The ethanolic extract of Aralia continentalis ameliorates cognitive deficits via modifications of BDNF expression and anti-inflammatory effects in a rat model of post-traumatic stress disorder.

BACKGROUND: Post-traumatic stress disorder (PTSD) is a disease associated with that the experience of traumatic stress. The traumatic experience results in the development of a prolonged stress response that causes impaired memory function and increased inflammation in the hippocampus. Currently, antidepressants are the only approved therapy for PTSD. However, the efficacy of antidepressants in the treatment of PTSD is marginal. The ethanol extract of Aralia continentalis (AC) is traditionally used in oriental medicine, and has been showed to possess pharmacological properties, including anti-inflammatory, anti-cancer, anti-atherosclerotic, and anti-diabetic effects. Nevertheless, the effects of AC on cognitive memory and its mechanism of action in PTSD remain unclear. Given the necessity of further treatment options for PTSD, we investigated the effect of AC on the spatial cognitive impairment caused by single prolonged stress (SPS) in a rat model of PTSD. METHODS: Male rats were treated with various intraperitoneal (i.p.) doses of AC for 21 consecutive days after inducing chronic stress with the SPS procedure. RESULTS: Cognitive impairment caused by SPS were inhibited after treatment with 100 mg/kg AC, as measured by the Morris water maze test and an object recognition test. Additionally, AC treatment significantly alleviated memory-related decreases in brain-derived neurotrophic factor (BDNF) mRNA and protein levels in the hippocampus. Our results suggest that AC significantly inhibited the cognitive deficits caused by SPS via increased expression of pro-inflammatory cytokines, including tumor necrosis factor-α and interleukin-6, in the rat brain. CONCLUSIONS: AC reversed the behavioral impairments and inflammation triggered by SPS-derived traumatic stress and should be further evaluated as a potential therapeutic drug for PTSD.

Extract of Polygala tenuifolia Alleviates Stress-Exacerbated Atopy-Like Skin Dermatitis through the Modulation of Protein Kinase A and p38 Mitogen-Activated Protein Kinase Signaling Pathway.

Atopic dermatitis (AD) and stress create a vicious cycle: stress exacerbates atopic symptoms, and atopic disease elicits stress and anxiety. Targeting multiple pathways including stress and allergic inflammation is, therefore, important for treating AD. In this study, we investigated the remedial value of Polygala tenuifolia Willd. (PTW) for treating immobilization (IMO) stress-exacerbated atopy-like skin dermatitis and its underlying mechanism. Trimellitic anhydride (TMA) was applied to dorsal skin for sensitization and subsequently both ears for eliciting T-cell-dependent contact hypersensitivity in mice, which underwent 2 h-IMO stress and PTW administration for the latter 6 and 9 days in the ear exposure period of TMA, respectively. To elicit in vitro degranulation of human mast cell line-1 (HMC-1), 10 µM substance P (SP) and 200 nM corticotrophin-releasing factor (CRF) were sequentially added with 48 h-interval. PTW extract (500 µg/mL) was added 30 min before CRF treatment. IMO stress exacerbated TMA-induced scratching behavior by 252%, and increased their blood corticosterone levels by two-fold. Treatment with 250 mg/kg PTW significantly restored IMO stress-exacerbated scratching behavior and other indicators such as skin inflammation and water content, lymph node weights, and serum histamine and immunoglobulin E (lgE) levels. Furthermore, it also reversed TMA-stimulated expression of tumor necrosis factor (TNF)-α and interleukin (IL)-4 mRNAs in ear tissues. PTW significantly inhibited SP/CRF-stimulated degranulation of HMC-1 cells, subsequent tryptase secretion, and protein kinase A (PKA) activity. PTW also selectively inhibited p38 mitogen-activated protein kinase (MAPK) phosphorylation in SP/CRF-treated HMC-1 cells. PTW significantly inhibited HMC-1 cell degranulation and alleviated IMO stress-exacerbated atopic dermatitis symptoms by modulating the PKA/p38 MAPK signaling pathway.