ABSTRACT
Objective: To evaluate the effect of RBa-I, an extract of Rosa bracteata Wend1, against withdrawa1 syndrome in morphine-dependent rats and to explore its mechanism. Methods: The mode1 rats of morphine dependent were established. The scores of withdrawa1 syndrome,?-EP level in hypotha1amus and pituitary body were observed to evaluate the effect of RBa-I in rats. Results: RBa-I can antagonize the urging withdrawa1 syndrome in morphine-dependent rats (ora1ly, 5 mg?kg -1 ), and the effect was inferior to chlonidine (oral1y, 0.2 mg?kg -1 ). It can a1so antagonize the natural withdrawal syndrome, decrease the tota1 scores of withdrawa1 syndrome and inhibit the decreasing of body weight. After a seven-day treatment course, the tota1 scores of withdrawa1 syndrome were decreased remarkab1y. The content of ?-EP in hypotha1amus and pituitary body were increased. Conclusion: RBa-I can antagonize the withdrawa1 syndrome of morphine-dependent rats and this may be related to the increase of ?-EP level in hypothalamus and pituitary body in rats.