J Pharmacol Exp Ther. 2003 Oct 16 [Epub ahead of print].
Anticociceptive effects of novel A2B adenosine receptor antagonists.
Abo Salem OM, Hayalah AM, Bilkei-Gorzo A, Filipo B, Zimmer A, Muller CE.
University of Bonn.
Caffeine, an adenosine A1, A2A and A2B receptor antagonist, is frequently used as an adjuvant analgesic in combination with non-steroidal 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. Co- administration of low, sub-effective 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.
("Excedrine" and equivalents...... used to me my miracle, until the headaches got so bad that a bigger weapon was required.) |
