The Effects of Long Term Treatment with Withania somnifera on Cognitive Function

Graduate #31
Discipline: Biological Sciences
Subcategory: Plant Research

Shazia Ali - California State University, Los Angeles
Co-Author(s): Andrew Li, Jessy Martinez, Hoda Ahmed, Leticia Galvez, Amelia Russo-Neustadt, California State University, Los Angeles, CA

Withania somnifera is an adaptogenic herb that has been traditionally used in the Indian Ayurvedic medical system for thousands of years. It has been found to have many beneficial properties, such as promoting relaxation, improving muscle strength, and exhibiting neuroprotective characteristics. Previous studies have suggested that Withania somnifera protects the brain against neurodegeneration. We hypothesize that, during the course of aging, long-term treatment with Withania somnifera will improve the performance of older rats in cognitive/behavioral tasks, and will also increase the expression of genes associated with learning and memory. The novel object recognition test, which assesses recognition memory by distinguishing a novel object from a familiar one, was employed in our studies. Briefly, Sprague-Dawley rats were placed in an open field arena in the presence of two objects, one of which was novel after a 24-hour delay. Rats that were treated with Withania somnifera for fourteen months showed an increase in environmental engagement and higher discrimination index during the novel object recognition test. It was found that Withania somnifera treated rats had a mean discrimination index of 0.36 – 0.05, while the mean discrimination index of the control group was 0.12 – 0.03. A two-tailed unpaired t-test revealed a p-value of 0.0013. In order to assess the changes in gene expression during the course of the treatment, RTqPCR analysis of hippocampi from these animals were conducted. RNA was isolated from hippocampal using the RNeasy Kit (Qiagen) and cDNA was generated using the BioRad’s iScript cDNA synthesis kit. The resulting cDNA was used as a template to perform qPCR with the SYBR Green mix from Bio-Rad and an iCycler real-time PCR machine. Our analysis revealed an elevation in the expression of glutamate AMPA receptor 2 (about twice the number of transcript vs. control, p=0.015, n=8). These results suggest that long term Withania somnifera treatment preserves recognition memory and environmental exploration/engagement, and may also enhance gene expression associated with excitation/inhibition balance in the CNS.

Funder Acknowledgement(s): Funding for this research is provided by NSF grant# HRD-1463889.

Faculty Advisor: Amelia Russo-Neustadt, ARusson@exchange.calstatela.edu

Role: I was involved with conducting the behavioral assays, as well as the qRTPCR work. Additionally, I performed the statistical analysis of all of the experiments.