Opioid receptor sub-types involved in the control of transmitter release in cortex of the brain of the rat.
Electrical stimulation (3 Hz, 2 msec duration, 5-12 V for 2 min every 20 min) of cortical slices from the rat, previously incubated with [3H]noradrenaline, evoked a release of tritium which was inhibited by morphine, normorphine, Tyr-D-Ala-Gly-MePhe-NH(CH2) 2OH ( RX783006 ) and D-Ala2-D-Leu5-enkephalin ( pIC30 5.90, 6.32, 7.45 and 6.74 respectively). Naloxone did not affect the release of tritium when given alone but antagonised the actions of the opioids, giving a Ke value of about 3 nM irrespective of the particular agonist used, which suggests an action at mu receptors. The delta opioid receptor blocker, ICI154129 , antagonised the opioids only in large concentrations (Ke 21300 nM). In slices previously incubated with [3H]5-hydroxytryptamine, electrical stimulation increased overflow of tritium but neither naloxone nor the opioid agonists affected evoked overflow of tritium at concentrations which were effective in slices incubated with [3H]noradrenaline. It is concluded that stimulation of mu opioid receptors may inhibit release of noradrenaline from central noradrenergic neurones and that these receptors are not present in significant numbers on neurones releasing 5-hydroxytryptamine in the cortex.
D000818:Animals; D002540:Cerebral Cortex / Q000378:metabolism*; D002997:Clomipramine / Q000494:pharmacology; D004492:Edetic Acid / Q000494:pharmacology; D020875:Enkephalin, Ala(2)-MePhe(4)-Gly(5)-; D004743:Enkephalin, Leucine / Q000031:analogs & derivatives / Q000494:pharmacology; D016308:Enkephalin, Leucine-2-Alanine; D004958:Estradiol / Q000494:pharmacology; D066298:In Vitro Techniques; D008297:Male; D009020:Morphine / Q000494:pharmacology; D009022:Morphine Derivatives / Q000494:pharmacology; D009270:Naloxone / Q000494:pharmacology; D009294:Narcotics / Q000494:pharmacology; D018377:Neurotransmitter Agents / Q000378:metabolism*; D009638:Norepinephrine / Q000494:pharmacology; D010446:Peptide Fragments / Q000494:pharmacology; D051381:Rats; D011919:Rats, Inbred Strains; D011957:Receptors, Opioid / Q000145:classification / Q000187:drug effects*; D012701:Serotonin / Q000378:metabolism; D008083:beta-Lipotropin / Q000494:pharmacology
D009022:Morphine Derivatives; D009294:Narcotics; D018377:Neurotransmitter Agents; D010446:Peptide Fragments; D011957:Receptors, Opioid; D020875:Enkephalin, Ala(2)-MePhe(4)-Gly(5)-; D012701:Serotonin; D009270:Naloxone; D004958:Estradiol; D004743:Enkephalin, Leucine; D016308:Enkephalin, Leucine-2-Alanine; D009020:Morphine; D008083:beta-Lipotropin; C036405:ICI 154129; D004492:Edetic Acid; D002997:Clomipramine; D009638:Norepinephrine; C010616:normorphine