Although long term gene transfer and expression have been demonstrated within the central nervous system, it is important to validate specific gene transfer and expression strategies in animal models before attempting application to the treatment of chronic neurological disorders, such as epilepsy. Using an adeno-associated virus (AAV) vector with a cytomegalovirus promoter (CMV) we have demonstrated stable, long term (3 months) expression of a foreign reporter gene in the rat inferior colliculus, a site of seizure genesis (McCown et al., Brain Res. 713:99, 1996). Therefore, it is hypothesized that AAV-CMV vectors will transfer and express the genes for specific receptor subunit proteins in the inferior colliculus, causing the assembly of functional neurotransmitter receptors, or in the case of anti sense constructs, disrupt assembly of specific receptors. To test this hypothesis, AAV-CMV vectors will be constructed with one of three GABA receptor subunit cassettes, or an NMDA receptor subunit cassette. These vectors will be infused into the inferior colliculus of rats. Seven days and 3 months later, we will determine if the vector-mediated gene delivery 1) increases the amount of specific subunit mRNA by quantitative RT-PGR, 2) increases the amount of receptor subunit protein using quantitative immunohistochemistry and 3) increases functional GABA receptor assembly using a chloride up take measure or functional NMDA receptor assembly using NMDA specific [3H]glutamate binding. Because the inferior colliculus is central to a number of seizure models, the same vectors will be infused into the inferior colliculus of normal or genetic epilepsy-prone rats, and in vivo seizure sensitivity will be evaluated. These studies represent a unique opportunity to evaluate gene delivery strategies in vivo. Moreover, since we are targeting receptors that modulate seizure sensitivity, the findings may have direct application to the treatment of focal seizure disorders.
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