Tolerance to morphine-induced calcium depletion in regional brain areas: characterization with reserpine and protein synthesis inhibitors.
1 Administration of a single dose of morphine sulphate (25 mg/kg) induces tolerance to calcium depletion lasting seven days. 2 There are no apparent changes in calcium content in any of eight discrete brain regions throughout this seven day period. 3 Pretreatment with reserpine (5 mg/kg) did not alter the ability of morphine to induce tolerance. Reserpine alone produced no tolerance to its own calcium depleting action. 4 Cycloheximide (500 mug/kg) but not chloramphenicol (200 mg/kg) effectively prevented development of tolerance. 5 It is concluded that the induction of tolerance to calcium depletion seen after morphine may involve changes in various proteins in membranes of synaptic origin.
D000818:Animals; D001921:Brain / Q000187:drug effects / Q000378:metabolism*; D002118:Calcium / Q000378:metabolism*; D002701:Chloramphenicol / Q000494:pharmacology*; D003513:Cycloheximide / Q000494:pharmacology*; D004361:Drug Tolerance; D008297:Male; D009020:Morphine / Q000494:pharmacology*; D051381:Rats; D012110:Reserpine / Q000494:pharmacology*; D013997:Time Factors
D002701:Chloramphenicol; D009020:Morphine; D012110:Reserpine; D003513:Cycloheximide; D002118:Calcium