Effects of honokiol and magnolol on beta-endorphin in relieving morphine withdrawal symptoms in rats

Debin HUANG; Zhaofen YU; Quanwen LI

ABSTRACT

BACKGROUND:

It has been verified pharmacologically that honokiol (HL) and magnolol (ML) have distinct effects on central inhibition and muscle relaxation, and some reports prove that they can relieve morphine withdrawal symptoms in animals.

OBJECTIVE:

To explore the effects of HL and ML on β-endorphin (β-EP) in relieving morphine withdrawal symptoms in rats.

DESIGN:

Randomized controlled study.

SETTING:

Pharmacological Department, the Medical School of Hubei national College.

PARTICIPANTS:

The experiment was conducted from 13 to 29 April,2003. Among 100 adult male SD rats, 30 rats as control group were randomly divided into three subgroups saline group, HL group and ML group with 10 in each group. The other 70 rats as morphine-dependent group were divided into normal saline group, 5, 40 and 80 mg/kg HL and ML groups with 10 in each group.

METHODS:

0.2 mL normal saline, 80 mg/kg HL and 80 mg/kg ML were injected intraperitoneally into rats in control group. The dose of morphine subcutaneously injected was increased in the rats in morphine-dependent group for 6 days to establish the model of acute morphine dependence and model of natural morphine withdrawal symptoms. The last injection was performed at 900 on the morning of day 6, and the intraperitoneal injection was performed at 1030 on the same morning. 0.2 mL normal saline was injected into the rats of saline group. 5, 40 and 80 mg/kg HL and 5,40 and 80 mg/kg ML were given to rats in the other six groups, respectively. Starting from 1100, half an hour later, all natural morphine withdrawal symptoms were observed in rats within an hour.compared among rats in the 7 morphine-dependent subgroups.control groups than in normal saline group (P ＜ 0.01), and HL group had higher β-EP level than ML group (P ＜ 0.05). β-EP level was obviously lower in morphine-dependent+saline groups than in control+saline groups (P ＜ 0.01).β-EP level in morphine-dependent+5, 40 and 80 mg/kg HL groups and in morphine-dependent+5, 40 and 80 mg/kg ML groups was obviously higher Scores of natural morphine withdrawal symptoms in rats of morphine-dependent group Scores of wetshakes, penile licking, escape attempts, and weight lost in HL and ML subgroups were obviously lower than those in saline group (P ＜ 0.01).

CONCLUSION:

HL and ML can markedly restrain morphine withdrawal symptoms and this restraint is related to the increase of β-EP level in the brain. HL and ML have equal inhibitory effects on morphine-dependent rats, but HL is more effective than ML in normal rats.