Cerebrolysin improves sciatic nerve dysfunction in a mouse model of diabetic peripheral neuropathy

Animal Models of Type 2 Diabetes Complications: A Review

Diabetes mellitus is a multifactorial metabolic disease, of which type 2 diabetes (T2D) is one of the most common. The complications of diabetes are far more harmful than diabetes itself. Type 2 diabetes complications include diabetic nephropathy (DN), diabetic heart disease, diabetic foot ulcers (DFU), diabetic peripheral neuropathy (DPN), and diabetic retinopathy (DR) et al. Many animal models have been developed to study the pathogenesis of T2D and discover an effective strategy to treat its consequences. In this sense, it is crucial to choose the right animal model for the corresponding diabetic complication. This paper summarizes and classifies the animal modeling approaches to T2D complications and provides a comprehensive review of their advantages and disadvantages. It is hopeful that this paper will provide theoretical support for animal trials of diabetic complications.

The effects of voluntary exercise on histological and stereological changes of sciatic nerve, nitric oxide levels, and peripheral neuropathy caused by high-fat diet-induced type 2 diabetes in male rats

This research was conducted to investigate the possible beneficial impacts of voluntary exercise on sciatic tissue, nitric oxide levels, stereological changes, and peripheral neuropathy caused by "high-fat-diet (HFD)"-induced "type 2 diabetes mellitus (T2DM)" in male rats. Rats were put into four experimental groups at random: "healthy control (C), voluntary exercise (VE), diabetic (D), and diabetic rats treated by voluntary exercise (VED)"; each group contain eight animals. Animals in VE and VED groups performed "voluntary exercise (VE)" for ten weeks. Animals in D and VED groups became diabetic after receiving a HFD for four weeks and an intraperitoneal injection (IP) of "streptozotocin (STZ)" (35 mg/kg). In order to evaluate mechanical and thermal algesia, hot plate, tail withdrawal, and von Frey tests were carried out. At the end of this study, serum NOx levels were assessed, and histological and stereological analyses were conducted. Mechanical nociceptive thresholds indicated considerable reduction (p < 0.001) which was followed by a remarkable enhance (p < 0.001) in thermal nociceptive threshold of D group. Tissue changes were also seen in sciatic nerve of D group. Voluntary exercise modified thermal and mechanical sensitivity in diabetic rats. It also improved the damaged sciatic nerve in diabetic animals.

Comparative neuroprotective effects of Cerebrolysin, dexamethasone, and ascorbic acid on sciatic nerve injury model: Behavioral and histopathological study

Background

The majority of the suggested experimental modalities for peripheral nerve injury (PNI) result in varying degrees of recovery in animal models; however, there are not many reliable clinical pharmacological treatment models available. To alleviate PNI complications, research on approaches to accelerate peripheral nerve regeneration is encouraged. Cerebrolysin, dexamethasone, and ascorbic acid (vitamin C) drug models were selected in our study because of their reported curative effects of different mechanisms of action.

Methodology

A total of 40 adult male albino rats were used in this study. Sciatic nerve crush injury was induced in 32 rats, which were divided equally into four groups (model, Cerebrolysin, dexamethasone, and vitamin C groups) and compared to the sham group (n = 8). The sciatic nerve sensory and motor function regeneration after crushing together with gastrocnemius muscle histopathological changes were evaluated by the sciatic function index, the hot plate test, gastrocnemius muscle mass ratio, and immune expression of S100 and apoptosis cascade (BAX, BCL2, and BAX/BCL2 ratio).

Results

Significant improvement of the behavioral status and histopathological assessment scores occurred after the use of Cerebrolysin (as a neurotrophic factor), dexamethasone (as an anti-inflammatory), and vitamin C (as an antioxidant). Despite these seemingly concomitant, robust behavioral and pathological changes, vitamin C appeared to have the best results among the three main outcome measures. There was a positive correlation between motor and sensory improvement and also between behavioral and histopathological changes, boosting the effectiveness, and implication of the sciatic function index as a mirror for changes occurring on the tissue level.

Conclusion

Vitamin C is a promising therapeutic in the treatment of PNI. The sciatic function index (SFI) test is a reliable accurate method for assessing sciatic nerve integrity after both partial disruption and regrowth.

Mitochondrial function in spinal cord injury and regeneration

Many people around the world suffer from some form of paralysis caused by spinal cord injury (SCI), which has an impact on quality and life expectancy. The spinal cord is part of the central nervous system (CNS), which in mammals is unable to regenerate, and to date, there is a lack of full functional recovery therapies for SCI. These injuries start with a rapid and mechanical insult, followed by a secondary phase leading progressively to greater damage. This secondary phase can be potentially modifiable through targeted therapies. The growing literature, derived from mammalian and regenerative model studies, supports a leading role for mitochondria in every cellular response after SCI: mitochondrial dysfunction is the common event of different triggers leading to cell death, cellular metabolism regulates the immune response, mitochondrial number and localization correlate with axon regenerative capacity, while mitochondrial abundance and substrate utilization regulate neural stem progenitor cells self-renewal and differentiation. Herein, we present a comprehensive review of the cellular responses during the secondary phase of SCI, the mitochondrial contribution to each of them, as well as evidence of mitochondrial involvement in spinal cord regeneration, suggesting that a more in-depth study of mitochondrial function and regulation is needed to identify potential targets for SCI therapeutic intervention.

Progression in translational research on spinal cord injury based on microenvironment imbalance

Spinal cord injury (SCI) leads to loss of motor and sensory function below the injury level and imposes a considerable burden on patients, families, and society. Repair of the injured spinal cord has been recognized as a global medical challenge for many years. Significant progress has been made in research on the pathological mechanism of spinal cord injury. In particular, with the development of gene regulation, cell sequencing, and cell tracing technologies, in-depth explorations of the SCI microenvironment have become more feasible. However, translational studies related to repair of the injured spinal cord have not yielded significant results. This review summarizes the latest research progress on two aspects of SCI pathology: intraneuronal microenvironment imbalance and regenerative microenvironment imbalance. We also review repair strategies for the injured spinal cord based on microenvironment imbalance, including medications, cell transplantation, exosomes, tissue engineering, cell reprogramming, and rehabilitation. The current state of translational research on SCI and future directions are also discussed. The development of a combined, precise, and multitemporal strategy for repairing the injured spinal cord is a potential future direction.

Endothelial Yes-Associated Protein 1 Promotes Astrocyte Proliferation and Maturation via Cytoplasmic Leukemia Inhibitory Factor Secretion in Oxygen-Induced Retinopathy

Purpose

Purpose The role of endothelial Yes-associated protein 1 (YAP) in the pathogenesis of retinal angiogenesis and the astrocyte network in the mouse oxygen-induced retinopathy (OIR) model is unknown.

Methods

For in vivo studies, OIR was induced in conditional endothelial YAP knockout mice and their wild-type littermates. Retinal vascularization and the astrocyte network were evaluated by whole-mount fluorescence and Western blotting. In vitro experiments were performed in astrocytes cultured with human microvascular endothelial cell-1–conditioned medium to analyze the mechanisms underlying the effect of endothelial YAP on astrocytes.

Results

Endothelial YAP deletion not only impaired retinal blood vessels, but also caused a sparse and disrupted astrocyte network in response to OIR. Levels of the immature astrocyte marker (platelet-derived growth factor A) in the retina were substantially increased owing to YAP deficiency, suggesting a possible failure in astrocyte maturation, whereas retinal expression of leukemia inhibitory factor (LIF) was decreased. In vitro studies suggested that loss or overexpression of YAP resulted in elevated or decreased LIF secretion by human microvascular endothelial cell-1, respectively. Increased LIF levels in the culture medium promoted astrocyte maturation and proliferation and rescued YAP inhibition-induced astrocyte loss. Finally, activating YAP could protect against the pathology of the astrocyte network and even suppress pathologic retinal vascularization in control OIR mice, but not in endothelial YAP-deficient OIR mice.

Conclusions

Endothelial YAP regulation of LIF secretion is required for normalized astrocyte network formation in OIR, thereby providing a novel target for protecting the astrocyte network and thus benefiting retinal blood vessels.

Cerebrolysin ameliorates prefrontal cortex and hippocampus neural atrophy of spontaneous hypertensive rats with hyperglycemia

Hyperglycemia of diabetes mellitus causes damage at the vascular level, which at the renal level represents diabetic nephropathy. In this pathology, there is arterial hypertension. In addition, several reports suggest that hyperglycemia and arterial hypertension affect interneuronal communication at the level of dendritic morphology. We studied these changes in an animal model with streptozotocin-induced diabetes mellitus in the spontaneous hypertensive (SH) rat. Recent reports from our laboratory have demonstrated that cerebrolysin (CBL), a preparation of neuropeptides with protective and repairing properties, reduces dendritic deterioration in both pathologies, in separate studies. In the present study, we evaluated the effect of CBL using the animal model with hyperglycemia and arterial hypertension and assessed the dendritic morphology using a Golgi-Cox staining procedure. Our results suggest that CBL ameliorated the reduction in the number of dendritic spines in the PFC and hippocampus caused by hyperglycemia in the SH rat. In addition, CBL also increased distal dendritic length in the PFC and hippocampus in hyperglycemic SH rats. Consequently, the CBL could be a therapeutic tool used to reduce the damage at the level of dendritic communication present in both pathologies.

[An analysis of the peptide composition of a 'light' peptide fraction of cerebrolysin]

AIM

To analyze the peptide composition of a light peptide fraction of cerebrolysin.

MATERIAL AND METHODS

Mass spectrometry (MS) with orbital ion traps and modern de novo MS-sequencing algorithms was performed.

RESULTS

The amino acid sequences of 14 635 peptides corresponding to the 1643 porcine proteome neuronal proteins are identified. An analysis of the human proteome annotation shows that these peptides can mimic the corresponding human peptides. In particular, 405 peptide fragments correspond to 300 known biologically active peptides, including fragments of antibacterial peptides (defensins, histatins), immunomodulatory (granulin, manserin) and vasoactive (endothelin, VIP) peptides. At the same time, 8953 of 14 635 peptides can modulate the activity of 275 human signaling proteins, including kinases CDK1, CDK2, TGFBR2, GSK3, MTOR, pro-apoptotic caspases CASP1, CASP3 and CASP6 etc. The results confirm the presence of Leu- and Met-enkephalins, fragments of neuropeptide orexin, neuropeptide VF, galanin and nerve growth factor that have a neurotrophic effect.

CONCLUSION

The results of a proteomic study of the peptide composition of cerebrolysin indicate the widest range of molecular mechanisms responsible for the clinical efficacy of this drug.

Cerebrolysin improves peripheral inflammatory pain: Sex differences in two models of acute and chronic mechanical hypersensitivity

Chronic inflammatory pain is a major health problem worldwide with high prevalence in women. Cerebrolysin is a multimodal neuropeptide preparation that crosses the blood brain barrier and displays neuroprotective properties in aging and disease. Previously, we showed that cerebrolysin reduced mechanical allodynia in a model of persistent inflammation and pain. We aim to build upon the findings of our previous study by investigating the response to acute administration of cerebrolysin in two models of peripheral inflammation and assessing sex differences. We utilized the complete Freund's adjuvant (CFA) that produces maximal oedema and mechanical allodynia within days and carrageenan that produces similar effects within hours. Cerebrolysin reversed the mechanical allodynia in both sexes in CFA-treated rats. On the other hand, in rats treated with carrageenan, cerebrolysin was only effective in reducing mechanical allodynia in female rats. In conclusion, the present study shows that cerebrolysin effects may be sex-specific depending on different mechanisms that are at play in these two models of peripheral inflammatory pain. Further investigations are required to determine the factors contributing to sex differences.

The effect of rho kinase inhibition on morphological and electrophysiological maturity in iPSC-derived neurons

Induced pluripotent stem cell (iPSC)-derived neurons permit the study of neurogenesis and neurological disease in a human setting. However, the electrophysiological properties of iPSC-derived neurons are consistent with those observed in immature cortical neurons, including a high membrane resistance depolarized resting membrane potential and immature firing properties, limiting their use in modeling neuronal activity in adult cells. Based on the proven association between inhibiting rho kinase (ROCK) and increased neurite complexity, we seek to determine if short-term ROCK inhibition during the first 1-2 weeks of differentiation would increase morphological complexity and electrophysiological maturity after several weeks of differentiation. While inhibiting ROCK resulted in increased neurite formation after 24 h, this effect did not persist at 3 and 6 weeks of age. Additionally, there was no effect of ROCK inhibition on electrophysiological properties at 2-3, 6, or 12 weeks of age, despite an increase in evoked and spontaneous firing and a more hyperpolarized resting membrane potential over time. These results indicate that while there is a clear effect of time on electrophysiological maturity, ROCK inhibition did not accelerate maturity.

Electroconductive nanoscale topography for enhanced neuronal differentiation and electrophysiological maturation of human neural stem cells

Biophysical cues, such as topography, and electrical cues can provide external stimulation for the promotion of stem cell neurogenesis. Here, we demonstrate an electroconductive surface nanotopography for enhancing neuronal differentiation and the functional maturation of human neural stem cells (hNSCs). The electroconductive nanopatterned substrates were prepared by depositing a thin layer of titanium (Ti) with nanograting topographies (150 to 300 nm groove/ridge, the thickness of the groove - 150 μm) onto polymer surfaces. The Ti-coated nanopatterned substrate (TNS) induced cellular alignment along the groove pattern via contact guidance and promoted focal adhesion and cytoskeletal reorganization, which ultimately led to enhanced neuronal differentiation and maturation of hNSCs as indicated by significantly elevated neurite extension and the upregulated expression of the neuronal markers Tuj1 and NeuN compared with the Ti-coated flat substrate (TFS) and the nanopatterned substrate (NS) without Ti coating. Mechanosensitive cellular events, such as β1-integrin binding/clustering and myosin-actin interaction, and the Rho-associated protein kinase (ROCK) and mitogen-activated protein kinase/extracellular signal regulated kinase (MEK-ERK) pathways, were found to be associated with enhanced focal adhesion and neuronal differentiation of hNSCs by the TNS. Among the neuronal subtypes, differentiation into dopaminergic and glutamatergic neurons was promoted on the TNS. Importantly, the TNS increased the induction rate of neuron-like cells exhibiting electrophysiological properties from hNSCs. Finally, the application of pulsed electrical stimulation to the TNS further enhanced neuronal differentiation of hNSCs due probably to calcium channel activation, indicating a combined effect of topographical and electrical cues on stem cell neurogenesis, which postulates the novelty of our current study. The present work suggests that an electroconductive nanopatterned substrate can serve as an effective culture platform for deriving highly mature, functional neuronal lineage cells from stem cells.

Brain injury in combination with tacrolimus promotes the regeneration of injured peripheral nerves

Both brain injury and tacrolimus have been reported to promote the regeneration of injured peripheral nerves. In this study, before transection of rat sciatic nerve, moderate brain contusion was (or was not) induced. After sciatic nerve injury, tacrolimus, an immunosuppressant, was (or was not) intraperitoneally administered. At 4, 8 and 12 weeks after surgery, Masson's trichrome, hematoxylin-eosin, and toluidine blue staining results revealed that brain injury or tacrolimus alone or their combination alleviated gastrocnemius muscle atrophy and sciatic nerve fiber impairment on the experimental side, simultaneously improved sciatic nerve function, and increased gastrocnemius muscle wet weight on the experimental side. At 8 and 12 weeks after surgery, brain injury induction and/or tacrolimus treatment increased action potential amplitude in the sciatic nerve trunk. Horseradish peroxidase retrograde tracing revealed that the number of horseradish peroxidase-positive neurons in the anterior horn of the spinal cord was greatly increased. Brain injury in combination with tacrolimus exhibited better effects on repair of injured peripheral nerves than brain injury or tacrolimus alone. This result suggests that brain injury in combination with tacrolimus promotes repair of peripheral nerve injury.

Huangqi Guizhi Wuwu Decoction for treating diabetic peripheral neuropathy: a meta-analysis of 16 randomized controlled trials

OBJECTIVE:

This meta-analysis was performed to systematically assess the efficacy and safety of the Chinese herbal medicine Huangqi Guizhi Wuwu Decoction (HGWWD) for treating diabetic peripheral neuropathy.

DATA SOURCES:

Six electronic databases, including the Cochrane Library, MEDLINE database, Chinese Biomedical Database, Chinese National Knowledge Infrastructure Database, Chinese Science and Technique Journals Database, and the Wanfang Database, were searched on the internet for randomized controlled trials published up until 1 December 2015. The search terms included “Chinese herbal medicine”, “diabetic peripheral neuropathy” and “randomized controlled trials” in Chinese and in English.

DATA SELECTION:

We included randomized controlled trials using HGWWD/modified HGWWD for the treatment group, without restriction for the control group. We assessed literature quality in accordance with the Cochrane Review Handbook. A random or a fixed effects model was used to analyze outcomes using RevMan 5.2 software.

OUTCOME MEASURES:

The primary outcomes were changes in symptoms and nerve conduction velocities. The secondary outcomes were fasting blood glucose and hemorheological indexes.

RESULTS:

Sixteen randomized controlled trials, with a total of 1,173 patients, were included. Meta-analysis revealed that the efficacy of HGWWD for diabetic peripheral neuropathy was significantly superior compared with the control treatment (i.e., control group) (risk ratio = 0.36, 95% confidence interval (CI): 0.29–0.46, Z =8.33, P < 0.00001) Compared with the control group, there was an increase in median motor nerve conduction velocity (mean difference (MD) = 3.46, 95%CI: 1.88–5.04, Z = 4.30, P < 0.01) and median sensory nerve conduction velocity (MD = 3.30, 95%CI: 2.04–4.56, Z = 5.14, P < 0.01). There was also an increase in peroneal motor nerve conduction velocity (MD = 3.22, 95%CI: 2.45–3.98, Z = 8.21, P < 0.01) and peroneal sensory nerve conduction velocity (MD = 3.05, 95%CI: 2.01–4.09, Z = 5.75, P < 0.01) in the treatment groups. No significant difference in fasting blood glucose was found between the treatment groups and the control groups (MD = −0.12, 95%CI: −0.42–0.19, Z = 0.76, P = 0.45). Plasma viscosity was significantly decreased after treatment (MD = −0.11, 95%CI: −0.21 to −0.02, Z = 2.30, P = 0.02). No significant difference in fibrinogen was detectable (MD = −0.53, 95%CI: −1.28–0.22, Z = 1.38, P = 0.17). Four trials reported that treatment groups experienced no adverse reactions. Adverse events were not mentioned in the other 12 trials. No trial reported the incidence of complications, quality of life outcomes, or health economics.

CONCLUSION:

HGWWD treatment improves diabetic neurologic symptoms and ameliorates nerve conduction velocities. Our study suggests that HGWWD may have significant therapeutic efficacy for the treatment of diabetic peripheral neuropathy. However, the methodological quality of the randomized controlled trials was generally low. Larger and better-designed randomized controlled trials are required to more reliably assess the clinical effectiveness of HGWWD.