-
[show abstract]
[hide abstract]
ABSTRACT: The time course of aminoglycoside neurotoxic effect on cochlear nucleus is still obscure. We examined dynamic pathological changes of dorsal cochlear nucleus (DCN) and investigated whether apoptosis or autophagy was upregulated in the neurotoxic course of kanamycin on DCN after kanamycin treatment. Rats were treated with kanamycin sulfate/kg/day at dose of 500mg by subcutaneous injection for 10 days. Dynamic pathological changes, neuron density and neuron apoptosis of the DCN were examined at 1, 7, 14, 28, 56, 70 and 140 days after kanamycin treatment. The expression of JNK1, DAPK2, Bcl-2, p-Bcl-2, Caspase-3, LC3B and Beclin-1 were also detected. Under transmission electron microscopy, the mitochondrial swelling and focal vacuoles as well as endoplasmic reticulum dilation were progressively aggravated from 1 day to 14 days, and gradually recovered from 28 days to 140 days. Meanwhile, both autophagosomes and autolysosomes were increased from 1 day to 56 days. Only few neurons were positive to the TUNEL staining. Moreover, neither the expressions of caspase-3 and DAPK2 nor neurons density of DCN changed significantly. LC3-II was drastically increased at 7 days. Beclin-1 was upgraded at 1 and 7 days. P-Bcl-2 increased at 1, 7, 14 and 28 days. JNK1 increased at 7 days, and Bcl-2 was downgraded at 140 days. LC3-B positive neurons were increased at 1, 7 and 14 days. These data demonstrated that the neurons damage of the DCN caused by kanamycin was reversible and autophagy was upregulated in the neurotoxic course of kanamycin on DCN through JNK1-mediated phosphorylation of Bcl-2 pathway.
Brain research 01/2013; · 2.46 Impact Factor
-
Zhonghua er bi yan hou tou jing wai ke za zhi = Chinese journal of otorhinolaryngology head and neck surgery 01/2012; 47(1):3-5.
-
[show abstract]
[hide abstract]
ABSTRACT: Aging has been associated with mitochondrial DNA damage. P66Shc is an age-related adaptor protein that has a substantial impact on mitochondrial metabolism through regulation of the cellular response to oxidative stress. Our study aimed to establish a D-galactose (D-gal)-induced inner ear aging mouse model and to investigate the potential role of p66Shc and its serine 36-phosphorylated form in the inner ear during aging by using this model. Real-time PCR was performed to detect the mtDNA 3873-bp deletion and the level of p66Shc mRNA in the cochlear lateral wall. Western blot analysis was performed to analyze the total and mitochondrial protein levels of p66Shc and the level of Ser36-P-p66Shc in the cochlear lateral wall. Immunofluoresence was performed to detect the location of the Ser36-P-p66Shc expression in the cochlear lateral wall. The results showed that the accumulation of the mtDNA 3873-bp deletion, total and mitochondrial protein levels of p66Shc and level of Ser36-P-p66Shc were significantly increased in the cochlear lateral wall of the D-gal-treated group when compared to the control group and that Ser36-P-p66Shc was mainly localized in the cytoplasm of the cells in the stria vascularis. During aging, the oxidative stress-related increase of p66Shc and Ser36-P-p66Shc might be associated with the accumulation of the mtDNA 3873-bp deletion in the inner ear.
PLoS ONE 01/2012; 7(11):e50483. · 4.09 Impact Factor
-
[show abstract]
[hide abstract]
ABSTRACT: Computed tomography (CT) scan with three-dimensional (3D) reconstruction of the inner ear provides a more accurate image of the relationship of the electrode within the cochlear canal, with direct demonstration of electrode insertion depth in the cochlea in comparison with X-ray plain film.
This study was designed to evaluate the value of spiral CT scans with 3D reconstruction in determining the insertion site and depth of implanted cochlear implant electrodes.
A total of 172 cochlear implant recipients were involved in this study. The implanted electrodes of all patients were examined by X-ray plain film, and 157 cochlear recipients were examined by spiral CT scans with axial 1 mm image slices. The data from the CT scans were transferred to a workstation for 3D reconstruction (direct volume rendering) of the inner ear. The pseudocolor technique was used to display the electrode.
The insertion depth of the electrode could be evaluated indirectly by the X-ray plain film. In contrast, the stereoscopic images from a CT scan with 3D reconstruction of the inner ear demonstrated the shape, position, and insertion depth of the electrode more accurately.
Acta oto-laryngologica 11/2011; 132(2):116-22. · 0.98 Impact Factor
-
[show abstract]
[hide abstract]
ABSTRACT: Mitochondrial DNA (mtDNA) mutations, especially deletions, have been suggested to play an important role in aging and degenerative diseases. In particular, the common deletion in humans and rats (4977bp and 4834bp deletion, respectively) has been shown to accumulate with age in post-mitotic tissues with high energetic demands. Among numerous deletions, the common deletion has been proposed to serve as a molecular marker for aging and play a critical role in presbyacusis. However, so far no previous publication has quantified the contribution of common deletion to the total burden of mtDNA deletions in tissues during aging process. In the present study, we established a rat model with various degrees of aging in inner ear induced by three different doses of d-galactose (d-gal) administration. Firstly, multiple mtDNA deletions in inner ear were detected by nested PCR and long range PCR. In addition to the common deletion, three novel mtDNA deletions were identified. All four deletions, located in the major arc of mtDNA, are flanked by direct repeats and involve the cytochrome c oxidase (COX) subunit III gene, encoded by mtDNA. Additionally, absolute quantitative real-time PCR assay was used to detect the level of common deletion and total deletion burden of mtDNA. The quantitative data show that the common deletion is the most frequent type of mtDNA deletions, exceeding 67.86% of the total deletion burden. Finally, increased mtDNA copy number, reduced COX activity and mosaic ultrastructural impairments in inner ear were identified in d-gal-induced aging rats. The increase of mtDNA replication may contribute to the accelerated accumulation of mtDNA deletions, which may result in impairment of mitochondrial function in inner ear. Taken together, these findings suggest that the common deletion may serve as an ideal molecular marker to assess the mtDNA damage in inner ear during aging.
Mutation Research/Fundamental and Molecular Mechanisms of Mutagenesis 07/2011; 712(1-2):11-9. · 2.85 Impact Factor
-
[show abstract]
[hide abstract]
ABSTRACT: Oxidative damage to mtDNA is associated with excessive reactive oxygen species production. The mitochondrial common deletion (mtDNA 4977-bp and 4834-bp deletion in humans and rats, respectively) is the most typical and frequent form of mtDNA damage associated with aging and degenerative diseases. The accumulation of the mitochondrial common deletion has been proposed to play a crucial role in age-related hearing loss (presbycusis). However, the mechanisms underlying the formation and accumulation of mtDNA deletions are still obscure. In the present study, a rat mimetic aging model induced by D-Gal was used to explore the origin of deletion mutations and how mtDNA repair systems modulate this process in the inner ear during aging. We found that the mitochondrial common deletion was greatly increased and mitochondrial base excision repair capacity was significantly reduced in the inner ear in D-Gal-treated rats as compared with controls. The overexpression of mitochondrial transcription factor A induced by D-Gal significantly stimulated mtDNA replication, resulting in an increase in mtDNA copy number. In addition, an age-related loss of auditory sensory cells in the inner ear was observed in D-Gal-treated rats. Taken together, our data suggest that mitochondrial base excision repair capacity deficiency and an increase in mtDNA replication resulting from mitochondrial transcription factor A overexpression may contribute to the accumulation of mtDNA deletions in the inner ear during aging. This study also provides new insights into the development of presbycusis.
FEBS Journal 05/2011; 278(14):2500-10. · 3.79 Impact Factor
-
[show abstract]
[hide abstract]
ABSTRACT: A better animal model of autoimmune inner ear disease (AIED) in Sprague-Dawley rats has been developed by combination with high dose of pertussis toxin. This study also indicated that inner ear-specific antigens can be involved in autoimmune reactions. Cell-mediated immune injury can play an important role in the induction of AIED, at least in the earlier stage.
The purpose of this study was to develop a more suitable rat model that demonstrated closer resemblance to the pathophysiological process in AIED.
Ninety-six female Sprague-Dawley rats were divided into four groups. They were subcutaneously immunized with crude inner ear antigen/complete Freund's adjuvant (CIEAg/CFA), or intraperitoneal injection of 500 ng pertussis toxin (PT), or injection of CIEAg/CFA+PT, or phosphate-buffered saline (PBS) alone. The auditory function, histopathology of the inner ear, and autoantibodies were examined.
Significant differences in the time course of auditory brainstem response (ABR) threshold and mean score of cellular infiltration were demonstrated in the CIEAg/CFA+PT group of animals. Missing hair cells, degeneration of the spiral ganglion cells, endolymphatic hydrops, and autoantibodies were all noted after immunization. There were no significant differences in ABR threshold or histopathology in any other group of animals.
Acta oto-laryngologica 03/2011; 131(7):692-700. · 0.98 Impact Factor
-
[show abstract]
[hide abstract]
ABSTRACT: To evaluate the function of vestibular ocular reflex (VOR) in patients with unilateral peripheral vestibular disorder (uPVD) by the head impulse test (HIT).
The HIT and caloric test were carried out in 135 cases of patients with uPVD. The results of HIT were considered as normal (negative reaction) and abnormal (positive reaction). The results of vestibular function evaluated by caloric test were divided into three kinds, including normal, decreased and deficit according to the degree of canal paresis as less than 30 percent, from 30 to 99 percent, and equal to 100 percent, respectively. The sensitivity, specificity, positive and negative predictive value of HIT in assessing the vestibular function was analyzed.
For the 135 patients with uPVD, the HIT was normal in 90 (66.7%) cases and abnormal in 45 (33.3%) cases. When the caloric test was normal, the HIT was normal or abnormal in 58 cases and 6 cases, respectively. And when the canal paresis was from 30 to 99 percent, the HIT was normal or abnormal in 28 and 24 cases, respectively. When the vestibular function was deficit (CP was 100%), the HIT was normal or abnormal in 4 cases and 15 cases, respectively. When the results of caloric test were considered as the standard method to evaluate the VOR, the sensitivity, specificity, positive and negative predictive value of HIT were 54.9%, 90.6%, 86.7%, and 64.4%, respectively.
When assessing the function of VOR in patients with uPVD, the HIT could not replace the caloric test, but it can be a supplementary method. The information from both the HIT and caloric test can be combined to evaluate the patients with vestibular hypofunction comprehensively.
Zhonghua er bi yan hou tou jing wai ke za zhi = Chinese journal of otorhinolaryngology head and neck surgery 01/2011; 46(1):40-3.
-
[show abstract]
[hide abstract]
ABSTRACT: Aging has been associated with mitochondrial DNA (mtDNA) common deletion (CD). Age changes in the central auditory system are well known to affect speech perception. Base excision repair (BER) is the major type of DNA repair in mitochondria. The current study was designed to investigate potential causative mechanisms of central presbycusis by using a rat mimetic aging model induced by subcutaneous administration of D-galactose (D-gal). Quantitative real-time PCR and Western blotting analyses were performed to identify the mtDNA 4834 bp deletion and selected mitochondrial DNA repair enzymes, DNA polymerase γ (pol γ) and 8-oxoguanine DNA glycosylase (OGG1). Cell apoptosis in the auditory cortex was detected using terminal deoxynucleotidyltransferase mediated UTP nick-end labeling (TUNEL). Our data showed that mtDNA 4834 bp deletion and TUNEL-positive cells were significantly increased and the expression of pol γ and OGG1 were remarkably down-regulated in the auditory cortex in D-gal-treated rats compared to control rats. During aging, increased mtDNA damage likely results from decreased DNA repair capacity in the auditory cortex. DNA repair enzymes such as pol γ and OGG1 may provide novel pharmacological targets to promote DNA repair and rescue the central auditory system in patients with degenerative diseases.
Molecular Biology Reports 11/2010; 38(6):3635-42. · 2.93 Impact Factor
-
[show abstract]
[hide abstract]
ABSTRACT: One of the most common complaints among aging individuals is difficulty in understanding speech in a compromised listening environment, such as when background noise is present. Age-related hearing loss (presbycusis) is associated with both peripheral and central neural processing deficits, as it occurs even in those with only a mild peripheral hearing impairment. The current study was designed to investigate potential causative mechanisms of this impairment by using a rat model in which presbycusis is inducible by administration of D-galactose (D-gal). One group of these rats was injected subcutaneously with 150 mg D-gal daily for 8 weeks, while control animals received vehicle only. These groups were compared to naturally aged rats (24 months) that had received no other treatment. Central auditory function of the three groups was evaluated by measuring the auditory brainstem response (ABR) and middle latency response (MLR). A TaqMan real time PCR assay was used to quantify a 4834-bp deletion in the mitochondrial DNA (mtDNA) of the auditory cortex (AC), inferior colliculus (IC) and cochlear nucleus (CN). We assessed changes in lipid peroxidation levels and apoptosis rates, and examined pathological changes corresponding to D-gal-induced aging and natural aging. Both groups of aged rats exhibited delayed ABR latencies (III, IV, V), MLR Pa latency, and I-IV interpeak latency. Moreover, increased mtDNA 4834 bp deletion rates, lipid peroxidation levels, rates of neuronal apoptosis and neurodegenerative changes in the AC, IC and CN were similar among the D-gal induced and NA rats. However, the threshold of ABR in the D-gal group showed no significant change from the control group. These observations suggest that age-related central auditory dysfunction and its corresponding pathological changes are present in both naturally aging rats and the D-gal mimetic aging model. Oxidative stress, large-scale mtDNA 4834 bp deletion, and apoptosis are likely to be involved in the progressive weakening of the central auditory system associated with the aging process.
Brain research 07/2010; 1344:43-53. · 2.46 Impact Factor
-
Cancer biology & therapy 07/2010; 10(1):110. · 2.64 Impact Factor
-
[show abstract]
[hide abstract]
ABSTRACT: To investigate the effects of trans-cinnamaldehyde (TCA) on the human leukemia K562 cell line and the cytotoxicity of cytokine-induced killer (CIK) cells against K562 cells.
Apoptosis, Fas expression, and mitochondrial transmembrane potential in K652 cells were analyzed using flow cytometry. K562 cells were labeled with CFSE. The cytotoxic effect of expanded CIK cells on CFSE-labeled K562 cells was determined by FACS flow cytometry.
Treatment with TCA 180 micromol/L for 9 h induced apoptosis in 8.9%+/-1.23% of K562 cells. Treatment with 120 or 180 micromol/L TCA for 24 h significantly increased the apoptotic cells to 18.63%+/-1.42 % and 38.98%+/-2.74%, respectively. TCA significantly upregulates Fas expression and decreases mitochondrial transmembrane potential in K562 cells. TCA treatment at 120 and 180 micromol/L for 9 h enhanced the percentage of lysis of K562 cells by expanded CIK cells from 34.84%+/-2.13% to 48.21%+/-2.22 % and 64.81%+/-3.22% at the E:F ratio of 25:1 and from 49.26%+/-3.22% to 57.81%+/-5.13% and 73.36%+/-5.98% at E:F ratio of 50:1.
TCA exerts cytotoxic effects on human leukemia K562 cells by inducing apoptosis and synergizing the cytotoxicity of CIK cells against K562 cells. These properties of TCA are beneficial to the treatment of leukemia, even in the patients who have received hematopoietic stem cells transplantation (HSCT).
Acta Pharmacologica Sinica 07/2010; 31(7):861-6. · 1.95 Impact Factor
-
Biochemical and Biophysical Research Communications 06/2010; · 2.48 Impact Factor
-
[show abstract]
[hide abstract]
ABSTRACT: To investigate the effect of early allergen exposure on later development of allergic rhinitis in mouse.
Twenty-four BALB/c neonates were randomly divided into 4 groups (low-dose group, high-dose group, negative control group and positive control group), each group had 6 mice. The mice were administered ovalbumin (OVA) by subcutaneous injection on day 1, 5, 12 after birth (10 μg OVA in 0.05 ml saline for low-dose group, 1000 μg OVA in 0.05 ml saline for high-dose group, only saline for negative and positive control group). Then the mice were sensitized and intranasally challenged with OVA (saline without OVA was used in negative control group) after 6 weeks. Symptoms, histopathological changes of nasal mucosa were observed, OVA-IgE in serum was examined, cytokines IL-4, IL-5 and IFN-gamma were detected in the supernatant of cultured splenic mononuclear cells.
Compared to the positive control group, symptoms and nasal mucosa histological changes of high-dose group was indistinctive. The level of OVA-IgE and cytokines IL-4, IL-5 (x(-) +/- s) in high-dose group [(265.11 +/- 26.29), (446.39 +/- 72.83) and (171.24 +/- 15.66) pg/ml, respectively] were significantly lower than those in positive control group [(665.85 +/- 43.15), (1113.45 +/- 30.47), (255.36 +/- 30.96) pg/ml, respectively, t value were 0.000, 0.000 and 0.009, respectively, all P < 0.05]. The level of IFN-γ in high-dose group [(319.74 +/- 56.30) pg/ml] was significantly higher than those in positive control group [(170.02 +/- 14.50) pg/ml, t = 0.000, P < 0.05]. There was no significant difference of the results between the low-dose group and positive control group.
Neonatal immunization with high-dose OVA inhibited the future allergic rhinitis symptoms, nasal histological changes, serum OVA-IgE levels and Th1/Th2 cytokine imbalance, resulting in the protective effect.
Zhonghua er bi yan hou tou jing wai ke za zhi = Chinese journal of otorhinolaryngology head and neck surgery 01/2010; 45(1):52-5.
-
[show abstract]
[hide abstract]
ABSTRACT: determine the feasibility of manganese superoxide dismutase (MnSOD) gene therapy for protecting the cochlear function against aminoglycoside-induced oxidative stress in aging rats.
The aging model of SD rats were obtained with 8 weeks daily of D-gal (150 mg/kg per day) hypodermic injection. In the 9th week, amikacin (500 mg/kg per day) were injected intramuscularly into some aging SD rats. The viral particles of recombinant adeno-associated viral vector II/MnSOD (6 microl, 5 x 10(11) vector genomes/ml) were injected into the perilymph through the round window membrane (RWM). The feasibility of MnSOD gene therapy against aminoglycoside-induced oxidative stress in aging rats was evaluated with the methods of caspase-3 protein analysis, apoptosis detection with immunohistochemical, the detection of MnSOD concentration, stretched preparation of basilar membrane and evaluation of hearing threshold with ABR-click.
Compared with the control group, the concentration of MnSOD of cochlear tissue was increased (P < 0.05), and the active fragment expression of caspase-3, the numbers of apoptosis bodies and the hearing threshold were decreased (P < 0.05).
MnSOD could play a partly role to treat cochlear aminoglycoside-induced oxidative damage in aging rats.
Zhonghua er bi yan hou tou jing wai ke za zhi = Chinese journal of otorhinolaryngology head and neck surgery 08/2009; 44(8):657-63.
-
[show abstract]
[hide abstract]
ABSTRACT: To determine which of the two, recombinant adeno-associated viral vector 2 (rAAV2) and recombinant adenovirus vector 5 (rAd5), is more suitable for gene transfer in rodent cochlea.
The rAAV2-EGFP and rAd5-EGFP particles were injected into the perilymph through round window membrane. The target tissue accessibility, time course of expression, tissue toxicity of gene transfer and effects on hearing were evaluated.
The expression of EGFP was detected in spiral ligament, strial vascukarises, Reissner membrane, basilar membrane, spiral ganglion, and contralateral cochlea. EGFP expression in the rAAV2 lasted over 60 days, with peak expression between days 14 and 60. EGFP in the rAd5 was detected within 24 h of transfection, and peak expression was observed between days 1 to 21. EGFP activity decreased sharply on day 30 after transfection with rAd5, while high EGFP expression was observed 60 days after transfection with rAAV2.
AAV has significant advantages for long-term transgene expression and no ototoxicity in the cochlea compared to adenovirus vectors.
Zhonghua yi xue za zhi 06/2009; 89(19):1351-5.
-
[show abstract]
[hide abstract]
ABSTRACT: To evaluate the treatment responses of persistent allergic rhinitis with and without nasal discharge eosinophilia (EOS) to inhaled glucocorticosteroid (CS), and therefore to verify whether low nasal discharge eosinophils predict poor response to treatment with CS.
Forty-two symptomatic allergic rhinitis patients, who had not received CS therapy in three months preceding the study, were examined before and 2 month,4 months and 6 months after treatment with CS. At each visit, all patients underwent symptom scoring and physical sign scoring. The level of eosinophil cationic protein (ECP) in the nasal discharge supernatants was measured by radioimmunoassay. The patients were divided into 2 groups according to nasal discharge EOS percentages, an EOS group (group A, EOS > or = 0.03) and a non-EOS group (group B, EOS < 0.03). The response to CS therapy (as measured by symptom and physical sign scores) and the changes of nasal discharge measurements were compared between the 2 groups.
In the group A, the baseline EOS [0.086 (0.065; 0.176)] and ECP level [(326 +/- 145) microg/L] were significantly higher than those of the group B [0.016 (0.005; 0.022)] and ECP level (154 +/- 58) microg/L], respectively, t = 4.40, 3.33, both, all P < 0.01. After 2 month and 6 months CS therapy, the nasal discharge EOS, ECP pred were 0.038 (0.006; 0.070), 0.019 (0.010; 0.060), (175 +/- 122) microg/L, (175 +/- 153) microg/L, respectively in the EOS group, which were significantly different as compared to baseline values (F = 6.73, 7.38, respectively, all P < 0.05). But in the non-EOS group, the nasal discharge EOS ECP pred were 0.014 (0.004; 0.032), 0.015 (0.000; 0.026), (118 +/- 60) microg/L, (112 +/- 60) microg/L, respectively at 2 and 6 months, which showed that the the nasal discharge EOS pred and the symptom and physical sign scores improved did not change (F = 0.82, P > 0.05), but the ECP level improved (F = 3.78, P < 0.05). and the average daily dose of CS wear not different between the two groups at any visits.
In persistent allergic rhinitis with low nasal discharge EOS, CS therapy for 6 months failed to improve symptom and physical sign.
Zhonghua er bi yan hou tou jing wai ke za zhi = Chinese journal of otorhinolaryngology head and neck surgery 03/2009; 44(3):209-13.
-
[show abstract]
[hide abstract]
ABSTRACT: To evaluate the Integrated Cochlear Profile for Assessing Auditory Nerve-Auditory Pathway Integrity (ICP-API), as proposed by our group, in the selection of cochlear implant candidates.
The API of the candidates for cochlear implantation were assessed with the ICP-API, which consists of 5 categories including: audiological testing; radiological imaging study; ear-canal electric response audiometry; response to environmental sounds; speech development level. The auditory rehabilitation effects of the cochlear implantation receivers were evaluated postoperatively.
Sixty-six of 68 candidates who met the criteria of the ICP-API received cochlear implantation with improved hearing and speech development postoperatively. The remaining 2 of the 68 candidates were diagnosed with bilateral auditory nerves aplasia, and therefore failed cochlear implants were avoided.
The ICP-API is valuable and feasible for the selection of cochlear implant candidates. The API should be considered as one of the most important criteria for cochlear implant candidate selection.
ORL 02/2009; 71(4):196-208. · 0.91 Impact Factor
-
[show abstract]
[hide abstract]
ABSTRACT: A trans-superior meatus endoscopic approach to treat diseases in the sphenoid sinus and sellar area is a safe, minimally traumatic, and effective method.
To avoid complications, we explored the use of the superior meatus and superior turbinate in the endoscope approach to the sphenoid sinus and sellar area.
This was a retrospective analysis of the curative effect of the trans-superior meatus approach for diseases in the sphenoid sinus and sellar area in 138 cases.
All of 138 patients had successful operations and no serious complication occurred. All cases were followed up for a period of 1-3 years. No recurrence was found in 94 patients with isolated sphenoid sinus disease (sinusitis, mucoceles, or mycosis). Of 24 patients with pituitary adenoma, 17 patients had entire resection and no recurrence was found. Four patients had subtotal resection and three patients had partial resection with postoperative radiotherapy, and preoperative symptoms were improved. Of 13 cases of cerebrospinal rhinorrhea in the sphenoid sinus, 12 cases were successfully repaired by a single operation and 1 case was successfully repaired by a repeat operation. Among seven cases with decompression of the optic canal, four had obvious effect, two cases showed improvement, and there was no improvement in one case.
Acta Oto-Laryngologica 12/2008; 128(11):1233-7. · 1.08 Impact Factor
-
[show abstract]
[hide abstract]
ABSTRACT: To study the membrane properties of rat medial vestibular nucleus (MVN) neurons and their firing responses to simulated input signals of peripheral vestibular system, and to discuss how the intrinsic membrane properties contribute to physiologic functions in central vestibular system.
By using infrared differential interference contrast technique, whole-cell recordings were made from rat MVN neurons under direct observation. On the basis of their averaged action potential shapes, the MVN neurons were classified. Linear and non-linear currents were put into the neurons to simulate the input signals of peripheral vestibular system. The differences of intrinsic membrane properties and firing response dynamics were observed between two types.
The discharge activities were recorded in MVN neurons, which remained in low Ca2+-high Mg2+ artificial cerebrospinal fluid (ACSF). Neurons are classified as type A (33%) characterized by a single deep after-hyperpolarization (AHP) and A-like rectification, or type B (63%) characterized by double AHP, and another two neurons with all or none of the characters. The passive membrane properties were not significantly different between type A and type B neurons, while part of active membrane properties was significantly different. Both type A and B neurons well responded to simulated current inputs, but disparities existed in response range and firing dynamics.
The discharge activities of MVN neurons were initiated by their intrinsic membrane properties. Most MVN neurons were classified as type A and B, while several showed unrepresentative firing properties. Linear and nonlinear inputs evoked a heterogeneous range of firing responses. The differences of response range and firing dynamics between neurons may determine their different physiological functions.
Zhonghua er bi yan hou tou jing wai ke za zhi = Chinese journal of otorhinolaryngology head and neck surgery 11/2008; 43(10):767-72.
