GABA SYNTHESIS IN ASTROCYTES AFTER INFECTION WITH DEFECTIVE HERPES-SIMPLEX VIRUS VECTORS EXPRESSING GLUTAMIC-ACID DECARBOXYLASE-65 OR DECARBOXYLASE-67

Defective herpes simplex virus (HSV) vectors containing glutamic acid decarboxylase (GAD) cDNAs, either GAD65 or GAD67, were used to examine GAD function and GABA synthesis in rat cortical astrocytes, CNS cells that do not endogenously synthesize GABA. GAD vector infection result ed in isoform-specific expression of GAD as determined by western blot ting and immunohistochemistry. Astrocytes infected with a beta-galacto sidase vector or uninfected expressed no GAD and contained no detectab le GABA. GABA was detected in glial fibrillary acid protein-expressing cells after GAD65 vector infection. Significant amounts of GABA, as d etermined by HPLC, were synthesized in cultures infected with either G AD vector. The levels of GABA in GAD67 vector-infected cells were almo st twofold higher than in GAD65 vector-infected cells. Vector infectio n did not alter levels of other intracellular amino acids. GABA was to nically released from astrocytes infected with the GAD67 vector, but n o increase in release could be detected after treatment of the cells w ith K+, veratridine, glutamate, or bradykinin, The ability to transduc e astrocytes so that they express GAD and thereby increase GABA levels provides a potential strategy for the treatment of neurologic disorde rs associated with hyperexcitable or diminished inhibitory activity.