Anti-depressive effect of liquiritin on chronic stress depression in rats. [Chinese]

Abstract

Aim: To observe the effect of liquiritin on chronic stress depression in rats, and investigate the possible mechanism of its antidepressant-like effects. Methods: The experiment was conducted at Peking University Health Science Center from June to July in 2005. Seventy-two adult male SD rats were randomly assigned into six groups with 12 in each: control group, model group (stress+bidistilled water), fluoxetine group (stress+fluoxetine), and three liquiritin groups (stress +liquiritin) at the doses of 10, 20 and 40 mg/kg, respectively. The chronic stress duration and isolated breeding ran for 5 weeks, and the drug administrations were conducted from the third week. The fluoxertine hydrochloride was provided by Changzhou Siyao Pharmaceutical Company, while liquiritin came from Biotechnology Institute, School of Pharmaceutical Sciences, Peking University. The behavior of rats was detected by sucrose consumption test and forced swimming test. After experiments, all the rats were excised from brains to fetch blood samples and separate the plasm and erythrocyte. Then superoxide dismutase (SOD) activity and plasma malondialdehyde (MDA) level were assayed using special kits. Results: A total of 69 rats were involved in the result analysis, except one injury and two accidental deaths. 1 Compared with control rats, the stressed rats showed obvious reduction of sucrose consumption [(8.3+/-0.9), (14.4+/-0.8) g, P < 0.01], which was significantly increased after treatment [three liquiritin groups: (11.4+/-1.2), (14.1+/-1.0), (14.0+/-0.8) g; fluoxetine group: (13.0+/-1.9) g, P < 0.05 or 0.01]. 2 Compared with control group and treatment groups, the immobility time was markedly extended in model group [(37+/-9), (96+/-10) s, P < 0.01; three liquiritin groups: (66+/-10), (26 +/-8), (41+/-11) s; fluoxetine group: (63+/-8) g, P < 0.05 or 0.01]. 3 The erythrocyte SOD activity was lower in model group than in control group and liquiritin groups [(35.4+/-6.8), (44.5+/-4.6) mukat/g, P < 0.01; 20 mg/kg: (42.2+/-3.8) mukat/ g, P < 0.05; 40 mg/ kg: (45.3+/-7.9) mukat/g, P < 0.01]. There was insignificant difference in SOD activity between fluoxetine group and model group. 4 The plasma MDA level increased in model group as compared with control group [(3.4+/-0.6), (1.9+/-0.4) mumol/L, P < 0.01]; Liquiritin significantly decreased MDA level [20 mg/kg: (2.2+/-0.9) mumol/ L, P < 0.05; 40 mg/kg: (1.9+/-0.7) mumol/L, P < 0.01]. Conclusion: The treatment of liquiritin can effectively improve anhedonia symptom, confront the despair behavior in depression models, and is proved to possess antidepressant-like effect. Liquiritin can increase SOD activity, clear free radicals, inhibit lipid peroxidation, and lessen production of MDA, which may produce its antidepressant-like effects.