[Effect of beta-phenylethylamine derivatives on the central nervous system. II. Pharmacological effect of the intracerebral administration of metaraminol on the central nervous system]

Six hours after intracerebral administration, the central effects of metaraminol were examined with the following results. 1) Metaraminol in doses of 40 approximately 160 mug decreased spontaneous motor activity in mice as measured by the photo-cell counters method, the wheel cage method or the open-field test. Ptosis and catalepsy induced at these doses. 2) Metaraminol in doses of 40 approximately 80 mug which influenced the spontaneous motor activity in mice, blocked the avoidance behaviour but not escape. 3) Metaraminol in doses of 1.25 approximately 10 mug which did not influence the spontaneous motor activity in mice, markedly blocked the attaching response induced by the electroshock. 4) Ten min after intraventricular administration, metaraminol in a dose of 500 mug induced the arousal pattern of EEG in sensory cortex of cats and this pattern lasted for 30 min. Ninety min after administration, EEG tracings reverted to the drowsy pattern.

[Effect of beta-phenylethylamine derivatives on the central nervous system. III. Motor activity changes in mice due to the intracerebral administration of metaraminol]

Influence of metaraminol on behavioural changes in mice was studied with the following results. 1) When metaraminol was injected i.c., spontaneous motor activity as tested by either the photocell counters method or open-field test markedly increased within 90 min after injection, while on the contrary greatly decreased 3 hr later as compared with control group. Thus, these biphasic effects of metaraminol were clearly established. 2) 30 min after injection, metaraminol in doses of 160 mug did not alter brain catecholamines in mice, however, 6 hr after injection, brain dopamine and norepinephrine markedly decreased. 3) When metaraminol was injected into mice pretreated with reserpine of 6-hydroxydopamine, spontaneous motor activity tested by photo-cell counters method markedly increased and anti-6-hydroxydopamine activity of metaraminol was stronger than anti-reserpine. 4) Metaraminol completely antagonized ptosis and catalepsy induced by rerserpine. 5) Six hr after injection, anti-methamphetamine activity was observed.