Post-exposure treatment with ginsenoside compound K ameliorates auditory functional injury associated with noise-induced hearing loss in mice

Noise-induced hearing loss (NIHL) is thought to primarily involve damage to the sensory hair cells of the cochlea via mechanical and metabolic mechanisms. Unfortunately, initial studies assessing the effectiveness of post-exposure treatment after hearing loss have yielded largely disappointing results. This study explored the effects of oral treatment with Korean red ginseng (RG) and with two bioavailable ginsenoside metabolites, ginsenoside Rh1 and ginsenoside compound K (GCK), in response to NIHL in a murine model. Pharmacological treatments began 24h after noise exposure and were continued once daily for 7 days. Central auditory function was evaluated using auditory middle latency responses, and cochlear function was determined based on transient evoked otoacoustic emissions. Additionally, cochlear hair cell morphology was investigated after noise exposure. Both Korean red ginseng and compound K reduced threshold shifts, central auditory function damage, and cochlear functional and morphological deficits. In contrast, treatment with ginsenoside Rh1 did not result in recovery of NIHL in mice. These results suggest that consumption of Korean red ginseng may facilitate recovery from noise-induced hearing loss. Furthermore, one of the active constituents in ginseng is likely ginsenoside compound K.     

Basic helix-loop-helix gene Hes6 delineates the sensory hair cell lineage in the inner ear.

The basic helix-loop-helix (bHLH) gene Hes6 is known to promote neural differentiation in vitro. Here, we report the expression and functional studies of Hes6 in the inner ear. The expression of Hes6 appears to be parallel to that of Math1 (also known as Atoh1), a bHLH gene necessary and sufficient for hair cell differentiation. Hes6 is expressed initially in the presumptive hair cell precursors in the cochlea. Subsequently, the expression of Hes6 is restricted to morphologically differentiated hair cells. Similarly, the expression of Hes6 in the vestibule is in the hair cell lineage. Hes6 is dispensable for hair cell differentiation, and its expression in inner ear hair cells is abolished in the Math1-null animals. Furthermore, the introduction of Hes6 into the cochlea in vitro is not sufficient to promote sensory or neuronal differentiation. Therefore, Hes6 is downstream of Math1 and its expression in the inner ear delineates the sensory lineage. However, the role of Hes6 in the inner ear remains elusive.     

Inhaled hydrogen gas therapy for prevention of noise-induced hearing loss through reducing reactive oxygen species

Reactive oxygen species (ROS) that form in the inner ear play an important role in noise-induced hearing loss (NIHL). Recent studies have revealed that molecular hydrogen (H₂) has great potential for reducing ROS. In this study, we examined the potential of hydrogen gas to protect against NIHL. We tested this hypothesis in guinea pigs with 0.5%, 1.0% and 1.5% H₂ inhalation in air for 5 h a day after noise exposure, for five consecutive days. All animals underwent measurements for auditory brainstem response after the noise exposure; the results revealed that there was a better improvement in the threshold shift for the 1.0% and 1.5% H₂-treated groups than the non-treated group. Furthermore, outer hair cell (OHC) loss was examined 7 days after noise exposure. A significantly higher survival rate of OHCs was observed in the 1.0% and 1.5% H₂-treated group as compared to that of the non-treated group in the basal turn. Immunohistochemical analyses for 8-hydroxy-2′-deoxyguanosine (8-OHdG) were performed to examine the amount of oxidative DNA damage. While strong immunoreactivities against 8-OHdG were observed of the non-treated group, the H₂-treated group showed decreased immunoreactivity for 8-OHdG. These findings strongly suggest that inhaled hydrogen gas protects against NIHL.     

Noise-induced cell death in the mouse medial geniculate body and primary auditory cortex

Noise-induced effects within the inner ear have been well investigated for several years. However, this peripheral damage cannot fully explain the audiological symptoms in noise-induced hearing loss (NIHL), e.g. tinnitus, recruitment, reduced speech intelligibility, hyperacusis. There are few reports on central noise effects. Noise can induce an apoptosis of neuronal tissue within the lower auditory pathway. Higher auditory structures (e.g. medial geniculate body, auditory cortex) are characterized by metabolic changes after noise exposure. However, little is known about the microstructural changes of the higher auditory pathway after noise exposure. The present paper was therefore aimed at investigating the cell density in the medial geniculate body (MGB) and the primary auditory cortex (AI) after noise exposure. Normal hearing mice were exposed to noise (10 kHz center frequency at 115 dB SPL for 3 h) at the age of 21 days under anesthesia (Ketamin/Rompun, 10:1). After 1 week, auditory brainstem response recordings (ABR) were performed in noise exposed and normal hearing animals. After fixation, the brain was microdissected and stained (Kluever-Barrera). The cell density in the MGB subdivisions and the AI were determined by counting the cells within a grid. Noise-exposed animals showed a significant ABR threshold shift over the whole frequency range. Cell density was significantly reduced in all subdivisions of the MGB and in layers IV-VI of AI. The present findings demonstrate a significant noise-induced change of the neuronal cytoarchitecture in central key areas of auditory processing. These changes could contribute to the complex psychoacoustic symptoms after NIHL.     

大鼠Hes1基因真核表达载体的构建及瞬时表达在神经前体细胞分化中的作用

目的 探讨Hes1基因高表达对神经前体细胞分化的影响. 方法从大鼠脑组织中提取总BNA,用RT-PCR方法获得Hes1基因的全长cDNA,插入pGEM-T-Easy克隆载体中进行序列测定,测序正确后将其亚克隆至表达载体pCDNA3.1,用脂质体将重组质粒转染原代培养的神经前体细胞,经G418筛选获得抗性细胞克隆,用RT-PCR方法鉴定Hes1基因在神经前体细胞基因组中的存在,实时荧光定量PCR检测Hes1基因在转染细胞中的过表达情况. 结果 经限制性内切酶酶切图谱分析和DNA序列测定,证实目的 基因已插入重组质粒,RT-PCR证明,经G418筛选得到的转基因神经前体细胞克隆的基因组DNA中存在Hes1基因;实时荧光定量PCR进一步证明,转基因神经前体细胞Hes1基因的mRNA高表达. 结论 构建了大鼠Hes1基因的真核表达载体,获得了高表达Hes1基因的神经前体细胞克隆.Hes1基因高表达可抑制神经前体细胞Ngn1的表达,并促进神经前体细胞向神经胶质细胞的分化.     

Involvement of Notch1/Hes signaling pathway in ankylosing spondylitis

We aimed to investigate the role of Notch1/Hes signaling pathway in the pathogenesis of abnormal ossification of hip ligament in patients with ankylosing spondylitis (AS). 22 AS patients scheduled for artificial hip arthroplasty were randomly chosen as AS group. As controls, we used 4 patients diagnosed with transcervical fracture who underwent hip replacement surgery. Notch1 and Hes mRNA expressions were detected by real-time fluorescent quantitative polymerase chain reaction (RFQ-PCR). Immunohistochemistry (IHC) was used to detect Notch1 and Hes protein expression. Correlation analyses of Notch-l and Hes with AS-related clinical factors were conducted with spearman’s correlation analysis and partial correlation analysis. RFQ-PCR results showed significant differences in Notch1 and Hes mRNA expressions between AS group and the control group (all P < 0.05). IHC analysis further indicated positive nuclear signals of Notch1 and Hes protein, indicating functional activation of the Notch1 and Hes pathways. Semi-quantitative IHC showed a higher Notch1 and Hes expression levels in AS group compared to the control group (all P < 0.05). Correlation analysis suggested that Hes protein expression was positively associated with the clinical course of the disease in AS patients. In conclusion, Notch1 and Hes overexpression was clearly detected in hip joint ligaments of AS patients, Hes protein expression was associated with the clinical course of AS. Taken together, we suggest that signaling pathways mediated by Notch1-Hes may contribute to ligament ossification of hip joints in AS patients.     

Effect of baicalein from Scutellaria baicalensis on prevention of noise-induced hearing loss

Noise-induced hearing loss (NIHL) has been thought to primarily involve damage to the sensory hair cells of the cochlea via mechanical and metabolic mechanisms. This study examined the effects of baicalin, baicalein, and Scutellaria baicalensis (SB) extract against NIHL in a mouse model. Mice received oral treatment with SB, baicalin, baicalein beginning 30 min prior to noise exposure and continuing once daily throughout the study. Hearing threshold shift was assessed by auditory brain stem responses for 35 days following noise exposure. Central auditory function was evaluated by auditory middle latency responses. Cochlear function was determined based on transient evoked otoacoustic emissions. SB significantly reduced threshold shift, central auditory function damage, and cochlear function deficits, suggesting that SB may protect auditory function in NIHL and that the active constituent may be a flavonoid, baicalein.     

白藜芦醇抑制高糖诱导的H9C2心肌细胞系肥大

目的观察白藜芦醇对高糖诱导H9C2心肌细胞系氧化应激和肥大的作用及其可能机制。方法将H9C2心肌细胞分为正常糖浓度组(NG组)、高糖组(HG组)、白芦藜醇组(Res组)和白藜芦醇+DAPT组(Res+DAPT组)。用鬼笔环肽检测细胞表面积;DCFH-DA法检测细胞内活性氧簇(ROS);比色法检测超氧化物歧化酶(SOD)活性及丙二醛(MDA)含量;实时荧光定量PCR及Western blot检测Notch1、Hes1、ANP、BNP mRNA和蛋白表达。结果与NG组相比,高糖可诱导心肌细胞肥大(P0.01),ROS和MDA含量增加(P0.01),SOD活性下降(P0.01),伴随ANP和BNP基因及蛋白表达增加(P0.05),Notch1和Hes1表达下降(P0.05),白藜芦醇处理后可逆转心肌细胞肥大(P0.01),减轻ROS和MDA氧化损伤(P0.01),增加SOD活性(P0.01),抑制ANP和BNP表达(P0.05),增加Notch1及Hes1表达(P0.05)。结论白藜芦醇可能通过改善氧化应激,活化Notch1/Hes1信号通路抑制高糖引起的H9C2心肌细胞肥大。     

Association between variations in CAT and noise-induced hearing loss in two independent noise-exposed populations

Noise-induced hearing loss (NIHL) is an important occupational hazard that results from an interaction between genetic and environmental factors. Although the environmental risk factors have been studied quite extensively, little is known about the genetic factors. On the basis of multiple studies, it was proposed that oxidative stress plays an important role in the development of NIHL. Here, we investigated whether variations (single nucleotide polymorphisms; SNPs) in the catalase gene (CAT), one of the genes involved in oxidative stress, influence noise susceptibility. Audiometric data from 1261 Swedish and 4500 Polish noise-exposed labourers were analysed. DNA samples were collected from the 10% most susceptible and the 10% most resistant individuals. Twelve SNPs were selected and genotyped. Subsequently, the interaction between noise exposure and genotypes and their effect on NIHL were analysed using logistic regression. Significant interactions were observed between noise exposure levels and genotypes of two SNPs for the Swedish population and of five SNPs for the Polish population. Two of these SNPs were significant in both populations. The interaction between predictor haplotypes and tagSNP haplotypes and noise exposure levels and their effect on NIHL were also analysed, resulting in several significant associations. In conclusion, this study identified significant associations between catalase SNPs and haplotypes and susceptibility to development of NIHL. These results indicate that catalase is a NIHL susceptibility gene, but that the effect of CAT polymorphisms can only be detected when noise exposure levels are taken into account.     

Variations in HSP70 genes associated with noise-induced hearing loss in two independent populations

Noise-induced hearing loss (NIHL) is one of the most important occupational health hazards. Millions of people worldwide are exposed daily to harmful levels of noise. NIHL is a complex disease resulting from an interaction between genetic and environmental factors. Although the environmental risk factors have been studied extensively, little is known about the genetic factors. Heat-shock proteins (HSPs) are induced after exposure to severe noise. When first induced by exposure to moderate sound levels, they can protect the ear from damage from excessive noise exposure. This protection is highly variable between individuals. An association of HSP70 genes with NIHL has been described by Yang et al (2006) in a Chinese sample set of noise-exposed workers. In this study, three polymorphisms (rs1043618, rs1061581 and rs2227956) in HSP70-1, HSP70-2 and HSP70-hom, respectively, were genotyped in 206 Swedish and 238 Polish DNA samples of noise-exposed subjects and analyzed. One SNP, rs2227956 in HSP70-hom, resulted in a significant association with NIHL in both sample sets. In addition, rs1043618 and rs1061581 were significant in the Swedish sample set. Analysis of the haplotypes composed of the three SNPs revealed significant associations between NIHL and haplotype GAC in both sample sets and with haplotype CGT in the Swedish sample set. In conclusion, this study replicated the association of HSP70 genes with NIHL in a second and third independent noise-exposed sample set, hereby adding to the evidence that HSP70 genes may be NIHL susceptibility genes.     

Candidate Gene Association Study for Noise-induced Hearing Loss in Two Independent Noise-exposed Populations

Millions of people are daily exposed to high levels of noise. Consequently, noise-induced hearing loss (NIHL) is one of the most important occupational health hazards worldwide. In this study, we performed an association study for NIHL based on a candidate gene approach. 644 Single Nucleotide Polymorphisms (SNPs) in 53 candidate genes were analyzed in two independent NIHL sample sets, a Swedish set and part of a Polish set. Eight SNPs with promising results were selected and analysed in the remaining part of the Polish samples. One SNP in PCDH15 (rs7095441), resulted in significant associations in both sample sets while two SNPs in MYH14 (rs667907 and rs588035), resulted in significant associations in the Polish sample set and significant interactions with noise exposure level in the Swedish sample set. Calculation of odds ratios revealed a significant association of rs588035 with NIHL in the Swedish high noise exposure level group. Our studies suggest that PCDH15 and MYH14 may be NIHL susceptibility genes, but further replication in independent sample sets is mandatory.     

下调SLP-2基因表达抑制脑胶质瘤细胞增殖及诱导凋亡的机制研究

目的：探讨下调人Stomatin like protein 2(SLP-2)基因表达对脑胶质瘤细胞增殖凋亡的影响。方法：SLP-2的靶向siRNA序列转染人脑胶质瘤U251细胞（SLP-2敲低组）,另设空白组（细胞未做任何处理）和阴性对照组（细胞转染无义siRNA序列）,转染48 h后Western blot检测各组细胞中SLP-2、B细胞淋巴瘤/白血病-2（Bcl-2）、Bcl-2相关X蛋白(Bax)、Notch1、Hes1的蛋白表达;CCK8检测细胞增殖;流式细胞仪检测细胞凋亡。结果：阴性对照组SLP-2的蛋白表达与空白组差异无统计学意义（P>0.05）,而SLP-2敲低组SLP-2的蛋白表达显著低于空白组（P<0.05）;阴性对照组细胞存活率、细胞凋亡率、IL-6和TNF-α的mRNA表达及Bcl-2、Bax、Notch1、Hes1蛋白表达与空白组差异无统计学意义（P>0.05）,而SLP-2敲低组细胞存活率、IL-6和TNF-α的mRNA表达及Bcl-2、Notch1、Hes1的蛋白表达显著低于空白组,细胞凋亡率及Bax蛋白表达显著高于空白组（P>0.05）。结论：下调SLP-2基因表达可显著抑制脑胶质瘤细胞增殖及诱导细胞的凋亡,下调炎症细胞因子IL-6和TNF-α的表达,其机制与抑制Notch1信号通路有关。     

Notch1/Hes1信号调控C/EBPα表达对AECII细胞增殖与分化的影响

目的:探讨Notch1/Hes1信号通路能否通过调控CCAAT/增强子结合蛋白α(C/EBPα)的表达从而影响肺泡Ⅱ型上皮细胞(AECⅡ)的增殖与分化功能。方法:体外培养人AECⅡ,将细胞随机分为对照组、激活剂组(加入Notch通路激活剂Jagged1蛋白500μg/L)和抑制剂组(加入Notch通路抑制剂DAPT 10μmol/L),于干预后24 h收获各组细胞。采用RT-qPCR和Western blot法分别检测Notch1、Hes1及C/EBPα的mRNA与蛋白表达水平;CCK-8法检测细胞活力;细胞计数检测细胞增殖;流式细胞术检测细胞周期及分化。结果:与对照组相比,激活剂组Notch1、Hes1和C/EBPα的mRNA和蛋白表达显著增加(P0.05),促进AECⅡ从S期进入G_2/M期,增殖增加而分化减少(P0.05);抑制剂组Notch1、Hes1和C/EBPαmRNA和蛋白表达水平明显降低(P0.05),AECⅡ被阻滞于G_0/G_1期,增殖减少而分化增加(P0.05)。结论:Notch1/Hes1信号可调控C/EBPα表达并能影响AECⅡ增殖与分化。     

MicroRNA9 regulates neural stem cell differentiation by controlling Hes1 expression dynamics in the developing brain

Earlier studies show that Hes1 expression is oscillatory in neural stem cells but sustained and high in the roof plate and the floor plate, and that such different dynamics of Hes1 expression (oscillatory versus sustained) regulate different proliferation and differentiation characteristics of these cells (active in neural stem cells but rather dormant in roof/floor plate cells). The mechanism of how different dynamics of Hes1 expression is controlled remains to be determined. Here, we found that the seed sequence of microRNA‐9 (miR‐9) is complementary to the 3′‐UTR sequence of Hes1 mRNA. MiR‐9 is highly expressed in the ventricular zone of the developing brain, which contains neural stem cells, but it is not expressed in the roof plate or the floor plate. Over‐expression of miR‐9 negatively regulates the Hes1 protein expression by interacting with the 3′‐UTR of Hes1 mRNA, thereby inducing cell cycle exit and neuronal differentiation. Conversely, knockdown of miR‐9 inhibits neuronal differentiation. Furthermore, knockdown of miR‐9 inhibits the oscillatory expression of Hes1 mRNA in neural stem cells. These results indicate that miR‐9 regulates the proliferation and differentiation of neural stem cells by controlling the dynamics of Hes1 expression in the developing brain.     

Industrial noise pollution and its effects on the hearing capabilities of workers: A study from saw mills, printing presses and corn mills

The purpose of this study was to ascertain industrial noise pollution and its effects on the hearing capabilities of workers. The procedure adopted included noise measurements, otoscopy, audiometric evaluation and assessment of medical history. The results showed that noise levels in corn mills and saw mills exceed 85dBA. The average noise level measured in the printing industry was 85dBA. It was also found that 23 %, 20 % and 7.9 % of workers in corn mills, saw mills and the printing industry have evidence of noise-induced hearing loss (NIHL). A highly significant correlation was found between noise exposure level, duration of exposure and the development of NIHL in corm mills and saw mills but not in the printers. Hearing - impairment was also observed at the speech frequencies among some of the workers exposed to hazardous noise. These findings suggest that more specific intervention is required to protect workers exposed to such hazards at the work places employed in this study.     

脂多糖调控Notch 信号通路作用于人牙髓干细胞增殖、分化、凋亡的实验研究

目的:探讨脂多糖调控Notch 信号通路对人牙髓干细胞增殖、分化、凋亡的影响及机制。方法:从牙髓组织中分离出人牙髓干细胞(hDPSCs),CCK8 实验检测0、0.1、1、10 μg/ ml 的脂多糖处理hDPSCs 1、3、5、7 d 后细胞的增殖情况;RT-PCR 检测1 μg/ ml 的脂多糖处理hDPSCs 0、3、7、14、21 d 后矿化相关基因ALP、DSPP、DMP1 的mRNA 表达情况;流式细胞仪检测1 μg/ ml 的脂多糖处理hDPSCs 0、7、14、21 d 后的细胞凋亡情况;Western blot 检测Cleaved caspase3、Notch1、Hes1 的蛋白表达。结果:不同浓度的脂多糖刺激hDPSCs 1、3、5 d 后细胞的增殖均无显著差异,培养至第7 天时,0.1、1、10 μg/ ml 的脂多糖组细胞的增殖均显著低于0 滋g/ ml 的脂多糖组(P<0.01);脂多糖处理hDPSCs 3 d 时ALP、DSPP、DMP1 的mRNA 表达与对照组比较差异均无统计学意义(P>0.05),7、14、21 d 时ALP、DSPP、DMP1 的mRNA 表达均显著高于对照组(P<0.01);脂多糖处理hDPSCs 7、14、21 d 时细胞的凋亡率及Cleaved caspase3、Notch1、Hes1 蛋白表达均显著高于对照组(P<0.01),21 d 时ALP、DSPP、DMP1 的mRNA 表达及细胞凋亡率和Cleaved caspase3、Notch1、Hes1 蛋白表达均有下降趋势。结论:脂多糖可降低hDPSCs 的增殖,促进其矿化和凋亡,其机制与激活Notch 信号通路有关。