Ashwagandha and Its Active Ingredient, Withanolide A, Increase Activation of the Phosphatidylinositol 3’ Kinase/Akt Cascade in Hippocampal Neurons
Dahae Hwang
Department of Biological Sciences, California State University, Los Angeles, 5151 State University Dr., Los Angeles, CA 90032, USA
Isabel Vasquez
Department of Biological Sciences, California State University, Los Angeles, 5151 State University Dr., Los Angeles, CA 90032, USA
Leticia Galvez
Department of Biological Sciences, California State University, Los Angeles, 5151 State University Dr., Los Angeles, CA 90032, USA
Huong Do
Department of Biological Sciences, California State University, Los Angeles, 5151 State University Dr., Los Angeles, CA 90032, USA
Anthony Lopez de Santa Ana
Department of Chemistry and Biochemistry, California State University, Los Angeles, 5151 State University Dr., Los Angeles, CA 90032, USA
Shane Matta
Department of Chemistry and Biochemistry, California State University, Los Angeles, 5151 State University Dr., Los Angeles, CA 90032, USA
Feimeng Zhou
Department of Chemistry and Biochemistry, California State University, Los Angeles, 5151 State University Dr., Los Angeles, CA 90032, USA
Michael Chen *
Department of Biological Sciences, California State University, Los Angeles, 5151 State University Dr., Los Angeles, CA 90032, USA
Amelia Russo-Neustadt
Department of Biological Sciences, California State University, Los Angeles, 5151 State University Dr., Los Angeles, CA 90032, USA
*Author to whom correspondence should be addressed.
Abstract
Aims: To determine if whether, in a hippocampal neuron culture model subjected to nutrient deprivation stress (simulating degenerative disease state), Ashwagandha and/or two of its putative active ingredients, withanolide A or withaferin A, affect any of the following: neurite outgrowth, neuronal survival, activation of the pro-survival PI-3K/Akt and MAPK cascades, phosphorylation of CREB and expression of brain-derived neurotrophic factor (BDNF).
Study Design: To primary rat embryonic hippocampal neurons in culture, half of which were subjected to nutrient deprivation stress, inhibitors of the PI-3K/Akt and MAPK cascade (LY294002 and PD98059, respectively) were applied, followed by Ashwagandha, withanolide A or withaferin A.
Methodology: Neuronal survival was determined by using fluorescently labeled markers for live vs dead cells and by lactate dehydrogenase assay. Average neurite length was measured under phase-contrast microscopy. And intracellular signal transduction activity was determined by Western blotting.
Results: Ashwagandha increased average neurite length. Ashwagandha, withanolide A and withaferin A all increased neuron survival in nutrient deprived conditions. Ashwagandha and withanolide A increased phosphorylation of Akt, but not MAPK, in both nutrient-adequate and nutrient-deprived conditions. Withaferin A increased BDNF expression under nutrient-deprived conditions, but decreased BDNF expression under adequate nutrient conditions; withaferin A still activated Akt under both types of nutrient conditions.
Conclusion: Using our model of nutrient deprivation stress, we showed that withaferin A helps cells adapt to stressful conditions, such as by increasing expression of BDNF, while withanolide A, continues to maintain cell survival and neural protection by increasing baseline levels of PI-3K/Akt. Our results are in agreement with extant literature on the effects of Ashwagandha or withaferin A on disease, such as cancer.
Keywords: Ashwagandha, ayurveda, depression, stress, signal transduction, hippocampal neurons