Abstracts

We previously found that recombinant adenoassociated viral vector (rAAV) mediates long-term human neuropeptide [Upsilon] (NP[Upsilon]) gene expression and peptide transduction into the normal rat hippocampus. From 15 days up to at least for 6 months after AAV-NP[Upsilon] injection, NP[Upsilon] was overexpressed in hilar interneurons, pyramidal cells and in mossy fibres from [sim]2.5 mm around the injection site. NP[Upsilon] overexpressing rats were protected from acute kainate seizures and status epilepticus, and kindling epileptogenesis was delayed.
The aim of this study was to investigate whether rAAV-mediated NP[Upsilon] gene expression in the hippocampus of chronically epileptic rats was effective in reducing spontaneous seizure activity. Epileptogenesis was induced by status epilepticus that was triggered with electrical stimulation of the ventral hippocampus (n= 20). Three months after status epilepticus, rats were continuously (24 h/d) video-EEG monitored for 2 weeks to obtain baseline spontaneous seizure (SS) frequency. Rats were randomized into two groups (n=10), then injected with rAAV carrying the human NP[Upsilon] gene under the control of CBA promoter (2 [micro]l 5.2x10e12) in the septal and temporal aspects of the hippocampus bilaterally. Control rats were injected with equivalent volumes of AAV-empty cassette. Three to four weeks after AAV delivery, rats were video-EEG monitored for 2 weeks. In the AAV-NP[Upsilon] injected group (n =10), 4 rats showed a 50 % reduction in the frequency of SS and a 40% reduction in the total time spent in EEG seizures; 3 rats had similar SS frequency as during baseline and 3 rats had a [sim]150 % increase in SS frequency and in their total duration. In the AAV-Empty injected group (n= 10), none of the rats showed a decrease in SS frequency. In particular, 3 out of 10 rats had SS frequency similar to baseline, and the remaing 7 rats had a [sim]300% increase in SS frequency and [sim]250% increase in their total duration. These data show that the overexpression of the human AAV-NP[Upsilon] gene in the rat hippocampus reduces SS frequency and their duration in 40% of rats and delays or suppress the progressive increase in SS frequency. Further analysis of behavioral seizure severity and histopathology are in progress. These data provide important preclinical information on the therapeutic potential of gene therapy for controlling seizures at focal onset. (Supported by Neurologix Res, Inc.,NJ, USA.)