title: Effect of drugs active at adenosine receptors upon chronic stress-induced hyperalgesia in rats.
abstract: 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 A(1) receptor agonist, N(6)-cyclopentyladenosine (CPA, 3.35 mg/kg, i.p.), adenosine A(1) 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 A(1) 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.
authors.affiliation: Departamento de Bioquímica, Instituto de Ciências Básicas da Saúde, Universidade Federal do Rio Grande do Sul, Porto Alegre, RS, Brazil. torresf@terra.com.br
authors.forename: Iraci Lucena
authors.initials: IL
authors.lastname: da Silva Torres
authors.forename: Carla Denise
authors.initials: CD
authors.lastname: Bonan
authors.forename: Leonardo
authors.initials: L
authors.lastname: Crema
authors.forename: Marcele
authors.initials: M
authors.lastname: De Leon Nunes
authors.forename: Ana Maria Oliveira
authors.initials: AM
authors.lastname: Battastini
authors.forename: João José Freitas
authors.initials: JJ
authors.lastname: Sarkis
authors.forename: Carla
authors.initials: C
authors.lastname: Dalmaz
authors.forename: Maria Beatriz C
authors.initials: MB
authors.lastname: Ferreira
mesh_terms: D000241:Adenosine / Q000031:analogs & derivatives* / Q000494:pharmacology / Q000627:therapeutic use; D000818:Animals; D002908:Chronic Disease; D006930:Hyperalgesia / Q000188:drug therapy* / Q000503:physiopathology; D008297:Male; D010147:Pain Measurement / Q000187:drug effects / Q000379:methods; D058906:Purinergic P1 Receptor Agonists; D058915:Purinergic P1 Receptor Antagonists; D051381:Rats; D017208:Rats, Wistar; D018047:Receptors, Purinergic P1 / Q000502:physiology; D013312:Stress, Physiological / Q000188:drug therapy* / Q000503:physiopathology; D014970:Xanthines / Q000494:pharmacology / Q000627:therapeutic use
chemical_list: D058906:Purinergic P1 Receptor Agonists; D058915:Purinergic P1 Receptor Antagonists; D018047:Receptors, Purinergic P1; D014970:Xanthines; C048599:N(6)-cyclopentyladenosine; C051360:1,3-dipropyl-8-cyclopentylxanthine; D000241:Adenosine