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Objective: To investigate mRNA expression of dopamine receptor subtypes in the rat cochlear spiral ganglion neurons (SGN) following exposure to the sodium salicylate. In addition, we observed the effect of sodium salicylate on N methyl-D-aspartic acid (NMDA) receptor subunit NR1 and gamma aminobutyric acid (GABA)a receptor subunit GABRα2 mRNA under the circumstance of DR activation or blocking. Moreover, we also focused on the the interaction between receptors mediated by SS. Method: Immunofluorescence techniques were applied to detect DR (DR1 and DR2) expression in cultured rat SGN. Moreover, RT-PCR was performed to assess NR1 and GABRα2 subunit mRNA. Result: Immunofluorescence images showed co-localization of DR1/DR2 and βⅢ-tubulin protein in SGN bodies and axons. RT-PCR results illustrated that ①DR subtypes of DRd1-5 were detected in the SGN. ②The mRNA expression of all subtypes of DR and GABRα2, NR1 subunits were obviously upregulated except DRd3 after treatment with sodium salicylate. Among them, DRd1 expression increased 34.64%( t =-5.123, P =0.007),DRd2 expression increased 34.60%( t =-5.206, P =0.006),DRd4 expression increased 20.87%( t =-3.337, P =0.029),DRd5 expression increased 26.42%( t =-6.054, P =0.004),GABRα2 expression increased 30.41%( t =-2.839, P =0.047),NR1 expression increased 39.22%( t =-6.243, P =0.003).③After exposure to sodium salicylate (5 mmol/L), dopamine (100 μmol/L), DR1 agonist (SKF38393,20 μmol/L), DR2 agonist (Quinpirole,20 μmol/L), GABRα2 expression increased 21.78%,27.45%,33.02%,33.42% respectively ( F =12.399, P =0.001),and NR1 expression increased 28.70%,26.82%,29.03%,35.05%( F =50.395, P =0.000) respectively.④Compared with the group of sodium salicylate treatment alone, both sodium salicylate + DR1 antagonist (SCH23390,20 μmol/L) group and sodium salicylate + DR2 antagonists (Eticlopride,20 μmol/L) group had a suppression on GABRα2 and NR1 mRNA expression.GABRα2 mRNA reduced 29.56%,37.10%( F =22.101, P =0.000) and NR1 mRNA expression decreased 37.62%,32.83% respectively( F =72.933, P =0.000). Conclusion: Most of the DR subtypes mRNA expression in SGN were increased following exposure to sodium salicylate. DR may be involved in the effect of sodium salicylate on GABAaR and NMDAR mRNA expression., Competing Interests: The authors of this article and the planning committee members and staff have no relevant financial relationships with commercial interests to disclose., (Copyright© by the Editorial Department of Journal of Clinical Otorhinolaryngology Head and Neck Surgery.)

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.

Objective: To 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., Methods: Forty 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., Results: After 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)., Conclusion: The 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.

Objective: To study the differences of regulation of sodium salicylate on the auditory brain stem response (ABR) threshold and expression of glutamic acid decarboxylase (GAD) protein in spiral ganglion of juvenile and adult guinea pigs., Methods: Fourty juvenile guinea pigs which were born just four days and fourty adult guinea pigs which were born thirty days were selected. They were divided four groups (group A; group B; group C; group D). ABR threshold was detected before administration, after administration for 15 days and after administration stopped for 30 days. The protein expression of GAD were measured after administration for 15 days and after administration stopped for 30 days by the method of immunohistochemistry., Results: ABR threshold of juvenile sodium salicylate groups (group C) was increased remarkably than that of before administration and the control after administration for 15 days (P < 0.001). ABR threshold of group C was returned to the level of that of before administration and after administration stopped for 30 days. ABR threshold of adult sodium salicylate groups (group D) was increased remarkably than that of before administration and the control after administration for 15 days (P < 0.001). ABR threshold of group D was kept the high level after administration stopped for 30 days. The protein expression of GAD of sodium salicylate groups (group C and D) was decreased than that of the control after administration for 15 days. The protein expression of group C was more visible regression than that of group D (t = 4.7, P < 0.001). The protein expression of group C was returned the level of before administration after administration stopped for 30 days, but the protein expression of group D was kept the high level., Conclusions: The results suggest that sodium salicylate can regulate differently ABR threshold and expression of GAD protein in spiral ganglion of juvenile and adult guinea pigs. The effects of sodium salicylate on ABR threshold and expression of GAD protein in spiral ganglion of juvenile pigs are more noticeable than that of adult guinea pigs, but these changes are easier to return the normal than that of adult guinea pigs.

Objective: To investigate the mechanism of the tinnitus inducer, sodium salicylate, on voltage-gated sodium channels., Method: The effects of salicylate on voltage-gated sodium channels in freshly dissociated inferior colliculus neurons of rats were studied, using the whole-cell voltage clamp method., Result: Salicylate blocked sodium current (INa) in concentration-dependent manner (0.1-10 mmol/L). The IC50 value for the blocking action of salicylate was 1.43 mmol/L. Salicylate did not affect the conductance-voltage curve and the steady-state activation curve of INa. The steady-state INa inactivation curve of INa was shifted by about 9 mV in the hyperpolarizing direction. In addition, salicylate delayed the sodium channel recovery from INa inactivation by increasing the slow time constant., Conclusion: Our results suggest that salicylate causes a concentration-dependent blockade of INa and shifts the INa inactivation curve to more hyperpolarized potentials, which could be related to the mechanism of salicylate-induced tinnitus.

The effects of sodium salicylate (NaSA) on the expressions of gamma-aminobutyricacid (GABA) and glutamate (Glu), and auditory response properties of the inferior colliculus neurons in mice were studied. Thirty-six Kunming mice were divided into three groups: control group (saline injection); NaSA group (NaSA 450 mg/kg, i.p., each day for 15 d); NaSA + lidocaine group (NaSA 450 mg/kg + lidocaine 10 mg/kg, i.p., each day for 15 d). The expressions of GABA and Glu were examined with immunohistochemical method. The intensity-rate function, intensity-latency function and frequency-tuning curve were determined with extracellular electrophysiological recording. Results are as follows: (1) The expression of GABA in the NaSA and NaSA + lidocaine groups decreased remarkably compared with that in the control group; there was no noticeable difference between the NaSA and NaSA + lidocaine groups. The expression of Glu in the NaSA group increased significantly compared with that in the control and NaSA + lidocaine groups. No difference in the expression of Glu was found between the control and NaSA + lidocaine groups. (2) In NaSA group, the intensity-rate function displayed a non-monotonic pattern, rising at low intensity and descending at high intensity; the tip of frequency-tuning curves became broad after administration of NaSA. (3) The changes in intensity-rate function and intensity-latency function were not evident and the tips of the frequency-tuning curves sharpened in the NaSA + lidocaine group. These results suggest that administration of NaSA increases the expression of Glu-positive neurons and reduces that of GABA-positive neurons in the inferior colliculus. NaSA changes the auditory response properties of the inferior colliculus and lidocaine can reverse these changes.

Objective: To study the effect of sodium salicylate on the nuclear factor-kappaB (NF-kappaB) protein expression in spiral ganglion cells., Method: Forty-eight healthy guinea pigs were randomly divided into four groups: group A: the control group (0.9% sodium chloride); group B: sodium salicylate [450 mg/(kg x d)] group; group C: sodium salicylate [450 mg/(kg x d)]+chlorpromazine [5 mg/(kg x d)] group; group D: sodium salicylate [450 mg/(kg x d)] +nimodipine [3 mg/(kg x d)] group. The protein expression level of NF-kappaB was examined by immunohistochemical method., Result: The protein expression of NF-kappaB in spiral ganglion cells of group B was significantly higher than that of other groups., Conclusion: Sodium salicylate can promote the protein expression of NF-kappaB in cochlear spiral ganglion cells. Nimodipine and chloropazine can weaken the protein expression of NF-kappaB, which is caused by sodium salicylate in cochlear spiral ganglion cells.

Aim: To study the effects of sodium salicylate on the expression of GABAalpha NR1 and hearing response properties of inferior colliculus neurons in mice., Methods: Thirty-six kunming mice were divided into three groups (A, B, C,). The expression of GABAalpha NR1 were measured by using RT-PCR. The intensity-rates functions, intensity-latency functions and frequency-turning curves were recorded by extracellular electrophysiological recording techniques., Results: (1) The expression of GABAalpha mRNA of B group was decreased remarkably than the control group (A group, P < 0.05), there weren't noticeable differences between A group and C group (P > 0.05). The expression of NR1 mRNA of B group was increased remarkably than the control group (A group, P < 0.01), there were noticeable differences between A group and C group P < 0.05). (2) The intensity-rates functions, intensity-latency functions were monotonic while the frequency-turning curves were more broad when sodium salicylate was given. (3) The intensity-rates functions, intensity-latency functions were non-monotonic while the frequency-turning curves were sharpened after lidocaine was given., Conclusions: (1) The results suggested that administration of sodium salicylate decreased the expression of GABAalpha while increased the expression of NR1mRNA. (2) The intensity-rates functions, intensity-latency functions were monotonic, the frequency-turning curves were more broad when salicylate was given and the changes above could be reversed by given lidocaine.

Objective: To study the mechanism of electrophysiologic changes caused by different type of sodium salicylate injection., Methods: Decapitated three group rats ( acute injected, chronic injected and normal rats ) separately, dissected the temporal bones to collect cochlea, and the otic capsules were removed. Then the cochlear materials from each groups were pooled and homogenized respectively, extracted the total RNA, obtained cDNA from purified total RNA by reversed transcription, cDNA were transcripted to cRNA probes in vitro. Hybridized the cRNA probes with tester chip to evaluate the quality of probes, if good, hybridized the probes with real chip. Obtained three gene expression profiles of different groups of cochlea Analyzed the differentially expressed genes among three groups by SOM. Analogized the SOM result to electrophysiologic changes. Then analyzed the genes in clusters of analog results by Gene Ontology. Then the genes in clusters of analog results were analyzed by Gene Ontology. Hsp27 was chosen to validate the result of gene chip using real time quantitative reverse transcription PCR ( RTQ RT-PCR)., Results: The probes was good, and the chip hybridization results was credible. We obtained 6 clusters genes by SOM analysis, in which we choose cluster 3 and cluster 4 as candidate cluster. There were 46 genes in cluster 3 and 30 genes in cluster 4 employing GO analysis, which involved in cell communication, cell motility, metabolism, immune response and nerve ensheathment, et al. The result of RTQ RT-PCR showed high concordance with that of gene chip., Conclusion: It's a new method to study the mechanism of electrophysiologic changes caused by sodium salicylate by gene chip and SOM analysis.

Objective: To investigate the effects of sodium salicylate and extracellular K(+) on the functions of outer hair cells (OHCs) and the relations between their actions., Methods: Sodium salicylate at the concentration of 1 mmol/L was administered either alone or following 10 mmol/L KCl into the extracellular solution of OHCs isolated from guinea pig cochlea. The outward potassium current (IK) and resting potential (RP) of OHCs was measured using patch-clamp whole cell recording technique., Results: Time-dependent changes in the effect of sodium salicylate on IK was observed, namely, IK underwent transient increase and then declined after sodium salicylate administration. When KCl was administered previously into the extracellular solution, the effect of sodium salicylate on IK was reduced. Sodium salicylate could decrease RP but not time-dependently in the absence of KCl, and when prior KCl treatment was administered, only temporary increase in RP took place before RP returned to the level before sodium salicylate administration.??, Conclusions: The effects of sodium salicylate on OHC functions were related to K(+), and the former agent may affect K(+) conduction and internal and external distribution of K(+) in OHCs, and causes the changes in the excitability and mechanical activity of OHCs by means of affecting IK and RP. This hypothesis might be one of the cochlear mechanisms by which sodium salicylate affects OHC functions.

Objectives: To study effects of sodium salicylate on the outward potassium current (IK), resting potential (RP) and membrane electric capacitance (MEC) of outer hair cells isolated from guinea pig cochleas and the cytoelectrophysiological mechanisms of effects of sodium salicylate on functions of hair cells., Methods: Using the patch-clamp whole cell recording technique, IK, RP and MEC were measured before and after the administration of sodium salicylate at concentration of 0.1 or 1.0 mmol/L. The effects of sodium salicylate on IK, RP and MEC were observed., Results: The effects of sodium salicylate on IK had time- and dosage-effect relations, of which the former mean IK increasing and then decreasing after administration, the later meant that the effects of sodium salicylate being much more dominant during either increasing or decreasing IK in higher concentration than in lower concentration. The mean RP was approximately--60 mV and the mean MEC was approximately 39 pF. Sodium salicylate could decrease RP and MEC, which possessed a dosage-effect relation, that is, the effect was stronger in higher concentration than in lower concentration, and there was no clear evidence for time-effect relation., Conclusions: The sodium salicylate might affect the K+ conduction at the lateral membrane and internal and external distribution of K+ in the outer hair cell. Sodium salicylate might affect the excitability and mechanical activity of the outer hair cell by means of affecting IK, RP and MEC, which might be one of the cochlear mechanisms of the effects of sodium salicylate on the functions of hair cells.