CGP 35348 and CGP 55845A block the baclofen-induced depression of dorsal root evoked potentials in lumbar motoneurons of the neonatal rat.
In vitro brainstem-spinal cord preparations isolated from neonatal (0-5 days old) rats were used to investigate the GABAB receptor-mediated modulation of the dorsal root evoked potentials in lumbar motoneurons recorded intracellularly. The GABAB receptor agonist, baclofen, at low concentrations (1-10 microM), caused a reduction of the amplitude of the monosynaptic excitatory postsynaptic potential (EPSP), in a concentration-dependent manner. The depression of EPSPs was likely exerted at a presynaptic level since it occurred without any significant change of the passive membrane properties of the motoneurons. The two GABAB receptor antagonists, CGP 35348 and CGP 55845A blocked the effects of baclofen. These two compounds may be useful tools to study the evolution of GABAB receptor-mediated presynaptic inhibition during ontogenesis.
Vinay
L
L
CNRS, UPR Neurobiologie et Mouvements, Marseille, France. vinay@Inf.cnrs-mrs.fr
Clarac
F
F
D000818:Animals; D000831:Animals, Newborn; D001418:Baclofen / Q000037:antagonists & inhibitors* / Q000494:pharmacology; D003655:Decerebrate State; D003864:Depression, Chemical; D005071:Evoked Potentials / Q000187:drug effects / Q000502:physiology; D018755:GABA Agonists / Q000494:pharmacology*; D018756:GABA Antagonists / Q000494:pharmacology*; D058786:GABA-B Receptor Agonists; D058788:GABA-B Receptor Antagonists; D005727:Ganglia, Spinal / Q000166:cytology / Q000187:drug effects / Q000502:physiology*; D009046:Motor Neurons / Q000187:drug effects*; D009943:Organophosphorus Compounds / Q000494:pharmacology*; D010721:Phosphinic Acids / Q000494:pharmacology*; D011412:Propanolamines / Q000494:pharmacology*; D051381:Rats; D017208:Rats, Wistar; D012023:Reflex, Monosynaptic / Q000187:drug effects; D013116:Spinal Cord / Q000166:cytology / Q000187:drug effects / Q000502:physiology; D013570:Synaptic Membranes / Q000187:drug effects / Q000502:physiology
D018755:GABA Agonists; D018756:GABA Antagonists; D058786:GABA-B Receptor Agonists; D058788:GABA-B Receptor Antagonists; D009943:Organophosphorus Compounds; D010721:Phosphinic Acids; D011412:Propanolamines; C085075:CGP 55845A; C066430:CGP 35348; D001418:Baclofen