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Effect of drugs active at adenosine receptors upon chronic stress-induced hyperalgesia in rats

2003; Elsevier BV; Volume: 481; Issue: 2-3 Linguagem: Inglês

10.1016/j.ejphar.2003.09.045

1879-0712

Iraci Lucena da Silva Torres, Carla Denise Bonan, Leonardo Machado Crema, Marcele de Leon Nunes, Ana Maria Oliveira Battastini, João José Freitas Sarkis, Carla Dalmaz, Maria Beatriz Cardoso Ferreira,

Pharmacological Receptor Mechanisms and Effects

Hyperalgesia and altered activities of enzymes involved in nucleotide hydrolysis are observed after exposure to repeated restraint in rats. Here, we investigated the effect of an adenosine A1 receptor agonist, N6-cyclopentyladenosine (CPA, 3.35 mg/kg, i.p.), adenosine A1 receptor antagonist, 1,3-dipropyl-8-cyclopentylxanthine (DPCPX, 0.8 mg/kg, i.p.) as well the effect of an adenosine reuptake blocker, dipyridamole (5 mg/kg, i.p.), on nociception in chronically stressed and control rats. We repeatedly submitted rats to restraint for 40 days. Nociception was assessed with a tail-flick apparatus. The control group presented increased tail-flick latencies after administration of CPA and dipyridamole, but this effect was not observed in the stressed group. DPCPX by itself had no effect on nociception. The analgesic effect of CPA and dipyridamole observed in the control group was reverted by DPCPX. These results indicate the involvement of adenosine A1 receptor in the antinociception observed in control animals and suggest that the pain signaling induced by chronic stress presents a different modulation involving the adenosinergic system.