Effect of drugs active at adenosine receptors upon chronic stress-induced hyperalgesia in rats.
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.
da Silva Torres
Iraci Lucena
IL
Departamento de Bioquímica, Instituto de Ciências Básicas da Saúde, Universidade Federal do Rio Grande do Sul, Porto Alegre, RS, Brazil. torresf@terra.com.br
Bonan
Carla Denise
CD
Crema
Leonardo
L
De Leon Nunes
Marcele
M
Battastini
Ana Maria Oliveira
AM
Sarkis
João José Freitas
JJ
Dalmaz
Carla
C
Ferreira
Maria Beatriz C
MB
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
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