Distinct inhibitory effects of spinal endomorphin-1 and endomorphin-2 on evoked dorsal horn neuronal responses in the rat.
Intrathecal endomorphin-1 and endomorphin-2 (0.25-50 micrograms) dose-relatedly reduced all components of electrical evoked C-fibre responses of spinal neurones. These effects were partially reversed by naloxone. Endomorphin-1, but not endomorphin-2, dose-relatedly reduced the A beta-fibre evoked responses. Peak inhibitory effects of endomorphin-1 and -2 were at 15-20 min post-administration. Thus spinal endomorphin-2 had selective effects on noxious responses, whereas endomorphin-1 was non-selective.
Chapman
V
V
Department of Pharmacology, University College London.
Diaz
A
A
Dickenson
A H
AH
D000701:Analgesics, Opioid / Q000494:pharmacology*; D000818:Animals; D004305:Dose-Response Relationship, Drug; D004558:Electric Stimulation; D005071:Evoked Potentials; D009474:Neurons / Q000187:drug effects* / Q000378:metabolism; D009842:Oligopeptides / Q000494:pharmacology*; D051381:Rats; D017207:Rats, Sprague-Dawley; D013116:Spinal Cord / Q000187:drug effects* / Q000378:metabolism
D000701:Analgesics, Opioid; D009842:Oligopeptides; C105293:endomorphin 1; C105294:endomorphin 2