Effect of Kidney-nourishing,Blood-activating,Phlegm-resolving and Resuscitation-inducing Decoction on Expression of NMDA Receptor Subtypes in Cochlear Spiral Ganglion Neurons of Tinnitus Rats / 广州中医药大学学报

Objective To observe the effect of Kidney-nourishing, Blood-activating, Phlegm-resolving and Resuscitation-inducing Decoction(KBPRD)on the expression of N-methyl-D-aspartate(NMDA)receptor subtype 1,2A,2B(NR1,NR2A,NR2B)in the cochlear spiral ganglion neurons(SGN)of tinnitus rats and to explore its mechanism, thus to provide experimental evidence for the treatment of tinnitus with KBPRD. Methods Sixty rats were randomly divided into normal group,model group,western medicine group,and low-,middle-,and high-dose Chinese medicine groups, 10 rats in each group. Rats were given intraperitoneal injection of sodium salicylate combined with water deprivation to induce tinnitus model. After successful establishment of the model, the rats in low-,middle-,and high-dose Chinese medicine groups were given gastric administration of KBPRD in the dosage of 5.5, 11, 22 g·kg-1·d-1 respectively, the rats in western medicine group were given gastric administration of 5 mg·kg-1·d-1 of carbamazepine,and rats in the model group and normal group were given gastric administration of 2 mL of normal saline,once every day,treatment time covering 8 weeks. The expression levels of NR1,NR2A,and NR2B in the cochlear SGN was detected by immunoblotting and real-time quantitative reverse transcription-polymerase chain reaction(qRT-PCR)after 8 weeks of treatment. Results Compared with the normal group,the expression levels of NR1, NR2A and NR2B in the model group were increased, the difference being significant (P < 0.05). Compared with the model group,the expression of NR1,NR2A and NR2B in low-,middle-,and high-dose Chinese medicine groups were significantly decreased(P<0.05).Conclusion KBPRD is effective on relieving tinnitus of rats, and its mechanism is correlated with lowering the increased expression of NR1,NR2A and NR2B in SGN of tinnitus rats.

Correlation of PDCD5 and Apoptosis in Hair Cells and Spiral Ganglion Neurons of Different Age of C57BL/6J Mice / 华中科技大学学报（医学）（英德文版）

This study examined the expression pattern of programmed cell death 5 (PDCD5) in cochlear hair cells and spiral ganglion neurons (SGNs) and its association with age-related hearing loss in mice.Sixty C57BL/6J (C57) mice at different ages were divided into four groups (3,6,9 or 12 months).PDCD5 expression was detected by using immunohistochemistry,real-time PCR and Western blot.Morphological change of the cochleae was also evaluated by using immunoassay.The results showed that the expression of PDCD5 had a gradual increase with ageing in both protein and RNA levels in C57 mice,as well as gradually increased apoptosis of cochlear hair cells and SGNs.In addition,we also found that caspase-3 activity was enhanced and its expression was enhanced with ageing.It is implied that overexpression of PDCD5 causes the increase in caspase-3 activity and the subsequent increase of apoptosis in cochlear hair cells and SGNs,and thereby plays a role in the pathogenesis of presbycusis.Thus,PDCD5 may be a new target site for the treatment and prevention of age-related hearing loss.

The Effect of Ginkgo Biloba on the Survival of Spiral Ganglion Neurons in Rats / 대한이비인후과학회지

BACKGROUND AND OBJECTIVES: Ginkgo biloba extract (GBE) enhances cell survival in various organs. GBE protects nerve cells in the central nervous system and is clinically applied in Parkinson's and Alzheimer's disease. GBE can protect ototoxicity caused by cisplantin and gentamycin through rescue of hair cells in Organ of Corti and is accepted as one of the therapeutic agents for sudden deafness and tinnitus. The experimental study on GBE for the inner ear is confined to the hair cells, not to the spiral ganglion neurons (SGNs) which is the stimulated part by the electrode of cochlear implant. The aim of this study is to elucidate the effect of GBE on the survival of SGNs after hair cell loss in rats. MATERIALS AND METHOD: Ten Sprague-Dawley rats aged 50 days (P50) were deafened with kanamycin sulfate. GBE (EGb 761) was injected into the right cochlea and artificial perilymph was injected into the left side. The number and size of SGNs were compared after immunohistochemical statin in both groups. The expression of pJun, which is well-known as a proapoptotic transcription factor in the cochlea, was also compared. RESULTS: The number of SGNs was significantly larger in the GBE group than the control. The expression of pJun activity was significantly decreased in GBE group than the control. The size of SGNs in both groups was similar. CONCLUSION: These results suggest that GBE can protect SGNs death by inhibiting the pJun-C-jun N-terminal kinase pathway. GBE might be a potential drug for the patients with total deafness before or after cochlear implantation surgery for better hearing results.

Electrophisiologic study of routine spiral ganglion neurons / 临床耳鼻咽喉头颈外科杂志

Objective: To explore the nature of voltage dependent ion channels and basic electrophysiological characteristics of cochlear spiral ganglion neurons of apical and basal turn by patch clamp techniques of whole cell configure on murine spiral ganglion neurons. Method: Different voltage dependent ionic currents were recorded with patch clamp techniques of whole cell configure on the condition of different internal electrode solution,blockers and stimulus protocol. Result: Inward sodium channel current(I_(Na)), hyperpolarization-activated inward cationic current(I_h) ,outward delay rectification potassium current (I_k) and outward transient potassium current (I_A)were recorded , significant difference of electrophysiological characteristics of I_A and I_k was found between apical and basal turns(P＜0.05). Conclusion: Various ionic currents are recorded,which shows that spiral ganglion neurons have the base of ionic channels to complete formation,conduction and modulation of action potential for auditory information transduction, the difference of electrophysiological characteristics between apical and basal turns contributes to the course of hearing formation.

Preliminary Study on Firing Patterns of Murine spiral Ganglion Neurons by Patch-clamp Technique / 听力学及言语疾病杂志

Objective To investigate the fire patterns of the primary cultured postnatal mouse spiral ganglion neurons.Methods Current-clamp recordings with the use of the whole cell configuration of the patch-clamp technique were made from the primary cultured spiral ganglion neurons. Results The action potential was recorded from the spiral ganglion neurons. The neurons had non-uniform firing characteristics. Conclusion There were two firing patterns observed in the spiral ganglion neurons, rapid adaptation, and slow adaptation and the largest neurons showing rapidly adapting.