Assessment of cholinergic neuronal activity in the brain.

Endogenous acetylcholine (ACh), ACh turnover and high affinity choline uptake (H.A. Ch uptake) have all been considered valuable markers for cholinergic neural activity. The present communication compare the markers regarding regional differences in the brain of normal mice as well as in mice treated with oxotremorine (OT), nicotine and sodium pentabarbital. A relationship is obtained between in vivo turnover values for 5 different brain regions and in vitro H.A. Ch uptake. Pretreatment with OT and sodium pentobarbital produces specific regional changes in both turnover and H.A. Ch uptake. However, both drugs produce shifts of the correlation lines due to uptake being less affected than turnover. Atropine completely prevented the effects of OT regarding turnover and H.A. Ch uptake. A convulsant dose of nicotine did not produce significant changes in any of the brain regions studied neither on turnover nor on H.A. Ch uptake.