Bilateral intranigral microinjection of morphine and opioid peptides produces antinociception in rats.
Bilateral intranigral microinjection of morphine produced dose-related and naloxone-reversible antinociceptive effects on the tail-flick and hot-plate tests. Intranigral injection of enkephalin had antinociceptive effects on both tests, and dynorphin had an antinociceptive effect on the hot-plate test. This is the first report of evidence that nigral opiate receptors may mediate antinociception.
D000818:Animals; D004399:Dynorphins / Q000031:analogs & derivatives / Q000494:pharmacology; D004723:Endorphins / Q000494:pharmacology; D004743:Enkephalin, Leucine / Q000031:analogs & derivatives / Q000494:pharmacology; D016308:Enkephalin, Leucine-2-Alanine; D004745:Enkephalins / Q000494:pharmacology*; D008297:Male; D008845:Microinjections; D009020:Morphine / Q000494:pharmacology*; D009270:Naloxone / Q000494:pharmacology; D010146:Pain / Q000503:physiopathology*; D010147:Pain Measurement; D051381:Rats; D011919:Rats, Inbred Strains; D011930:Reaction Time / Q000187:drug effects; D013378:Substantia Nigra / Q000187:drug effects* / Q000503:physiopathology
D004723:Endorphins; D004745:Enkephalins; D009270:Naloxone; D004743:Enkephalin, Leucine; D016308:Enkephalin, Leucine-2-Alanine; D004399:Dynorphins; D009020:Morphine; C036200:rimorphin