Orally administered atropine enhances motor cortex excitability: a transcranial magnetic stimulation study in human subjects.
Oral application of atropine was used to test if a modulation of cholinergic neurotransmission changed motor excitability. Healthy volunteers received either 1 or 2 mg atropine. Paired transcranial magnetic stimulation was used to study intracortical inhibition and intracortical facilitation before, 1 h and 24 h after ingestion of atropine. In addition, the silent period, motor threshold, F wave and motor response amplitudes were measured. The 1 mg dose of atropine induced a loss of intracortical inhibition, the 2 mg dose produced an intracortical disinhibition and enhanced intracortical facilitation. These changes returned to baseline after 24 h. Other electrophysiological parameters remained unchanged. Thus, an antagonist of pre- and postsynaptic muscarinic receptors increased excitability in the human motor cortex in a dose-dependent manner, indicating an influence of the cholinergic system on motor cortex excitation.
Liepert
J
J
Department of Neurology, Friedrich Schiller University, Jena, Germany. liepert@uke.uni-hamburg.de
Schardt
S
S
Weiller
C
C
D000284:Administration, Oral; D000328:Adult; D000704:Analysis of Variance; D001285:Atropine / Q000008:administration & dosage / Q000494:pharmacology*; D004558:Electric Stimulation; D055590:Electromagnetic Phenomena; D005260:Female; D006801:Humans; D008297:Male; D009044:Motor Cortex / Q000187:drug effects* / Q000502:physiology; D018727:Muscarinic Antagonists / Q000008:administration & dosage / Q000494:pharmacology*
D018727:Muscarinic Antagonists; D001285:Atropine