CENTRAL NORADRENERGIC-CHOLINERGIC INTERACTION AND LOCOMOTOR BEHAVIOR

Depletion of forebrain noradrenaline (norepinephrine) by intracerebral injection of 4 .mu.g of 6-hydroxydopamine into the fibers of the dorsal noradrenergic bundle blocked the cataleptic effects of the muscarinic cholinergic agonist arecoline and to potentiate the locomotor stimulant effects of the muscarinic cholinergic blocker scopolamine. The nicotinic drugs, mecamylamine, a nicotinic blocker, and nicotine itself were unaffected in their actions by the depletion of forebrain noradrenaline. A noradrenergic-cholinergic interaction of the muscarinic type exists in rat brain and may have a function in the control of arousal, with catalepsy at 1 extreme and locomotor stimulation at the other.