RT Journal Article SR Electronic T1 Antinociceptive Effects of Novel A2B Adenosine Receptor Antagonists JF Journal of Pharmacology and Experimental Therapeutics JO J Pharmacol Exp Ther FD American Society for Pharmacology and Experimental Therapeutics SP 358 OP 366 DO 10.1124/jpet.103.056036 VO 308 IS 1 A1 Osama M. Abo-Salem A1 Alaa M. Hayallah A1 Andras Bilkei-Gorzo A1 Barbara Filipek A1 Andreas Zimmer A1 Christa E. Müller YR 2004 UL http://jpet.aspetjournals.org/content/308/1/358.abstract AB Caffeine, an adenosine A1, A2A, and A2B receptor antagonist, is frequently used as an adjuvant analgesic in combination with nonsteroidal anti-inflammatory drugs or opioids. In this study, we have examined the effects of novel specific adenosine receptor antagonists in an acute animal model of nociception. Several A2B-selective compounds showed antinociceptive effects in the hot-plate test. In contrast, A1- and A2A-selective compounds did not alter pain thresholds, and an A3 adenosine receptor antagonist produced thermal hyperalgesia. Evaluation of psychostimulant effects of these compounds in the open field showed only small effects of some antagonists at high doses. Coadministration of low, subeffective doses of A2B-selective antagonists with a low dose of morphine enhanced the efficacy of morphine. Our results indicate that analgesic effects of caffeine are mediated, at least in part, by A2B adenosine receptors. The American Society for Pharmacology and Experimental Therapeutics