Comparison of the analgesic effects of various opioid peptides by a newly devised intracisternal injection technique in conscious mice.
To determine accurately the central analgesic effects of opioid peptides, we devised a special technique for intracisternal administration of drugs to conscious mice. When this method was utilized we found that a series of endogenous opioid peptides and enkephalin analogues, (D-Ala2,Met5)-enkephalinamide and (D-Met2,Pro5)-enkephalinamide produced dose-related analgesic effects, as determined by the tail pinch test. These effects were antagonized by pretreatment with naloxone 0.5 mg/kg s.c. This technique should be a most accurate one for the determination of central analgesic effects of various drugs in conscious mice.
D000818:Animals; D002946:Cisterna Magna; D004723:Endorphins / Q000008:administration & dosage / Q000494:pharmacology*; D004745:Enkephalins / Q000494:pharmacology*; D007278:Injections, Spinal / Q000379:methods; D008297:Male; D051379:Mice; D009020:Morphine / Q000494:pharmacology; D009043:Motor Activity / Q000187:drug effects; D009270:Naloxone / Q000494:pharmacology
D004723:Endorphins; D004745:Enkephalins; D009270:Naloxone; D009020:Morphine