Effects of A(1) and A(2A) adenosine receptor ligands in mouse acute models of pain

• Published in: Neuroscience letters 2002-08, Vol.328 (3), p.241-244
• Main Authors: Bastia, Elena, Varani, Katia, Monopoli, Angela, Bertorelli, Rosalia
• Format: Article
• Language: English
• Subjects: Acute Disease; Adenosine - analogs & derivatives; Adenosine - pharmacology; Animals; Behavior, Animal - drug effects; Ligands; Mice; Nociceptors - drug effects; Pain - metabolism; Pain - psychology; Pain Measurement - methods; Pyrimidines - pharmacology; Receptor, Adenosine A2A; Receptors, Purinergic P1 - metabolism; Triazoles - pharmacology
• ISSN: 0304-3940
• DOI: 10.1016/S0304-3940(02)00524-4

The effects of selective A(1) and A(2A) adenosine receptor compounds in two mouse models of acute nociception were studied: acetic acid-induced writhing and the hot plate assays. Stimulation of A(1) receptors by 2-chloro-N(6)-cyclopentyl-adenosine (CCPA, 0.01-0.1 mg/kg, i.p.; A(1)K(i)=6 nM) or blockade of A(2A) receptors by 5-amino-7-(beta-phenylethyl)-2-(8-furyl)pyrazolo[4,3-e]-1,2,4-triazolo[1,5-c]pyrimidine (SCH58261, 1-10 mg/kg, i.p.; A(2)(A)K(i)=1.3 nM) produced anti-nociceptive effects. At the highest dose tested, CCPA and SCH58261 reduced the number of writhings by 79 and 99%, respectively. On the contrary, the A(1) antagonist 8-cyclopentyl-1,3-dipropylxanthine (DPCPX) (A(1)K(i)=2.8 nM) and the A(2A) agonist 2-(4-[2-carboxyethyl])phenethylamino-5'-N-ethylcarboxamido-adenosine-hydrochloride (GGS21680) produced pro-nociceptive effects in both tests. These findings suggest for the first time that blockade of A(2A) adenosine receptors produces anti-nociceptive effects.