Dataset Information

Tremorolytic effect of 5'-chloro-5'-deoxy-(±)-ENBA, a potent and selective adenosine A1 receptor agonist, evaluated in the harmaline-induced model in rats.

ABSTRACT:

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.

SUBMITTER: Kosmowska B

PROVIDER: S-EPMC6492700 | biostudies-literature | 2017 May

REPOSITORIES: biostudies-literature

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Publications

Tremorolytic effect of 5'-chloro-5'-deoxy-(±)-ENBA, a potent and selective adenosine A1 receptor agonist, evaluated in the harmaline-induced model in rats.

Kosmowska Barbara B Ossowska Krystyna K Głowacka Urszula U Wardas Jadwiga J

CNS neuroscience & therapeutics 20170329 5

<h4>Aim</h4>The aim of this study was to examine the role of adenosine A<sub>1</sub> 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 A<sub>1</sub> receptor agonist.<h4>Methods</h4>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 differen ...[more]

PMID: 28371468

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Project description:Background and purposeAdenosine may be generated by hydrolysis of extracellular nucleotides by ectonucleotidases, including ectonucleoside triphosphate diphosphohydrolase 1 (CD39), ecto-5'-nucleotidase (CD73), nucleotide pyrophosphatase phosphodiesterase 1 (NPP-1) and tissue non-specific alkaline phosphatase (TNAP). Previous work from our laboratory has uncovered a critical role for adenosine A1 receptors (A1 R) in osteoclastogenesis; blockade or deletion of these receptors diminishes osteoclast differentiation. Interestingly, selective A1 R agonists neither affect basal osteoclastogenesis nor do they reverse A1 R antagonist-mediated inhibition of osteoclastogenesis. In this study, we determined whether ectonucleotidase-mediated adenosine production was required for A1 R antagonist-mediated inhibition, and, when we saw no effect, determined whether A1 R was constitutively activated and the antagonist was acting as an inverse agonist to diminish osteoclast differentiation.Experimental approachOsteoclast formation derived from wild-type, CD39 knockout (KO), CD73 KO, NPP-1 KO and TNAP KO mice was examined by tartrate-resistant acid phosphatase staining of receptor activator of NF-κB ligand-macrophage colony-stimulating factor-stimulated osteoclasts and osteoclast gene expression (Ctsk, Acp5, MMP-9 and NFATc1). Intracellular cAMP concentration was determined by elisa.Key resultsRolofylline inhibited osteoclast formation in a dose-dependent manner (IC50 = 20-70 nM) in mice lacking all four of these phosphatases, although baseline osteoclast formation was significantly less in precursors from CD73 KO mice. Rolofylline (1 μM) stimulates cAMP production in bone marrow macrophages by 10.23 ± 0.89-fold.Conclusions and implicationsBased on these findings, we hypothesize that the A1 R is constitutively activated in osteoclast precursors, thereby diminishing basal AC activity, and that A1 R antagonists act as inverse agonists to release A1 R-mediated inhibition of basal AC activity and permit osteoclast differentiation. The constitutive activity of A1 R promotes osteoclast formation and down-regulation of this activity blocks osteoclast formation.

Dataset Information

Tremorolytic effect of 5'-chloro-5'-deoxy-(±)-ENBA, a potent and selective adenosine A1 receptor agonist, evaluated in the harmaline-induced model in rats.

Aim

Methods

Results

Conclusion

Publications

Tremorolytic effect of 5'-chloro-5'-deoxy-(±)-ENBA, a potent and selective adenosine A1 receptor agonist, evaluated in the harmaline-induced model in rats.

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