Central action of adrenaline

Adrenaline (A) administered in doses of 10, 50 and 100 micrograms/rat into the right lateral ventricle of the brain (i.v.c.) in rats reduced the spontaneous and exploratory locomotor activity, decreased the body temperature, and increased the effects of narcotics. The reduction of the locomotor activity after A was antagonized by nialamide, alpha-MT, and yohimbine. Total chemical destruction of catecholaminergic neurons and selective destruction of dopaminergic neurons caused increase in A-induced locomotor activity. A had no effect on the locomotor activity in rats subjected to the action of reserpine, reserpine with 6-OHDA, and phenoxybenzamine or propranolol. In rats treated with phenoxybenzamine, propranolol, spiroperidol or subjected to selective destruction of noradrenalinergic neurons adrenaline decreased significantly the locomotor activity. A (10 micrograms) increased and in higher doses inhibited amphetamine-induced hyperactivity. It potentiated amphetamine and apomorphine stereotypy and antagonized catalepsy induced with haloperidol or fluphenazine. In the despair test adrenaline reduced the duration of akinesia. In doses of 0.1, 1.0 and 10 micrograms/kg i.v. A increased slightly the flexor reflex of the hind paw of spinal rats. This action was antagonized by phentolamine as well as by propranolol. In biochemical investigations it was demonstrated that A decreased the level of dopamine in rat brain but had no effect on its utilization. The obtained results indicate that A i.v.c. stimulated catecholaminergic receptors.