Central effects of anisodamine, atropine, anisodine and scopolamine after intraventricular injection

Anisodine and anisodamine are new tropine alkaloids isolated from Scopolia tangutica. The chemical structure of anisodine is different from scopolamine by a hydroxy group on the tropine acid moiety. Anisodamine is different from atropine by a hydroxy group on the 6th position of tropine. In unanesthetized rabbits, intracere-broventricular(icv) injection of anisodin e-HBr 2.4mg/kg or' scopolamine-HBr 0.8 mg/kg produced a high synchronization and blocked the EEG arousal response. Rabbits became quiet. 5-10 min after icv anisodamine-HBr l-2 mg/kg or atropine sulfate 0.25-1mg/kg, cerebral electrical activity showed a low amplitude and a fast frequency, follovred by frequent spikes and seizure discharges. .The rabbits appeared excited with tachypnea, nystagmus and clonic convulsion. It suggests that aniso-dine and scopolamine are mainly CNS de-pressants; anisodamine and atropine are mainly stim ulants. Intravenous (iv) injections of 4 tro-pine alkaloids induced a high synchroni-zation and blocked the EEG arousal re-sponse in rabbits. Effects of anisodamine and atropine on EEG and the behavior of rabbits depended on the route of admini-stration. In mice icv of these tropine alkaloids produced similar behavioral effects as in rabbits. Physostigmine, pilocarpine, ani-sodine, mecamylamine, reserpine, chlorpro-mazine, 5-HTP, glycine, picrotoxin, caf-feine and pentobarbital did not affect CD60 0f anisodamine and atropine. But ip diazepam (5-20 mg/kg) significantly in-creased CD60. This suggests that central stimulation by anisodamine and atropine may be related to the mechanism modula-ting the GABA-ergic function.