title: Suppression of LTP-like plasticity in human motor cortex by the GABAB receptor agonist baclofen.
abstract: Previous experiments in slice preparations revealed that pharmacological activation of GABAB receptors down- or up-regulates long-term potentiation (LTP), depending on whether increase of GABAB receptor mediated inhibitory postsynaptic potentials or decrease of presynaptic auto-inhibition of GABAA receptor mediated inhibition predominates. The effects of GABAB receptor activation on LTP in humans in vivo are unknown. Here we show, by using transcranial magnetic stimulation, that the GABAB receptor agonist baclofen decreases paired associative stimulation induced LTP-like plasticity in human motor cortex. This suggests that increased GABAB mediated inhibitory postsynaptic potentials drive this effect, and that baclofen may have a negative impact on LTP-dependent behavioural processes such as motor learning.
authors.affiliation: Research Centre for Human Movement Control, The University of Adelaide, Adelaide, Australia.
authors.forename: Michelle N
authors.initials: MN
authors.lastname: McDonnell
authors.forename: Yuri
authors.initials: Y
authors.lastname: Orekhov
authors.forename: Ulf
authors.initials: U
authors.lastname: Ziemann
mesh_terms: D000328:Adult; D000704:Analysis of Variance; D001418:Baclofen / Q000494:pharmacology*; D018592:Cross-Over Studies; D004311:Double-Blind Method; D004558:Electric Stimulation / Q000379:methods; D004576:Electromyography; D019054:Evoked Potentials, Motor / Q000187:drug effects / Q000528:radiation effects; D005260:Female; D018755:GABA Agonists / Q000494:pharmacology*; D006801:Humans; D016014:Linear Models; D017774:Long-Term Potentiation / Q000187:drug effects* / Q000528:radiation effects; D008297:Male; D008475:Median Nerve / Q000502:physiology / Q000528:radiation effects; D009044:Motor Cortex / Q000187:drug effects* / Q000528:radiation effects; D011712:Pyramidal Tracts / Q000187:drug effects / Q000502:physiology / Q000528:radiation effects; D050781:Transcranial Magnetic Stimulation / Q000379:methods
chemical_list: D018755:GABA Agonists; D001418:Baclofen