Peripheral injection of DNS-RFa, a FMRFa agonist, suppresses morphine-induced analgesia in rats.
The present results demonstrate an antagonistic effect of DNS-RFa on morphine-induced analgesia in rats. This confirms previous evidence presented by others on the effects of FMRFa-related peptides when applied centrally. Unlike these peptides, however, it is shown here that DNS-RFa is effective upon peripheral injection. The effects of DNS-RFa on morphine-induced analgesia were dose-dependent (ED50 = 0.5 mg/kg). DNS-RFa alone (5 mg/kg) did not affect the control level of nociception. Peripheral injection of FMRFa (5 mg/kg) did not affect morphine-induced analgesia. DNS-RFa defines the minimal configuration to activate neuronal FMRFa receptors in the pond snail. The present report suggests also that in vertebrates the Arg-Phe-NH2 sequence is essential and that DNS-RFa readily penetrates the blood-brain barrier.
Brussaard
A B
AB
Department of Biology, Free University, Amsterdam, The Netherlands.
Kits
K S
KS
Ter Maat
A
A
Mulder
A H
AH
Schoffelmeer
A N
AN
D000698:Analgesia; D000818:Animals; D001812:Blood-Brain Barrier / Q000187:drug effects; D055598:Chemical Phenomena; D002627:Chemistry, Physical; D003619:Dansyl Compounds / Q000008:administration & dosage / Q000494:pharmacology*; D004151:Dipeptides / Q000008:administration & dosage / Q000494:pharmacology*; D019835:FMRFamide; D007274:Injections, Intraperitoneal; D008055:Lipids; D008297:Male; D009020:Morphine / Q000037:antagonists & inhibitors*; D009479:Neuropeptides / Q000008:administration & dosage / Q000494:pharmacology*; D051381:Rats; D011919:Rats, Inbred Strains; D011930:Reaction Time / Q000187:drug effects
D003619:Dansyl Compounds; D004151:Dipeptides; D008055:Lipids; D009479:Neuropeptides; C061784:dansyl-arginyl-phenylalaninamide; D019835:FMRFamide; D009020:Morphine