst activity via recurrent excitatory synapses of CA3 pyramidal cells. Mature slice cultures lack the reactive synaptogenesis , spontaneous epileptiform activity, and short life span that limit the use of slice cultures isolated from immature rats. Mature slice cultures are a nticipated to be a useful addition for the in vitro study of normal and pat hological hippocampal function. (C) 2000 Elsevier Science B.V. All rights r eserved.