Sodium salicylate is an anti-inflammatory medication with a side-effect of tinnitus. Here, we used mouse cochlear cultures to explore the effects of salicylate treatment on cochlear inner hair cells (IHCs). We found that IHCs showed significant damage after exposure to a high concentration of salicylate. Whole-cell patch clamp recordings showed that 1-5 mmol/L salicylate did not affect the exocytosis of IHCs, indicating that IHCs are not involved in tinnitus generation by enhancing their neuronal input. Instead, salicylate induced a larger peak amplitude, a more negative half-activation voltage, and a steeper slope factor of Ca²⁺ current. Using noise analysis of Ca²⁺ tail currents and qRT-PCR, we further found that salicylate increased the number of Ca²⁺ channels along with Ca_V1.3 expression. All these changes could act synergistically to enhance the Ca²⁺ influx into IHCs. Inhibition of intracellular Ca²⁺ overload significantly attenuated IHC death after 10 mmol/L salicylate treatment. These results implicate a cellular mechanism for tinnitus generation in the peripheral auditory system.
Animals ; Calcium ; Exocytosis ; Hair Cells, Auditory, Inner ; Mice ; Sodium Salicylate/pharmacology* ; Tinnitus/chemically induced*

OBJECTIVES.: Sodium salicylate (SS) is well known for its ototoxic properties that induce functional and morphological changes in the cochlea and brain. Ginkgo biloba extract (GBE) has been widely used for treatment of various neurodegenerative diseases; however, its effects on salicylate-induced ototoxicity remain unclear. Herein, we examined the effects of EGb 761 (EGb), a standard form of GBE, on the plasticity of the N-methyl-D-aspartate receptor subunit 2B (GluN2B) in the inferior colliculus (IC) following SS administration. METHODS.: Seven-week-old Sprague Dawley rats (n=24) were randomly allocated to control, SS, EGb, and EGb+SS groups. The SS group received a single intraperitoneal SS injection (350 mg/kg), the EGb group received EGb orally for 5 consecutive days (40 mg/kg), and the EGb+SS group received EGb for 5 consecutive days, followed by an SS injection. The auditory brainstem responses (ABRs) were assessed at baseline and 2 hours after SS administration. GluN2B expression was examined by Western blot and immunohistochemistry. RESULTS.: There were no significant differences in ABR threshold shifts among the groups. The expression of the GluN2B protein normalized by which of glyceraldehyde 3-phosphate dehydrogenase (GAPDH) was significantly lower in the EGb+SS group, as compared to the SS group (P=0.012). Weak and diffused GluN2B immunoreactivity was detected in the IC neural cells of the EGb+SS group, while those of the SS group exhibited strong and diffused GluN2B positivity. CONCLUSION.: EGb may play a role in regulating the GluN2B expression in the IC of salicylate-induced ototoxicity model.
Blotting, Western ; Brain ; Cochlea ; Evoked Potentials, Auditory, Brain Stem ; Ginkgo biloba ; Glyceraldehyde 3-Phosphate ; Immunohistochemistry ; Inferior Colliculi ; N-Methylaspartate ; Neurodegenerative Diseases ; Oxidoreductases ; Plastics ; Rats, Sprague-Dawley ; Sodium Salicylate

The aim of the present study was to observe whether dopamine receptor (DR) was involved in the effects of sodium salicylate (SS) on the expressions of N-methyl-D-aspartic acid (NMDA) and γ-aminobutyric acid (GABA) receptors in rat cochlear spiral ganglion neurons (SGNs). Forty-eight hours after primary culture of rat SGNs, immunofluorescence technique was applied to detect expressions of DR1 and DR2, the two subtypes of dopamine receptors. Western blot was performed to assess NMDA receptor NR1 subunit and GABAreceptor subunit α2 (GABRα2) protein expressions in the SGNs after the treatments of SS alone or in combination with DR antagonists. The results demonstrated that: (1) The DR1 and DR2 were expressed in the bodies and axons of the SGN; (2) After the treatment with SS, the surface protein expressions of GABRα2 and NR1 were decreased by 44.69% and 21.57%, respectively, while the total protein expressions showed no significant changes; (3) Neither SS + SCH23390 (DR1 antagonist) group nor SS + Eticlopride (DR2 antagonist) group showed significant differences in GABRα2 and NR1 surface protein expressions compared with the control group. These results suggest that SS regulates the surface GABAand NMDA receptors trafficking on SGN, and the mechanism may involve DR mediation.
Animals ; Benzazepines ; pharmacology ; Cells, Cultured ; Cochlea ; cytology ; Neurons ; drug effects ; Rats ; Receptors, Dopamine ; metabolism ; Receptors, GABA-A ; metabolism ; Receptors, N-Methyl-D-Aspartate ; metabolism ; Sodium Salicylate ; toxicity ; Spiral Ganglion ; drug effects

OBJECTIVE: To investigate mRNA expression of GABAa receptor(GABAaR) subunits in the rat cochlear spiral ganglion neurons (SGN) and explore the effect of sodium salicylate (SS) on the expression of GABAaR subunits. METHOD: The realtime fluorescent quantitative PCR (FQ-PCR) was used to detect mRNA expression of twelve GABAaR subunits in the newborn rat SGN and then investigate mRNA expression of GABAaR subunits after treatment with 5 mmol/L SS for 15 min, 30 min, 1 h, 3 h and 6 h in the primary culture SGN. RESULT: (1) GABAaR subunits of α1-6, β1-3, and γ1-3 were detected in the SGN, and the expression of GABAaR subunits was lower than those in the cerebral cortex. In the subunit α family of GABAaR, the expression rank was α2>α3/α5>α4>a1>α6, and the expression of α3 and α5 had no difference (P>0. 05). In the subunit β family, the expression rank was β3>β2>β1. In the subunit γ family, the expression rank was γ1>γ2>γ3. (2) The expression of all subunits of GABAa receptor was obviously fluctuated excepting subunit α5 after treatment with SS. At 15 min post-SS, α1, α2 , β1 and γ1-3 were upregulated, and α3 was downregulated; At 30 min post-SS, α3, β1 and β3 were upregulated, and γ1 was downregulated; At 1 h post-SS, β2 was upregulated and γ3 was downregulated; At 3 h post-SS, β1 and β2 were upregulated, and α3 and γ2 were downregulated; At 6 h post-SS, αl, α3 ,β2, β3 and γ1 were upregulated, and α2, α4 and β1 were downregulated. CONCLUSION The mRNA of GABAaR was expressed in the rat SGN, and the expression of GABAaR subunits was lower in SGN than the cerebral cortex. SS could alter the GABAaR expression quantity in rat SGN; Most of the subunits expression were elevated obviously in the early post SS (15 min), followed by a slight fluctuation.
Animals ; Cells, Cultured ; Cochlea ; cytology ; In Situ Hybridization ; Neurons ; drug effects ; RNA, Messenger ; Rats ; Receptors, GABA-A ; metabolism ; Sodium Salicylate ; pharmacology ; Spiral Ganglion ; drug effects

Salicylate, the active ingredient of aspirin can cause sensorineural hearing loss and tinnitus when plasma concentrations reach a critical level. The ototoxic mechanisms of salicylate remain unclear but hearing and tinnitus usually recovers a few days after intoxication. There have been few reports of salicylate-induced ototoxicity in Korea, and the majority is caused by a low dose of aspirin. Herein, we report a case of sudden hearing loss and tinnitus after acute salicylate intoxication and review recent updates on salicylate ototoxicity.
Aspirin ; Hearing ; Hearing Loss ; Hearing Loss, Sensorineural ; Hearing Loss, Sudden ; Korea ; Plasma ; Sodium Salicylate ; Tinnitus

OBJECTIVETo probe the effect of sodium para-aminosalicylate (PAS-Na) on concentration of amino acid neurotransmitters including glutamate (Glu), glutamine (Gln), glycine (Gly) and gamma-aminobutyric acid (GABA) in basal ganglia of subacute manganese (Mn)-exposed rats.

METHODSForty Sprague-Dawley male rats were randomly divided into the control, Mn-exposed, low dose PAS-Na (L-PAS) and high dose PAS-Na (H-PAS) groups. Rats in experiment groups received daily intraperitoneally injections of manganese chloride (MnCl₂ · 4H₂O, 15 mg/kg), while rats in control group received daily intraperitoneally injections of normal saline (NS), all at 5 days/week for 4 weeks. Then the rats in PAS groups followed by a daily subcutaneously dose of PAS-Na (100 and 200 mg/kg as the L-PAS and H-PAS groups, respectively) for another 3 and 6 weeks; while the rats in Mn-exposed and control group received NS. The concentrations of Glu, Gln, Gly and GABA in basal ganglia of rat was detected by the high performance liquid chromatography fluorescence detection technique.

RESULTSAfter treating with PAS-Na for 3 weeks, the concentration of Gly in the Mn-exposed rats decreased to (0.165 ± 0.022) µmol/L (control = (0.271 ± 0.074) µmol/L, Mn vs control, t = 4.65, P < 0.05). After the further 6-week therapy with PAS-Na, the concentrations of Glu, Gln, Gly in the Mn-exposed rats were lower than those of the control rats ((0.942 ± 0.121), (0.377 ± 0.070), (0.142 ± 0.048), (1.590 ± 0.302), (0.563 ± 0.040), (0.247 ± 0.084) µmol/L; t = 7.72, 5.85, 4.30, P < 0.05); and also lower than in L-PAS and H-PAS groups, whose concentrations were separately (1.268 ± 0.124), (1.465 ± 0.196), (0.497 ± 0.050), (0.514 ± 0.103), (0.219 ± 0.034) µmol/L (L-PAS Glu and Gln vs Mn, t = 3.87, 3.77, P < 0.05; H-PAS Glu, Gln and Gly vs Mn, t = 6.78, 4.70, 3.42, P < 0.05).

CONCLUSIONThe toxic effect of manganese on Glu, Gln and Gly in basal ganglia of Mn-exposed rats is obvious, especially appears earlier on Gly. The toxic effect still continues to develop when relieved from the exposure. PAS-Na may play an antagonism role in toxic effect of manganese on concentration of Glu, Gln and Gly in basal ganglia of Mn-exposed rats.

Amino Acids ; metabolism ; Animals ; Basal Ganglia ; drug effects ; metabolism ; Glutamic Acid ; metabolism ; Male ; Manganese ; toxicity ; Neurotransmitter Agents ; metabolism ; Rats ; Rats, Sprague-Dawley ; Sodium Salicylate ; pharmacology ; gamma-Aminobutyric Acid ; metabolism

BACKGROUND: Reactive oxygen species (ROS) induce lipid peroxidation and tissue damage in the endothelium. We tested the antioxidant effect of lidocaine and procaine on ROS-induced endothelial damage in the rabbit aorta. METHODS: Aortic rings isolated from rabbits were suspended in an organ bath filled with Krebs-Henseleit (K-H) solution bubbled with 5% CO2 and 95% O2 at 37.5degrees C. After precontraction with phenylephrine (PE, 10(-6) M), changes in tension were recorded following a cumulative administration of acetylcholine (ACh 3 x 10(-8) to 10(-6) M). Differences were measured as percentages of ACh-induced relaxation of aortic rings before and after exposure to ROS as generated by electrolysis of the K-H solution. The aortic rings were pretreated with lidocaine or procaine (10(-5) M to 3 x 10(-3) M) to compare their effects, as well as ROS scavengers, catalase, mannitol, sodium salicylate, and deferoxamine, and a catalase inhibitor, 3-amino-1,2,4-triazole (3AT). RESULTS: Lidocaine and procaine dose-dependently maintained endothelium-dependent relaxation induced by ACh despite ROS activity (P < 0.05 vs control value). The 3AT pretreated procaine (3 x 10(-3) M) group decreased more significantly than the un-pretreated procaine group (P < 0.05). CONCLUSIONS: These findings suggest that lidocaine and procaine dose-dependently preserve endothelium-dependent vasorelaxation against ROS attack, potentially via hydrogen peroxide scavenging.
Acetylcholine ; Amitrole ; Antioxidants ; Aorta ; Aorta, Abdominal ; Baths ; Catalase ; Deferoxamine ; Electrolysis ; Endothelium ; Hydrogen Peroxide ; Lidocaine ; Lipid Peroxidation ; Mannitol ; Oxygen ; Phenylephrine ; Procaine ; Rabbits ; Reactive Oxygen Species ; Relaxation ; Sodium Salicylate ; Vasodilation

Years before insulin was discovered, anti-inflammatory sodium salicylate was used to treat diabetes in 1901. Intriguingly for many years that followed, diabetes was viewed as a disorder of glucose metabolism, and then it was described as a disease of dysregulated lipid metabolism. The diabetes research focused on the causal relationship between obesity and insulin resistance, a major characteristic of type 2 diabetes. It is only within the past 20 years when the notion of inflammation as a cause of insulin resistance began to surface. In obesity, inflammation develops when macrophages infiltrate adipose tissue and stimulate adipocyte secretion of inflammatory cytokines, that in turn affect energy balance, glucose and lipid metabolism, leading to insulin resistance. This report reviews recent discoveries of stress kinase signaling involving molecular scaffolds and endoplasmic reticulum chaperones that regulate energy balance and glucose homeostasis. As we advance from a conceptual understanding to molecular discoveries, a century-old story of inflammation and insulin resistance is re-born with new ideas.
Adipocytes ; Adipose Tissue ; Cytokines ; Endoplasmic Reticulum ; Glucose ; Homeostasis ; Inflammation ; Insulin ; Insulin Resistance ; Lipid Metabolism ; Macrophages ; Obesity ; Phosphotransferases ; Sodium Salicylate

BACKGROUND: Reactive oxygen species (ROS) induce lipid peroxidation and tissue damage in endothelium. We studied the influences of ketorolac and diclofenac on ROS effects using the endothelium of rabbit abdominal aorta. METHODS: Isolated rabbit aortic rings were suspended in an organ bath filled with Krebs-Henseleit (K-H) solution bubbled with 5% CO2 and 95% O2 at 37.5degrees C. After being stimulated to contract with phenylephrine (PE, 10(-6) M), changes in arterial tension were recorded following the cumulative administration of acetylcholine (ACh, 3 x 10(-8) to 10(-6) M). The percentages of ACh-induced relaxation of aortic rings before and after exposure to ROS, generated by electrolysis of K-H solution, were used as the control and experimental values, respectively. The aortic rings were pretreated with ketorolac or diclofenac at the same concentrations (10(-5) M to 3 x 10(-4) M), and the effects of these agents were compared with the effects of ROS scavengers: catalase, mannitol, sodium salicylate and deferoxamine and the catalase inhibitor, 3-amino-1,2,4-triazole (3AT). RESULTS: Both ketorolac and diclofenac maintained endothlium-dependent relaxation induced by ACh in a dose-related manner inspite of ROS attack (P < 0.05 vs. control value). The 3AT pretreated ketorolac (3 x 10(-3) M) group was decreased more significantly than un-pretreated ketorolac (P < 0.05). CONCLUSIONS: These findings suggest that ketorlac and diclofenac preserve the endothelium-dependent vasorelaxation against the attack of ROS, in a concentration-related manner. One of the endothelial protection mechanisms of ketorolac may be hydrogen peroxide scavenging.
Acetylcholine ; Amitrole ; Aorta, Abdominal ; Arterial Pressure ; Baths ; Catalase ; Contracts ; Deferoxamine ; Diclofenac ; Electrolysis ; Endothelium ; Hydrogen Peroxide ; Ketorolac ; Lipid Peroxidation ; Mannitol ; Phenylephrine ; Reactive Oxygen Species ; Relaxation ; Sodium Salicylate ; Vasodilation

Salicylates, such as aspirin, are considered the most commonly used medicine in Korea for its anti-inflammatory, anti-pyretic, and analgesic properties. In spite of its wide range of benefits, aspirin produces unwanted adverse effects such as mucosal bleeding in the gastrointestinal tract, renal and hepatic dysfunction, Reye's syndrome in children, and hypersensitivity reactions, etc. Aspirin can also induce ototoxicity, such as reversible hearing loss and tinnitus. The pattern of hearing loss is typically mild to moderate and bilaterally flat in the absence of preexisting hearing loss. Hearing usually recovers in 72 hours after medication. However, it's rare that salicylate-induced ototoxicity are encountered. So we present this case of bilateral hearing loss that occurred after salicylate intoxication with a review of relevant literature.
Aspirin ; Child ; Ear, Inner ; Gastrointestinal Tract ; Hearing ; Hearing Loss ; Hearing Loss, Bilateral ; Hearing Loss, Sensorineural ; Hemorrhage ; Humans ; Hypersensitivity ; Korea ; Reye Syndrome ; Salicylates ; Sodium Salicylate ; Tinnitus