Absence of seizure activity following focal cerebral injection of enkephalins in a primate

Baboons (Papio papio) with photosensitive epilepsy have been chronically prepared with guide cannulae and deep electrodes to study the effects of focal injections of opioids.In the hippocampus, amygdala and thalamus (centre median) 50–100 μg morphine, 20–100 μg Met-enkephalin or 2–10 μg FK 33,824 do not induce local or general electrographic or motor signs of epilepsy.The acute epileptogenic effect of morphine and enkephalins observed in rats is not a general phenomenon whereas the anticonvulsant action of opioids acting on μ-receptors is seen in rodents and primates.