AIM: To investigate inhibitory effect of tea pigment on withdrawal syndrome of morphine-
dependent mice and rats and analyze
its possible mechanism. METHODS: The experiment was completed in the Pharmacological Department of Dalian Medical University from March 2003 to March 2004. Totally 110 Kunming mice were divided randomly into normal control group (n=20), morphine-
dependent group (n=20), high, middle and low dosage of tea pigment groups (n=20) and levamisole positive control group (n=10);40 SD rats were divided randomly normal control group, morphine-dependent group, high and low dosage of tea pigment groups with 10 in each group. Morphine-dependent models of mice and rats were established with subcutaneous injection, respectively. Jumping times and latency of mice were measured within 10 minutes, and changes of body mass were compared 1 hour before and after jumping response. Immunological functions, activity of superoxide dismutase (SOD) and content of malondialdehyde (MDA) of mice were assayed, respectively. RESULTS: All mice and rats entered the final analysis. ① Results of withdrawal test: Jumping times of mice in high dosage group was less than those in morphine-dependent group (P < 0.05), and latency of jumping response was longer in high and middle dosage groups than that in morphine-dependent group (P < 0.05). After jumping response, body mass of mice in high dosage group was decreased remarkably (P < 0.05), and as compared with rats in morphine-dependent group, scores of withdrawal symptom in high and low dosage groups were decreased obviously, and also body mass in high dosage group. ② Results of immunological functions of mice in morphine-dependent group: As compared with those in morphine-dependent group, serum semi-hemolysis value in three dosage groups and levamisole group was
increased, and there was significantly different (P < 0.05); swelling value of feet induced by dinitrofluorobenzene was increased in three dosage groups and levamisole group (P < 0.01-0.05); index of thymus was increased in high dosage group and levamisole group (P < 0.05). ③ Assay of SOD activity and MDA content: As compared with those in normal control group, SOD activity of mice in morphine-dependent group was decreased, but MDA content was increased (P < 0.05). As compared with those in morphine-dependent group, SOD activity of mice in high dosage group was increased remarkably, and SOD activity in serum of mice in middle dosage group was also increased, but there was not significantly different. MDA content was decreased in high and middle groups (P < 0.05), but the decrease in low dosage group was not significant. CONCLUSION: Tea pigment has obvious drug-abstinent effect on morphine-dependent mice and rats, and the effect may be related to its immune improvement and antioxidant ability.