Afferent stimulation frequency modulates GABAergic phenomena in the spinal cord: reversal by benzodiazepine antagonists.
Switching from a low (0.5 Hz) to a higher (5 Hz) frequency repetitive stimulation of hindlimb muscle nerve afferents reduced GABA-mediated dorsal root potentials and dorsal root reflexes in the lumbosacral cord of spinal cats. Benzodiazepine receptor antagonists flumazenil and Ro 15-3505 in a very low dose (0.03 mg/kg i.v.) reversed this effect suggesting a stimulation-coupled release of an endogenous benzodiazepine receptor ligand down-regulating GABAA-receptors in the spinal cord.
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Pharma Research Department, F. Hoffmann-La Roche Ltd., Basel, Switzerland.
Ducić
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D000344:Afferent Pathways / Q000187:drug effects / Q000502:physiology*; D000818:Animals; D001569:Benzodiazepines / Q000037:antagonists & inhibitors*; D001570:Benzodiazepinones / Q000494:pharmacology*; D002415:Cats; D004558:Electric Stimulation; D005442:Flumazenil / Q000494:pharmacology*; D005727:Ganglia, Spinal / Q000187:drug effects / Q000502:physiology*; D009132:Muscles / Q000294:innervation; D011963:Receptors, GABA-A / Q000502:physiology; D012018:Reflex / Q000187:drug effects; D013116:Spinal Cord / Q000187:drug effects / Q000502:physiology*; D013569:Synapses / Q000187:drug effects / Q000502:physiology; D005680:gamma-Aminobutyric Acid / Q000502:physiology*
D001570:Benzodiazepinones; D011963:Receptors, GABA-A; D001569:Benzodiazepines; D005442:Flumazenil; D005680:gamma-Aminobutyric Acid; C040725:Ro 15-3505