Table 3.
Anti-anxiety effects of Ashwagandha (Withania somnifera, WS) in animal studies.
| Nature of Extract, Standardization | Dosage | Model |
Behavioral
Effects |
Biological Effects | Refs. | |||||||
|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Aqueous leaf extract (ASH-WEX), NR | 140 mg/kg/day p.o. for 8 weeks | Rat (LPS-induced neuroinflammation) | ▼anxiety-like behavior (EPM) |
▼ pro-inflammatory cytokines (TNFα, IL-1β, IL-6)*^ ▼reactive gliosis and neuroinflammation (Iba-1, GFAP, NOX2, iNOS, COX2, MCP-1, HSP70)^ ▼inflammatory pathways (NFκB, p38, JNK)^ |
[79] | |||||||
| Aqueous leaf extract (ASH-WEX), NR | 140 mg/kg/bwt, p.o. for 15 days prior to acute sleep deprivation | Rat (acute sleep deprivation) | ▼anxiety-like behavior (EPM) |
▼reactive gliosis (GFAP), ▼OX-18 ▼pro-inflammatory cytokines (TNFα, IL-6)^ ▼cell survival proteins (NFκB, AP-1) ▼apoptosis (▲Bcl-xL, ▼Cytochrome c) |
[76] | |||||||
| Aqueous leaf extract (ASH-WEX), NR | 140 mg/kg/bwt, p.o. for 15 days prior to acute sleep deprivation | Rat (acute sleep deprivation) | ▼anxiety-like behavior (▼grooming activity) ▼stress-induced learning and memory impairments ▼stress-induced motor dysfunction |
Modulated markers of synaptic plasticity (▼hippocampal PSA-NCAM and NCAM, ▲PSA-NCAM in the pyriform cortex)^ ▼mortalin^, ▲Akt-1 phosphorylation^ |
[45] | |||||||
| Dry leaf powder, NR | 1 mg/g/bwt p.o. for 12 weeks | Rat (high fat diet-induced obesity) | ▼anxiety-like behavior (EPM) | ▼ pro-inflammatory cytokines (TNFα, IL-1β, IL-6)*^ ▼reactive gliosis and neuroinflammation (GFAP, Iba1, PPARγ, iNOS, MCP-1, COX2)^ ▼NFκB pathway^ ▼apoptosis (▼AP-1, ▲Bcl-xL, ▼BAD)^ |
[88] | |||||||
| Aqueous leaf extract, NR | 0.3% concentration (2.8 mg/L water), waterborne administration for 72 hrs | Zebrafish (benzo[a]pyrene-induced neurotoxicity) | ▼anxiety-like behavior (LDPT, NTDT) | ▼pyknotic cells in periventricular gray zone ▼oxidative stress (▼lipid peroxidation ▼protein carbonylation, ▲catalase activity, ▲GSH)^ |
[86] | |||||||
| Withanolide-free root extract | 3.3, 10, 33.3, and 100 mg/kg p.o. for 12 days | Rat (stress) | ▼anxiety-like or depression-like behavior (MBT) | ▼stress-induced weight loss ▼stress-induced increase in rectal temperature ▼transient hyperthermic response ▼stress-induced increase in adrenal weight ▼stress-induced increase in plasma cortisol and blood glucose |
[54] | |||||||
| Root extract, 2.7% (w/w) withanolides | 10, 20, and 40 mg/kg/day p.o. for 12 days, or as a single dose | Mouse (acute stress) | ▼anxiety-like behavior (MBT) | ▼stress-induced changes in weight, basal core temperature, and hyperthermic response | [73] | |||||||
| Hydro-alcoholic root extract, standardized to 2% (w/w) withanolides | 300 mg/kg/bwt p.o. for 30 days | Rat (ischemic stroke) | ▼anxiety-like behavior (EPM) ▲cognitive function (MWM) ▲locomotor function (NDS, NBW, RTT) |
▲acetylcholinesterase activity^ ▼lipid peroxidation^ ▲antioxidant activity^ ▼infarct volume ▼stroke-induced histopathological changes |
[87] | |||||||
| Nature of Extract, Standardization | Dosage | Model |
Behavioral
Effects |
Biological Effects | Refs. | |||||||
| Methanolic (MEWS) and aqueous root extracts (AEWS), NR |
10, 25, 50, and 100 mg/kg i.p., 30 mins prior to assessment | Mouse (obsessive-compulsive behavior) |
▼obsessive compulsive behavior (MBT) ▲anti-OCD action of subtherapeutic dose of fluoxetine at subtherapeutic dose (50 mg/kg) of WS (MBT) |
Not reported | [83] | |||||||
| Several root extracts, using various solvents (alcohol, water, hydro-alcohol (50:50)), ratios (1:6, 1:8, 1:10), and methods (hot continuous percolation (10 hrs) and maceration (10 hrs)), NR |
100 or 200 mg/kg p.o., 30 mins prior to assessment | Mouse (acute stress) | ▼anxiety-like behavior (EPM) for water and hydro-alcoholic extracts prepared by maceration and for hydro-alcoholic extract prepared by hot continuous percolation | Not reported | [74] | |||||||
| Withaferin A and Hydroalcoholic (4:1) root extract, NR | Withaferin A: 10-50 mg/kg i.p., 1-2 hrs prior to assessment Root extract: 100-500 mg/kg p.o., 1-2 hrs prior to assessment |
Rat (acute stress) | ▼anxiety-like behavior (EPM, OFT) | Not reported | [75] | |||||||
| Ethanolic root extract, NR | 50, 100, 200, or 500 mg/kg p.o., one hr prior to assessment | Rat (acute ethanol-induced anxiolysis and withdrawal from chronic ethanol consumption) | ▼anxiety-like behavior (EPM) ▲anti-anxiety action of a subtherapeutic dose of ethanol at subtherapeutic dose (50 mg/kg) of WS (EPM) |
Not reported | [80] | |||||||
| Root extract, NR | 50, 100, 200, or 500 mg/kg p.o. on days 38-42 of social isolation and 1 hr prior to assessment | Rat (social isolation) |
▼anxiety-like behavior (EPM) ▲anti-anxiety action of diazepam at subtherapeutic dose (50 mg/kg) of WS (EPM) ▼depression-like behavior (FST) |
Not assessed | [78] | |||||||
| Root extract, NR | 100 and 200 mg/kg p.o. for 5 days, beginning 3 days prior to sleep deprivation | Mouse (sleep deprivation) |
▼anxiety-like behavior (EPM) ▲locomotor activity |
▼sleep deprivation-induced weight loss ▼oxidative stress (▼lipid peroxidation, ▼nitrite activity, ▲catalase activity, ▲GSH)^ |
[77] | |||||||
| Glycowithanolide-rich fraction (WSG, containing sitoindosides VII-X and withaferin) isolated from aqueous root extract, standardized to 1.13% total steroid content |
20 and 50 mg/kg p.o. for 5 days | Rat (anxiety and depression) | ▼depression-like behavior (LHT, FST) ▼anxiety-like behavior (EPM, SIT, NSFLT) |
▼PTZ-induced increase in rat brain tribulin activity (PTZ) | [81] | |||||||
| Nature of Extract, Standardization | Dosage | Model |
Behavioral
Effects |
Biological Effects | Refs. | |||||||
| Sitoindosides VII and VIII | PTZ: 20 mg/kg i.p., 30 mins prior to assessment FST: 20 and 50 mg/kg i.p., 30 mins prior to assessment OST, TCT: 50 mg/kg p.o. for 4 days prior to assessment RST: 50 and 100 mg/kg p.o. for 4 days prior to restraint; 100 mg/kg i.p., 30 mins before morphine administration Morphine toxicity: 50 mg/kg p.o. for 4 days |
Mouse, rat (stress) | ▼anxiety-like behavior (PTZ-induced) ▼depression-like behavior (FST) |
▼stress-induced autoanalgesia, gastric ulcers (RST) ▼morphine-induced hypothermia (RST) ▼morphine toxicity (OST, TCT) ▼tribulin activity in urine (RST) ▲stress-induced decrease in adrenal content of ascorbic acid, corticosterone |
[17] | |||||||
*Peripheral; ^CNS; ▲ – Increased; ▼ – Decreased; AP-1 = Activator protein 1; Bcl-xL = B-cell lymphoma extra-large; BAD = Bcl-2 associated agonist of cell death; COX-2 = Cyclooxygenase 2; EPM = Elevated plus maze test; FST = Forced swim test; GFAP = Glial fibrillary acidic protein; GSH = Reduced glutathione; HSP70 = Heat shock protein 70; Iba1 = Ionized calcium binding adaptor molecule 1; IL-1β = Interleukin 1 beta; IL-6 = Interleukin 6; iNOS = Inducible nitric oxide synthase; JNK = c-Jun N-terminal kinase; LDPT = Light/dark preference test; LHT = Learned helplessness test; LPS = Lipopolysaccharide; MBT = Marble burying test; MCP-1 = Monocyte chemoattractant protein; MWM = Morris water maze test; NBW = Narrow beam walking test; NDS = Neurological deficit score; NFκB = Nuclear factor kappa B; NOX2 = NADPH oxidase 2; NSFLT = Novelty-suppressed feeding latency test; NTDT = Novel tank diving test; OFT = Open field test; OST = Overcrowding stress test; PPARγ = Peroxisome proliferator-activated receptor gamma; PTZ = pentylenetetrazol administration; RST = Restraint stress test; RTT = Rotarod test; SIT = Social interaction test; TCT = Tactile stress test; TNFα = Tumor necrosis factor alpha.