ABSTRACT
Adult rats chronic unpredictable stress model of depression (CUS) was adopted to elucidate the antidepressant pharmacological activity and related neurogenesis protective effect of the total flavonoids extract (licorice flavonoids, LF) from the Glycyrrhiza uralensis Fisch. cultivated locally in Ningxia. The rats were exposed to 9 kinds of unpredictable sequence of stressors and were given flavonoids (300 mg x kg(-1), 100 mg x kg(-1) and 30 mg x kg(-1)) for 28 days. The antidepressant effect was elucidated by open field test, forced swimming test and tail suspension test. The level of serum corticosterone was detected by radioimmunoassay. 5'-Bromo-2'-deoxyuridine (BrdU) labeling experiments was employed to study the neurogenesis protective activities. The flavonoids can increase the sum of line crosses and number of rears, and decrease the number of fecal boli produced in the open field test of the CUS rats. Also the flavonoids can decrease the immobility time in forced swim test as well as in the tail suspension test. In addition, the flavonoids (300 mg x kg(-1)) can decrease the serum corticosterone level of the CUS rats, and increase the number of the new born BrdU positive progenitor cells at the subgranular zone (SGZ) of dentate gyrus (DG) region in hippocampus. The results demonstrated that the total flavonoids extract from the cultivated Glycyrrhiza uralensis Fisch. could produce the anti-depressive effect on chronic unpredictable stress of depression model rats and its mechanism may be associated with its neurogenesis protective effect.