Physiological Effects Provoked by Opilong, a Synthetic Analog of Dermorphin

Abstract

We report here studies of the effects of five doses of the synthetic dermorphin analog opilog (50 μg/kg) on behavior in Wistar rats in a problem situation. This agent induced marked anxiolytic and analgesic effects as, despite repeated pretraining pain stimuli, the animals were able to learn (90%, versus 40% in controls). Small doses of opilong shifted the ratio of excitatory to inhibitory processes towards a significant predominance of excitation, which persisted stably for the period of a month in the absence of the agent in the body. Increased peripheral sensitivity in all the experimental rats correlated with CNS hyperexcitability, apparent in stress and neurotic reactions and as active avoidance. Blood biochemistry showed signs of prethrombosis, i.e., depression of fibrinolysis and hypercoagulation, in the experimental rats. It is suggested that the main point of action of opilong may be the brain neurotransmitter systems responsible for the excitatory-inhibitory conditions of CNS functioning, directed to generating stability of the conditioned reflex focus.