TRANSIENT ALTERATIONS IN NEUROTRANSMITTER ACTIVITY IN THE CAUDATE-NUCLEUS OF RAT-BRAIN AFTER A HIGH-DOSE OF IONIZING-RADIATION

A single 10,000-rad dose of high-energy electrons induced an increase in dopaminergic and cholinergic activity in the caudate nucleus of the rat brain as assessed by K+-stimulated dopamine release in vitro and high-affinity choline uptake. These alterations occur during early transient incapacitation (ETI) and dissipate as the animal recovers behaviorally, in about 30 min after irradiation. Although the responses observed resemble those that result from blockade of dopamine receptors, no radiation-induced changes were found in dopamine-sensitive adenylate cyclase activity and [3H]haloperidol binding, two indices of dopaminergic receptor function. The data suggest that changes in dopaminergic and cholinergic activity are associated with the development of ETI and may play a role in the behavioral decrement observed under this condition.