Effects of ultrarapid opiate detoxification during general anesthesia on plasma morphine concentration and brain ?-endorphin content in rats addicted to morphine / 中华麻醉学杂志

ABSTRACT

Objective To investigate the effects of ultrarapid opiate detoxification during general anesthesia on the plasma morphine concentration and brain ?-endorphin content in rats addicted to morphine. Methods Ninety male Wistar rats aged 12-15 weeks weighing 180-220 g were randomized into 6 groups group I normal animal ( n = 5); group II morphine addiction ( n = 5); group III natural withdrawal ( n = 20); group IV general anesthesia ( n = 20); group V general anesthesia + naloxone ( n = 20) and group VI clonidine pretreatment ( n = 20). Morphine addiction was induced by subcutaneous injection of increasing doses of morphine sulphate for 5 days (5, 10, 20, 40 and 50 mg? kg-1 t.i.d. ? 5 days) . Morphine detoxification was started on the 6th day. General anesthesia was induced and maintained with ?-OH and midazolam i.m. supplemented with intermittent isoflurane inhalation to maintain loss of righting reflex. Spontaneous breathing was kept during general anesthesia. In group V naloxone 0.05, 0.1 and 0.2 mg was injected subcutaneously at 5, 30 and 60 min after loss of righting reflex. Successful detoxification was defined as no withdrawal symptoms after subcutaneous injection of naloxone 0.1 mg. In group VI clonidine 0.05 mg ? kg-1 was given i. v. 1 hour before induction of anesthesia. Blood samples and brain tissue were obtained before detoxification in group I (normal animal) and II (morphine addiction) while in the other 4 groups they were obtained immediately and 1,2,3 day after detoxification.Results The plasma morphine concentration was 224 ? 164 ng?ml-1 in group II (morphine addiction), significantly higher than in all the detoxification groups ( P V ) (P