[Role of cholinergic and serotoninergic processes in modulating the activity of the negative reinforcement system]

The influence of choline- and serotoninergic drugs upon the latency of switching off the central aversive stimulation was investigated. Physostigmine and fluoxetine were shown to increase the latency of escape. Scopolamine and p-chloroamphetamine could both increase the time of active escape and decrease it. Fluoxetine diminished the activation effect and inversed the inhibitory effect of scopolamine. Fluoxetine potentiated the inhibitory action of physostigmine. p-Chloroamphetamine attenuated the inhibitory effect of physostigmine and increased scopolamine effect. It is suggested that choline- and serotoninergic mechanisms depressed the activity of the negative reinforcement system. Functional interaction is postulated between these neuromediator systems.