First, a little background derived from wikipedia. Withania somnifera, also known as Ashwagandha, Indian ginseng, Winter cherry, Ajagandha, Kanaje Hindi, Amukkuram in Malayalam and Samm Al Ferakh, is a plant in Solanaceae or nightshade family. It grows as a stout shrub that reaches a height of 170 cm (5.6 ft). In Ayurveda ashwagandha is considered a rasayana herb. This herb is also considered an adaptogen which is an herb that works to normalize physiological function, working on the HPA axis and the neuroendocrine system.
Although I'm starting this thread to discuss relevant neuroprotective effects of Withania somnifera, it is important to note that Withania somnifera is also cited as having:
- Valuable Anti-oxidant effects
- Valuable Anti-Inflammatory effects
- Tumor fighting properties
Neuroprotection:
Withania somnifera falls into what I would consider two different areas of neruoprotective functioning. It has been cited to inhibit anxiety in various different diseases. It has also been cited to neuronal regrowth.
To start with here are a few pieces of research done on anxiety inhibition.
From: Pub Med
Naturopathic care for anxiety: a randomized controlled trial ISRCTN78958974.
Cooley K, Szczurko O, Perri D, Mills EJ, Bernhardt B, Zhou Q, Seely D.
Department of Research and Clinical Epidemiology, The Canadian College of Naturopathic Medicine, Toronto, Canada. kcooley@ccnm.edu
Abstract
BACKGROUND: Anxiety is a serious personal health condition and represents a substantial burden to overall quality of life. Additionally anxiety disorders represent a significant cost to the health care system as well as employers through benefits coverage and days missed due to incapacity. This study sought to explore the effectiveness of naturopathic care on anxiety symptoms using a randomized trial. METHODS: Employees with moderate to severe anxiety of longer than 6 weeks duration were randomized based on age and gender to receive naturopathic care (NC) (n = 41) or standardized psychotherapy intervention (PT) (n = 40) over a period of 12 weeks. Blinding of investigators and participants during randomization and allocation was maintained. Participants in the NC group received dietary counseling, deep breathing relaxation techniques, a standard multi-vitamin, and the herbal medicine, ashwagandha (Withania somnifera) (300 mg b.i.d. standardized to 1.5% with anolides, prepared from root). The PT intervention received psychotherapy, and matched deep breathing relaxation techniques, and placebo. The primary outcome measure was the Beck Anxiety Inventory (BAI) and secondary outcome measures included the Short Form 36 (SF-36), Fatigue Symptom Inventory (FSI), and Measure Yourself Medical Outcomes Profile (MY-MOP) to measure anxiety, mental health, and quality of life respectively. Participants were blinded to the placebo-controlled intervention. RESULTS: Seventy-five participants (93%) were followed for 8 or more weeks on the trial. Final BAI scores decreased by 56.5% (p<0.0001) in the NC group and 30.5% (p<0.0001) in the PT group. BAI group scores were significantly decreased in the NC group compared to PT group (p = 0.003). Significant differences between groups were also observed in mental health, concentration, fatigue, social functioning, vitality, and overall quality of life with the NC group exhibiting greater clinical benefit. No serious adverse reactions were observed in either group. RELEVANCE: Many patients seek alternatives and/or complementary care to conventional anxiety treatments. To date, no study has evaluated the potential of a naturopathic treatment protocol to effectively treat anxiety. Knowledge of the efficacy, safety or risk of natural health products, and naturopathic treatments is important for physicians and the public in order to make informed decisions. INTERPRETATION: Both NC and PT led to significant improvements in patients' anxiety. Group comparison demonstrated a significant decrease in anxiety levels in the NC group over the PT group. Significant improvements in secondary quality of life measures were also observed in the NC group as compared to PT. The whole system of naturopathic care for anxiety needs to be investigated further including a closer examination of the individual components within the context of their additive effect.
In summary, this study took a group of people who suffered from anxiety, randomly divided the group, administered dietary counseling, deep breathing relaxation techniques, a multi vitamin, and withania somnifera (300mg) (WS) to half the group and gave the other half the same minus the WS. After 8 weeks the test groups Beck Anxiety Inventory scores had decreased by 56.5% and the control groups had decrease by 30.5%. With these results two things become obvious, proper diet and stress therapy are capable of reducing anxiety by a significant amount on their own; and WS is capable of controlling anxiety in individuals by a significant amount.
From Pub Med:
Neuroprotective effects of Withania somnifera dunal.: A possible mechanism.
Bhatnagar M, Sharma D, Salvi M.
M.L. Sukhadia University, Udaipur, India. m.maheep@gmail.com
Abstract
Present study was carried out to understand the possible mechanism of neuroprotective action of the root extract of Withania somnifera Dunal (WS). The study is focused on WS mediated inhibition of nitric oxide production, which is known to mediate neurodegeneration during stress. Adult mice (28 +/- 5 g) were exposed to restraint stress for 30 days. Activity of NADPH diaphorase (NADPH-d) and factors (Acetylcholine, serotonin and corticosterone), which regulates NADPH-d activity were studied. Treatment with WS extract for 30 days during stress, significantly reversed the stress induced NADPH-d activation. Observations suggest that inhibition of NADPH-d by WS is not a direct effect of extract on NADPH-d, instead it inhibits via suppressing corticosterone release and activating cholineacetyltransferase, which in turn increase serotonin level in hippocampus to inhibit NADPH-d. Together, the main mechanism underlying the neuroprotective effects of WS can be attributed to its role in the down regulation of nNOS and neurochemical alterations of specific neurotransmitter systems. These observations thus suggest that WS root extract could be developed as a potential preventive or therapeutic drug for stress induced neurological disorders.
In summary, this research studied mice who were exposed to stress induced by restraint. It was observed that administration of WS inhibit nitric oxide production during times of stress via suppression of corticosterone release and activation of choline acetyltransferase (wiki).
Treatment of Neurogenerative Diseases:
From Pub Med:
J Ethnopharmacol. 2009 Sep 25;125(3):369-73. Epub 2009 Aug 8.
Withania somnifera root extract improves catecholamines and physiological abnormalities seen in a Parkinson's disease model mouse.
RajaSankar S, Manivasagam T, Sankar V, Prakash S, Muthusamy R, Krishnamurti A, Surendran S.
Department of Anatomy, Annamalai University, Tamilnadu, India.
Abstract
ETHNOPHARMACOLOGICAL RELEVANCE: Withania somnifera root extract (Ws)/Ashwagandha/Indian ginseng is a traditional herbal medicine, used over 4000 years in India, shown to have effect on neural growth and locomotor function. Although catecholamines and oxidative stress resulting in neurodegeneration and locomotor disorder are the main events in Parkinson's disease (PD), efficacy of the drug on these molecules and physiological abnormality are not clear. AIM OF THE STUDY: The objective of the study was to examine effect of Ws on catecholamines and physiological abnormalities seen in PD using PD model mouse. MATERIALS AND METHODS: Mouse were treated with 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP) for 4 days to show biochemical and physiological abnormalities similar to patients with PD. PD mice were treated with Ws 100mg/kg body weight for 7 or 28 days. Catecholamines: dopamine (DA), 3,4-dihydroxy-phenylacetic acid (DOPAC) and homovanillic acid (HVA); antioxidants: glutathione (GSH) and glutathione peroxidase (GPx); and lipid peroxidation marker (TBARS) were analyzed in the Ws treated and untreated PD mouse striatum. RESULTS: Mouse treated with MPTP showed reduced levels of DA, DOPAC, HVA, GSH and GPx and induced thiobarbituric acid reactive substance (TBARS) level compared to the control. Physiological abnormalities were seen in the mouse as determined by hang test and rotarod test. Oral treatment of PD mouse Ws root extract (100mg/kg body weight) for 7 days or 28 days increased DA, DOPAC and HVA levels and normalized TBARS levels in the corpus striatum of the PD mouse. The 7 days Ws treated mice showed improved motor function as determined by hang test and rotarod test. Treatment with Ws for 28 days increased GSH and GPx levels in the striatum compared to the Ws untreated PD mouse striatum. CONCLUSION: These data suggest that Ws is a potential drug in treating catecholamines, oxidative damage and physiological abnormalities seen in the PD mouse.
In summary, this research induced Parkinson's Disease on a group of mice and administered WS. After administration of the MPTP (PD emulator) mice showed reduced levels of dopamine (DA), 3,4-dihydroxy-phenylacetic acid (DOPAC) and homovanillic acid (HVA), glutathione (GSH) and glutathione peroxidase (GPx) and the group also showed signs of decreased motor function and physiological abnormalities. After administration of WS for 7 days the mice showed increased levels of DA, DOPAC, HVA and normalized TBARS levels. After 28 days of treatment GSH and GPx levels increased as well. This shows significant promised for treatment of Parkinson's as WS appears to positively affect all negative aspects of Parkinson's effects.
This next study is similar to the previous study but I'm incorporating it because the abstract is written in plain english.
From Pub Med:
Neurosci Lett. 2009 Apr 17;454(1):11-5. Epub 2009 Feb 26.
Ashwagandha leaf extract: a potential agent in treating oxidative damage and physiological abnormalities seen in a mouse model of Parkinson's disease.
Rajasankar S, Manivasagam T, Surendran S.
Department of Anatomy, Melmaruvathur Adhi Parasakthi Institute of Medical Sciences, Tamil Nadu, India.
Abstract
Parkinson's disease (PD) is a neurodegenerative disorder that leads to impairment of balance and coordination. Therapy for the disease is still under investigation. Withania somnifera (A-Extract), a herbal medicine, has been known for a spectrum of health-promoting effects including activation of immune, muscle and neuronal systems. Therefore effect of A-Extract in the mouse model of PD was examined. The midbrain and corpus striatum of PD mouse showed increased levels of superoxide dismutase, catalase and malondialdehyde; and reduced levels of glutathione and glutathione peroxidase compared to the control. Treatment with A-Extract 100mg/kg for 7 days significantly improved all these enzyme levels compared to A-Extract untreated PD mouse brain. In the PD mouse grooming, stride length, movement, rearing were found to be decreased compared to the control. In addition, narrow beam walk and foot slippery errors were increased. Treatment with A-Extract improved all these physiological abnormalities. These data suggests that A-Extract is a potential drug in treating oxidative damage and physiological abnormalities seen in the PD mouse, if documented also in patients with PD.
This study is interesting to me because it makes use of an extract derived from a different part of the WS plant, the leaves. Most WS extract is made from the root of the plant. This study surmises the same as the previous study but investigates dismutase, catalase and malondialdehyde levels.
From Pub Med:
J Med Food. 2009 Jun;12(3):591-600.
Possible neuroprotective effect of Withania somnifera root extract against 3-nitropropionic acid-induced behavioral, biochemical, and mitochondrial dysfunction in an animal model of Huntington's disease.
Kumar P, Kumar A.
University Institute of Pharmaceutical Sciences, Panjab University, Chandigarh, India.
Abstract
Huntington's disease (HD) is a neurodegenerative disorder that results from the destruction of neurons in the basal ganglia, and oxidative stress has been implicated in its pathogenesis. 3-Nitropropionic acid (3-NP), a potent neurotoxin, has been reported to induce oxidative/nitrosative stress and causes neurobehavioral and biochemical changes that mimic HD in humans. It also inhibits complex II of the mitochondrial electron transport chain, thereby causing cellular energy deficit. In the present work, we evaluated the effects of a well-known antioxidant on behavioral, biochemical, and mitochondrial dysfunction induced by 3-NP. The study was designed to investigate the effects of Withania somnifera root extract against 3-NP-induced gait abnormalities, oxidative stress, and mitochondrial dysfunction in striatum and cortex of rat brain. Intraperitoneal administration of 3-NP (10 mg/kg for 14 days) caused a loss in body weight and a decline in motor function (locomotor activity and impaired rotarod activity). Chronic treatment with W. somnifera root extracts (100 and 200 mg/kg) for a period of 2 weeks dose-dependently improved 3-NP-induced behavioral, biochemical, and enzymatic changes (P < .05). Biochemical analysis revealed that systemic 3-NP administration significantly increased lipid peroxidation and nitrite and lactate dehydrogenase enzyme levels, depleted antioxidant enzyme (superoxide dismutase and catalase) levels, and blocked ATP synthesis by inhibiting the mitochondrial complex activity in the different regions (striatum and cortex) of the brain. Chronic administration of W. somnifera root extract (100 and 200 mg/kg) dose-dependently restored biochemical alterations induced by chronic 3-NP treatment (P < .05). These findings suggest that neuroprotective actions of W. somnifera are mediated via its antioxidant activity. However, further studies are required to elucidate the molecular mechanisms involved in order to support the clinical use of the plant extract as a therapeutic agent for the treatment of HD.
This study links the benefits of WS to it's potent anti-oxidant activity, like so many others do. There are quite a few studies that cite WS as a potent treatment for oxidative stress in other regions of the body. Unfortunately, very few studies attempt to understand the mechanism of action behind WS beyond this level.
Neural Regrowth:
These were the only two studies I found for suggesting WS has an effect on neural regrowth. The first study is very comprehensive and covers a good number of the active constituents of WS and is also free online...if you can read Japanese. The second study is about WS's effect on the neutrophic factor receptor RET.
From Pub Med:
[Overcoming several neurodegenerative diseases by traditional medicines: the development of therapeutic medicines and unraveling pathophysiological mechanisms]
[Article in Japanese]
Tohda C.
Division of Biofunctional Evaluation, Research Center for Ethnomedicine, Insitute of Natural Medicine, University of Toyama, Toyama City, Japan. chihiro@inm.u-toyama.ac.jp
Abstract
Ashwagandha (root of Withania somnifera) has been used for many purposes, it is mainly considered a tonic in traditional Ayurvedic medicine. This review focuses on the effects of compounds isolated from Ashwagandha on dementia models and on the spinal cord injury model. Our study demonstrated that the active constituents, withanolide A, withanoside IV, and withanoside VI, restored presynapses and postsynapses, in addition to both axons and dendrites in cortical neurons after Abeta(25-35)-induced injury. In vivo, oral withanolide A, withanoside IV, and withanoside VI (10 micromol/kg/day for 12 days) improved Abeta(25-35)-induced memory impairment, neurite atrophy, and synaptic loss in the cerebral cortex and hippocampus in mice. Since spinal cord injury (SCI) is also difficult to treat, and therefore practical and curable strategies for SCI are desired. Oral treatment with withanoside IV improved locomotor functions in mice with SCI. In mice treated with withanoside IV (10 micromol/kg/day for 21 days), the axonal density and peripheral nervous system myelin level increased. The loss of CNS myelin and increase in reactive gliosis were not affected by withanoside IV. Additionally, sominone, an aglycone of withanoside IV, was identified as the main metabolite after oral administration of withanoside IV in mice. Withanolide A, withanoside IV, and withanoside VI are therefore important candidates for the therapeutic treatment of neurodegenerative diseases. In particular, withanoside IV was shown to control neurons as well as glial cells for reconstruction neuronal networks. To clarify key events in overcoming neurodegeneration, we are now studying the molecular targets and signal cascades of sominone.
This abstract is a pretty straightforward read so I'll spare myself the pain of summary. One thing to take away from this is the discussion of sominone which is the constituent under inspection in the next abstract.
From Pub Med:
Br J Pharmacol. 2009 Aug;157(8):1427-40. Epub 2009 Jul 8.
Sominone enhances neurite outgrowth and spatial memory mediated by the neurotrophic factor receptor, RET.
Tohda C, Joyashiki E.
Division of Biofunctional Evaluation, Research Center for Ethnomedicine, Institute of Natural Medicine, University of Toyama, Toyama, Japan. chihiro@inm.u-toyama.ac.jp
Abstract
BACKGROUND AND PURPOSE: Orally administered withanoside IV (a compound isolated from the roots of Withania somnifera) improved memory deficits in mice with a model of Alzheimer's disease induced by the amyloid peptide Abeta(25-35). Sominone, an aglycone of withanoside IV, was identified as an active metabolite after oral administration of withanoside IV. We aimed to identify receptors or associated molecules of sominone, and to investigate the effects of sominone on memory in normal mice. EXPERIMENTAL APPROACH: Phosphorylation levels of 71 molecules were compared between control and sominone-stimulated cortical cultured cells to search for target molecules of sominone. Object location memory and neurite density in the brain were evaluated in sominone-injected mice. KEY RESULTS: Phosphorylation of RET (a receptor for the glial cell line-derived neurotrophic factor, GDNF) was increased in neurons by sominone, without affecting the synthesis and secretion of GDNF. Knockdown of RET prevented sominone-induced outgrowths of axons and dendrites. After a single i.p. injection of sominone into normal mice, they could better memorize scenery information than control mice. Sixty minutes after sominone injection, RET phosphorylation was increased, particularly in the hippocampus of mice. After the memory tests, the densities of axons and dendrites were increased in the hippocampus by sominone administration. CONCLUSIONS AND IMPLICATIONS: Sominone could reinforce the morphological plasticity of neurons by activation of the RET pathway and thus enhance memory. Sominone, a compound with low molecular weight, may be a GDNF-independent stimulator of the RET pathway and/or a novel modulator of RET signalling.
This was probably the most interesting study to me as it might point to a GDNF-independent (wiki) stimulator of the RET pathway. GDNF possibly promotes the survival and growth of many neurons through RET signaling.
I'm kicking off this thread after reading about many people's stack that include WS without ever really citing and research as to why they take it. I also notice that many people take WS before bed (perhaps because it's that sedating?) but from the first studies I posted it appears WS may be helpful in controlling stress which would lead one to believe it should be taken during waking hours. Well hopefully this will kick off some discussion about WS and it potential benefits/negatives. Just wanted to research it a bit before I jumped on board.
To get the negatives going here are two studies I came across in my searching, one is on the heavy metal buildup contained in Ashwagandha and the other is on cytotoxicity.
From Pub Med:
J Environ Sci Health B. 2010 Feb;45(2):174-81.
Heavy metal bioaccumulation in selected medicinal plants collected from Khetri copper mines and comparison with those collected from fertile soil in Haridwar, India.
Maharia RS, Dutta RK, Acharya R, Reddy AV.
Department of Chemistry, Indian Institute of Technology Roorkee, Roorkee, India.
Abstract
Heavy metal distribution in medicinal plants is gaining importance not only as an alternative medicine, but also for possible concern due to effects of metal toxicity. The present study has been focused on emphasizing the heavy metal status and bioaccumulation factors of V, Mn, Fe, Co, Cu, Zn, Se (essential metals) and Cr, Ni, Cd, As and Pb (potentially toxic metals) in medicinal plants grown under two different environmental conditions e.g., near to Khetri copper mine and those in fertile soils of Haridwar, both in India, using Instrumental Neutron Activation Analysis (relative method) and Atomic Absorption Spectrometry. The copper levels in the medicinal plants from Khetri were found to be 3-4 folds higher (31.6-76.5 mg kg(-1)) than those from Haridwar samples (7.40-15.3 mg kg(-1)), which is correlated with very high copper levels (763 mg kg(-1)) in Khetri soil. Among various heavy metals, Cr (2.60-5.92 mg kg(-1)), Cd (1.47-2.97 mg kg(-1)) and Pb (3.97-6.63 mg kg(-1)) are also higher in concentration in the medicinal plants from Khetri. The essential metals like Mn (36.4-69.3 mg kg(-1)), Fe (192-601 mg kg(-1)), Zn (24.9-49.9 mg kg(-1)) and Se (0.13-0.91 mg kg(-1)) and potentially toxic metals like Ni (3.09-9.01 mg kg(-1)) and As (0.41-2.09 mg kg(-1)) did not show much variations in concentration in the medicinal plants from both Khetri and Haridwar. The medicinal plants from Khetri, e.g., Ocimum sanctum, Cassia fistula, Withania somnifera and Azadirachta Indica were found rich in Ca and Mg contents while Aloe barbadensis showed moderately high Ca and Mg. Higher levels of Ca-Mg were found to correlate with Zn (except Azadirachta Indica). The bioaccumulation factors (BAFS) of the heavy metals were estimated to understand the soil-to-plant transfer pattern of the heavy metals. Significantly lower BAF values of Cu and Cr were found in the medicinal plants from Khetri, indicating majority fraction of these metals are precipitated and were immobilized species unsuitable for plant uptake. Overall, Withania somnifera (Ashwagandha) showed very high metal bioaccumulation.
Take this with a grain of salt as samples were pulled from a copper mine so IMO the results are fairly skewed. But the important thing to take away is the last line. WS has a high metal absorption which would make one want to make sure the quality of their WS supplements were high. I would imagine one would want to verify where their WS was being grown especially if consuming the plant itself.
From Pub Med:
Afr J Tradit Complement Altern Med. 2009 May 7;6(3):275-80.
Comparing the cytotoxic potential of Withania somnifera water and methanol extracts.
Pretorius E, Oberholzer HM, Becker PJ.
Department of Anatomy, School of Health Sciences, Faculty of Health Sciences, University of Pretoria, South Africa. resia.pretorius@up.ac.za
Abstract
The plant Withania somnifera (Linn.) (Solanacea) is a well-known herbal medicine used in many parts of the world. It has anti-inflammatory, antioxidant, and antitumor as well as neural protective properties. It seems as if the two most active withanolide components, namely withaferin A and withanolide D, found in methanol (MeOH) extracts, are responsible for the anti-inflammatory and antioxidant properties of the plant. The current research evaluated and compared the cytotoxic potential of water and methanol extracts of W. somnifera using a combined crystal violet MTT and Neutral Red assay. MRC-5 cells, a human embryonic lung-derived diploid fibroblast cell line, were the cells of choice. We found that the three lowest concentrations (0.007, 0.042, 0.250 microg/ml) of the plant material extracted in double distilled H(2)O and MeOH do not differ significantly in any of the assays. We therefore suggest that low concentrations of MeOH extracts (up to 0.250 microg/ml plant material) do not cause cell damage to the MRC-5 cells, however, higher levels should be avoided as cell viability and cell numbers are negatively influenced.
Take away from this is "everything in moderation."
Hope this will shed some light on Ashwagandha's actions.
Edited by Athanasios, 24 June 2010 - 10:06 PM.