GABA mechanisms in audiogenic seizures studied using herpes virus and lentivirus mediated gene transfer.

Viral gene transfer was used to alter expression of GABA receptor a-1 subunits and GAD production to study effects on the audiogenic seizure (AGS) model for epilepsy. Long-Evans rats acoustically primed with a 125-dB 10-kHz tone at postnatal day (PND) 18 were tested at PND 32 for AGS using 125 dB white noise stimulation. Seizure resistant animals were not exposed to a priming signal. Subjects (n = 8) were AGS-tested 2 and 3 days before surgery on PND 50-100, and again 2, 3, and 4 days after surgery; additional post-testing to 30 days was added for lentivirus animals to study the effects of long-term expression. The central nucleus of the inferior colliculus was bilaterally injected with replication-defective herpes virus (ICP4-; 2 x [10.sup.6] plaque forming units) encoding [GABA.sub.A] a-1 subunit in the antisense; lentivirus vectors (multiply attenuated, replication defective and self-inactivating) encoded [GABA.sub.A] a-1 sense or antisense (10% lacZ-encoding virus; controls 100% lacZ-encoding virus or vehicle), or GAD sense. In nonsusceptible animals, herpes [GABA.sub.A] a-1 antisense significantly increased AGS-related wild running and clonus activity (p<.05). Control groups showed no significant increases in seizure behaviors. In lentivirus [GABA.sub.A] a-1 sense AGS animals wild running and clonus latencies showed significant increases during the posttests 2 and 3 (t=3.305, p<0.03); the overall incidences of wild running and clonus during this period was significantly reduced (p<0.05). Preliminary studies using [GAD.sub.65] sense lentivirus suggest that this vector is highly effective in decreasing the incidence of seizure behaviors. Staining for lacZ (B-galactosidase expression) showed typical collicular fusiform and stellate cells. These results show that manipulation of the production of GABA through the GAD enzyme or the [GABA.sub.A] receptor subunits using viral constructs can directly alter epilepsy. Supported by NSF SES-0244632 and EPSCoR EPS-0132573/NIH BRIN 8- P0RR16461A (JRC).