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Tremorolytic effect of 5'-chloro-5'-deoxy-(±)-ENBA, a potent and selective adenosine A1 receptor agonist, evaluated
Barbara Kosmowska1, Krystyna Ossowska1, Urszula Głowacka1
1Department of Neuro-Psychopharmacology, Institute of Pharmacology, Polish Academy of Sciences, Kraków, Poland.
Aim:
The aim of this study was to examine the role of adenosine A1 receptors in the harmaline-induced tremor in rats using 5'-chloro-5'-deoxy-(±)-ENBA (5'Cl5'd-(±)-ENBA), a brain-penetrant, potent, and selective adenosine A1 receptor agonist.
Methods:
Harmaline was injected at a dose of 15 mg/kg ip and tremor was measured automatically in force-plate actimeters by an increased averaged power in the frequency band of 9-15 Hz (AP2) and by tremor index (a difference in power between AP2 and averaged power in the frequency band of 0-8 Hz). The zif-268 mRNA expression was additionally analyzed by in situ hybridization in several brain structures.
Results:
5'Cl5'd-(±)-ENBA (0.05-0.5 mg/kg ip) dose dependently reduced the harmaline-induced tremor and this effect was reversed by 8-cyclopentyl-1,3-dipropylxanthine (DPCPX), a selective antagonist of adenosine A1 receptors (1 mg/kg ip). Harmaline increased the zif-268 mRNA expression in the inferior olive, cerebellar cortex, ventroanterior/ventrolateral thalamic nuclei, and motor cortex. 5'Cl5'd-(±)-ENBA reversed these increases in all the above structures. DPCPX reduced the effect of 5'Cl5'd-(±)-ENBA on zif-268 mRNA in the motor cortex.
Conclusion:
This study suggests that adenosine A1 receptors may be a potential target for the treatment of essential tremor.
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