The in vitro inhibition of GABA release by tetanus toxin

The in vitro effects of tetanus toxin on the potassium (K+)-evoked release of radiolabelled gamma-aminobutyric acid (GABA) from slices prepared from substantia nigra of the rat have been investigated. The addition of tetanus toxin (750-15,000 mouse LD50 ml-1) to the slices produced a dose- and time-dependent reduction in the K+-evoked release of [3H]GABA. These effects of the toxin were diminished at low temperature and in the absence of calcium ions in the bathing medium. It is suggested that this relatively simple in vitro system may allow more quantitative studies to be made concerning the action of the toxin on inhibitory amino acid release from the mammalian central nervous system.