Effect of scopolamine on the cerebral accumulation of ¹⁴c-catecholamines from ¹⁴c-tyrosine

The effect of the anti-muscarinic and psychotomimetic agent, scopolamine, on the accumulation of ¹⁴C- catecholamines formed from ¹⁴C-tyrosine administered intra- cerebrally to the mouse was studied. In doses from 3 to 30mg/kg, scopolamine was found to decrease the cerebral accumulation of ¹⁴C-dopamine and ¹⁴C-norepinephrine but increase the accumulation of ¹⁴C-normetanephrine. Similar effects on ¹⁴C-catecholamine accumulation were observed when ¹⁴C-DOPA was used as substrate. These effects are causally postulated to be related to blockade of inhibitory muscarinic responses which decrease CA output. The relevance of these findings to the toxic psychosis induced by scopolamine is discussed.