The impairment of long-term potentiation in rats with medial septal lesion and its restoration by cognition enhancers.

The effect of medial septal lesion on long-term potentiation (LTP) and the action of four cognition enhancers were studied in rat dentate gyrus, in vivo. The medial septum was partially lesioned by a radiofrequency lesion generator. The effect of lesion was studied on hippocampal function measuring two parameters; the amplitude of the maximal population spikes and the increase in population spikes evoked by high frequency stimulation of the perforant path (LTP). Both parameters were found to be significantly lower in the lesioned group than in the non-lesioned one. Four drugs (physostigmine, piracetam, vinpocetine and Hydergine), known to be effective in dementia and/or in cognitive impairments, were administered 1 h after the lesion procedure and thereafter once a day for 6 days after the operation. LTP was induced and measured at day 7. All drugs produced a complete restoration of the measured parameters affected by the lesion. These findings provided further evidence that the medial septum plays an important role in the induction of LTP in the dentate gyrus. This experimental model might be useful for studying new drugs against dementia.