title: Changes in succinic dehydrogenase activity in the central nervous system of mice during morphine dependence development, withdrawal and naloxone treatment.
abstract: The possible role of succinic dehydrogenase (SD) in producing physical dependence to morphine by affecting tissue respiration was investigated in Swiss albino mice during the development of morphine tolerance through a period of addiction and naloxone withdrawal therapy. Tolerance and physical dependence were induced by injecting the mice with morphine sulfate subcutaneously at 8-hour intervals, increasing the dose from 10 mg/kg BW every 24 h for 15 days. The animals were considered to be addicted when they were able to tolerate an otherwise lethal dose of 150 mg/kg 3 times a day. Results indicated that succinic dehydrogenase was inhibited throughout the 15-day period of morphine administration and that this effect was greatest in tolerant animals. Increasing the dose and duration of treatment did not cause further decreases in enzyme activity; instead, after 15 days levels of enzyme activity increased in addicted animals compared with tolerant mice. Furthermore, morphine abstinence for 2 days, markedly increased the levels of SD activity, while 6 days of abstinence had little effect. Naloxone withdrawal at each stage was associated with increased SD activity, but the increase was significant only in tolerant mice.
mesh_terms: D000818:Animals; D001921:Brain / Q000201:enzymology*; D006801:Humans; D051379:Mice; D009021:Morphine Dependence / Q000201:enzymology*; D009270:Naloxone / Q000494:pharmacology*; D010084:Oxidation-Reduction; D013375:Substance Withdrawal Syndrome / Q000201:enzymology*; D013385:Succinate Dehydrogenase / Q000037:antagonists & inhibitors / Q000378:metabolism*; D013997:Time Factors
chemical_list: D009270:Naloxone; D013385:Succinate Dehydrogenase