Bisperoxovanadium Mediates Neuronal Protection through Inhibition of PTEN and Activation of PI3K/AKT-mTOR Signaling after Traumatic Spinal Injuries

Combination therapy enhances efficacy and overcomes toxicity of metal-based anti-diabetic agent

BACKGROUND AND PURPOSE

Metal-based therapeutic agents are limited by the required concentration of metal-based agents. Hereby, we determined if combination with 17β-oestradiol (E2) could reduce such levels and the therapy still be effective in type 2 diabetes mellitus (T2DM).

EXPERIMENTAL APPROACH

The metal-based agent (vanadyl acetylacetonate [VAC])- 17β-oestradiol (E2) combination is administered using the membrane-permeable graphene quantum dots (GQD), the vehicle, to form the active GQD-E2-VAC complexes, which was characterized by fluorescence spectra, infrared spectra and X-ray photoelectron spectroscopy. In db/db type 2 diabetic mice, the anti-diabetic effects of GQD-E2-VAC complexes were evaluated using blood glucose levels, oral glucose tolerance test (OGTT), serum insulin levels, homeostasis model assessment (homeostasis model assessment of insulin resistance [HOMA-IR] and homeostasis model assessment of β-cell function [HOMA-β]), histochemical assays and western blot.

KEY RESULTS

In diabetic mice, GQD-E2-VAC complex had comprehensive anti-diabetic effects, including control of hyperglycaemia, improved insulin sensitivity, correction of hyperinsulinaemia and prevention of β-cell loss. Co-regulation of thioredoxin interacting protein (TXNIP) activation by the combination of metal complex and 17β-oestradiol contributed to the enhanced anti-diabetic effects. Furthermore, a potent mitochondrial protective antioxidant, coniferaldehyde, significantly potentiates the protective effects of GQD-E2-VAC complexes.

CONCLUSION AND IMPLICATIONS

A metal complex-E2 combinatorial approach achieved simultaneously the protection of β cells and insulin enhancement at an unprecedented low dose, similar to the daily intake of dietary metals in vitamin supplements. This study demonstrates the positive effects of combination and multi-modal therapies towards type 2 diabetes treatment.

5-HT1F receptor agonism induces mitochondrial biogenesis and increases cellular function in brain microvascular endothelial cells

Introduction

Vascular and mitochondrial dysfunction are well-established consequences of multiple central nervous system (CNS) disorders, including neurodegenerative diseases and traumatic injuries. We previously reported that 5-hydroxytryptamine 1F receptor (5-HT1FR) agonism induces mitochondrial biogenesis (MB) in multiple organ systems, including the CNS.

Methods

Lasmiditan is a selective 5-HT1FR agonist that is FDA-approved for the treatment of migraines. We have recently shown that lasmiditan treatment induces MB, promotes vascular recovery and improves locomotor function in a mouse model of spinal cord injury (SCI). To investigate the mechanism of this effect, primary cerebral microvascular endothelial cells from C57bl/6 mice (mBMEC) were used.

Results

Lasmiditan treatment increased the maximal oxygen consumption rate, mitochondrial proteins and mitochondrial density in mBMEC, indicative of MB induction. Lasmiditan also enhanced endothelial cell migration and tube formation, key components of angiogenesis. Trans-endothelial electrical resistance (TEER) and tight junction protein expression, including claudin-5, were also increased with lasmiditan, suggesting improved barrier function. Finally, lasmiditan treatment decreased phosphorylated VE-Cadherin and induced activation of the Akt-FoxO1 pathway, which decreases FoxO1-mediated inhibition of claudin-5 transcription.

Discussion

These data demonstrate that lasmiditan induces MB and enhances endothelial cell function, likely via the VE-Cadherin-Akt-FoxO1-claudin-5 signaling axis. Given the importance of mitochondrial and vascular dysfunction in neuropathologies, 5-HT1FR agonism may have broad therapeutic potential to address multiple facets of disease progression by promoting MB and vascular recovery.

Applying Proteomics and Computational Approaches to Identify Novel Targets in Blast-Associated Post-Traumatic Epilepsy

Traumatic brain injury (TBI) can lead to post-traumatic epilepsy (PTE). Blast TBI (bTBI) found in Veterans presents with several complications, including cognitive and behavioral disturbances and PTE; however, the underlying mechanisms that drive the long-term sequelae are not well understood. Using an unbiased proteomics approach in a mouse model of repeated bTBI (rbTBI), this study addresses this gap in the knowledge. After rbTBI, mice were monitored using continuous, uninterrupted video-EEG for up to four months. Following this period, we collected cortex and hippocampus tissues from three groups of mice: those with post-traumatic epilepsy (PTE+), those without epilepsy (PTE-), and the control group (sham). Hundreds of differentially expressed proteins were identified in the cortex and hippocampus of PTE+ and PTE- relative to sham. Focusing on protein pathways unique to PTE+, pathways related to mitochondrial function, post-translational modifications, and transport were disrupted. Computational metabolic modeling using dysregulated protein expression predicted mitochondrial proton pump dysregulation, suggesting electron transport chain dysregulation in the epileptic tissue relative to PTE-. Finally, data mining enabled the identification of several novel and previously validated TBI and epilepsy biomarkers in our data set, many of which were found to already be targeted by drugs in various phases of clinical testing. These findings highlight novel proteins and protein pathways that may drive the chronic PTE sequelae following rbTBI.

Vanadium administration ameliorates cortical structural and functional changes in juvenile hydrocephalic mice

Vanadium is a prevalent neurotoxic transition metal with therapeutic potentials in some neurological conditions. Hydrocephalus poses a major clinical burden in neurological practice in Africa. Its primary treatment (shunting) has complications, including infection and blockage; alternative drug-based therapies are therefore necessary. This study investigates the function and cytoarchitecture of motor and cerebellar cortices in juvenile hydrocephalic mice following treatment with varying doses of vanadium. Fifty juvenile mice were allocated into five groups (n = 10 each): controls, hydrocephalus-only, low- (0.15 mg/kg), moderate- (0.3 mg/kg), and high- (3.0 mg/kg) dose vanadium groups. Hydrocephalus was induced by the intracisternal injection of kaolin and sodium metavanadate administered by intraperitoneal injection 72hourly for 28 days. Neurobehavioral tests: open field, hanging wire, and pole tests, were carried out to assess locomotion, muscular strength, and motor coordination, respectively. The cerebral motor and the cerebellar cortices were processed for cresyl violet staining and immunohistochemistry for neurons (NeuN) and astrocytes (glial fibrillary acidic protein). Hydrocephalic mice exhibited body weight loss and behavioral deficits. Horizontal and vertical movements and latency to fall from hanging wire were significantly reduced, while latency to turn and descend the pole were prolonged in hydrocephalic mice, suggesting impaired motor ability; this was improved in vanadium-treated mice. Increased neuronal count, pyknotic cells, neurodegeneration and reactive astrogliosis were observed in the hydrocephalic mice. These were mostly mitigated in the vanadium-treated mice, except in the high-dose group where astrogliosis persisted. These results demonstrate a neuroprotective potential of vanadium administration in hydrocephalus. The molecular basis of these effects needs further exploration.

PTEN knockout using retrogradely transported AAVs transiently restores locomotor abilities in both acute and chronic spinal cord injury

Restoring function in chronic stages of spinal cord injury (SCI) has often been met with failure or reduced efficacy when regenerative strategies are delayed past the acute or sub-acute stages of injury. Restoring function in the chronically injured spinal cord remains a critical challenge. We found that a single injection of retrogradely transported adeno-associated viruses (AAVrg) to knockout the phosphatase and tensin homolog protein (PTEN) in chronic SCI can effectively target both damaged and spared axons and transiently restore locomotor functions in near-complete injury models. AAVrg's were injected to deliver cre recombinase and/or a red fluorescent protein (RFP) under the human Synapsin 1 promoter (hSyn1) into the spinal cords of C57BL/6 PTENFloxΔ/Δ mice to knockout PTEN (PTEN-KO) in a severe thoracic SCI crush model at both acute and chronic time points. PTEN-KO improved locomotor abilities in both acute and chronic SCI conditions over a 9-week period. Regardless of whether treatment was initiated at the time of injury (acute), or three months after SCI (chronic), mice with limited hindlimb joint movement gained hindlimb weight support after treatment. Interestingly, functional improvements were not sustained beyond 9 weeks coincident with a loss of RFP reporter-gene expression and a near-complete loss of treatment-associated functional recovery by 6 months post-treatment. Treatment effects were also specific to severely injured mice; animals with weight support at the time of treatment lost function over a 6-month period. Retrograde tracing with Fluorogold revealed viable neurons throughout the motor cortex despite a loss of RFP expression at 9 weeks post-PTEN-KO. However, few Fluorogold labeled neurons were detected within the motor cortex at 6 months post-treatment. BDA labeling from the motor cortex revealed a dense corticospinal tract (CST) bundle in all groups except chronically treated PTEN-KO mice, indicating a potential long-term toxic effect of PTEN-KO to neurons in the motor cortex which was corroborated by a loss of β-tubulin III labeling above the lesion within spinal cords after PTEN-KO. PTEN-KO mice had significantly more β-tubulin III labeled axons within the lesion when treatment was delivered acutely, but not chronically post-SCI. In conclusion, we have found that using AAVrg's to knockout PTEN is an effective manipulation capable of restoring motor functions in chronic SCI and can enhance axon growth of currently unidentified axon populations when delivered acutely after injury. However, the long-term consequences of PTEN-KO on neuronal health and viability should be further explored.

The Temporal and Spatial Changes of Autophagy and PI3K Isoforms in Different Neural Cells After Hypoxia/Reoxygenation Injury

There are limited therapeutic options for patient with traumatic spinal cord injury (SCI). Phosphoinositide 3-kinase family (PI3Ks) are the key molecules for regulating cell autophagy, which is a possible way of treating SCI. As we know, PI3K family are composed of eight isoforms, which are distributed into three classes. While the role of PI3Ks in regulating autophagy is controversial and the effects may be in a cell-specific manner. Different isoforms do not distribute in neural cells consistently and it is not clear how the PI3K isoforms regulate and interact with autophagy. Therefore, we explored the distributions and expression of different PI3K isoforms in two key neural cells (PC12 cells and astrocytes). The results showed that the expression of LC3II/I and p62, which are the markers of autophagy, changed in different patterns in PC12 cells and astrocytes after hypoxia/reoxygenation injury (H/R). Furthermore, the mRNA level of eight PI3K isoforms did not change in the same way, and even for the same isoform the mRNA activities are different between PC12 cells and astrocytes. What is more, the results of western blot of PI3K isoforms after H/R were inconsistent with the relevant mRNA. Based on this study, the therapeutic effects of regulating autophagy on SCI are not confirmed definitely, and its molecular mechanisms may be related with different temporal and spatial patterns of activation and distributions of PI3K isoforms.

Acetylglutamine facilitates motor recovery and alleviates neuropathic pain after brachial plexus root avulsion in rats

BACKGROUND

Brachial plexus root avulsion (BPRA), a disabling peripheral nerve injury, induces substantial motoneuron death, motor axon degeneration and denervation of biceps muscles, leading to the loss of upper limb motor function. Acetylglutamine (N-acetyl-L-glutamine, NAG) has been proven to exert neuroprotective and anti-inflammatory effects on various disorders of the nervous system. Thus, the present study mainly focused on the influence of NAG on motor and sensory recovery after BPRA in rats and the underlying mechanisms.

METHODS

Male adult Sprague Dawley (SD) rats were subjected to BPRA and reimplantation surgery and subsequently treated with NAG or saline. Behavioral tests were conducted to evaluate motor function recovery and the mechanical pain threshold of the affected forelimb. The morphological appearance of the spinal cord, musculocutaneous nerve, and biceps brachii was assessed by histological staining. Quantitative real-time PCR (qRT‒PCR) was used to measure the mRNA levels of remyelination and regeneration indicators in myocutaneous nerves. The protein levels of inflammatory and pyroptotic indicators in the spinal cord anterior horn were measured using Western blotting.

RESULTS

NAG significantly accelerated the recovery of motor function in the injured forelimbs, enhanced motoneuronal survival in the anterior horn of the spinal cord, inhibited the expression of proinflammatory cytokines and pyroptosis pathway factors, facilitated axonal remyelination in the myocutaneous nerve and alleviated atrophy of the biceps brachii. Additionally, NAG attenuated neuropathic pain following BPRA.

CONCLUSION

NAG promotes functional motor recovery and alleviates neuropathic pain by enhancing motoneuronal survival and axonal remyelination and inhibiting the pyroptosis pathway after BPRA in rats, laying the foundation for the use of NAG as a novel treatment for BPRA.

Supramolecular assemblies with spatio-temporal sequential drug delivery capability treat spinal cord injury via neuroprotection and immunoregulation

Spinal cord injury (SCI) can result in irreversible motor and sensory deficits. However, up to data, clinical first-line drugs have ambiguous benefits and debilitating side effects, mainly due to the insufficient accumulation, poor physiological barrier penetration, and lack of spatio-temporal controlled release at lesion tissue. Herein, we proposed a supramolecular assemblies composed of hyperbranched polymer-formed core/shell structure through host-guest interactions. Such HPAA-BM@CD-HPG-C assemblies co-loaded with p38 inhibitor (SB203580) and insulin-like growth factor 1(IGF-1) are able to achieve time- and space-programmed sequential delivery benefiting from their cascaded responsiveness. The core-shell disassembly of HPAA-BM@CD-HPG-C occurs in acidic micro-environment around lesion, achieving preferentially the burst release of IGF-1 to protect survival neurons. Subsequently, the HPAA-BM cores containing SB203580 are endocytosed by the recruited macrophages and degraded by intracellular GSH, accelerating the release of SB203580 to promote the conversion from M1 to M2 macrophage. Hence, the successive synergy of neuroprotection and immunoregulation effects contribute to subsequent nerve repair and locomotor recovery as demonstrated in vitro and in vivo studies. Thus, our fabrication provides a strategy that multiple drugs co-delivery in a spatio-temporal selective manner adapting to the disease progression through self-cascaded disintegration, are expected to realize multidimensional precise treatment of SCI.

Armcx1 attenuates secondary brain injury in an experimental traumatic brain injury model in male mice by alleviating mitochondrial dysfunction and neuronal cell death

Armcx1 is highly expressed in the brain and is located in the mitochondrial outer membrane of neurons, where it mediates mitochondrial transport. Mitochondrial transport promotes the removal of damaged mitochondria and the replenishment of healthy mitochondria, which is essential for neuronal survival after traumatic brain injury (TBI). This study investigated the role of Armcx1 and its potential regulator(s) in secondary brain injury (SBI) after TBI. An in vivo TBI model was established in male C57BL/6 mice via controlled cortical impact (CCI). Adeno-associated viruses (AAVs) with Armcx1 overexpression and knockdown were constructed and administered to mice via stereotactic cortical injection. Exogenous miR-223-3p mimic or inhibitor was transfected into cultured cortical neurons, which were then scratched to simulate TBI in vitro. It was found that Armcx1 expression decreased significantly, while miR-223-3p levels increased markedly in peri-lesion tissues after TBI. The overexpression of Armcx1 significantly reduced TBI-induced neurological dysfunction, neuronal cell death, mitochondrial dysfunction, and axonal injury, while the knockdown of Armcx1 had the opposite effect. Armcx1 was potentially a direct target of miR-223-3p. The miR-223-3p mimic obviously reduced the Armcx1 protein level, while the miR-223-3p inhibitor had the opposite effect. Finally, the miR-223-3p inhibitor dramatically improved mitochondrial membrane potential (MMP) and increased the total length of the neurites without affecting branching numbers. In summary, our results suggest that the decreased expression of Armcx1 protein in neurons after experimental TBI aggravates secondary brain injury, which may be regulated by miR-223-3p. Therefore, this study provides a potential therapeutic approach for treating TBI.

PTEN inhibitor bisperoxovanadium protects against noise-induced hearing loss

Studies have shown that phosphatase and tensin homolog deleted on chromosome ten (PTEN) participates in the regulation of cochlear hair cell survival. Bisperoxovanadium protects against neurodegeneration by inhibiting PTEN expression. However, whether bisperoxovanadium can protect against noise-induced hearing loss and the underlying mechanism remains unclear. In this study, we established a mouse model of noise-induced hearing loss by exposure to 105 dB sound for 2 hours. We found that PTEN expression was increased in the organ of Corti, including outer hair cells, inner hair cells, and lateral wall tissues. Intraperitoneal administration of bisperoxovanadium decreased the auditory threshold and the loss of cochlear hair cells and inner hair cell ribbons. In addition, noise exposure decreased p-PI3K and p-Akt levels. Bisperoxovanadium preconditioning or PTEN knockdown upregulated the activity of PI3K-Akt. Bisperoxovanadium also prevented H₂O₂-induced hair cell death by reducing mitochondrial reactive oxygen species generation in cochlear explants. These findings suggest that bisperoxovanadium reduces noise-induced hearing injury and reduces cochlear hair cell loss.

Deletion of PTEN in microglia ameliorates chronic neuroinflammation following repetitive mTBI

Traumatic brain injury is a leading cause of morbidity and mortality in adults and children in developed nations. Following the primary injury, microglia, the resident innate immune cells of the CNS, initiate several inflammatory signaling cascades and pathophysiological responses that may persist chronically; chronic neuroinflammation following TBI has been closely linked to the development of neurodegeneration and neurological dysfunction. Phosphoinositide 3-kinases (PI3Ks) are a family of lipid kinases that have been shown to regulate several key mechanisms in the inflammatory response to TBI. Increasing evidence has shown that the modulation of the PI3K/AKT signaling pathway has the potential to influence the cellular response to inflammatory stimuli. However, directly targeting PI3K signaling poses several challenges due to its regulatory role in several cell survival pathways. We have previously identified that the phosphatase and tensin homolog deleted on chromosome 10 (PTEN), the major negative regulator of PI3K/AKT signaling, is dysregulated following exposure to repetitive mild traumatic brain injury (r-mTBI). Moreover, this dysregulated PI3K/AKT signaling was correlated with chronic microglial-mediated neuroinflammation. Therefore, we interrogated microglial-specific PTEN as a therapeutic target in TBI by generating a microglial-specific, Tamoxifen inducible conditional PTEN knockout model using a CX3CR1 Cre recombinase mouse line PTEN^fl/fl/CX3CR1^+/CreERT2 (mcg-PTEN^cKO), and exposed them to our 20-hit r-mTBI paradigm. Animals were treated with tamoxifen at 76 days post-last injury, and the effects of microglia PTEN deletion on immune-inflammatory responses were assessed at 90-days post last injury. We observed that the deletion of microglial PTEN ameliorated the proinflammatory response to repetitive brain trauma, not only reducing chronic microglial activation and proinflammatory cytokine production but also rescuing TBI-induced reactive astrogliosis, demonstrating that these effects extended beyond microglia alone. Additionally, we observed that the pharmacological inhibition of PTEN with BpV(HOpic) ameliorated the LPS-induced activation of microglial NFκB signaling in vitro. Together, these data provide support for the role of PTEN as a regulator of chronic neuroinflammation following repetitive mild TBI.

PTEN knockout using retrogradely transported AAVs restores locomotor abilities in both acute and chronic spinal cord injury

Restoring function in chronic stages of spinal cord injury (SCI) has often been met with failure or reduced efficacy when regenerative strategies are delayed past the acute or sub-acute stages of injury. Restoring function in the chronically injured spinal cord remains a critical challenge. We found that a single injection of retrogradely transported adeno-associated viruses (AAVrg) to knockout the phosphatase and tensin homolog protein (PTEN) in chronic SCI can effectively target both damaged and spared axons and restore locomotor functions in near-complete injury models. AAVrg's were injected to deliver cre recombinase and/or a red fluorescent protein (RFP) under the human Synapsin 1 promoter (hSyn1) into the spinal cords of C57BL/6 PTEN FloxΔ / Δ mice to knockout PTEN (PTEN-KO) in a severe thoracic SCI crush model at both acute and chronic time points. PTEN-KO improved locomotor abilities in both acute and chronic SCI conditions over a 9-week period. Regardless of whether treatment was initiated at the time of injury (acute), or three months after SCI (chronic), mice with limited hindlimb joint movement gained hindlimb weight support after treatment. Interestingly, functional improvements were not sustained beyond 9 weeks coincident with a loss of RFP reporter-gene expression and a near-complete loss of treatment-associated functional recovery by 6 months post-treatment. Treatment effects were also specific to severely injured mice; animals with weight support at the time of treatment lost function over a 6-month period. Retrograde tracing with Fluorogold revealed viable neurons throughout the motor cortex despite a loss of RFP expression at 9 weeks post-PTEN-KO. However, few Fluorogold labeled neurons were detected within the motor cortex at 6 months post-treatment. BDA labeling from the motor cortex revealed a dense corticospinal tract (CST) bundle in all groups except chronically treated PTEN-KO mice indicating a potential long-term toxic effect of PTEN-KO to neurons in the motor cortex. PTEN-KO mice had significantly more β - tubulin III labeled axons within the lesion when treatment was delivered acutely, but not chronically post-SCI. In conclusion, we have found that using AAVrg's to knockout PTEN is an effective manipulation capable of restoring motor functions in chronic SCI and can enhance axon growth of currently unidentified axon populations when delivered acutely after injury. However, the long-term consequences of PTEN-KO may exert neurotoxic effects.

Carboxyl-terminal modulator protein (CTMP) deficiency mitigates denervation-induced skeletal muscle atrophy

Denervated skeletal muscles show decreased Akt activity and phosphorylation, resulting in atrophy. Akt inhibits downstream transcription of atrophy-associated ubiquitin ligases like muscle ring-finger protein 1 (MuRF-1). In addition, reduced Akt signaling contributes to aberrant protein synthesis in muscles. In ALS mice, we recently found that carboxyl-terminator modulator protein (CTMP) expression is increased and correlated with reduced Akt signaling in atrophic skeletal muscle. CTMP has also been implicated in promoting muscle degeneration and catabolism in an in vitro muscle atrophy model. The present study examined whether sciatic nerve injury (SNI) stimulated CTMP expression in denervated skeletal muscle during muscle atrophy. We hypothesized that CTMP deficiency would reduce neurogenic atrophy and reverse Akt signaling downregulation. Compared to the unaffected contralateral muscle, wild-type (WT) gastrocnemius muscle had a significant increase in CTMP (p < 0.05). Furthermore, denervated CTMP knockout (CTMP-KO) gastrocnemius weighed more than WT muscle (p < 0.05). Denervated CTMP-KO gastrocnemius also showed higher Akt and downstream glycogen synthase kinase 3β (GSK3β) phosphorylation compared to WT muscle (p < 0.05) as well as ribosomal proteins S6 and 4E-BP1 phosphorylation (p < 0.001 and p < 0.05, respectively). Moreover, CTMP-KO mice showed significantly lower levels of E3 ubiquitin ligase MuRF-1 and myostatin than WT muscle (p < 0.05). Our findings suggest that CTMP is essential to muscle atrophy after denervation and it may act by reducing Akt signaling, protein synthesis, and increasing myocellular catabolism.

Vanadium improves memory and spatial learning and protects the pyramidal cells of the hippocampus in juvenile hydrocephalic mice

Background

Hydrocephalus is a neurological condition known to cause learning and memory disabilities due to its damaging effect on the hippocampal neurons, especially pyramidal neurons. Vanadium at low doses has been observed to improve learning and memory abilities in neurological disorders but it is uncertain whether such protection will be provided in hydrocephalus. We investigated the morphology of hippocampal pyramidal neurons and neurobehavior in vanadium-treated and control juvenile hydrocephalic mice.

Methods

Hydrocephalus was induced by intra-cisternal injection of sterile-kaolin into juvenile mice which were then allocated into 4 groups of 10 pups each, with one group serving as an untreated hydrocephalic control while others were treated with 0.15, 0.3 and 3 mg/kg i.p of vanadium compound respectively, starting 7 days post-induction for 28 days. Non-hydrocephalic sham controls (n = 10) were sham operated without any treatment. Mice were weighed before dosing and sacrifice. Y-maze, Morris Water Maze and Novel Object Recognition tests were carried out before the sacrifice, the brains harvested, and processed for Cresyl Violet and immunohistochemistry for neurons (NeuN) and astrocytes (GFAP). The pyramidal neurons of the CA1 and CA3 regions of the hippocampus were assessed qualitatively and quantitatively. Data were analyzed using GraphPad prism 8.

Results

Escape latencies of vanadium-treated groups were significantly shorter (45.30 ± 26.30 s, 46.50 ± 26.35 s, 42.99 ± 18.44 s) than untreated group (62.06 ± 24.02 s) suggesting improvements in learning abilities. Time spent in the correct quadrant was significantly shorter in the untreated group (21.19 ± 4.15 s) compared to control (34.15 ± 9.44 s) and 3 mg/kg vanadium-treated group (34.35 ± 9.74 s). Recognition index and mean % alternation were lowest in untreated group (p = 0.0431, p=0.0158) suggesting memory impairments, with insignificant improvements in vanadium-treated groups. NeuN immuno-stained CA1 revealed loss of apical dendrites of the pyramidal cells in untreated hydrocephalus group relative to control and a gradual reversal attempt in the vanadium-treated groups. Astrocytic activation (GFAP stain) in the untreated hydrocephalus group were attenuated in the vanadium-treated groups under the GFAP stain. Pyknotic index in CA1 pyramidal layer of untreated (18.82 ± 2.59) and 0.15mg/kg vanadium-treated groups (18.14 ± 5.92) were significantly higher than control (11.11 ± 0.93; p = 0.0205, p = 0.0373) while there was no significant difference in CA3 pyknotic index across all groups.

Conclusion

Our results suggest that vanadium has a dose-dependent protective effect on the pyramidal cells of the hippocampus and on memory and spatial learning functions in juvenile hydrocephalic mice.

Dulaglutide Improves Gliosis and Suppresses Apoptosis/Autophagy Through the PI3K/Akt/mTOR Signaling Pathway in Vascular Dementia Rats

Dulaglutide is a new type of hypoglycemic agent that agonizes glucagon-like peptide-1 receptor (GLP-1RA). It can be concluded from previous studies that a GLP-1RA can reduce apoptosis and regulate autophagy in the nervous system, while related research on dulaglutide in vascular dementia (VD) has not been reported. In our study, the VD rat model was established by bilateral carotid artery occlusion, and the results of the Morris water maze test (MWM) and open-field test showed that the application of dulaglutide could effectively reduce the cognitive decline of VD rats without changing the behavior in the open-field test, which was used to assess an anxiety-like phenotype. We applied HE staining and immunofluorescence labeling to show that dulaglutide treatment significantly alleviated neuronal damage in the hippocampal region of VD rats, and reduced microglial and astrocyte proliferation. Western blot results showed that dulaglutide reduced VD-induced neuronal apoptosis (BCL2/BAX, c-caspase3) and autophagy (P62, LC3B, Beclin-1), and upregulated phosphorylation of PI3K/Akt/mTOR signaling pathway. KEGG pathway analysis of RNA-Sequence results showed that the differentially expressed genes in the dulaglutide treatment group were significantly enriched in the mTOR signaling pathway, and the repressor of mTOR, Deptor, was down-regulated. In conclusion, this study suggested that dulaglutide may alleviate learning and memory impairment and neuron damage in VD rats by attenuating apoptosis, regulating autophagy, and activating the PI3K/Akt/mTOR signaling pathway in neurons, which may make it a promising candidate for the simultaneous treatment of VD and diabetes.

Extracellular vesicles from human umbilical cord mesenchymal stem cells reduce lipopolysaccharide-induced spinal cord injury neuronal apoptosis by mediating miR-29b-3p/PTEN

OBJECTIVE

This study investigated the molecular mechanism of whether hUC-MSCs-EVs repressed PTEN expression and activated the PI3K/AKT pathway through miR-29b-3p, thus inhibiting LPS-induced neuronal injury.

METHODS

hUC-MSCs were cultured and then identified. Cell morphology was observed. Alizarin red, oil red O, and alcian blue staining were used for inducing osteogenesis, adipogenesis, and chondrogenesis. EVs were extracted from hUC-MSCs and identified by transmission electron microscope observation and Western blot. SCI neuron model was established by 24h lipopolysaccharide (LPS) induction. After the cells were cultured with EVs without any treatment, uptake of EVs by SCI neurons, miR-29b-3p expression, cell viability, apoptosis, caspase-3, cleaved caspase-3, caspase 9, Bcl-2, PTEN, PI3K, AKT, and p-Akt protein levels, caspase 3 and caspase 9 activities, and inflammatory factors IL-6 and IL-1β levels were detected by immunofluorescence labeling, RT-qPCR, MTT, flow cytometry, Western blot, caspase 3 and caspase 9 activity detection kits, and ELISA. The binding sites between PTEN and miR-29b-3p were predicted by the database and verified by dual-luciferase assay.

RESULTS

LPS-induced SCI cell model was successfully established, and hUC-MSCs-EVs inhibited LPS-induced apoptosis of injured spinal cord neurons. EVs transferred miR-29b-3p into LPS-induced injured neurons. miR-29b-3p silencing reversed EV effects on reducing LPS-induced neuronal apoptosis. miR-29b-3p reduced LPS-induced neuronal apoptosis by targeting PTEN. After EVs-miR-inhi and si-PTEN treatment, inhibition of the PI3K/AKT pathway reversed hUC-MSCs-EVs effects on reducing LPS-induced neuronal apoptosis.

CONCLUSION

hUC-MSCs-EVs activated the PI3K/AKT pathway by carrying miR-29b-3p into SCI neurons and silencing PTEN, thus reducing neuronal apoptosis.

Icariin: A Potential Neuroprotective Agent in Alzheimer's Disease and Parkinson's Disease

Alzheimer's disease (AD) and Parkinson's disease (PD) are the most common neurodegenerative diseases worldwide. They are characterized by the loss of neurons and synapses in special parts of the central nervous system (CNS). There is no definitive treatment for AD and PD, but extensive studies are underway to identify the effective drugs which can slow the progression of these diseases by affecting the factors involved in their pathophysiology (i.e., aggregated proteins, neuroinflammation, and oxidative stress). Icariin, a natural compound isolated from Epimedii herba, is known because of its anti-inflammatory and anti-oxidant properties. In this regard, there are numerous studies indicating its potential as a natural compound against the progression of CNS disorders, such as neurodegenerative diseases. Therefore, this review aims to re-examine findings on the pharmacologic effects of icariin on factors involved in the pathophysiology of AD and PD.

Natural Products for the Treatment of Post-stroke Depression

Post-stroke depression (PSD) is the most frequent and important neuropsychiatric consequence of stroke. It is strongly associated with exacerbated deterioration of functional recovery, physical and cognitive recoveries, and quality of life. However, its mechanism is remarkably complicated, including the neurotransmitters hypothesis (which consists of a monoaminergic hypothesis and glutamate-mediated excitotoxicity hypothesis), inflammation hypothesis, dysfunction of the hypothalamic-pituitary-adrenal (HPA) axis, and neurotrophic hypothesis and neuroplasticity. So far, the underlying pathogenesis of PSD has not been clearly defined yet. At present, selective serotonin reuptake inhibitors (SSRIs) have been used as the first-line drugs to treat patients with PSD. Additionally, more than SSRIs, a majority of the current antidepressants complied with multiple side effects, which limits their clinical application. Currently, a wide variety of studies revealed the therapeutic potential of natural products in the management of several diseases, especially PSD, with minor side effects. Accordingly, in our present review, we aim to summarize the therapeutic targets of these compounds and their potential role in-clinic therapy for patients with PSD.

Novel Therapeutic Effects in Rat Spinal Cord Injuries: Recovery of the Definitive and Early Spinal Cord Injury by the Administration of Pentadecapeptide BPC 157 Therapy

Recently, marked therapeutic effects pertaining to the recovery of injured rat spinal cords (1 min compression injury of the sacrocaudal spinal cord (S2-Co1) resulting in tail paralysis) appeared after a single intraperitoneal administration of the stable gastric pentadecapeptide BPC 157 at 10 min post-injury. Besides the demonstrated rapid and sustained recovery (1 year), we showed the particular points of the immediate effect of the BPC 157 therapy that began rapidly after its administration, (i) soon after injury (10 min), or (ii) later (4 days), in the rats with a definitive spinal cord injury. Specifically, in counteracting spinal cord hematoma and swelling, (i) in rats that had undergone acute spinal cord injury, followed by intraperitoneal BPC 157 application at 10 min, we focused on the first 10–30 min post-injury period (assessment of gross, microscopic, and gene expression changes). Taking day 4 post-injury as the definitive injury, (ii) we focused on the immediate effects after the BPC 157 intragastric application over 20 min of the post-therapy period. Comparable long-time recovery was noted in treated rats which had definitive tail paralysis: (iii) the therapy was continuously given per orally in drinking water, beginning at day 4 after injury and lasting one month after injury. BPC 157 rats presented only discrete edema and minimal hemorrhage and increased Nos1, Nos2, and Nos3 values (30 min post-injury, (i)) or only mild hemorrhage, and only discrete vacuolation of tissue (day 4, (ii)). In the day 4–30 post-injury study (iii), BPC 157 rats rapidly presented tail function recovery, and no demyelination process (Luxol fast blue staining).

Cryogenic 3D Printing of ß-TCP/PLGA Composite Scaffolds Incorporated With BpV (Pic) for Treating Early Avascular Necrosis of Femoral Head

Avascular necrosis of femoral head (ANFH) is a disease that is characterized by structural changes and collapse of the femoral head. The exact causes of ANFH are not yet clear, but small advances in etiopathogenesis, diagnosis and treatment are achieved. In this study, ß-tricalcium phosphate/poly lactic-co-glycolic acid composite scaffolds incorporated with bisperoxovanadium [bpV (pic)] (bPTCP) was fabricated through cryogenic 3D printing and were utilized to treat rat models with early ANFH, which were constructed by alcohol gavage for 6 months. The physical properties of bPTCP scaffolds and in vitro bpV (pic) release from the scaffolds were assessed. It was found that the sustained release of bpV (pic) promoted osteogenic differentiation and inhibited adipose differentiation of bone marrow-derived mesenchymal stem cells. Micro-computed tomography scanning and histological analysis confirmed that the progression of ANFH in rats was notably alleviated in bPTCP scaffolds. Moreover, it was noted that the bPTCP scaffolds inhibited phosphatase and tensin homolog and activated the mechanistic target of rapamycin signaling. The autophagy induced by bPTCP scaffolds could partially prevent apoptosis, promote osteogenesis and angiogenesis, and hence eventually prevent the progression of ANFH, suggesting that the bPTCP scaffold are promising candidate to treat ANFH.

Promoting axon regeneration in the central nervous system by increasing PI3-kinase signaling

Much research has focused on the PI3-kinase and PTEN signaling pathway with the aim to stimulate repair of the injured central nervous system. Axons in the central nervous system fail to regenerate, meaning that injuries or diseases that cause loss of axonal connectivity have life-changing consequences. In 2008, genetic deletion of PTEN was identified as a means of stimulating robust regeneration in the optic nerve. PTEN is a phosphatase that opposes the actions of PI3-kinase, a family of enzymes that function to generate the membrane phospholipid PIP₃ from PIP₂ (phosphatidylinositol (3,4,5)-trisphosphate from phosphatidylinositol (4,5)-bisphosphate). Deletion of PTEN therefore allows elevated signaling downstream of PI3-kinase, and was initially demonstrated to promote axon regeneration by signaling through mTOR. More recently, additional mechanisms have been identified that contribute to the neuron-intrinsic control of regenerative ability. This review describes neuronal signaling pathways downstream of PI3-kinase and PIP₃, and considers them in relation to both developmental and regenerative axon growth. We briefly discuss the key neuron-intrinsic mechanisms that govern regenerative ability, and describe how these are affected by signaling through PI3-kinase. We highlight the recent finding of a developmental decline in the generation of PIP₃ as a key reason for regenerative failure, and summarize the studies that target an increase in signaling downstream of PI3-kinase to facilitate regeneration in the adult central nervous system. Finally, we discuss obstacles that remain to be overcome in order to generate a robust strategy for repairing the injured central nervous system through manipulation of PI3-kinase signaling.

Bisperoxovanadium promotes motor neuron survival and neuromuscular innervation in amyotrophic lateral sclerosis

Amyotrophic lateral sclerosis (ALS) is the most common motor neuron (MN) disease, with no present cure. The progressive loss of MNs is the hallmark of ALS. We have previously shown the therapeutic effects of the phosphatase and tensin homolog (PTEN) inhibitor, potassium bisperoxo (picolinato) vanadium (bpV[pic]), in models of neurological injury and demonstrated significant neuroprotective effects on MN survival. However, accumulating evidence suggests PTEN is detrimental for MN survival in ALS. Therefore, we hypothesized that treating the mutant superoxide dismutase 1 G93A (mSOD1^G93A) mouse model of ALS during motor neuron degeneration and an in vitro model of mSOD1^G93A motor neuron injury with bpV(pic) would prevent motor neuron loss. To test our hypothesis, we treated mSOD1^G93A mice intraperitoneally daily with 400 μg/kg bpV(pic) from 70 to 90 days of age. Immunolabeled MNs and microglial reactivity were analyzed in lumbar spinal cord tissue, and bpV(pic) treatment significantly ameliorated ventral horn motor neuron loss in mSOD1^G93A mice (p = 0.003) while not significantly altering microglial reactivity (p = 0.701). Treatment with bpV(pic) also significantly increased neuromuscular innervation (p = 0.018) but did not affect muscle atrophy. We also cultured motor neuron-like NSC-34 cells transfected with a plasmid to overexpress mutant SOD1^G93A and starved them in serum-free medium for 24 h with and without bpV(pic) and downstream inhibitor of Akt signaling, LY294002. In vitro, bpV(pic) improved neuronal viability, and Akt inhibition reversed this protective effect (p < 0.05). In conclusion, our study indicates systemic bpV(pic) treatment could be a valuable neuroprotective therapy for ALS.

MicroRNAs 21 and 199a-3p Regulate Axon Growth Potential through Modulation of Pten and mTor mRNAs

Increased mTOR activity has been shown to enhance regeneration of injured axons by increasing neuronal protein synthesis, while PTEN signaling can block mTOR activity to attenuate protein synthesis. MicroRNAs (miRs) have been implicated in regulation of PTEN and mTOR expression, and previous work in spinal cord showed an increase in miR-199a-3p after spinal cord injury (SCI) and increase in miR-21 in SCI animals that had undergone exercise. Pten mRNA is a target for miR-21 and miR-199a-3p is predicted to target mTor mRNA. Here, we show that miR-21 and miR-199a-3p are expressed in adult dorsal root ganglion (DRG) neurons, and we used culture preparations to test functions of the rat miRs in adult DRG and embryonic cortical neurons. miR-21 increases and miR-199a-3p decreases in DRG neurons after in vivo axotomy. In both the adult DRG and embryonic cortical neurons, miR-21 promotes and miR-199a-3p attenuates neurite growth. miR-21 directly bound to Pten mRNA and miR-21 overexpression decreased Pten mRNA levels. Conversely, miR-199a-3p directly bound to mTor mRNA and miR-199a-3p overexpression decreased mTor mRNA levels. Overexpressing miR-21 increased both overall and intra-axonal protein synthesis in cultured DRGs, while miR-199a-3p overexpression decreased this protein synthesis. The axon growth phenotypes seen with miR-21 and miR-199a-3p overexpression were reversed by co-transfecting PTEN and mTOR cDNA expression constructs with the predicted 3′ untranslated region (UTR) miR target sequences deleted. Taken together, these studies indicate that injury-induced alterations in miR-21 and miR-199a-3p expression can alter axon growth capacity by changing overall and intra-axonal protein synthesis through regulation of the PTEN/mTOR pathway.

Traumatic Brain Injury: Mechanistic Insight on Pathophysiology and Potential Therapeutic Targets

Traumatic brain injury (TBI) causes brain damage, which involves primary and secondary injury mechanisms. Primary injury causes local brain damage, while secondary damage begins with inflammatory activity followed by disruption of the blood-brain barrier (BBB), peripheral blood cells infiltration, brain edema, and the discharge of numerous immune mediators including chemotactic factors and interleukins. TBI alters molecular signaling, cell structures, and functions. Besides tissue damage such as axonal damage, contusions, and hemorrhage, TBI in general interrupts brain physiology including cognition, decision-making, memory, attention, and speech capability. Regardless of the deep understanding of the pathophysiology of TBI, the underlying mechanisms still need to be assessed with a desired therapeutic agent to control the consequences of TBI. The current review gives a brief outline of the pathophysiological mechanism of TBI and various biochemical pathways involved in brain injury, pharmacological treatment approaches, and novel targets for therapy.

Sinisan Protects Primary Hippocampal Neurons Against Corticosterone by Inhibiting Autophagy via the PI3K/Akt/mTOR Pathway

Objective: Corticosterone causes significant neurotoxicity in primary hippocampal neurons which is associated with depression. Dysfunctional autophagy is implicated in cognitive impairment and depressive-like behavior. The traditional Chinese medicine Sinisan (SNS) is highly effective in clinical treatment of depression. However, the molecular mechanisms underlying therapeutic effects of SNS are unknown. Purpose: The aim of this study was to elucidate the protective effect of SNS and the underlying mechanisms against corticosterone-induced neuronal damage. Study Design: The effects of serum derived from rats containing SNS (or untreated controls) on the expression of autophagy-related molecules in primary rat hippocampal neurons exposed to different concentrations of corticosterone for different intervals were explored. Methods: CCK-8 assay, LDH assay were used to analyze cell viability and LDH activity. Western blot, qRT-PCR, and immunofluorescence assays were used to determine protein and mRNA expression levels of molecules such as LC3, p62, Beclin1, ULK1, PI3K, p-PI3K, Akt p-Akt, mTOR, p-mTOR, p70S6, p-p70S6, 4ebp1 and p-4ebp1. Results: Corticosterone induced a dose- and time-dependent reduction in cellular viability. Moreover, corticosterone (100-400 μM) treatment for 24 h increased LC3-II/LC3-I protein ratio, increased Beclin1 and ULK1 protein expression levels, and decreased p62, PI3K, p-PI3K, p-Akt, p-mTOR, p-p70S6, and p-4ebp1 protein expression levels. Notably, SNS-containing serum reversed corticosterone-induced reduction of neuronal viability, and increased p62, PI3K, p-Akt, p-mTOR, p-p70S6, and p-4ebp1 protein and mRNA expression levels. In addition, SNS-containing serum decreased LC3-II/LC3-I protein ratio, and downregulated Beclin1, and ULK1 protein and mRNA expression in primary hippocampal neurons. Conclusion: SNS protects primary hippocampal neurons against corticosterone-induced neurotoxicity by preventing excessive autophagy through activation of PI3K/AKT/mTOR pathway.

PTEN activation contributes to neuronal and synaptic engulfment by microglia in tauopathy

Phosphatase and tensin homolog (PTEN) regulates synaptic density in development; however, whether PTEN also regulates synapse loss in a neurodegenerative disorder such as frontotemporal lobar degeneration with Tau deposition (FTLD-Tau) has not been explored. Here, we found that pathological Tau promotes early activation of PTEN, which precedes apoptotic caspase-3 cleavage in the rTg4510 mouse model of FTLD-Tau. We further demonstrate increased synaptic and neuronal exposure of the apoptotic signal phosphatidylserine that tags neuronal structures for microglial uptake, thereby linking PTEN activation to synaptic and neuronal structure elimination. By applying pharmacological inhibition of PTEN's protein phosphatase activity, we observed that microglial uptake can be decreased in Tau transgenic mice. Finally, we reveal a dichotomous relationship between PTEN activation and age in FTLD-Tau patients and healthy controls. Together, our findings suggest that in tauopathy, PTEN has a role in the synaptotoxicity of pathological Tau and promotes microglial removal of affected neuronal structures.

Effect of Electroacupuncture Treatment at Dazhui (GV14) and Mingmen (GV4) Modulates the PI3K/AKT/mTOR Signaling Pathway in Rats after Spinal Cord Injury

Electroacupuncture (EA) is widely recognized as clinical treatment of spinal cord injury (SCI). The purpose of this study is to elucidate whether and how the PI3K/AKT/mTOR signaling pathway plays any role in EA treating SCI. Rats were randomly divided into four equal groups: Control Group, Sham-operation Group, Model Group, and EA Group, then further randomly divided into the following subgroups: 1-day (n = 12), 1-day rapamycin (n = 6), 14-day (n = 18), and 28-day (n = 18). A rat model of SCI was established by a modified Allen's weight-drop method. In the EA Group, rats were stimulated on Dazhui (GV14) and Mingmen (GV4) for 20 min by sterilized stainless steel needles. In the EA Group, the Basso, Beattie, and Bresnahan locomotor rating scale showed obvious improved locomotor function, and hematoxylin-eosin staining and magnetic resonance imaging showed that the histological morphology change of injured spinal cord tissue was obviously alleviated. Also, blocking spinal mTOR by injection of rapamycin showed that mTOR existed in the injured spinal cord, and EA could significantly activate mTOR in SCI rats. And immunohistochemistry and western blot analysis on the PI3K/AKT/mTOR signaling pathway showed that levels of PI3K, AKT, mTOR, and p70S6K in the injured spinal cord tissue were greatly increased in the EA Group, while the levels of PTEN and caspase 3 were decreased. The present study suggests that EA could affect cell growth, apoptosis, and autophagy through the PI3K/AKT/mTOR signaling pathway.

Polygalasaponin F inhibits neuronal apoptosis induced by oxygen-glucose deprivation and reoxygenation through the PI3K/Akt pathway

Cerebral ischaemia is a common cerebrovascular disease and often induces neuronal apoptosis, leading to brain damage. Polygalasaponin F (PGSF) is one of the components in Polygala japonica Houtt, and it is a triterpenoid saponin monomer. This research focused on anti-apoptotic effect of PGSF during oxygen-glucose deprivation and reoxygenation (OGD/R) injury in rat adrenal pheochromocytoma cells (PC12) and primary rat cortical neurons. OGD/R treatment reduced viability of PC12 cells and primary neurons. This reduced viability was prevented by PGSF, as shown by MTT assay. OGD/R insult decreased expression of Bcl-2/Bax both in PC12 cells and primary neurons but elevated levels of caspase-3 in primary neurons. However, PGSF may up-regulate expression of Bcl-2/Bax and down-regulate caspase-3 in these particular cells. Furthermore, Bcl-2/Bax and the ratio between phosphorylated Akt and total Akt were decreased in PC12 cells treated with OGD/R, and both were increased by PGSF. Moreover, increase in the ratios of Bcl-2/Bax and phosphorylated Akt/total Akt in PC12 cells was suppressed by phosphatidylinositol 3-kinase (PI3K) inhibitor. Data suggest PGSF might prevent OGD/R-induced injury via activation of PI3K/Akt signalling. The ability of PGSF to block the effects of OGD/R appears to involve regulation of Bcl-2, Bax and caspase-3, which are related to apoptosis.

Hydrogen sulfide promotes lipopolysaccharide-induced apoptosis of osteoblasts by inhibiting the AKT/NF-κB signaling pathway

Apoptosis of osteoblasts plays a crucial role in osteomyelitis. Hydrogen sulfide (H₂S) levels are increased in the pathophysiological processes of osteomyelitis. However, the effect of H₂S on the apoptosis of osteoblasts remains unclear. To investigate the specific role of H₂S in osteoblast apoptosis, MC3T3-E1 and hFOB cells were treated with NaHS or Na₂S, a donor of H₂S, and lipopolysaccharide (LPS), during osteomyelitis. 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide assays, flow cytometry analysis, western blotting, immunofluorescence, polymerase chain reaction, and Alizarin red staining were performed to examine the effects of H₂S on osteoblast cell apoptosis, cell osteogenic differentiation, and AKT kinase (AKT)/nuclear factor kappa B (NF-κB) signaling. Hydrogen sulfide increased cell apoptosis, and inhibited the proliferation and osteogenic differentiation of osteoblast cells impaired by LPS. H₂S increased apoptosis through upregulation of the FAS ligand (FASL) signaling pathway. H₂S-induced apoptosis was alleviated using a FAS/FASL signaling pathway inhibitor. Treatment with NaHS also increased cell apoptosis by downregulating AKT/NF-κB signaling. In addition, treatment with an AKT signaling pathway activator decreased apoptosis and reversed the inhibitory effects of H₂S on osteogenic differentiation. Hydrogen sulfide promotes LPS-induced apoptosis of osteoblast cells by inhibiting AKT/NF-κB signaling.

Hemin treatment protects neonatal rats from sevoflurane-induced neurotoxicity via the phosphoinositide 3-kinase/Akt pathway

AIMS

Anaesthesia-related neurotoxicity in the developing brain is a controversial issue that has recently attracted much attention. Hemin plays a protective role in hypoxic and ischemic brain damage; however, its effects on sevoflurane-induced neurotoxicity remain unclear. Our aim was to investigate the mechanisms of sevoflurane neurotoxicity and potential neuroprotective roles of hemin upon sevoflurane exposure.

MAIN METHODS

Hippocampi were harvested 18 h after sevoflurane exposure. Haem oxygenase 1 (HMOX1), superoxide dismutase 2 (SOD2), discs large MAGUK scaffold protein 4 (DLG4), phosphorylated Akt, Akt, cleaved caspase 3, and neuroglobin were detected by western blotting. A water maze test was used to assess learning and memory ability in P30 rats.

KEY FINDINGS

Sevoflurane inhalation increased cleaved caspase 3 levels. Hemin treatment enhanced the antioxidant defence response, protecting rats from oxidative stress injury. Hemin plays its neuroprotective role via phosphoinositide 3-kinase (PI3K)/Akt signalling. A single inhalation of sevoflurane did not affect DLG4 expression, while hemin treatment did. Platform crossing increased in rats treated with hemin as well, which may be related to increased DLG4. Neuroglobin expression was not affected, suggesting that it may act upstream of PI3K/Akt signalling.

SIGNIFICANCE

Our study demonstrates that hemin plays a protective role in anaesthesia-induced neurotoxicity by both inhibiting apoptosis via the PI3K/Akt pathway and increasing the expression of antioxidant enzymes, reducing oxidative damage. The results provide mechanistic insight into the effects of sevoflurane anaesthesia on the developing brain and suggest that hemin could help avoid these effects.

Carbamazepine Alleviates Retinal and Optic Nerve Neural Degeneration in Diabetic Mice via Nerve Growth Factor-Induced PI3K/Akt/mTOR Activation

Aim: Diabetic retinopathy causes loss of vision in adults at working-age. Few therapeutic options are available for treatment of diabetic retinopathy. Carbamazepine (CARB), a widely used antiepileptic drug, was recently accounted for its neuroprotective effect. Nerve growth factor (NGF) activates various cascades among which, PI3K/Akt/mTOR pathway has a vital action in NGF-mediated neuronal differentiation and survival. This study evaluated the effect of CARB in the treatment of diabetic retina and unveiled some of the underlying molecular mechanisms. Main Methods: Alloxan diabetes model was induced in 36 albino well-acclimatized mice. After establishment of the diabetic model in 9 weeks, mice were assigned to treatment groups: (1) saline, (2) alloxan-diabetic, (3 and 4) alloxan+CARB (25 or 50 mg per kg p.o) for 4 weeks. After completion of the therapeutic period, mice were sacrificed and eyeballs were enucleated. Retinal levels of NGF and PI3K/Akt were assessed using real-time polymerase chain reaction. Further, total and phosphorylated TrKA, PI3K, Akt, mTOR as well as Caspase-3 were measured by Western blot analysis. Key Findings: Histopathological examination demonstrated that CARB attenuated vacuolization and restored normal thickness and organization of retinal cell layers. In addition, CARB increased pTrKA/TrKA ratio and ameliorated diabetes-induced reduction of NGF mRNA and immunostaining in retina. Additionally, it augmented the mRNA expression of PI3K and Akt, as well as the protein level of the phosphorylated PI3/Akt/mTOR. Significance: Results highlighted, for the first time, the neuronal protective effect for CARB in diabetic retina, which is mediated, at least in part, by activation of the NGF/PI3K/Akt/mTOR pathway.

Berberine enhances survival and axonal regeneration of motoneurons following spinal root avulsion and re-implantation in rats

Brachial plexus avulsion (BPA) occurs when the spinal nerve roots are pulled away from the surface of the spinal cord and disconnects neuronal cell body from its distal downstream axon, which induces massive motoneuron death, motor axon degeneration and de-innervation of targeted muscles, thereby resulting in permanent paralysis of motor functions in the upper limb. Avulsion injury triggers oxidative stress and intense local neuroinflammation at the lesioned site, leading to the death of most motoneurons. Berberine (BBR), a natural isoquinoline alkaloid derived from medicinal herbs of Berberis and Coptis species, has been reported to possess neuro-protective, anti-inflammatory and anti-oxidative effects in various animal models of central nervous system (CNS)-related disorders. In this study, we aimed to investigate the effect of BBR on motoneuron survival and axonal regeneration following spinal root avulsion plus re-implantation in rats. Our results indicated BBR significantly accelerated motor function recovery in the forelimb as revealed by the increased Terzis grooming test score, facilitated motor axon regeneration as evidenced by the elevated number of Fluoro-Gold-labeled and P75-positive regenerative motoneurons. The survival of motoneurons was notably promoted by BBR administration presented with boosted ChAT-immunopositive and neutral red-stained neurons. BBR treatment efficiently alleviated muscle atrophy, attenuated functional motor endplates loss in biceps and prevented the reduction of motor axons in the musculocutaneous nerve. Additionally, BBR treatment markedly mitigated the avulsion-induced neuroinflammation via inhibiting microglial and astroglial reactivity, up-regulated the expression of antioxidative indicator Cu/Zn SOD, and down-regulated the levels of nNOS, 3-NT, lipid peroxidation and NF-κB, as well as promoted SIRT1, PI3K and Akt activation. Collectively, BBR might be a promising therapy to assist re-implantation surgery for the treatment of BPA.

miRNA-26a-5p Accelerates Healing via Downregulation of PTEN in Fracture Patients with Traumatic Brain Injury

Patients who sustain a traumatic brain injury (TBI) are known to have a significantly quicker fracture healing time than patients with isolated fractures, but the underlying mechanism has yet to be identified. In this study, we found that the upregulation of miRNA-26a-5p induced by TBI correlated with a decrease in phosphatase and tensin homolog (PTEN) in callus formation. In vitro, overexpressing miRNA-26a-5p inhibited PTEN expression and accelerated osteoblast differentiation, whereas silencing of miRNA-26a-5p inhibited osteoblast activity. Reduction of PTEN facilitated osteoblast differentiation via the PI3K/AKT signaling pathway. Through luciferase assays, we found evidence that PTEN is a miRNA-26a-5p target gene that negatively regulates the differentiation of osteoblasts. Moreover, the present study confirmed that preinjection of agomiR-26a-5p leads to increased bone formation. Collectively, these results indicate that miRNA-26a-5p overexpression may be a key factor governing the improved fracture healing observed in TBI patients after the downregulation of PTEN and PI3K/AKT signaling. Upregulation of miRNA-26a-5p may therefore be a promising therapeutic strategy for promoting fracture healing.