Noradrenergic modulation of human cortex excitability by the presynaptic alpha(2)-antagonist yohimbine.
The objective of this study was to determine if yohimbine, a central norepinephrine enhancing drug, increases cortico-motoneuronal excitability in intact humans. Transcranial magnetic stimulation was used to assess excitability of the motor system reflected in the parameters motor threshold, recruitment curve, intracortical inhibition and intracortical facilitation before and after oral administration of 20 and 40 mg yohimbine. Oral intake of 40 but not 20 mg yohimbine increased slope and plateau of the recruitment curve and intracortical facilitation. Motor threshold and intracortical inhibition remained unchanged. The data show that pharmacological enhancement of central norepinephrine in humans is effective to increase the cortico-motoneuronal excitability. Since cortical excitability is closely linked to neuroplasticity, this observation might be of possible relevance for strategies to enhance rehabilitative processes after cortical lesions by pairing noradrenergic drugs with motor training.
Plewnia
C
C
Neurophysiology Section, Department of Psychiatry, University of Tuebingen, Osianderstrasse 24, 72076 Tuebingen, Germany.
Bartels
M
M
Cohen
L
L
Gerloff
C
C
D000317:Adrenergic alpha-Antagonists / Q000008:administration & dosage* / Q000009:adverse effects; D000328:Adult; D001930:Brain Injuries / Q000188:drug therapy / Q000378:metabolism / Q000503:physiopathology; D004305:Dose-Response Relationship, Drug; D004558:Electric Stimulation; D019054:Evoked Potentials, Motor / Q000187:drug effects / Q000502:physiology; D006801:Humans; D008280:Magnetics; D008297:Male; D009044:Motor Cortex / Q000187:drug effects* / Q000378:metabolism; D009046:Motor Neurons / Q000187:drug effects / Q000378:metabolism; D009433:Neural Inhibition / Q000187:drug effects* / Q000502:physiology; D009473:Neuronal Plasticity / Q000187:drug effects / Q000502:physiology; D009638:Norepinephrine / Q000378:metabolism*; D017729:Presynaptic Terminals / Q000187:drug effects* / Q000378:metabolism; D011712:Pyramidal Tracts / Q000187:drug effects / Q000378:metabolism; D018341:Receptors, Adrenergic, alpha-2 / Q000187:drug effects / Q000378:metabolism; D020127:Recovery of Function / Q000187:drug effects* / Q000502:physiology; D015016:Yohimbine / Q000008:administration & dosage* / Q000009:adverse effects
D000317:Adrenergic alpha-Antagonists; D018341:Receptors, Adrenergic, alpha-2; D015016:Yohimbine; D009638:Norepinephrine