Phaclofen antagonizes post-tetanic disinhibition in the rat dentate gyrus

Tetanic mossy fiber stimulation transiently reduced recurrent inhibition in the rat dentate gyrus. The post-tetanic depression of inhibition was maximal 200 ms after the tetanus and typically lasted for about 2 s. Phaclofen, a selective gamma-aminobutyric acid-B (GABAB) receptor antagonist, significantly increased the post-tetanic level of inhibition. These results suggest that GABAB receptor activation is important for the development of post tetanic disinhibition. We suggest that GABA released during repetitive firing acts on GABAB receptors on inhibitory interneurons to suppress recurrent inhibition.