Dopamine receptors in the subthalamic nucleus are involved in the regulation of muscle tone in the rat.
The effects of injecting an irreversible dopamine receptor antagonist, N-ethoxycarbonyl-2-ethoxy-1,2-dihydroquinoline (EEDQ) bilaterally into the subthalamic nucleus (STN) on changes in muscle tone and behaviour were investigated. Increased muscle tone (i.e. rigidity) was assessed quantitatively as increases in tonic electromyographic (EMG) activity in the hindlimb muscles of conscious, unrestrained rats. Significant, sustained increases in EMG activity were observed for 3-5 h post-injection in the tibialis and gastrocnemius muscles following injection of EEDQ into the STN. This effect was associated with 73% dopamine D1 and 66% dopamine D2 receptor occupancy in the STN, while dopamine receptors in surrounding regions were minimally occupied. These results provide new evidence that dopamine receptors located in the STN play an important role in the regulation of normal muscle tone.
Hemsley
Kim M
KM
Department of Clinical Pharmacology and Centre for Neuroscience, The Flinders University of South Australia, Bedford Park SA 5042, Australia.
Farrall
Eleanor J
EJ
Crocker
Ann D
AD
D000818:Animals; D001667:Binding, Competitive / Q000187:drug effects / Q000502:physiology; D004298:Dopamine / Q000378:metabolism*; D018492:Dopamine Antagonists / Q000494:pharmacology; D065127:Dopamine D2 Receptor Antagonists; D004576:Electromyography / Q000187:drug effects; D008297:Male; D009129:Muscle Tonus / Q000187:drug effects / Q000502:physiology*; D018482:Muscle, Skeletal / Q000187:drug effects / Q000294:innervation / Q000502:physiology; D009474:Neurons / Q000166:cytology / Q000187:drug effects / Q000378:metabolism*; D010300:Parkinson Disease / Q000378:metabolism* / Q000473:pathology / Q000503:physiopathology; D011804:Quinolines / Q000494:pharmacology; D011869:Radioligand Assay; D051381:Rats; D017207:Rats, Sprague-Dawley; D011954:Receptors, Dopamine / Q000187:drug effects / Q000378:metabolism*; D017447:Receptors, Dopamine D1 / Q000037:antagonists & inhibitors / Q000378:metabolism; D017448:Receptors, Dopamine D2 / Q000378:metabolism; D020531:Subthalamic Nucleus / Q000166:cytology / Q000187:drug effects / Q000378:metabolism*; D009435:Synaptic Transmission / Q000187:drug effects / Q000502:physiology
D018492:Dopamine Antagonists; D065127:Dopamine D2 Receptor Antagonists; D011804:Quinolines; D011954:Receptors, Dopamine; D017447:Receptors, Dopamine D1; D017448:Receptors, Dopamine D2; C000470:EEDQ; D004298:Dopamine