Purine involvement in morphine antinociception.
The effects of a series of adenosine derivatives on morphine antinoceptive effect were investigated in rats by the 'tail-flick' method. 2-Chloroadenosine (CADO) and L-N6-phenylisopropyladenosine (L-PIA), given intraperitoneally, caused decreased morphine antinociception. Intracerebroventricular injections of CADO, L-PIA and 5'-N-ethylcarboxamide adenosine (NECA), but not of 2'-deoxyadenosine, antagonized morphine antinociception. The effects of both central and peripheral injections of CADO and L-PIA on morphine antinociception were partially reversed by caffeine. Intracerebroventricular injection of dibutyryl-cyclic 3', 5' adenosine monophosphate (db cyclic AMP) had no effect on morphine antinociception. These data indicate that adenosine plays a role in morphine-induced antinociception. The results are discussed in terms of postulated effects of adenosine derivatives on adenylate cyclase.
D015762:2-Chloroadenosine; D000241:Adenosine / Q000031:analogs & derivatives / Q000494:pharmacology / Q000502:physiology*; D000698:Analgesia; D000818:Animals; D001831:Body Temperature / Q000187:drug effects; D003994:Bucladesine / Q000494:pharmacology; D002110:Caffeine / Q000494:pharmacology; D008297:Male; D009020:Morphine / Q000494:pharmacology*; D010660:Phenylisopropyladenosine / Q000494:pharmacology; D051381:Rats; D011919:Rats, Inbred Strains
D015762:2-Chloroadenosine; D010660:Phenylisopropyladenosine; D002110:Caffeine; D003994:Bucladesine; D009020:Morphine; D000241:Adenosine