The effects of an irreversible dopamine receptor antagonist, N-ethoxycarbonyl-2-ethoxy-1,2-dihydroquinoline (EEDQ), on the regulation of muscle tone in the rat: the role of the substantia nigra

• Published in: Neuroscience letters Vol. 251; no. 2; pp. 77 - 80
• Main Authors: Hemsley, Kim M, Crocker, Ann D
• Format: Journal Article
• Language: English
• Published: Ireland Elsevier Ireland Ltd 24.07.1998
• Subjects: Animals; Basal ganglia; Dopamine Antagonists - pharmacology; Dopamine receptor; Male; Muscle tone; Muscle Tonus - drug effects; Muscle Tonus - physiology; N-Ethoxycarbonyl-2-ethoxy-1,2-dihydroquinoline; Quinolines - pharmacology; Rat; Rats; Rats, Sprague-Dawley; Substantia nigra; Substantia Nigra - physiology; N-Ethoxycarbonyl-2-ethoxy-1,2-dihydroquinoline; Muscle tone; Basal ganglia; Rat; Dopamine receptor; Substantia nigra
• ISSN: 0304-3940; 1872-7972
• DOI: 10.1016/S0304-3940(98)00463-7

Recent evidence has questioned the view that the increased muscle tone of Parkinson's disease results solely from reduced release of dopamine in the striatum, by emphasising the important role of the substantia nigra. The aim of the current study was to compare the effects on muscle tone of inactivating D 1 and D 2 dopamine receptors throughout the brain with those seen following their inactivation only in the substantia nigra. Inactivation of dopamine receptors by N-ethoxycarbonyl-2-ethoxy-1,2-dihydroquinoline injected either intraperitoneally, or bilaterally into the substantia nigra, resulted in similar increases in muscle tone, measured as changes in tonic electromyographic (EMG) activity. The magnitude and onset of EMG increases was related to the level of dopamine receptor inactivation. The results are consistent with the hypothesis that nigral dopamine mechanisms play a key role in the maintenance of muscle tone.