Presynaptic Block of Transmission In the Insect Cns By Mono-galactosyl and Di-galactosyl Analogs of Vespulakinin-1, A Wasp (paravespula-maculifrons) Venom Neurotoxin

1. The pharmacological properties of four synthetic analogues of the wasp neurotoxin, Vespulakinin 1, were studied using a cascade of mammalian smooth muscle preparations and the synaptic transmission from the cockroach cercal nerves to a giant interneuron. 2. All analogues have an extremely slow bradykinin-like effect on the smooth muscles. The carbohydrate-free and the two mono-glycosylated analogues are about equally active with bradykinin. 3. The double glycosylated derivative is about 5 times mom potent than bradykinin. 4. All analogues have two different effects on synaptic transmission in the insect CNS-at first a direct and reversible block of excitatory nicotinic transmission with a concurrent activation of the inhibitory GABA-ergic system and, secondly, a delayed irreversible block of the transmission, comparable to the block described earlier for bradykinin and Thr6-bradykinin. 5. For the synaptic transmission in the insect CNS the double glycosylated kinin is about 5 times more potent than bradykinin.