Effect of Cycloheximide and Actinomycin D on the Behaviour of the Headless Cockroach

Abstract

AVAILABLE evidence suggests that although actinomycin D and cycloheximide inhibit long term memory in mice and goldfish, these antibiotics have little or no effect on the primary acquisition of a new task^1,2. It was therefore very interesting that Brown and Noble³ should report that cycloheximide inhibited the ability of a headless cockroach to avoid an electric shock by keeping its leg raised⁴. This behavioural inhibition seems to be correlated with the extent of inhibition of protein synthesis⁵. There are many possible explanations, but Brown and Noble reported no change in sensitivity to the shock stimulus when cycloheximide was given, so that this factor can be ruled out. The activity of the leg, however, was greater after cycloheximide had been given. This suggested that if this drug caused increased activity, it would interfere with the achievement of a criterion (two shocks or less in 3 min) that depended on a relatively quiescent state. We report here the results of an attempt to ascertain whether cycloheximide affects learning performance by the increasing activity of the leg. As well as cycloheximide, we have investigated the effects of actinomycin D.