Effects of puerarin on learning-memory and amino acid transmitters of brain in ovariectomized mice

In the present study, the protective effects of puerarin (Pur) on learning and memory in ovariectomized mice were investigated. One week after ovariectomy (Ovx) or sham operation, female mice were given a 4-week treatment of Pur (50 or 100 mg/kg, i.p.) or estradiol benzoate (EB, I or 5 mug/day, i.p.). The results showed that, following treatment with 50 or 100 mg/kg Pur in Ovx mice, the training times for achieved learning criterion in a Y-maze declined by 11.8% and 17.8% (P > 0.05 and P < 0.05), and that memory retention increased by 23.3% and 28.3% (P < 0.05 and P < 0.05), respectively. In addition, the prolonged escape latency of platform finding in a water maze was shortened by 15.5% and 23.8% (P < 0.05 and P < 0.05). After a behavior test, the levels of glutamate (Glu) and GABA in the frontal cortex and hippocampus were assessed using high-performance liquid chromatography (HPLC). The results showed that 100 mg/kg Pur normalized the levels of Glu and GABA in the hippocampus of Ovx mice, while the Glu level was significantly elevated from 24.1 +/- 4.5 to 27.9 +/- 3.5 mg/g protein (P < 0.05), and GABA was decreased from 5.64 +/- 1.06 to 4.73 +/- 0.85 mg/g protein (P < 0.05). The results indicated that Pur possessed phytoestrogen activity, and long-term treatment of Pur ameliorated learning and memory deficits of Ovx mice through affecting the activity of the glutamatergic/GABAergic system in the hippocampus.