NMDA receptors in the rostral and intermediate-caudal striatum play an opposite role in regulation of the muscle tone in rats
Ossowska, K.; Konieczny, J.
Polish Journal of Pharmacology 48(3): 261-267
1996
ISSN/ISBN: 1230-6002 PMID: 9112661 Document Number: 464212
The aim of the study was to assess the contribution of the NMDA receptors in the caudate-putamen to the regulation of the muscle tone. The experiment was carried out on male Wistar rats. The hind foot of a rat was flexed or extended at the ankle joint by 25 degrees and the resistance of the foot to passive movements was measured. Haloperidol (1 mg/kg ip) induced the muscle rigidity. The competitive antagonist of NMDA receptors, (+/-)-2-amino-5-phosphonopentanoic acid (AP-5), injected in doses of 2 and 5 micrograms/0.5 microliter bilaterally into rostral regions of the caudate-putamen, inhibited the muscle rigidity induced by haloperidol. In contrast, AP-5 injected bilaterally in the same doses into the intermediate-caudal region of the caudate-putamen in rats not pretreated with haloperidol, induced muscle rigidity. The present results seem to suggest that NMDA receptors localized in the rostral and intermediate-caudal regions of the caudate-putamen play an opposite role in regulation of the muscle tone in rats.