Analgesia produced by centrally administered DAGO, DPDPE and U50488H in the formalin test. Eur J Pharmacol 1988 Aug 09;153(1):117-22
Date
08/09/1988Pubmed ID
3215276DOI
10.1016/0014-2999(88)90595-xScopus ID
2-s2.0-0023694073 (requires institutional sign-in at Scopus site) 43 CitationsAbstract
Three opioid agonists ([D-Ala2,N-MePhe4,Gly-ol5]enkephalin (DAGO), [D-Pen2,D-Pen5]enkephalin (DPDPE) and U50488H) were tested independently for their ability to produce analgesia in the formalin test. These agonists were chosen based upon their ability to act selectively at mu, delta and kappa opioid receptor types respectively. Rats received one intracerebroventricular (i.c.v.) injection of an agonist 20 min after subcutaneous injection of 15% formalin into a rear paw. Formalin injection produces continuous pain that results in two stereotypic behaviors, paw licking and paw lifting. Ten minutes after i.c.v. injection rats were observed for an 8 min period and scored for formalin-induced behavior. All agonists produced analgesia as indicated by a dose-dependent attenuation of formalin-induced behavior. At the doses tested, the rank order of analgesic efficacy was DAGO greater than DPDPE greater than U50488H. We suggest that centrally located mu, delta and kappa opioid receptors can each modulate the perception of this clinically relevant form of continuous pain. Additionally, the highest dose of DPDPE tested significantly increased rearing whereas DAGO and U50488H failed to affect rearing.
Author List
Calcagnetti DJ, Helmstetter FJ, Fanselow MSAuthor
Fred Helmstetter PhD Professor in the Psychology / Neuroscience department at University of Wisconsin - MilwaukeeMESH terms used to index this publication - Major topics in bold
3,4-Dichloro-N-methyl-N-(2-(1-pyrrolidinyl)-cyclohexyl)-benzeneacetamide, (trans)-IsomerAnalgesics
Animals
Behavior, Animal
Enkephalin, Ala(2)-MePhe(4)-Gly(5)-
Enkephalin, D-Penicillamine (2,5)-
Enkephalins
Formaldehyde
Injections, Intraventricular
Male
Nociceptors
Pyrrolidines
Rats
