Effects of pentylenetetrazol on GABA-A/benzodiazepine/picrotoxinin receptor complexes in rat brain regions.

The effects of acute convulsive doses of pentylenetetrazol (PTZ) on [35S]t-butyl-bicyclophosphorothionate (TBPS), [3H]flunitrazepam (FNP), [3H]muscimol, and [3H]gamma-aminobutyric acid (GABA) binding sites were examined in well-washed homogenates of various brain regions of rat. Except for a significant increase in the number of striatal [35S]TBPS binding sites, no significant change in [35S]TBPS, [3H]FNP, [3H]muscimol, and [3H]GABA binding was found in various brain regions 30 min after subcutaneous injection of PTZ at 90 or 100 mg/kg. Similarly, there were no significant changes in [35S]TBPS and [3H]FNP binding to unwashed P2 membranes of cerebral cortices 30 min following administration of convulsive doses of PTZ. These experiments failed to demonstrate acute modulation of GABA-A/benzodiazepine/picrotoxinin receptor complex by PTZ in the various brain regions examined except striatum. The significance of the increased [35S]TBPS binding in striatum caused by PTZ remains unclear.