Neuroprotective effect of Asparagus racemosus root extract via the enhancement of brain-derived neurotrophic factor and estrogen receptor in ovariectomized rats

Ethnopharmacological relevance: Asparagus racemosus (AR) is well known as an Ayurvedic rasayana which used traditionally by Ayurvedic practitioners for nervous disorders and prevent aging. In our previous study it was found that ethanol AR root extract can improve learning and memory impairment, induced by an ovariectomy, but the extract's mechanisms as a neuroprotective property are still unknown. Aim of the study: This study aimed to examine the effects and mechanisms of ethanol AR root extract on the alteration of brain-derived neurotrophic factor (BDNF) and estrogen receptor (ER) subtypes in ovariectomized (OVX) rats. Materials and methods: Adult female Wistar rats were divided into five groups, 4 groups underwent ovariectomy, and one group was designed to be the sham control group. Two groups were gavaged with propylene glycol for sham, and a second group similarly prepared for OVX. Two further groups of OVX rats were gavaged once daily, one group with 100 mg/kg b.w. of ethanol AR root extract and the second group with 1000 mg/kg b.w. of ethanol AR root extract. The fifth group was gavaged once daily with 0.1 mg/kg b.w. of 17 alpha-ethynylestradiol (EE). BDNF, ER alpha and ER beta expression were evaluated by western blot analysis. Results: The western blot analysis revealed that the OVX rats showed a significant decrease in BDNF and a down regulation of ERa and ERI3 in the frontal cortex and hippocampus. It was also demonstrated that EE and AR root extract increased BDNF, ERa and ER13 in the frontal cortex and hippocampus of ovariectomized rats. Conclusions: Based on these results, the enhancement of BDNF and ERs up-regulation may be involved in the neuroprotective effects of ethanol AR root extract in ovariectomized rat.