Comparison of the dose-response effects of morphine on brain amines, analgesia and activity in mice.
1. Noradrenaline, dopamine, 5-hydroxytryptamine and 5-hydroxyindoleacetic acid concentrations in the mouse brain were measured 30 min after subcutaneous injection of doses of morphine ranging from 0.1 to 100 mg/kg: motor activity was also measured.2. The noradrenaline concentration in the mouse brain was reduced by moderate (2 to 20 mg/kg) but not by high (above 20 mg/kg) and low (below 2 mg/kg) doses of morphine.3. The dopamine concentration in the mouse brain was reduced by moderate (1 to 20 mg/kg) doses but was raised by high doses (above 20 mg/kg) of morphine.4. The 5-hydroxytryptamine concentration in the mouse brain was reduced by moderate (1 to 20 mg/kg) doses of morphine but not by high (above 20 mg/kg) and low (below 1 mg/kg) doses of morphine.5. The 5-hydroxyindoleacetic acid concentration was not affected by low doses (0.1 to 2 mg/kg), raised by a dose of 5 mg/kg, lowered by doses of 10-50 mg/kg and not affected by 100 mg/kg of morphine.6. These results are discussed with reference to the possible implication of changes in monoamines for the analgesic and behavioural effects of morphine.
D000588:Amines / Q000032:analysis*; D000698:Analgesia; D000818:Animals; D001921:Brain / Q000187:drug effects; D001923:Brain Chemistry / Q000187:drug effects*; D004298:Dopamine / Q000032:analysis; D005260:Female; D006897:Hydroxyindoleacetic Acid / Q000032:analysis; D007279:Injections, Subcutaneous; D008297:Male; D051379:Mice; D009020:Morphine / Q000008:administration & dosage*; D009043:Motor Activity / Q000187:drug effects*; D009638:Norepinephrine / Q000032:analysis; D012701:Serotonin / Q000032:analysis
D000588:Amines; D012701:Serotonin; D006897:Hydroxyindoleacetic Acid; D009020:Morphine; D004298:Dopamine; D009638:Norepinephrine