In vivo treatment with diphenyl ditelluride induces neurodegeneration in striatum of young rats: Implications of MAPK and Akt pathways

In the present report 15 day-old Wistar rats were injected with 0.3 μmol of diphenyl ditelluride (PhTe)₂/kg body weight and parameters of neurodegeneration were analyzed in slices from striatum 6 days afterwards. We found hyperphosphorylation of intermediate filament (IF) proteins from astrocyte (glial fibrillary acidic protein—GFAP and vimentin) and from neuron (low-, medium- and high molecular weight neurofilament subunits: NF-L, NF-M and NF-H, respectively) and increased MAPK (Erk, JNK and p38MAPK) as well as PKA activities. The treatment induced reactive astrogliosis in the striatum, evidenced by increased GFAP and vimentin immunocontent as well as their mRNA overexpression. Also, (PhTe)₂ significantly increased the propidium iodide (PI) positive cells in NeuN positive population without altering PI incorporation into GFAP positive cells, indicating that in vivo exposure to (PhTe)₂ provoked neuronal damage. Immunohistochemistry showed a dramatic increase of GFAP staining characteristic of reactive astrogliosis. Moreover, increased caspase 3 in (PhTe)₂ treated striatal slices suggested apoptotic cell death. (PhTe)₂ exposure decreased Akt immunoreactivity, however phospho-GSK-3-β (Ser9) was unaltered, suggesting that this kinase is not directly implicated in the neurotoxicity of this compound. Therefore, the present results shed light into the mechanisms of (PhTe)₂-induced neurodegeneration in rat striatum, evidencing a critical role for the MAPK and Akt signaling pathways and disruption of cytoskeletal homeostasis, which could be related with apoptotic neuronal death and astrogliosis.     

重型颅脑损伤病人血清NF-L和TIMP-2水平变化及临床意义

目的 探讨重型颅脑损伤（TBI）病人血清神经丝蛋白轻链多肽（NF-L）、组织基质金属蛋白酶抑制因子-2(TIMP-2的水平变化及临床意义。方法 2019年8月～2021年8月前瞻性收集重型TBI共122例,采用酶联免疫吸附试验检查入院血清NF-1和TIMP-2水平;伤后6个月,应用GOS评分评估预后,其中4～5分为预后良好,1～3分为预后不良。结果 伤后6个月,预后良好72例,预后不良50例。预后不良组血清NF-L以及TIMP-2水平明显高于预后良好组（P<0.05）。入院血清NF-L水平（r=-0.585）、TIMP-2水平（r=-0.542）与入院GCS评分呈明显负相关（P<0.05）。多因素Cox回归分析显示,血清NF-L、TIMP-2水平增高是重型TBI伤后6个月预后不良的独立危险因素（P<0.05）。ROC曲线分析显示血清NF-L1≥54.60 pg/ml联合血清TIMP-2≥42.59 ng/ml预测重型TBI伤后6个月预后不良的曲线下面积为0.854(95%CI 0.789～0.919),灵敏度为82.0%,特异度为70.8。结论重型TBI病人血清NF-...     

神经再生素对背根神经节细胞GAP—43和NF—L基因表达的影响

目的：观察中药有效组分神经再生素作用于神经细胞生长过程中,相关基因的表达变化。探讨神经再生素促神经生长的分子生物学机制。方法：采用RT-PCR法,观察神经再生素在促大鼠背根神经节生长过程中（4h,12h,24h),生长相关蛋白43（GAP-43）和神经丝蛋白（NF-L）基因表达的变化。结果：神经再生素可使背根神经节细胞GAP-43和NF-LmRNA物表达量增加。结论：神经再生素可作用于体外培养的神经细胞,使神经生长相关基因表达上调。     

Quantitative analysis of neurofilament proteins in Alzheimer brain by enzyme linked immunosorbent assay system

The abnormality of cytoskeletal proteins is related to Alzheimer's disease. Because neurofilament proteins (NF) are major cytoskeletal components of neurones, abnormality of NF may be involved in the pathology of disease. In this study, insoluble NF in the grey matter of temporal lobes of Alzheimer and control brains were dissolved in a urea buffer and quantitatively measured by an enzyme linked immunosorbent assay system. No apparent quantitative changes of NF-L and NF-H were found between the Alzheimer and control brains, and there were also no significant differences in the mean molar ratio of NF-L to NF-H between them. However, the relative amount of phosphorylated NF-H in Alzheimer brains was increased in comparison with that in control brains. These results suggest that the increase of phosphorylated NF-H might be accompanied with Alzheimer's disease.     

神经生长液对衰老模型小鼠学习记忆能力的影响

目的:探讨神经生长液对D-半乳糖衰老模型小鼠学习记忆能力及海马神经丝蛋白表达的影响,为应用神经生长液防治神经退行性变疾病提供实验依据。方法:D-半乳糖致小鼠衰老模型,以Y型电迷宫检测其学习记忆能力;以抗低分子量神经丝蛋白(NF-L)抗体,采用WesternBlot法观察海马NF-L的表达。结果:与正常对照组相比(65.8±5.8),D-半乳糖衰老模型小鼠达到学会标准所用的次数明显增加(97.8±13.9,t=7.355,P<0.01),低、高剂量神经生长液可明显减少衰老模型小鼠的次数(80.1±9.3,67.7±8.2,t=3.6662,6.4609,P均<0.01)。衰老小鼠海马NF-L表达量明显下降;神经生长液防止衰老所致NF-L表达量减少。结论:神经生长液可改善D-半乳糖模型小鼠的学习记忆能力,防止衰老小鼠海马NF-L表达的减少。     

Cytoskeleton of hippocampal neurons as a target for valproic acid in an experimental model of depression

BACKGROUND: Atrophy of pyramidal hippocampal neurons and of the entire hippocampus has been reported in experimental models of depression and in depressive patients respectively. We investigated the efficacy of valproic acid (VPA) for reversing a depressive-like behaviour and a cytoskeletal alteration in the hippocampus, the loss of the light neurofilament subunit (NF-L). METHODS: Depressive-like behaviour was induced by inescapable stress. Animals were divided into four groups: two to assess the response to 21 days of treatment with 200 mg/kg (I.P.) of valproic acid, and two in which the treatment was interrupted and the effects of VPA were evaluated 90 days later. Depressive-like behaviour was evaluated by the quantification of escape movements in a swimming test. NF-L was quantified by immunohistochemistry in dentate gyrus and CA3 of hippocampus. RESULTS: VPA corrected the depressive-like behaviour and reversed the diminution of NF-L in the hippocampus. Ninety days after the end of the treatment, and in contrast to the results previously obtained with fluoxetine, no recurrence of the depressive-like behaviour was observed. CONCLUSIONS: Despite interruption of the treatment, a long-lasting effect of VPA was observed. A possible relationship between the effect on NF-L and the prevention of depressive-like behaviour recurrence could be suggested.     

Nitric oxide not carbon monoxide mediates nonadrenergic noncholinergic relaxation in the murine internal anal sphincter

BACKGROUND & AIMS: Inhibitory reflexes in the internal anal sphincter (IAS) are controlled by inhibitory nonadrenergic, noncholinergic innervation (i-NANC). We investigated the roles of 3 different neurohumoral agonists as possible i-NANC neurotransmitters: carbon monoxide (CO), nitric oxide (NO), and vasoactive intestinal peptide (VIP). METHODS: IAS smooth muscle strips were isolated from wild-type (WT), heme oxygenase (HO)-2 knockout (HO-2-/-) and neuronal NO synthase (nNOS) knockout (nNOS-/-) mice. Relaxation of IAS was induced by CO, NO, VIP, and electrical field stimulation (EFS) in the presence and absence of neurohumoral inhibitors (tin protoporphyrin IX [SnPP IX] for CO synthesis, N(omega)-nitro-L-arginine [L-NNA] for NO synthesis, and VIP(10-28) for VIP receptor). Western blot and immunohistochemistry were used to test the presence and localization of HO (for CO synthesis) types 1 (HO-1) and 2 (HO-2), neuronal NO synthase (nNOS, for NO synthesis), and VIP. RESULTS: All 3 neurohumoral agonists produced relaxation (with no difference between WT and HO-2-/- IAS), but CO was over 100 times less potent than NO and VIP. EFS produced relaxation in WT and HO-2-/- IAS with the same intensity. L-NNA and nNOS deletion (approximately 80%) and VIP(10-28) (approximately 15%) significantly inhibited the relaxations, whereas SnPP IX had no effect. Positive immunoreactivities for HO-2, nNOS, and VIP were found in the myenteric plexus of WT IAS. HO-2-/- IAS did not express immunoreactivity for HO-2. CONCLUSIONS: i-NANC relaxations of mouse IAS are primarily mediated via NO (by nNOS activity) and partly via VIP. CO directly relaxes the mouse IAS but does not play any significant role in the i-NANC relaxation.     

The genetic basis of auditory neuropathy spectrum disorder (ANSD)

Objective

Auditory neuropathy is a hearing disorder where outer hair cell function within the cochlea is normal, but inner hair cell and/or the auditory nerve function is disrupted. It is a heterogeneous disorder which can have either congenital or acquired causes. Furthermore, the aetiology of auditory neuropathy is vast, which may include prematurity, hyperbilirubinaemia, anoxia, hypoxia, congenital brain anomalies, ototoxic drug exposure, and genetic factors. It is estimated that approximately 40% of cases have an underlying genetic basis, which can be inherited in both syndromic and non syndromic conditions. This review paper provides an overview of the genetic conditions associated with auditory neuropathy spectrum disorders (ANSDs) and highlights some of the defective genes that have been found to be linked to the pathological auditory changes.

Method

Literature search was conducted using a number of resources including textbooks, professional journals and the relevant websites.

Results

The largest proportion of auditory neuropathy spectrum disorders (ANSDs) is due to genetic factors which can be syndromic, non-syndromic or mitochondrial related. The inheritance pattern can include all the four main types of inheritances such as autosomal dominant, autosomal recessive, X-linked and mitochondrial.

Conclusion

This paper has provided an overview of mutation with some of the genes and/or loci discovered to be the cause for auditory neuropathy spectrum disorders (ANSDs). It has been noted that different gene mutations may trigger different pathological changes in patients with this disorder. These discoveries have provided us with vital information as to the sites of pathology in auditory neuropathy spectrum disorders (ANSDs), and the results highlight the heterogeneity of the disorder.     

Colocalization of NOS and SOD1 in neurofilament accumulation within motor neurons of amyotrophic lateral sclerosis: an immunohistochemical study

Peroxynitrite, formed from nitric oxide and superoxide, may affect neurofilament assembly and cause neurofilament accumulation in motoneurons. This hypothesis may reconcile the mutations of two genes: superoxide dismutase-1 in some patients with familial amyotrophic lateral sclerosis, and the gene for the heavy neurofilament in some patients with sporadic amyotrophic lateral sclerosis previously reported. We found colocalization of superoxide dismutase-1 and nitric oxide synthase in the foci of neurofilament accumulation as ‘conglomerates’ in upper motor neurons and ‘axonal spheroids’ in lower motor neurons. In addition, all the specific molecules related to the reactions, including calmodulin, 3′,5′-cyclic guanosine-monophosphate, citrulline, and nitrotyrosine were found strongly immunopositive in the site of neurofilament accumulation. Our data support the view that the neurofilament aggregates are tightly linked with superoxide dismutase-1 and nitric oxide synthase activities. Both enzymes may focally contribute to peroxynitrite formation at light neurofilament, which is rich in both tyrosine and arginine residues and hence considered as the vulnerable site for nitrotyrosine formation. Nitrotyrosine is known to inhibit phosphorylation and if it impairs phosphorylation of neurofilament subunits, either light or heavy, may alter the slow axonal transport culminating in proximo-distal accumulation of NF and slowly progressive motoneuron death.     

Protein levels of neurofilament subunits in the hen central nervous system following prevention and potentiation of diisopropyl phosphorofluoridate (DFP)-induced delayed neurotoxicity(1).

Diisopropyl phosphorofluoridate (DFP) is an organophosphorus ester, which produces delayed neurotoxicity (OPIDN) in hens in 7-14 days. OPIDN is characterized by mild ataxia in its initial stages and severe ataxia or paralysis in about 3 weeks. It is marked by distal swollen axons, and exhibits aggregations of neurofilaments (NFs), microtubules, proliferated smooth endoplasmic reticulum, and multivesicular bodies. These aggregations subsequently undergo disintegration, leaving empty varicosities. Previous studies in this laboratory have shown an increased level of medium-molecular weight NF (NF-M) and decreased levels of high- and low-molecular weight NF (NF-H, NF-L) proteins in the spinal cord of DFP-treated hens. The main objective of this investigation was to study the effect of DFP administration on NF subunit levels when OPIDN is prevented or potentiated by pretreatment or post-treatment with phenylmethylsulfonyl fluoride (PMSF), respectively. Hens pretreated or post-treated with PMSF were killed 1, 5, 10, and 20 days after the last treatment. The alteration in NF subunit protein levels observed in DFP-treated hen spinal cords was not observed in protected hens. Estimation of NFs in the potentiation experiments, however, showed a different pattern of alteration in NF subunit levels. The results showed that an alteration in NF subunit levels in DFP-treated hens might be related to the development of OPIDN, since these changes were suppressed in PMSF-protected hens. However, results from PMSF post-treated hen spinal cords suggested that potentiation of OPIDN by PMSF was mediated by a mechanism different from that followed by DFP alone to produce OPIDN.