The role of striatal adenosine A(2A) receptors in regulation of the muscletone in rats

The aim of the present study was to assess contribution of striatal adenosi ne A(2A) receptors to regulation of the muscle tone in rats. The muscle ton e was examined by a combined mechano- and electromyographic method, which m easured simultaneously muscle resistance (MMG) of a rats hind foot to passi ve extension and flexion in the ankle joint and the electromyographic activ ity (EMG) of the antagonistic muscles: gastrocnemius and tibialis anterior. CGS 21680 (1 and 2 mu g/0.5 mu l), injected bilaterally into the rostral p art of the striatum, dose-dependently increased both MMG and the EMG. The p resent results show that stimulation of striatal adenosine A(2A) receptors by CGS 21680 evokes parkinsonian-like muscle rigidity which may be due to a ctivation of the GABAergic strio-pallidal pathway. (C) 1999 Elsevier Scienc e Ireland Ltd. All rights reserved.