GABAA receptor blockade inhibits A beta fibre evoked wind-up in the arthritic rat.
To clarify the mechanisms of allodynia we have examined whether 'wind-up' of nociceptive withdrawal reflexes (NWR), a phenomenon characteristic of nociceptive C fiber spinal processing, can be mimicked by stimulation of tactile A beta fibers in monoarthritic decerebrate spinal rats. Knee joint monoarthritis was induced by carrageenan/kaolin under halothane anaesthesia 5 h before recordings. In arthritic, but not in control rats, wind-up of NWR of the semitendinosus muscle could be evoked by repeated stimulation of A beta fibres. By contrast, peroneus longus reflexes did not exhibit marked wind-up. Bicuculline (0.03-0.3 mg/kg, i.v.) dose-dependently inhibited this wind-up. Hence, reflex wind-up can be elicited by tactile A beta fibers in arthritis rats through a GABAA dependent mechanism.
Weng
H R
HR
Department of Physiology and Neuroscience, Lund University, Sweden.
Laird
J M
JM
Cervero
F
F
Schouenborg
J
J
D000818:Animals; D001168:Arthritis / Q000139:chemically induced / Q000503:physiopathology*; D001640:Bicuculline / Q000494:pharmacology; D003655:Decerebrate State; D004305:Dose-Response Relationship, Drug; D004576:Electromyography; D005260:Female; D018756:GABA Antagonists / Q000494:pharmacology*; D058787:GABA-A Receptor Antagonists; D006614:Hindlimb; D007719:Knee Joint; D008297:Male; D009413:Nerve Fibers, Myelinated / Q000187:drug effects*; D010146:Pain / Q000503:physiopathology*; D051381:Rats; D017208:Rats, Wistar; D014110:Touch / Q000502:physiology*
D018756:GABA Antagonists; D058787:GABA-A Receptor Antagonists; D001640:Bicuculline