Chromatolysis: Do injured axons regenerate poorly when ribonucleases attack rough endoplasmic reticulum, ribosomes and RNA?

Co-exposure to Aluminium and Cadmium Mediates Postpartum Maternal Variation in Brain Architecture and Behaviour of Mice; Involvement of Oxido-nitrergic and Cholinergic Mechanisms : Postpartum effects of Aluminium and Cadmium co-exposure in pregnancy

Most research has not been done on the possible relationship between pregnant women's cross-metal exposures and postpartum neuroendocrine functions. The purpose of this study was to look into how co-exposure to aluminium chloride (AlCl3) and cadmium chloride (CdCl2) affected the neuroendocrine and neurometabolic changes in postpartum mice. A total of 24 adult pregnant female mice were used for the study. Group 1 served as control and received neither AlCl3 nor CdCl2 (n=6), group 2 comprised pregnant mice treated with AlCl3 (10mg/kg), group 3 with CdCl2 (1.5mg/kg), group 4 with a combination of AlCl3 (10 mg/kg) and CdCl2 (1.5 mg/kg).Oral treatment of animals was done daily from gestation day 7 to gestation day 20. Upon delivery and weaning on postnatal day 21 (PND 21), behavioural assessment was done on the postpartum mice and immediately followed by sacrifice for assessment of histological and neuroendocrine markers. Our findings revealed that the brain-to-body weight ratio was affected and brain oxidative stress was elevated in mice exposed to AlCl3 and CdCl2 during pregnancy. Given the strong association between postpartum hyperactivity, social interaction index, brain catalase and acetylcholinesterase activity, and the brain/body weight ratio, it is plausible that these effects have played a role in the adverse behavioural abnormalities observed in the postpartum maternal mice. Moreover, it was noted that in certain situations, co-exposures to the metals tended to have opposite effects to single metal exposures.

Dynamic changes in endoplasmic reticulum morphology and its contact with the plasma membrane in motor neurons in response to nerve injury

The endoplasmic reticulum (ER) extends throughout a cell and plays a critical role in maintaining cellular homeostasis. Changes in ER shape could provide a clue to explore the mechanisms that underlie the fate determination of neurons after axon injury because the ER drastically changes its morphology under neuronal stress to maintain cellular homeostasis and recover from damage. Because of their tiny structures and richness in the soma, the detailed morphology of the ER and its dynamics have not been well analysed. In this study, the focused ion beam/scanning electron microscopy (FIB/SEM) analysis was performed to explore the ultra-structures of the ER in the somata of motor neuron with axon regenerative injury models. In normal motor neurons, ER in the somata is abundantly localised near the perinucleus and represents lamella-like structures. After injury, analysis of the ER volume and ER branching points indicated a collapse of the normal distribution and a transformation from lamella-like structures to mesh-like structures. Furthermore, accompanied by ER accumulation near the plasma membrane (PM), the contact between the ER and PM (ER-PM contacts) significantly increased after injury. The accumulation of extended-synaptotagmin 1 (E-Syt1), a tethering protein of the ER and PM that regulates Ca2+-dependent lipid transfer, was also identified by immunohistochemistry and quantitative Real-time PCR after injury. These morphological alterations of ER and the increase in ER-PM contacts may be crucial events that occur in motor neurons as a resilient response for the survival after axonal injury.

Prenatal double-hit with aluminium and cadmium mediate testicular atrophy and hypothalamic hypoplasia: the role of oxido-nitrergic stress and endocrine perturbations

There is limited experimental evidence on the biochemical consequences of aluminium (Al) and cadmium (Cd) co-exposures during pregnancy and postnatal life.This study investigated the impacts of perinatal Al chloride (AlCl3) and Cd chloride (CdCl2) co-exposures on neuroendocrine functions in mice offspring during postnatal life. The study comprised of four pregnant experimental groups. Group 1 received AlCl3 (10 mg/kg), group 2 were administered CdCl2 (1.5 mg/kg), while group 3 received both AlCl3 (10 mg/kg) and CdCl2 (1.5 mg/kg) (AlCl3+CdCl2), and group 4 received saline (10 mL/kg) only and served as control group. All experimental animals were chemically exposed once daily from gestation days 7-20. Upon delivery, male pups were regrouped based on maternal chemical exposure on postnatal day 21 (PND 21) and allowed to grow to adulthood until PND 78, after which they were sacrificed for assessment of neuroendocrine markers and histological investigations. There was no statistical significance (p > 0.05) on follicle stimulating hormone, testosterone, estrogen and progesterone, thyroid stimulating hormone, thyroxine (T4) in all treatment groups relative to controls|. However, AlCl3 and AlCl3-CdCl2 significantly (p < 0.05) reduced triiodothyronine (T3) levels, with a profound increase in T3:T4 ratio by AlCl3, and AlCl3+CdCl2 compared to control. Furthermore, pups from pregnant mice treated with CdCl2 and AlCl3+CdCl2 demonstrated increased testicular malondialdehyde concentration with increased catalase activity relative to controls, suggesting oxidative imbalance. In addition, AlCl3, CdCl2, and AlCl3+CdCl2 exposures induced testicular and hypothalamic architectural disruption compared to controls, with marked architectural derangement in the AlCl3+CdCl2 group. Our findings suggest that prenatal co-exposures to Alcl3 and CdCl2 induce testicular and hypothalamic alterations in offspring via a testicular oxidative stress and thyrotoxicosis-dependent mechanisms.

Maf1 is an intrinsic suppressor against spontaneous neural repair and functional recovery after ischemic stroke

INTRODUCTION

Spontaneous recovery after CNS injury is often very limited and incomplete, leaving most stroke patients with permanent disability. Maf1 is known as a key growth suppressor in proliferating cells. However, its role in neuronal cells after stroke remains unclear.

OBJECTIVE

We aimed to investigate the mechanistic role of Maf1 in spontaneous neural repair and evaluated the therapeutic effect of targeting Maf1 on stroke recovery.

METHODS

We used mouse primary neurons to determine the signaling mechanism of Maf1, and the cleavage-under-targets-and-tagmentation-sequencing to map the whole-genome promoter binding sites of Maf1 in isolated mature cortical neurons. Photothrombotic stroke model was used to determine the therapeutic effect on neural repair and functional recovery by AAV-mediated Maf1 knockdown.

RESULTS

We found that Maf1 mediates mTOR signaling to regulate RNA polymerase III (Pol III)-dependent rRNA and tRNA transcription in mouse cortical neurons. mTOR regulates neuronal Maf1 phosphorylation and subcellular localization. Maf1 knockdown significantly increases Pol III transcription, neurite outgrowth and dendritic spine formation in neurons. Conversely, Maf1 overexpression suppresses such activities. In response to photothrombotic stroke in mice, Maf1 expression is increased and accumulates in the nucleus of neurons in the peripheral region of infarcted cortex, which is the key region for neural remodeling and repair during spontaneous recovery. Intriguingly, Maf1 knockdown in the peri-infarct cortex significantly enhances neural plasticity and functional recovery. Mechanistically, Maf1 not only interacts with the promoters and represses Pol III-transcribed genes, but also those of CREB-associated genes that are critical for promoting plasticity during neurodevelopment and neural repair.

CONCLUSION

These findings indicate Maf1 as an intrinsic neural repair suppressor against regenerative capability of mature CNS neurons, and suggest that Maf1 is a potential therapeutic target for enhancing functional recovery after ischemic stroke and other CNS injuries.

Blocking SP/NK1R signaling improves spinal cord hemisection by inhibiting the release of pro-inflammatory cytokines in rabbits

OBJECTIVE

Incomplete spinal cord injury (SCI) is the most common spinal cord injury in clinic, however its mechanism is still not fully understood.

DESIGN

We constructed the rabbit spinal cord hemisection (SCH) model and used RT-PCR, western blotting, immunohistochemistry, and immunofluorescence experiments to explore the potential mechanism of SCI.

SETTING

The sham operation (SH) group, the observation (OB, which is the SCH) group, the OB+ substance p (SP) inhibitor group, the OB + NK1R inhibitor group, the OB + NK1R agonist group and the OB + SP inhibitor + NK1R agonist group.

PARTICIPANTS

New Zealand white rabbits.

INTERVENTIONS

Use NK1R inhibitors, NK1R agonists, SP inhibitors to treat the SCH model.

OUTCOME MEASURES

IL-1β, IKKγ, IL-6 and NF-κB.

RESULTS

The results showed that nissl bodies, inflammatory cells and SP increased notably in the spinal cord cells of the rabbit SCH model. Through in vivo experiments with SP or NK1R inhibitors or NK1R agonists, we found that inhibiting SP/NK1R signaling can help improve SCH by inhibiting the release of pro-inflammatory cytokines IL-1β, IKKγ, IL-6 and NF-κB.

REGISTERED TRIALS

Animal experiments were approved by Ruijin Hospital, Shanghai Jiaotong University School of Medicine.

Bisphenol-A (BPA) Impairs Hippocampal Neurogenesis via Inhibiting Regulation of the Ubiquitin Proteasomal System

The ubiquitin-proteasome system (UPS) controls protein homeostasis to maintain cell functionality and survival. Neurogenesis relies on proteasome function, and a defective proteasome system during brain development leads to neurological disorders. An endocrine-disrupting xenoestrogen bisphenol-A (BPA) used in plastic products adversely affects human health and causes neurotoxicity. Previously, we reported that BPA reduces neural stem cells (NSCs) proliferation and differentiation, impairs myelination and mitochondrial protein import, and causes excessive mitochondrial fragmentation leading to cognitive impairments in rats. Herein, we examined the effect(s) of prenatal BPA exposure on UPS functions during NSCs proliferation and differentiation in the hippocampus. Rats were orally treated with 40 µg/kg body weight BPA during day 6 gestation to day 21 postnatal. BPA significantly reduced proteasome activity in a cellular extract of NSCs. Immunocytochemistry exhibited a significant reduction of 20S proteasome/Nestin⁺ and PSMB5/Nestin⁺ cells in NSCs culture. BPA decreased 20S/Tuj1⁺ and PSMB5/Tuj1⁺ cells, indicating disrupted UPS during neuronal differentiation. BPA reduced the expression of UPS genes, 20S, and PSMB5 protein levels and proteasome activity in the hippocampus. It significantly reduced overall protein synthesis by the loss of Nissl substances in the hippocampus. Pharmacological activation of UPS by a bioactive triterpenoid 18α-glycyrrhetinic acid (18α GA) caused increased proteasome activities, significantly increased neurosphere size and number, and enhanced NSCs proliferation in BPA exposed culture, while proteasome inhibition by MG132 further aggravates BPA-mediated effects. In silico studies demonstrated that BPA strongly binds to catalytic sites of UPS genes (PSMB5, TRIM11, Parkin, and PSMD4) which may result in UPS inactivation. These results suggest that BPA significantly reduces NSCs proliferation by impairing UPS, and UPS activation by 18α GA could suppress BPA-mediated neurotoxicity and exerts neuroprotection.

Motor and somatosensory degenerative myelopathy responsive to pantothenic acid in piglets

This report describes 2 events of degenerative myelopathy in 4- to 27-day-old piglets, with mortality rates reaching 40%. Sows were fed rations containing low levels of pantothenic acid. Piglets presented with severe depression, weakness, ataxia, and paresis, which were more pronounced in the pelvic limbs. No significant gross lesions were observed. Histologically, there were degeneration and necrosis of neurons in the spinal cord, primarily in the thoracic nucleus in the thoracic and lumbar segments, and motor neurons in nucleus IX of the ventral horn in the cervical and lumbar intumescence. Minimal-to-moderate axonal and myelin degeneration was observed in the dorsal funiculus of the spinal cord and in the dorsal and ventral nerve roots. Immunohistochemistry demonstrated depletion of acetylcholine neurotransmitters in motor neurons and accumulation of neurofilaments in the perikaryon of neurons in the thoracic nucleus and motor neurons. Ultrastructurally, the thoracic nucleus neurons and motor neurons showed dissolution of Nissl granulation. The topographical distribution of the lesions indicates damage to the second-order neurons of the spinocerebellar tract, first-order axon cuneocerebellar tract, and dorsal column-medial lemniscus pathway as the cause of the conscious and unconscious proprioceptive deficit, and damage to the alpha motor neuron as the cause of the motor deficit. Clinical signs reversed and no new cases occurred after pantothenic acid levels were corrected in the ration, and piglets received parenteral administration of pantothenic acid. This study highlights the important and practical use of detailed neuropathological analysis to refine differential diagnosis.

Alterations in Cerebellar Microtubule Cytoskeletal Network in a ValproicAcid-Induced Rat Model of Autism Spectrum Disorders

Autism spectrum disorders (ASD) are neurodevelopmental diseases characterised by deficits in social communication, restricted interests, and repetitive behaviours. The growing body of evidence points to a role for cerebellar changes in ASD pathology. Some of the findings suggest that not only motor problems but also social deficits, repetitive behaviours, and mental inflexibility associated with ASD are connected with damage to the cerebellum. However, the understanding of this brain structure's functions in ASD pathology needs future investigations. Therefore, in this study, we generated a rodent model of ASD through a single prenatal administration of valproic acid (VPA) into pregnant rats, followed by cerebellar morphological studies of the offspring, focusing on the alterations of key cytoskeletal elements. The expression (Western blot) of α/β-tubulin and the major neuronal MT-associated proteins (MAP) such as MAP-Tau and MAP1B, MAP2, MAP6 (STOP) along with actin-crosslinking αII-spectrin and neurofilament light polypeptide (NF-L) was investigated. We found that maternal exposure to VPA induces a significant decrease in the protein levels of α/β-tubulin, MAP-Tau, MAP1B, MAP2, and αII-spectrin. Moreover, excessive MAP-Tau phosphorylation at (Ser396) along with key Tau-kinases activation was indicated. Immunohistochemical staining showed chromatolysis in the cerebellum of autistic-like rats and loss of Purkinje cells shedding light on one of the possible molecular mechanisms underpinning neuroplasticity alterations in the ASD brain.

The effect of dietary sesame oil and ginger oil as antioxidants in the adult rat dorsal root ganglia after peripheral nerve crush injury

AIM

The purpose of this study was to investigate the effect of dietary sesame oil and ginger oil supplements on the dorsal root ganglia following a sciatic nerve crush model in male Wistar albino rats.

MATERIALS AND METHODS

Crush injury models have been done by means of graded forceps (50 Newton). The animals were given a daily sesame oil (4 ml/kg/day) and ginger oil (400 mg/kg/day) via oral gavage for a period of 28 days. Dorsal root ganglia from the L5 levels were harvested. Processing of tissues was done for electron microscopy and light microscopy. Immunohistochemical staining with active caspase-3 antibody and qualitative ultrastructural analyses of tissues were made by a light and a transmission electron microscope, respectively.

RESULTS

The results showed that crush injury leads to remarkable ultrastructural changes in sensory neurons, such as swollen mitochondria, disruption of cristae structure, glial cell proliferation and, consequently, phagocytosis of the damaged neuron. These ultrastructural changes were less evident in the treated groups, and both natural compounds reduced the expression of activated caspase-3, which may also affect ultrastructural changes.

CONCLUSION

The application of the natural products sesame oil and ginger oil may represent a supportive approach to the protection of sensory neurons against the destructive effects of peripheral nerve crush injury.

Events Occurring in the Axotomized Facial Nucleus

Transection of the rat facial nerve leads to a variety of alterations not only in motoneurons, but also in glial cells and inhibitory neurons in the ipsilateral facial nucleus. In injured motoneurons, the levels of energy metabolism-related molecules are elevated, while those of neurofunction-related molecules are decreased. In tandem with these motoneuron changes, microglia are activated and start to proliferate around injured motoneurons, and astrocytes become activated for a long period without mitosis. Inhibitory GABAergic neurons reduce the levels of neurofunction-related molecules. These facts indicate that injured motoneurons somehow closely interact with glial cells and inhibitory neurons. At the same time, these events allow us to predict the occurrence of tissue remodeling in the axotomized facial nucleus. This review summarizes the events occurring in the axotomized facial nucleus and the cellular and molecular mechanisms associated with each event.

Brain and pituitary-adrenal lesions of Trypanosoma brucei brucei and Trypanosoma congolense infections in the West African Dwarf rams: Is trypanotolerance overrated?

Trypanosomosis of the West African Dwarf (WAD) sheep is often neglected due to emphasis on trypanotolerance. Nevertheless, significant pathological changes may occur in tissues of infected WAD sheep. The purpose of this study was to evaluate the brain, pituitary, and adrenal lesions of Trypanosoma brucei brucei (Tbb) and Trypanosoma congolense (Tc) infections in WAD rams. Fifteen WAD rams were infected intraperitoneally with Tbb or Tc (10⁶ trypanosomes/animal) or were uninfected controls (5 rams per group). Adrenocorticotrophic hormone (ACTH) and cortisol were assayed in serum by enzyme immunoassay technique. The brain, pituitary, and adrenal glands were processed for histopathology. Serum ACTH levels of infected rams were significantly (P < .05) higher than that of controls on days 14 and 70 post infection (PI). Serum cortisol levels of infected rams were significantly (P < .05) higher than that of controls only on day 14 PI. Mortality was 60% in Tbb- and 40% in Tc-infected rams. The brain of the infected groups showed chromatolysis of cortical neurons and Purkinje cells with severe encephalitis. Degenerative, necrotic, and inflammatory changes were seen in the pituitary and adrenal glands of the infected rams. Adrenal corticomedullary ratio was significantly (P < .05) higher in Tc-infected rams than controls. Based on the high mortality levels, likely due to severe encephalitis, the WAD sheep may not be regarded as trypanotolerant.

Preclinical Evidence for the Role of Botulinum Neurotoxin A (BoNT/A) in the Treatment of Peripheral Nerve Injury

Traumatic peripheral nerve injuries tend to be more common in younger, working age populations and can lead to long-lasting disability. Peripheral nerves have an impressive capacity to regenerate; however, successful recovery after injury depends on a number of factors including the mechanism and severity of the trauma, the distance from injury to the reinnervation target, connective tissue sheath integrity, and delay between injury and treatment. Even though modern surgical procedures have greatly improved the success rate, many peripheral nerve injuries still culminate in persistent neuropathic pain and incomplete functional recovery. Recent studies in animals suggest that botulinum neurotoxin A (BoNT/A) can accelerate nerve regeneration and improve functional recovery after injury to peripheral nerves. Possible mechanisms of BoNT/A action include activation or proliferation of support cells (Schwann cells, mast cells, and macrophages), increased angiogenesis, and improvement of blood flow to regenerating nerves.

Revisiting the Role of Biologically Active Natural and Synthetic Compounds as an Intervention to Treat Injured Nerves

Traumatic lesions in nerves present high incidence and may culminate in sensorimotor and/or autonomic dysfunctions or a total loss of function, affecting the patient's quality of life. Although the microenvironment favors peripheral nerve regeneration, the regenerative process is not always successful. Some herbs, natural products, and synthetic drugs have been studied as potential pro-regenerative interventions. We reviewed and discussed the most recent articles published over the last ten years in high impact factor journals. Even though most of the articles contemplated in this review were in vitro and animal model studies, those with herbs showed promising results. Most of them presented antioxidant and anti-inflammatory effects. Drugs of several pharmacological classes also showed optimistic outcomes in nerve functional recovery, including clinical trials. The results are hopeful; however, mechanisms of action need to be elucidated, and there is a need for more high-quality clinical studies. The study presents careful compilation of findings of dozens of compounds with consistent pro-regenerative evidence published in respected scientific journals. It may be valuable for health professionals and researchers in the field.

The impairment of motor coordination following chronic carbamazepine-levetiracetam combination treatment with evidence of corticocerebellar toxicity in male Wistar rats

This study examined the effects of carbamazepine (CBZ) or levetiracetam (LEV) and sub-therapeutic doses of the combination of the two conventional antiepileptics on some of the markers of motor coordination. Twenty-four male Wistar rats (140 ± 5 g) were randomized into 4 groups (n = 6). Group I rats received physiological saline (0.2 ml), group II were administered CBZ (25.0 mg/kg), group III received LEV (50 mg/kg), while group IV rats were given sub-therapeutic doses of CBZ (12.5 mg/kg) and LEV (25 mg/kg) intraperitoneally for 28 days. Thereafter the animals were subjected to behavioral and biochemical investigations, while the frontal lobe and cerebellar tissue were preserved for histological investigation. Data were subjected to descriptive and inferential statistics, and the results presented as mean ± SEM, analyzed using one-way Analysis of variance (ANOVA) and Student- Newman Keuls post hoc analysis where appropriate. p < 0.05 was considered statistically significant. There was significant alteration in fine and skilled movement after the CBZ, and CBZ + LEV chronic treatment compared with the control. The CBZ, and CBZ + LEV combination treatment increased the frontal lobe and cerebellar activities of acetylcholinesterase, malondialdehyde concentration, tissue necrotic factor alpha and decreased the activities of super oxide dismutase relative to the control. Disorganization of the histoarchitecture of the frontal lobe and cerebellum was characterized by cellular atrophy, chromatolysis and hyalinization. Chronic CBZ, and CBZ + LEV combination treatment produced psychomotor dysfunction and neurotoxicity in this order CBZ + LEV > CBZ > LEV in the rats.

Combining Hypothermia and Oleuropein Subacutely Protects Subcortical White Matter in a Swine Model of Neonatal Hypoxic-Ischemic Encephalopathy

Neonatal hypoxia-ischemia (HI) causes white matter injury that is not fully prevented by therapeutic hypothermia. Adjuvant treatments are needed. We compared myelination in different piglet white matter regions. We then tested whether oleuropein (OLE) improves neuroprotection in 2- to 4-day-old piglets randomized to undergo HI or sham procedure and OLE or vehicle administration beginning at 15 minutes. All groups received overnight hypothermia and rewarming. Injury in the subcortical white matter, corpus callosum, internal capsule, putamen, and motor cortex gray matter was assessed 1 day later. At baseline, piglets had greater subcortical myelination than in corpus callosum. Hypothermic HI piglets had scant injury in putamen and cerebral cortex. However, hypothermia alone did not prevent the loss of subcortical myelinating oligodendrocytes or the reduction in subcortical myelin density after HI. Combining OLE with hypothermia improved post-HI subcortical white matter protection by preserving myelinating oligodendrocytes, myelin density, and oligodendrocyte markers. Corpus callosum and internal capsule showed little HI injury after hypothermia, and OLE accordingly had minimal effect. OLE did not affect putamen or motor cortex neuron counts. Thus, OLE combined with hypothermia protected subcortical white matter after HI. As an adjuvant to hypothermia, OLE may subacutely improve regional white matter protection after HI.

Morphological Heterogeneity of the Endoplasmic Reticulum within Neurons and Its Implications in Neurodegeneration

The endoplasmic reticulum (ER) is a multipurpose organelle comprising dynamic structural subdomains, such as ER sheets and tubules, serving to maintain protein, calcium, and lipid homeostasis. In neurons, the single ER is compartmentalized with a careful segregation of the structural subdomains in somatic and neurite (axodendritic) regions. The distribution and arrangement of these ER subdomains varies between different neuronal types. Mutations in ER membrane shaping proteins and morphological changes in the ER are associated with various neurodegenerative diseases implying significance of ER morphology in maintaining neuronal integrity. Specific neurons, such as the highly arborized dopaminergic neurons, are prone to stress and neurodegeneration. Differences in morphology and functionality of ER between the neurons may account for their varied sensitivity to stress and neurodegenerative changes. In this review, we explore the neuronal ER and discuss its distinct morphological attributes and specific functions. We hypothesize that morphological heterogeneity of the ER in neurons is an important factor that accounts for their selective susceptibility to neurodegeneration.

Alterations in Tau Protein Level and Phosphorylation State in the Brain of the Autistic-Like Rats Induced by Prenatal Exposure to Valproic Acid

Autism spectrum disorder (ASD) is a neurodevelopmental condition characterized by deficient social interaction and communication besides repetitive, stereotyped behaviours. A characteristic feature of ASD is altered dendritic spine density and morphology associated with synaptic plasticity disturbances. Since microtubules (MTs) regulate dendritic spine morphology and play an important role in spine development and plasticity the aim of the present study was to investigate the alterations in the content of neuronal α/β-tubulin and Tau protein level as well as phosphorylation state in the valproic acid (VPA)-induced rat model of autism. Our results indicated that maternal exposure to VPA induces: (1) decrease the level of α/β-tubulin along with Tau accumulation in the hippocampus and cerebral cortex; (2) excessive Tau phosphorylation and activation of Tau-kinases: CDK5, ERK1/2, and p70S6K in the cerebral cortex; (3) up-regulation of mTOR kinase-dependent signalling in the hippocampus and cerebral cortex of adolescent rat offspring. Moreover, immunohistochemical staining showed histopathological changes in neurons (chromatolysis) in both analysed brain structures of rats prenatally exposed to VPA. The observed changes in Tau protein together with an excessive decrease in α/β-tubulin level may suggest destabilization and thus dysfunction of the MT cytoskeleton network, which in consequence may lead to the disturbance in synaptic plasticity and the development of autistic-like behaviours.

The inhibition of LSD1 via sequestration contributes to tau-mediated neurodegeneration

Tauopathies are a class of neurodegenerative diseases associated with pathological tau. Despite many advances in our understanding of these diseases, the direct mechanism through which tau contributes to neurodegeneration remains poorly understood. Previously, our laboratory implicated the histone demethylase LSD1 in tau-induced neurodegeneration by showing that LSD1 localizes to pathological tau aggregates in Alzheimer's disease cases, and that it is continuously required for the survival of hippocampal and cortical neurons in mice. Here, we utilize the P301S tauopathy mouse model to demonstrate that pathological tau can exclude LSD1 from the nucleus in neurons. In addition, we show that reducing LSD1 in these mice is sufficient to highly exacerbate tau-mediated neurodegeneration and tau-induced gene expression changes. Finally, we find that overexpressing LSD1 in the hippocampus of tauopathy mice, even after pathology has formed, is sufficient to significantly delay neurodegeneration and counteract tau-induced expression changes. These results suggest that inhibiting LSD1 via sequestration contributes to tau-mediated neurodegeneration. Thus, LSD1 is a promising therapeutic target for tauopathies such as Alzheimer's disease.

The Need for SMN-Independent Treatments of Spinal Muscular Atrophy (SMA) to Complement SMN-Enhancing Drugs

Spinal Muscular Atrophy (SMA) is monogenic motoneuron disease caused by low levels of the Survival of Motoneuron protein (SMN). Recently, two different drugs were approved for the treatment of the disease. The antisense oligonucleotide Nusinersen/Spinraza® and the gene replacement therapy Onasemnogene Abeparvovec/Zolgensma® both enhance SMN levels. These treatments result in impressive benefits for the patients. However, there is a significant number of non-responders and an intervention delay has a strong negative impact on the efficacy. Obviously, later stages of motoneuron degeneration cannot be reversed by SMN-restoration. Therefore, complementary, SMN-independent strategies are needed which are able to address such SMN-irreversible degenerative processes. Those are defined as pathological alterations which are not reversed by SMN-restoration for a given dose and intervention delay. It is crucial to tailor SMN-independent approaches to the novel clinical situation with SMN-restoring treatments. On the molecular level, such SMN-irreversible changes become manifest in altered signaling modules as described by molecular systems biology. Based on our current knowledge about altered signaling, we introduce a network approach for an informed decision for the most potent SMN-independent treatment targets. Finally, we present recommendations for the identification of novel treatments which can be combined with SMN-restoring drugs.

Murine's amygdala microstructure and elevated plus maze activities following R. vomitoria root bark and G. latifolium leaf extracts administration

R. vomitoria (RV), a plant used locally in the management of psychotic disorders, adversely affects the brain functionally and structurally. Such adverse reports, as well as the potential of G. latifolium (GL) to mitigate same warranted this investigation on the combined actions of RV and GL on the amygdala. Twenty-four male CD-1 mice weighing 22-27 g were divided into four groups (n = 6): Control (20 ml/kg body weight, b.w., distilled water); RV (200 mg/kg b.w.), GL (200 mg/kg b.w.), and RV (200 mg/kg b.w.) and GL (200 mg/kg b.w.) combination orally, and for 14 days. On day 15, the elevated-plus maze test was carried out and the animals sacrificed, and processed for histological and immunohistochemical studies. Neurobehavioural results showed significant decrease (p[Formula: see text] 0.001) in stretch-attend posture, time spent in closed arms, grooming frequency, protected head-dip, as well as significantly (p [Formula: see text] 0.01) increased time spent in the open arms and unprotected head-dips of the RV group. The combined RV and GL groups showed no such differences in these parameters. Histologically, the amygdala showed hypertrophied cells, with pyknotic and karyorrhectic nuclei, and reduced expression of Nissl substance in the RV group, while the combined RV and GL group showed less degenerative features. Glial fibrillary acidic protein expression (GFAP) was increased in the RV group, while the combined RV and GL group showed reduced expression. In conclusion, RV root bark extract has adverse effects on the microstructure of murines' amygdala and their behaviour, which may be ameliorated by GL.

Transplantation of viable mitochondria attenuates neurologic injury after spinal cord ischemia

OBJECTIVES

Spinal cord ischemia (SCI) is one of the major concerns of postoperative paraplegia during major vascular or aortic surgery. Since mitochondrial dysfunction develops at the early stage of SCI, this study tested the neuronal protective effect of transplantation of viable mitochondria to the ischemic cord in rats.

METHODS

SCI was induced by crossclamping of thoracic aorta at T6 level for 25 minutes, followed by release of vascular clip to restore aortic blood flow in the anesthetized rats. Mitochondria (100 μg) were isolated from freshly harvested soleus muscle and delivered via the internal jugular vein before releasing of vascular clip. The motor function was assessed independently up to 7 days after reperfusion. Spinal cords were harvested and analyzed for molecular and histological changes.

RESULTS

Whole-body in vivo images acquired by an in vivo imaging system confirmed the enhancement of MitoTracker fluorescence at the regions below crossclamping and in the ischemic cord. Compared with control vehicles, transplantation of mitochondria significantly improved the lower-limb locomotor function of rats subjected to cord ischemia up to 7 days after surgery. Mitochondrial transplantation suppressed the regional endoplasmic reticulum stress in the ischemic cord by attenuating CCAAT-enhancer-binding protein homologous protein expression and restoring binding immunoglobulin protein levels. In accordance, tissue levels of interleukin-6, tumor necrosis factor-α, and caspase-3 were attenuated in the mitochondrial transplanted group. Histologic examination also showed significant increase in numbers of Nissls bodies in the neurons at the ventral horn of ischemic cord following mitochondrial transplantation.

CONCLUSIONS

Our study showed that transplantation of freshly isolated mitochondria during the early stage of spinal cord ischemia-reperfusion injury suppressed the oxidative stress in endoplasmic reticulum of the injured cord, thereby reducing neuroapoptosis and improving locomotor function of rats with SCI.

The Struggle to Make CNS Axons Regenerate: Why Has It Been so Difficult?

Axon regeneration in the CNS is inhibited by many extrinsic and intrinsic factors. Because these act in parallel, no single intervention has been sufficient to enable full regeneration of damaged axons in the adult mammalian CNS. In the external environment, NogoA and CSPGs are strongly inhibitory to the regeneration of adult axons. CNS neurons lose intrinsic regenerative ability as they mature: embryonic but not mature neurons can grow axons for long distances when transplanted into the adult CNS, and regeneration fails with maturity in in vitro axotomy models. The causes of this loss of regeneration include partitioning of neurons into axonal and dendritic fields with many growth-related molecules directed specifically to dendrites and excluded from axons, changes in axonal signalling due to changes in expression and localization of receptors and their ligands, changes in local translation of proteins in axons, and changes in cytoskeletal dynamics after injury. Also with neuronal maturation come epigenetic changes in neurons, with many of the transcription factor binding sites that drive axon growth-related genes becoming inaccessible. The overall aim for successful regeneration is to ensure that the right molecules are expressed after axotomy and to arrange for them to be transported to the right place in the neuron, including the damaged axon tip.

rRNA and tRNA Bridges to Neuronal Homeostasis in Health and Disease

Dysregulation of protein translation is emerging as a unifying mechanism in the pathogenesis of many neuronal disorders. Ribosomal RNA (rRNA) and transfer RNA (tRNA) are structural molecules that have complementary and coordinated functions in protein synthesis. Defects in both rRNAs and tRNAs have been described in mammalian brain development, neurological syndromes, and neurodegeneration. In this review, we present the molecular mechanisms that link aberrant rRNA and tRNA transcription, processing and modifications to translation deficits, and neuropathogenesis. We also discuss the interdependence of rRNA and tRNA biosynthesis and how their metabolism brings together proteotoxic stress and impaired neuronal homeostasis.

Intrinsic Determinants of Axon Regeneration

The failure of axons to regenerate in the damaged mammalian CNS is the main impediment to functional recovery. There are many molecules and structures in the environment of the injured nervous system that can inhibit regeneration, but even when these are removed or replaced with a permissive environment, most CNS neurons exhibit little regeneration of their axons. This contrasts with the extensive and vigorous axon growth that may occur when embryonic neurons are transplanted into the adult CNS. In the peripheral nervous system, the axons usually respond to axotomy with a vigorous regenerative response accompanied by a regenerative program of gene expression, usually referred to as the regeneration-associated gene (RAG) program. These different responses to axotomy in the mature and immature CNS and the PNS lead to the concept of the intrinsic regenerative response of axons. Analysis of the many mechanisms and issues that affect the intrinsic regenerative response is the topic of this special issue of Developmental Neurobiology. The review articles highlight the control of expression of growth and regeneration-associated genes, emphasizing the role of epigenetic mechanisms. The reviews also discuss changes within axons that lead to the developmental loss of regenerative ability. This is caused by changes in axonal transport and trafficking, in the cytoskeleton and in signaling pathways.