Presynaptic block of transmission in the insect CNS by mono- and di-galactosyl analogues of vespulakinin 1, a wasp (Paravespula maculifrons) venom neurotoxin

Abstract

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 cereal 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 more 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.