Noh-Yil Myung

The Protective Mechanism of Antioxidants in Cadmium-Induced Ototoxicity in Vitro and in Vivo

Background Several heavy metals have been shown to have toxic effects on the peripheral and central auditory system. Cadmium (Cd2+) is an environmental contaminant showing a variety of adverse effects. Given the current rate of release into the environment, the amount of Cd2+ present in the human body and the incidence of Cd2+-related diseases are expected to increase. Objective The overall aim of this study was to gain further insights into the mechanism of Cd2+-induced ototoxicity. Methods Cell viability, reactive oxygen species (ROS), mitochondrial membrane potential (MMP), cytochrome c (cyt c), phosphorylated extracellular signal-regulated protein kinase (p-ERK), caspases, morphologic change, and functional changes in HEI-OC1 cells, rat cochlear explants, and mouse cochlea after Cd2+ exposure were measured by flow cytometry, immunohistochemical staining, Western blot analysis, and auditory brainstem response (ABR) recording. Mechanisms underlying Cd2+ototoxicity were studied using inhibitors of different signaling pathways, caspases, and antioxidants. Results Cd2+ exposure caused cell death, ROS generation, MMP loss, cyt c release, activation of caspases, ERK activation, apoptosis, and finally auditory threshold shift. Cd2+ toxicity interfered with inhibitors of cellular signaling pathways, such as ERK and c-jun N-terminal kinase, and with caspase inhibitors, especially inhibitors of caspase-9 and caspase-3. The antioxidants N-acetyl-l-cysteine and ebselen showed a significant protective effect on the Cd2+ toxicity. Conlcusions Cd2+ is ototoxic with a complex underlying mechanism. However, ROS generation may be the cause of the toxicity, and application of antioxidants can prevent the toxic effect.

INHIBITORY EFFECTS OF MAST CELL-MEDIATED ALLERGIC REACTIONS BY CELL CULTURED SIBERIAN GINSENG

The crude drug “Siberian Ginseng (SG)” has long been used in empirical Oriental medicine for the nonspecific enhancement of resistance in humans and animals. In this study, we investigated the effect of cell cultured SG by oral administration in mast cell-mediated allergic reactions. SG dose-dependently inhibited compound 48/80-induced systemic allergy with doses of 10−2 to 1 g/kg 1 h before oral administration. Of special note, SG inhibited systemic allergy with the dose of 1 g/kg by 25%. SG (1 g/kg) also inhibited passive cutaneous allergic reaction by 51%. SG dose-dependently inhibited histamine release from rat peritoneal mast cells. When SG (0.01 mg/ml) was added, the secretion of tumor necrosis factor-α (TNF-α) and interleukin-6 in anti-dinitrophenyl (DNP) IgE antibody-stimulated mast cells was inhibited 39.5% and 23.3%, respectively. In addition, SG inhibited anti-DNP IgE antibody-stimulated TNF-α protein expression in mast cells. Our studies provide evidence that SG may be beneficial in the treatment of various types of allergic diseases.

Anti-Inflammatory Activity of Schizonepeta tenuifolia through the Inhibition of MAPK Phosphorylation in Mouse Peritoneal Macrophages

Schizonepeta tenuifolia (ST) is a well-known herb to treat the cold and its associated headache. However, the anti-inflammatory mechanism of ST in mouse peritoneal macrophages is not clear. In this study, we demonstrated that ST inhibited lipopolysaccaride (LPS)-induced tumor necrosis factor (TNF)-alpha and interleukin (IL)-6 production. The maximal inhibition rate of TNF-alpha and IL-6 production by ST (2 mg/ml) was 48.01 +/- 2.8% and 56.45 +/- 2.8%, respectively. During the inflammatory process, cyclooxygenase (COX)-2 and inducible nitric oxide synthase (iNOS) were increased in mouse peritoneal macrophages. However, treated with ST decreased the protein level of COX-2 and iNOS, as well as the production of PGE(2) and NO in LPS-stimulated mouse peritoneal macrophages. In addition, ST inhibited the phosphorylation of MAPK. Taken together, the results of this study suggest an important molecular mechanism by which ST reduces inflammation, which may explain its beneficial effect in the regulation of inflammatory reactions.

(-)-Epigallocatechin-3-Gallate Protects against NO-Induced Ototoxicity through the Regulation of Caspase- 1, Caspase-3, and NF-κB Activation

Excessive nitric oxide (NO) production is toxic to the cochlea and induces hearing loss. However, the mechanism through which NO induces ototoxicity has not been completely understood. The aim of this study was to gain further insight into the mechanism mediating NO-induced toxicity in auditory HEI-OC1 cells and in ex vivo analysis. We also elucidated whether and how epigallocatechin-3-gallate (EGCG), the main component of green tea polyphenols, regulates NO-induced auditory cell damage. To investigate NO-mediated ototoxicity, S-nitroso-N-acetylpenicillamine (SNAP) was used as an NO donor. SNAP was cytotoxic, generating reactive oxygen species, releasing cytochrome c, and activating caspase-3 in auditory cells. NO-induced ototoxicity also mediated the nuclear factor (NF)-κB/caspase-1 pathway. Furthermore, SNAP destroyed the orderly arrangement of the 3 outer rows of hair cells in the basal, middle, and apical turns of the organ of Corti from the cochlea of Sprague–Dawley rats at postnatal day 2. However, EGCG counteracted this ototoxicity by suppressing the activation of caspase-3/NF-κB and preventing the destruction of hair cell arrays in the organ of Corti. These findings may lead to the development of a model for pharmacological mechanism of EGCG and potential therapies against ototoxicity.

Protective effect of a Chrysanthemum indicum containing formulation in cadmium-induced ototoxicity.

Chungshinchongyitang (CSCYT) is an herbal drug formula containing Chrysanthemum indicum and 13 other herbs used for treating auditory diseases. Irreversible hearing loss is a characteristic effect of a number of heavy metals. Cadmium (Cd(2+)) is an environmental contaminant that causes a variety of adverse effects. In the present study, we investigate the protective effects of CSCYT against Cd(2+) induced ototoxicity in vitro and ex vivo. The findings of this study show that CSCYT prevents the destruction of hair cell arrays induced by Cd(2+) in the rat organ of Corti primary explants. CSCYT inhibited cell death, release of cytochrome c and generation of reactive oxygen species induced by Cd(2+) in HEI-OC1 auditory cell line. In addition, we also demonstrated that CSCYT exerted its effect by modulating of apoptosis via the caspase-3 activation and extracellular signal-regulated kinase activation. These results are expected to improve the understanding of the pharmacological mechanism of CSCYT and aid in the development of potential therapeutic strategies against ototoxicity.

Samsoeum inhibits systemic anaphylaxis and release of histamine, cytokine in vivo and in vitro

SUMMARY Samsoeum (SSE) is used in traditional oriental medicine for various medicinal purposes. However,the exact mechanism that accounts for the anti-allergy and anti-inflammatory effects of the SSE isstill not fully understood. The aim of the present study is to elucidate whether and how SSEmodulates the allergic reactions in vivo, and inflammatory reaction in vitro. In this study, weshowed that SSE significantly decreased compound 48/80-induced systemic anaphylaxis, ear-swelling response, histamine release from preparation of rat peritoneal mast cells and anti-dinitropheny IgE-induced passive cutaneous reaction. Also, SSE inhibited the expression ofinflammatory cytokine and cyclooxygenase-2 in PMA plus A23187-stimulated human mast cells(HMC-1). In addition, we showed that anti-inflammatory mechanism of SSE is throughsuppression of nuclear factor-κB activation and IκB-α phosphorylation/degradation in HMC-1.These results provided new insight into the pharmacological actions of SSE as a potentialmolecule for therapy of inflammatory allergic diseases.Key words: Samsoeum; Allergic reactions; Inflammation; Cyclooxygenase-2; Nuclear factor-κB

The anti-allergy and anti-inflammatory effect of Anemarrhenae Rhizoma in vivo and in vitro

Anemarrhenae Rhizoma (AR) is used in traditional oriental medicine for various medicinal purposes. However, the exact mechanism that accounts for the anti-allergy and anti-inflammatory effects of the AR is still not fully understood. The aim of The present study is to elucidate whether and how AR modulates the allergic reactions in vivo, and inflammatory reaction in vitro. In this study, we showed that AR significantly decreased compound 48/80-induced systemic anaphylaxis, paw oedema, and histamine release from preparation of rat peritoneal mast cells. Also, AR inhibited the expression of inflammatory cytokine in PMA plus A23187-stimulated human mast cells (HMC-1). In addition, we showed that anti-inflammatory mechanism of AR is through suppression of nuclear factor- activation degradation. These results provided new insight into the pharmacological actions of AR as a potential molecule for therapy of inflammatory allergic diseases.