Vitamin D2 potentiates axon regeneration

Unprecedented effect of vitamin D3 on T-cell receptor beta subunit and alpha7 nicotinic acetylcholine receptor expression in a 3-nitropropionic acid induced mouse model of Huntington's disease

Introduction

3-NP induction in rodent models has been shown to induce selective neurodegeneration in the striatum followed by the cortex (Brouillet, 2014). However, it remains unclear whether, under such a neurotoxic condition, characterized by neuroinflammation and oxidative stress, the gene expression of the immune resident protein, T-cell receptor beta subunit (TCR-β), α7 nicotinic acetylcholine receptor (α7 nAChRs), the nuclear factor kappa B (NF-κB), inflammatory cytokines (TNF-α and IL-6), and antioxidants (Cat and GpX4) get modulated on Vitamin D3 (VD) supplementation in the central nervous system.

Methods

In the present study, real-time polymerase chain reaction (RT-PCR) was performed to study the expression of respective genes. Male C57BL/6 mice (8-12 weeks) were divided into four groups namely, Group I: Control (saline); Group II: 3-NP induction via i.p (HD); Group III: Vitamin D3 (VD) and Group IV: (HD + VD) (Manjari et al., 2022).

Results

On administration of 500IU/kg/day of VD, HD mice showed a significant reduction in the gene expression of the immune receptor, TCR-β subunit, nuclear factor kappa B (NF-κB), inflammatory cytokines, and key antioxidants, followed by a decrease in the acetylcholinesterase activity.

Conclusion

A novel neuroprotective effect of VD in HD is demonstrated by combating the immune receptor, TCR-β gene expression, antioxidant markers, and inflammatory cytokines. In addition, HD mice on VD administration for 0-15 days showed an enhancement in cholinergic signaling with restoration in α7 nAChRs mRNA and protein expression in the striatum and cortex.

Maternal vitamin D status and attention deficit hyperactivity disorder (ADHD), an under diagnosed risk factor; A review

Vitamin D is important to mediate several brain processes such as proliferation, apoptosis, and neurotransmission in early stages of life. Vitamin D deficiency during critical periods of development can lead to persistent brain alterations. Vitamin D homeostasis during pregnancy is affected by two factors which includes an increase in mother’s calcitriol levels and an increase in mother’s Vitamin D Binding protein concentrations. Attention deficient hyperactivity disorder (ADHD) is an outcome of a complicated interaction between genetic, environmental, and developmental traits, and genetic factors cover about 80% of the cases. The efficiency of the immune system can be altered by a deficiency of Vitamin D in maternal body and maternal stress during gestation such as perinatal depression. Studies have proved that during gestation if there is a deficiency of vitamin D in maternal body, it can influence the brain development of the fetus and can also alter the synthesis of the brain-derived neurotropic factor. The current manuscript has been compiled to elaborate different factors which are associated with ADHD particularly focusing on the relationship of vitamin D deficiency in mothers. References material was selected from NCBI (PUBMED), Science direct, Google scholar, Publons etc. Using the terms ADHD, Vitamin D and Maternal nutritional status. Although, controversial relationship was found between the deficiency of Vitamin D level in pregnant women and development of ADHD in children but more controlled trials are required for future direction as well as to rule out other associated causes.

Decreased Levels of Vitamin D in Bipolar Patients

Recently, vitamin D is considered a pleiotropic hormone, and as such, it has also become a topic of renewed interest in neuropsychiatry for its proposed role in the aetiology and pathophysiology of different psychiatric conditions, including mood disorders (MDs). This seems particularly crucial while considering the relatively high and often neglected prevalence of hypovitaminosis D in the general population and in specific groups, such as patients suffering from the most common type of MDs, which are major depression (MDD) and bipolar disorders (BDs). Therefore, in view of the controversial literature and findings on this topic and its potential therapeutic implications, the present study aimed at evaluating vitamin D levels in the plasma of a sample of inpatients fulfilling the DSM-5 criteria for mood episodes within BDs. The clinical picture was assessed by means of specific rating scales. The results showed that the vitamin D levels (mean ± SD, nM/L) of the bipolar patients of our sample were significantly lower (14.58 ± 11.27 nmol/L) than the normative values (>30 nmol/L). Eleven patients had sufficient values and only 4 had optimal, while 19 showed insufficient, 18 critical, and 17 severely critical levels. No differences emerged according to different socio-demographic or clinical features. In our opinion, the present findings strengthen previous research highlighting decreased vitamin D levels in bipolar patients and support the role of this pleiotropic hormone in BDs. Nevertheless, further studies should follow to corroborate the data of this preliminary study and to address the potential benefits of vitamin D supplementation in the treatment of MDs.

Vitamin D3 Promotes Structural and Functional Recovery After Vincristine-Induced Peripheral Neuropathy in Rats: An Experimental Study

Background Vincristine-induced peripheral neuropathy (VIPN) is a distal axonopathy characterized by the loss of distal myelinated axons. This study aimed to assess the potential neuroregenerative roles of vitamin D3 using functional and electron microscopic analyses in a rat model of VIPN. Methodology A total of 40 female Wistar rats were randomly divided into four main groups: Group 1 (control, n = 10), Group 2 (vincristine, n = 10), Group 3 (vincristine + vitamin D3, n = 10), and Group 4 (vincristine + vehicle, n = 10). Vincristine was administered intraperitoneally at a dose of 0.15 mg/kg, for two weeks, to induce peripheral neuropathy. Following successful induction, vitamin D3 (500 IU/kg/day) and vehicle treatments were applied weekly over four weeks. Structural (electron microscopic analysis) and functional analysis (von Frey test, pinch test, and electrophysiological analysis) were performed to assess functional recovery after peripheral nerve impairment. Results Withdrawal responses to mechanical allodynia and pinch tests were significantly higher in the vitamin D3-treated group (P < 0.05). The electrophysiological analysis also supported these results. Electron microscopic evaluation revealed that the remyelinated nerve fibers in the vitamin D3-treated group (Group 3) had thick myelin sheaths and normal axonal morphology. Conclusions Our study demonstrated that vitamin D3 could promote functional and structural recovery in a rat model of VIPN. Further studies should be conducted to elucidate the underlying mechanisms by which vitamin D3 exerts its regenerative effects in VIPN, using alternative administration protocols.

Therapeutic and mechanistic intervention of vitamin D in neuropsychiatric disorders

Vitamin D deficiency is believed to affect between 35 and 55% of the world's population, making it a hidden pandemic. In addition to its role in bone and calcium homeostasis, vitamin D has also been linked in preclinical and clinical research to brain function. These outcomes have also been used for a variety of neuropsychiatric and neurodevelopmental problems. Nevertheless, these individuals are more prone to develop signs of cognitive decline. This review will emphasize the association between vitamin D and neuropsychiatric illnesses such as autism, schizophrenia, depression, and Attention Deficit Hyperactivity Disorder (ADHD). While numerous research show vitamin D's essential role in cognitive function in neuropsychiatric illnesses, it is too early to propose its effect on cognitive symptoms with certainty. It is necessary to conduct additional research into the associations between vitamin D deficiency and cognitive abnormalities, particularly those found in autism, schizophrenia, depression, and ADHD, to develop initiatives that address the pressing need for novel and effective preventative therapeutic strategies.

Vitamin D and the Central Nervous System: Causative and Preventative Mechanisms in Brain Disorders

Twenty of the last one hundred years of vitamin D research have involved investigations of the brain as a target organ for this hormone. Our group was one of the first to investigate brain outcomes resulting from primarily restricting dietary vitamin D during brain development. With the advent of new molecular and neurochemical techniques in neuroscience, there has been increasing interest in the potential neuroprotective actions of vitamin D in response to a variety of adverse exposures and how this hormone could affect brain development and function. Rather than provide an exhaustive summary of this data and a listing of neurological or psychiatric conditions that vitamin D deficiency has been associated with, here, we provide an update on the actions of this vitamin in the brain and cellular processes vitamin D may be targeting in psychiatry and neurology.

The Impact of Supplements on Recovery After Peripheral Nerve Injury: A Review of the Literature

Peripheral nerve injury (PNI) can result from trauma, surgical resection, iatrogenic injury, and/or local anesthetic toxicity. Damage to peripheral nerves may result in debilitating weakness, numbness, paresthesia, pain, and/or autonomic instability. As PNI is associated with inflammation and nerve degeneration, means to mitigate this response could result in improved outcomes. Numerous nutrients have been investigated to prevent the negative sequelae of PNI. Alpha-lipoic acid, cytidine diphosphate-choline (CDP Choline), curcumin, melatonin, vitamin B12, and vitamin E have demonstrated notable success in improving recovery following PNI within animal models. While animal studies show ample evidence that various supplements may improve recovery after PNI, similar evidence in human patients is limited. The goal of this review is to analyze supplements that have been used successfully in animal models of PNI to serve as a reference for future studies on human patients. By analyzing supplements that have shown efficacy in animal studies, healthcare providers will have a resource from which to guide decision-making regarding future human studies investigating the role that supplements could play in PNI recovery. Ultimately, establishing a comprehensive understanding of these supplements in human patients following PNI may significantly improve post-surgical outcomes, quality of life, and peripheral nerve regeneration.

How far is vitamin D implicated in cutaneous infections

Vitamin D is an important cornerstone in the immunologic cascade of many skin infections, systemic infections with cutaneous presentations, and other infectious dermatologic diseases where infections could be a culprit. Vitamin D supplementation is proposed as a protective measure against their occurrence and exacerbation, especially with the emergence of several viral pandemics in recent years. Vitamin D plays a key role in the maintenance of a balanced immunologic profile which could be reflected by a lowered incidence and morbidity of infections. Vitamin D screening and supplementation in patients with deficiencies or insufficiencies should be a part of the dermatologic approach to patients with these diseases.

The Role of Dietary Nutrients in Peripheral Nerve Regeneration

Peripheral nerves are highly susceptible to injuries induced from everyday activities such as falling or work and sport accidents as well as more severe incidents such as car and motorcycle accidents. Many efforts have been made to improve nerve regeneration, but a satisfactory outcome is still unachieved, highlighting the need for easy to apply supportive strategies for stimulating nerve growth and functional recovery. Recent focus has been made on the effect of the consumed diet and its relation to healthy and well-functioning body systems. Normally, a balanced, healthy daily diet should provide our body with all the needed nutritional elements for maintaining correct function. The health of the central and peripheral nervous system is largely dependent on balanced nutrients supply. While already addressed in many reviews with different focus, we comprehensively review here the possible role of different nutrients in maintaining a healthy peripheral nervous system and their possible role in supporting the process of peripheral nerve regeneration. In fact, many dietary supplements have already demonstrated an important role in peripheral nerve development and regeneration; thus, a tailored dietary plan supplied to a patient following nerve injury could play a non-negotiable role in accelerating and promoting the process of nerve regeneration.

Vitamin D: Brain and Behavior

It has been 20 years since we first proposed vitamin D as a "possible" neurosteroid.^{( 1 )} Our work over the last two decades, particularly results from our cellular and animal models, has confirmed the numerous ways in which vitamin D differentiates the developing brain. As a result, vitamin D can now confidently take its place among all other steroids known to regulate brain development.^{( 2 )} Others have concentrated on the possible neuroprotective functions of vitamin D in adult brains. Here these data are integrated, and possible mechanisms outlined for the various roles vitamin D appears to play in both developing and mature brains and how such actions shape behavior. There is now also good evidence linking gestational and/or neonatal vitamin D deficiency with an increased risk of neurodevelopmental disorders, such as schizophrenia and autism, and adult vitamin D deficiency with certain degenerative conditions. In this mini-review, the focus is on what we have learned over these past 20 years regarding the genomic and nongenomic actions of vitamin D in shaping brain development, neurophysiology, and behavior in animal models. © 2020 The Author. JBMR Plus published by Wiley Periodicals LLC on behalf of American Society for Bone and Mineral Research.

Effects of a multinutrient-fortified milk drink combined with exercise on functional performance, muscle strength, body composition, inflammation, and oxidative stress in middle-aged women: a 4-month, double-blind, placebo-controlled, randomized trial

BACKGROUND

Multinutrient protein-enriched supplements are promoted to augment the effects of exercise on muscle mass and strength, but their effectiveness in middle-aged women, or whether there are any additional benefits to physical function, remains uncertain.

OBJECTIVES

We aimed to evaluate whether a multinutrient-fortified milk drink (MFMD) could enhance the effects of exercise on functional muscle power (stair climbing) in middle-aged women. Secondary aims were to evaluate the intervention effects on physical function, muscle strength, lean mass (LM), fat mass (FM), bone mineral content (BMC), muscle cross-sectional area (CSA), muscle density, balance, flexibility, aerobic fitness, inflammation, oxidative stress, bone and cartilage turnover, blood pressure, and blood lipids.

METHODS

In this 4-mo, double-blind, placebo-controlled, randomized trial, 244 women (45-65 y) participated in a multimodal resistance-type exercise program 3 d/wk, with random allocation to a twice-daily MFMD containing added protein, vitamin D, calcium, milk fat globule membrane (phospholipids and other bioactives), and other micronutrients (Ex + MFMD, n = 123) or an energy-matched placebo (Ex + placebo, n = 121).

RESULTS

A total of 216 women (89%) completed the study. After 4 mo, both groups experienced similar 3.6%-4.3% improvements in the primary outcomes of fast-pace 5- and 10-step stair ascent power. In contrast, Ex + MFMD experienced greater improvements in 5-step regular-pace stair descent time [net difference (95% CI): -0.09 s (-0.18, 0.00 s), P = 0.045], countermovement jump height [0.5 cm (0.04, 1.0 cm), P = 0.038], total body LM [0.3 kg (0.04, 0.60 kg), P = 0.020], FM [-0.6 kg (-1.0, -0.2 kg), P = 0.004], BMC [0.4% (0.1%, 0.6%), P = 0.020], muscle CSA [thigh: 1.8% (0.6%, 2.9%), P = 0.003; lower leg: 0.9% (0.3%, 1.6%), P = 0.005], balance eyes closed [3.3 s (1.1, 5.4 s), P = 0.005], 2-min step performance [8 steps (3, 12 steps), P = 0.003], and sit-and-reach flexibility [1.4 cm (0.6, 2.2 cm), P = 0.026]. MFMD did not enhance the effects of exercise on any measures of muscle strength, gait speed, dynamic balance, reaction time, or blood lipids, and there was no effect of either intervention on blood pressure, markers of inflammation, or cartilage turnover. Ex + placebo had a greater improvement in the oxidative stress marker protein carbonyls (P < 0.01).

CONCLUSIONS

In middle-aged women, daily consumption of an MFMD did not enhance the effects of a multimodal exercise program on the primary outcome of stair climbing ascent power, but did elicit greater improvements in multiple secondary outcomes including various other measures of functional performance, LM, muscle size, FM, balance, aerobic capacity, flexibility, and bone metabolism.This trial was registered at www.anzctr.org.au as ACTRN12617000383369.

Relationship of Anabolic Hormones With Motor Unit Characteristics in Quadriceps Muscle in Healthy and Frail Aging Men

CONTEXT

Anabolic hormones are important factors in maintaining muscle mass for aging men, but their role in overall motor unit structure and function is unclear.

OBJECTIVE

The objective of this work is to determine associations of anabolic and reproductive hormone levels with motor unit characteristics in quadriceps muscle in older healthy and frail men.

DESIGN

This work is an observational cohort study of community-dwelling men.

PARTICIPANTS

Participants included healthy and frail men younger than 65 years.

INTERVENTION

No intervention was performed.

OUTCOME MEASURE

Quantitative assessments of electromyography-derived motor unit potential size (MUP) and compound muscle action potential size (CMAP) of the vastus lateralis muscle.

RESULTS

We studied 98 men (mean ± SD: age 73 ± 6 years; body mass index [BMI] 25.7 ± 4.0 kg/m2; diabetes 11%) of whom 45% were prefrail and 18% frail. After adjusting for age, BMI, and prevalent diabetes, higher total and free testosterone levels were significantly related to larger CMAP (total testosterone: β [95% CI]: 0.3 [0.08-0.53]; free testosterone: 0.34 [0.13-0.56]). Exploratory analysis showed the relationship between free testosterone and CMAP was stronger in frail rather than robust men. In univariate analyses, estradiol was associated with CMAP size (0.37 [0.16-0.57]); and vitamin D was associated with MUP size (0.22 [0.01-0.43]) but these relationships were no longer significant after adjusting for potential confounders.

CONCLUSION

Our data highlight the associations between androgen levels and the electrophysiological characteristics of older men, particularly in the frail. Clinical trials involving administration of androgens will help to elucidate the potential benefits of intervention on neuromuscular function and/or frailty status.

Neuroprotective effect of paricalcitol in a rat model of transient global cerebral ischemia

Background

Paricalcitol is known to attenuate ischemic-reperfusion injury of various organs. However, it is not known whether paricalcitol prevents neuronal injury after global cerebral ischemia. The purpose of this study is to investigate the neuroprotective effect of paricalcitol in a rat model of transient global cerebral ischemia.

Methods

This is a prospective, randomized experimental study. Male Sprague-Dawley rats that survived 10 min of four-vessel occlusion were randomly assigned to two treatment groups: one group was treated with paricalcitol 1 μg/kg IP, and the other was given an equivalent volume of normal saline IP. Drugs were administered at 5 min, 1 day, 2 days, and 3 days after ischemia. Neurologic function was assessed at 2 h, 1 day, 2 days, 3 days, and 4 days after ischemia. We tested motor function 3 days after ischemia using the rotarod test. Also, we tested memory function 4 days after ischemia using the passive avoidance test. We assessed neuronal degeneration in the hippocampus of surviving rats 4 days after ischemia.

Results

Eight rats were allocated to each group. No significant differences were found between the groups in terms of survival rate, motor coordination, or memory function. The neurological function score 2-h post-ischemia was significantly higher in the paricalcitol group (p = 0.04). Neuronal degeneration was significantly less in the paricalcitol group compared with the control group (p = 0.01).

Conclusions

Paricalcitol significantly attenuated neuronal injury in the hippocampus. Although motor coordination, memory function, and survival rate were not significantly improved by paricalcitol treatment in this study, paricalcitol remains a potential neuroprotective drug after global cerebral ischemia.

Vitamin D and Its Potential Interplay With Pain Signaling Pathways

About 50 million of the U.S. adult population suffer from chronic pain. It is a complex disease in its own right for which currently available analgesics have been deemed woefully inadequate since ~20% of the sufferers derive no benefit. Vitamin D, known for its role in calcium homeostasis and bone metabolism, is thought to be of clinical benefit in treating chronic pain without the side-effects of currently available analgesics. A strong correlation between hypovitaminosis D and incidence of bone pain is known. However, the potential underlying mechanisms by which vitamin D might exert its analgesic effects are poorly understood. In this review, we discuss pathways involved in pain sensing and processing primarily at the level of dorsal root ganglion (DRG) neurons and the potential interplay between vitamin D, its receptor (VDR) and known specific pain signaling pathways including nerve growth factor (NGF), glial-derived neurotrophic factor (GDNF), epidermal growth factor receptor (EGFR), and opioid receptors. We also discuss how vitamin D/VDR might influence immune cells and pain sensitization as well as review the increasingly important topic of vitamin D toxicity. Further in vitro and in vivo experimental studies will be required to study these potential interactions specifically in pain models. Such studies could highlight the potential usefulness of vitamin D either alone or in combination with existing analgesics to better treat chronic pain.

A Review of the Relationship Between Vitamin D and Parkinson Disease Symptoms

Vitamin D is a fat-soluble secosteroid that exerts its effects by binding to the vitamin D receptor (VDR), through which it directly and indirectly modulates the expression of hundreds to thousands of genes. While originally known for its role in regulating calcium homeostasis and metabolism, vitamin D is now associated with many other health conditions, including Parkinson's disease (PD). A high prevalence of vitamin D deficiency has been noted in PD for at least the past two decades. These findings, along with the discovery that the VDR and 1α-hydroxylase, the enzyme that converts vitamin D to its active form, are highly expressed in the substantia nigra, led to the hypothesis that inadequate levels of circulating vitamin D may lead to dysfunction or cell death within the substantia nigra. Studies investigating the relationship between vitamin D status and PD, however, have been inconsistent. Two prospective studies examined the association between mid-life vitamin D levels and risk of PD and produced conflicting results-one demonstrated an increased risk for PD with lower mid-life vitamin D levels, and the other showed no association between vitamin D and PD risk. One of the most consistent findings in the literature is the inverse association between serum vitamin D level and motor symptom severity in cross-sectional studies. While these data suggest that vitamin D may modify the disease, another likely explanation is confounding due to limited mobility. Fall risk has been associated with vitamin D in PD, but more study is needed to determine if supplementation decreases falls, which has been demonstrated in the general population. The association between vitamin D and non-motor symptoms is less clear. There is some evidence that vitamin D is associated with verbal fluency and verbal memory in PD. Studies in PD have also shown associations between vitamin D status and mood, orthostatic hypotension and olfactory impairment in PD. While more research is needed, given the numerous potential benefits and limited risks, vitamin D level assessment in PD patients and supplementation for those with deficiency and insufficiency seems justified.

Electrophysiological evaluation of carpal tunnel syndrome female patients after vitamin D replacement

OBJECTIVE

The effects of vitamin D on the central and peripheral nervous system continue to be investigated today. In the present study, we aimed to evaluate pain and electrophysiologic response in patients with carpal tunnel syndrome (CTS) who have undergone replacement therapy due to vitamin D deficiency.

METHODS

Fifty female patients diagnosed with mild and moderate CTS and accompanied by vitamin D deficiency were included in this study. Nerve conduction study (NCS) was performed before and after vitamin D replacement, and the patient's pain was evaluated with Visual Analogue Scale (VAS).

RESULTS

When NCS were compared before and after treatment, there was a statistically significant improvement in the median distal sensory onset latency (DSOL) and sensory conduction velocity (CV) and motor distal latencies (DML) values (p=0.001; p<0.001; p=0.001, respectively). At the same time, there was a decrease in the VAS values in patients (p<0.001). When the two groups were compared there was an improvement in DSOL and sensory CV in both groups, but in DML only in moderate CTS group.

CONCLUSION

In this study, it was shown that mild and moderate CTS patients had an improvement in pain and electrophysiological parameters after vitamin D replacement. Replacing vitamin D in early stages of CTS may be beneficial.

Immediate or Delayed Transplantation of a Vein Conduit Filled with Nasal Olfactory Stem Cells Improves Locomotion and Axogenesis in Rats after a Peroneal Nerve Loss of Substance

Over the recent years, several methods have been experienced to repair injured peripheral nerves. Among investigated strategies, the use of natural or synthetic conduits was validated for clinical application. In this study, we assessed the therapeutic potential of vein guides, transplanted immediately or two weeks after a peroneal nerve injury and filled with olfactory ecto-mesenchymal stem cells (OEMSC). Rats were randomly allocated to five groups. A3 mm peroneal nerve loss was bridged, acutely or chronically, with a 1 cm long femoral vein and with/without OEMSCs. These four groups were compared to unoperated rats (Control group). OEMSCs were purified from male olfactory mucosae and grafted into female hosts. Three months after surgery, nerve repair was analyzed by measuring locomotor function, mechanical muscle properties, muscle mass, axon number, and myelination. We observed that stem cells significantly (i) increased locomotor recovery, (ii) partially maintained the contractile phenotype of the target muscle, and (iii) augmented the number of growing axons. OEMSCs remained in the nerve and did not migrate in other organs. These results open the way for a phase I/IIa clinical trial based on the autologous engraftment of OEMSCs in patients with a nerve injury, especially those with neglected wounds.

Does Vitamin D Affect Diabetic Neuropathic Pain and Balance?

Purpose

This randomized, placebo-controlled study examined the effect of vitamin D replacement therapy on neuropathic symptoms and balance in patients with diabetic neuropathic pain and low vitamin D levels.

Patients and Methods

Among the 258 patients, the results in a total of 57 volunteers (32 in the treatment and 25 in the control arm) meeting the inclusion criteria are reported. Symptoms of neuropathic pain were assessed using Douleur Neuropathique 4 (DN4) questionnaire, and presence of polyneuropathy (PNP) was determined by performing electromyography (EMG). Balance was assessed using Berg balance test (BBT). After undergoing these examinations, the patients in the treatment group were intramuscularly (IM) injected with 300,000 IU vitamin D in a liquid formulation and those in the placebo group were IM injected with physiological saline. The DN4 and BBT were repeated after 12 weeks, and the results were compared.

Results

The patients in the treatment group showed a significant decrease in total DN4 scores from baseline to the study endpoint compared with the patients in the placebo group (p=0.008). The patients in the treatment group also showed a significant increase in BBT scores from baseline to the study endpoint compared with the patients in the placebo group (p=0.001). Furthermore, in subgroup analysis, these patients showed a significant decrease in electric shock and burning sensation scores from baseline to the study endpoint compared with the patients in the placebo group (p=0.006, p=0.001, respectively).

Conclusion

In patients with diabetic neuropathic pain, vitamin D levels should be measured and vitamin D replacement therapy should be administered as required to resolve neuropathic symptoms and to improve balance.

The advances in nerve tissue engineering: From fabrication of nerve conduit to in vivo nerve regeneration assays

Peripheral nerve damage is a common clinical complication of traumatic injury occurring after accident, tumorous outgrowth, or surgical side effects. Although the new methods and biomaterials have been improved recently, regeneration of peripheral nerve gaps is still a challenge. These injuries affect the quality of life of the patients negatively. In the recent years, many efforts have been made to develop innovative nerve tissue engineering approaches aiming to improve peripheral nerve treatment following nerve injuries. Herein, we will not only outline what we know about the peripheral nerve regeneration but also offer our insight regarding the types of nerve conduits, their fabrication process, and factors associated with conduits as well as types of animal and nerve models for evaluating conduit function. Finally, nerve regeneration in a rat sciatic nerve injury model by nerve conduits has been considered, and the main aspects that may affect the preclinical outcome have been discussed.

The influence of drugs on peripheral nerve regeneration

Currently, there are no established adjuvant drugs for the acceleration of peripheral nerve regeneration. In this paper, we reviewed the literature from the last 10 years and described the drugs proved to accelerate the functional and histological regeneration of the peripheral nerves, either after trauma or in neuropathy experimental models. The vast majority of the studies were experimental with very few small clinical studies, which indicates the need for prospective randomized studies to identify the best drugs to use as adjuvants for nerve regeneration.

Focus on 1,25-Dihydroxyvitamin D3 in the Peripheral Nervous System

In this review, we draw attention to the roles of calcitriol (1,25-dihydroxyvitamin D3) in the trophicity of the peripheral nervous system. Calcitriol has long been known to be crucial in phosphocalcium homeostasis. However, recent discoveries concerning its involvement in the immune system, anti-cancer defenses, and central nervous system development suggest a more pleiotropic role than previously thought. Several studies have highlighted the impact of calcitriol deficiency as a promoting factor of various central neurological diseases, such as multiple sclerosis, amyotrophic lateral sclerosis, Parkinson's disease, and Alzheimer's disease. Based on these findings and recent publications, a greater role for calcitriol may be envisioned in the peripheral nervous system. Indeed, calcitriol is involved in myelination, axonal homogeneity of peripheral nerves, and neuronal-cell differentiation. This may have useful clinical consequences, as calcitriol supplementation may be a simple means to avoid the onset and/or development of peripheral nervous-system disorders.

1,25-(OH)2D3 protects Schwann cells against advanced glycation end products-induced apoptosis through PKA-NF-κB pathway

AIMS

To explore the effect and mechanism of 1, 25-(OH)₂D₃ on Schwann cell apoptosis induced by advanced glycation end products.

MAIN METHODS

Schwann cells, isolated from rodent sciatic nerve were incubated with AGE-modified bovine serum albumin(AGE) to mimic diabetic conditions and 1,25-(OH)₂D₃ was used as protector. Cell apoptosis was detected by PI/Annexin-V staining, caspase 3 activity assay and western blotting for caspase 3 and PARP. The activation of protein kinase A (PKA) and nuclear factor kappa-B (NF-κB) was evaluated by western blot. Immunofluorescent staining was used for intercellular location of NF-κB. Cytokine secretion was evaluated by enzyme-linked immunosorbent assay.

KEY FINDINGS

Schwann cell apoptosis accelerated after incubating with AGE. However, if combining 1,25-(OH)₂D₃ with AGE, apoptosis decreased significantly. 1,25-(OH)₂D₃ enhanced PKA activity, but inhibited AGE-induced nuclear translocation of NF-κB. Furthermore, PKA activator (8-bromoadenoside cyclic adenoside monophosphate, 8-Br-cAMP) or NF-κB inhibitor (caffeic acid phenethyl ester, CAPE) could reduce the apoptosis, decreased cleaved caspase 3 and cleaved PARP, suggesting the involvement of PKA and NF-κB pathways in the protection of 1,25-(OH)₂D₃ on Schwann cells. Moreover, 8-Br-cAMP and CAPE could inhibit AGE-induced secretion of interleukin(IL)-1β, prostaglandin E2(PEG2) and cyclooxygenase 2(COX2). Interestingly, 8-Br-cAMP decreased phospho-NF-κB and inhibited nucleus translocation of NF-κB. It hinted at the regulation of PKA to NF-κB. Finally, a pre-treatment of H-89 (an inhibitor of PKA) could block the protection of 1,25-(OH)₂D₃ on cell apoptosis. In conclusion, 1,25-(OH)₂D₃ could protect Schwann cell against AGE-induced apoptosis through PKA/NF-κB pathway.

SIGNIFICANCE

These findings provide experimental rationales for using vitamin D for diabetic neuropathy.

Vitamin D3 deficiency in puberty rats causes presynaptic malfunctioning through alterations in exocytotic release and uptake of glutamate/GABA and expression of EAAC-1/GAT-3 transporters

Recent experimental and epidemiologic investigations have revealed that the central nervous system is a target for vitamin D3 action and also linked vitamin D3 deficiency to Alzheimer's and Parkinson's disease, autism and dementia. Abnormal homeostasis of glutamate and GABA and signaling disbalance are implicated in the pathogenesis of major neurological diseases. Here, key transport characteristics of glutamate and GABA were analysed in presynaptic nerve terminals (synaptosomes) isolated from the cortex of vitamin D3 deficient (VDD) rats. Puberty rats were kept at the VDD diet up to adulthood. VDD caused: (i) a decrease in the initial rates of L-[¹⁴C]glutamate and [³H]GABA uptake by plasma membrane transporters of nerve terminals; (ii) a decrease in exocytotic release of L-[¹⁴C]glutamate and [³H]GABA; (iii) changes in expression of glutamate (EAAC-1) and GABA (GAT-3) transporters. Whereas, the synaptosomal ambient levels and Ca²⁺-independent transporter-mediated release of L-[¹⁴C]glutamate and [³H]GABA were not significantly altered in VDD. Vitamin D3 is a potent neurosteroid and its nutritional deficiency can provoke development of neurological consequences changing glutamate/GABA transporter expressions and excitation/inhibition balance. Also, changes in glutamate transport can underlie lower resistance to hypoxia/ischemia, larger infarct volumes and worsened outcomes in ischemic stroke patients with VDD.

Body mass index and vitamin D level in carpal tunnel syndrome patients

Background

Carpal tunnel syndrome (CTS) is the most common entrapment neuropathy of the upper extremity. The aim of this study is to evaluate the body mass index (BMI) and vitamin D levels in CTS patients.

Methods

The current study was conducted at Zagazig University Hospitals. It included 50 CTS patients and 50 controls. Clinical assessment was carried out to exclude symptoms and signs of neuropathy. Laboratory investigations including vitamin D levels, glycosylated hemoglobin, liver, and kidney function were carried out for every participant. All patients underwent electrodiagnostic study and completed Boston questionnaire to assess their pain sum score, symptom severity (SSS), and functional status (FSS).

Results

Patients had significantly higher BMI and lower vitamin D levels compared to controls (p = 0.003 and p = 0.001, respectively). Those with severe CTS had a significantly higher BMI and lower vitamin D levels than the others (p = 0.03 and p = 0.01 respectively). No significant difference was found between CTS subgroups regarding the SSS, while a higher significant FSS and pain sum score were reported in the severe CTS patients compared to the other two groups (p = 0.01 and p = 0.04 respectively). A significant negative correlation was detected between vitamin D levels and both of BMI, and Boston pain sum scores (p = 0.01 and p = 0.03 respectively). Also, an inverse correlation was detected between vitamin D levels and both of SSS and FSS (p = 0.14, p = 0.06). Furthermore, a significant positive and negative correlation between vitamin D levels and both of conduction velocity and distal motor latency respectively was observed (p = 0.02 and p = 0.01 respectively).

Conclusions

Carpal tunnel syndrome was significantly associated with hypovitaminosis D especially in patients with higher BMI. This highlights the importance of vitamin D supplements and weight loss regimes to minimize the severity of their pain.

Repurposing and repositioning neurosteroids in the treatment of traumatic brain injury: A report from the trenches

The field of neuroprotection after brain injuries has been littered with failed clinical trials. Finding a safe and effective treatment for acute traumatic brain injury remains a serious unmet medical need. Repurposing drugs that have been in use for other disorders is receiving increasing attention as a strategy to move candidate drugs more quickly to trial while reducing the very high cost of new drug development. This paper describes our own serendipitous discovery of progesterone's neuroprotective potential, and the strategies we are using in repurposing and developing this hormone for use in brain injuries-applications very different from its classical uses in treating disorders of the reproductive system. We have been screening and testing a novel analog that maintains progesterone's therapeutic properties while overcoming its physiochemical challenges, and testing progesterone in combination treatment with another pleiotropic hormone, vitamin D. Finally, our paper, in the context of the problems and pitfalls we have encountered, surveys some of the factors we found to be critical in the clinical translation of repurposed drugs. This article is part of the Special Issue entitled 'Drug Repurposing: old molecules, new ways to fast track drug discovery and development for CNS disorders'.

Vitamin D Receptor Activation Influences NADPH Oxidase (NOX2) Activity and Protects against Neurological Deficits and Apoptosis in a Rat Model of Traumatic Brain Injury

Traumatic brain injury (TBI) is a worldwide phenomenon which results in significant neurological and cognitive deficits in humans. Vitamin D (VD) is implicated as a therapeutic strategy for various neurological diseases now. Recently, inhibition of the NADPH oxidase (NOX₂) was reported to protect against oxidative stress (ROS) production. However, whether alterations in NOX₂ expression and NOX activity are associated with calcitriol (active metabolite of VD) treatment following TBI remains unclear. In the present study, rats were randomly assigned to the sham, TBI, and calcitriol-treated groups. Calcitriol was administered intraperitoneally (2 μg/kg) at 30 min, 24 h, and 48 h after TBI insult. We observed that calcitriol treatment alleviated neurobehavioral deficits and brain edema following TBI. At the molecular levels, administration of calcitriol activated the expression of VDR and downregulated NOX₂ as well as suppressed apoptosis cell rate in the hippocampus CA1 region of TBI rats. In conclusion, our findings indicate that the protective effects of calcitriol may be related to the modulation of NADPH oxidase and thereby ultimately inhibited the progression of apoptosis. Calcitriol may be promising as a protective intervention following TBI, and more study is warranted for its clinical testing in the future.

The effect of vitamin D supplementation on pain, quality of life, and nerve conduction studies in women with chronic widespread pain

The aim of this study was to investigate the effects of vitamin D supplementation on pain, quality of life, and nerve conduction studies (NCSs) in women with chronic widespread pain (CWP) diagnosed with Vitamin D insufficiency. Thirty-three female participants with CWP and vitamin D insufficiency were included in this open-label trial. They were evaluated by routine NCSs in upper and lower limbs, pain scales, and the Nottingham Health Profile before and 8 weeks after starting vitamin D supplementation therapy. The P-value was adjusted to account for the number of comparisons performed in each assessment. After 8 weeks of treatment, participants reported significantly lower pain scores (P=0.000). The total Nottingham Health Profile score and subscores for pain, emotional reactions, and physical activity domains were significantly lower (0.000≤P≤0.008). However, no statistically significant changes in NCSs were detected, except trends toward increases in the amplitudes of left median and ulnar sensory nerve potentials and a decrease in the distal latency of the right median sensory potential (0.01≤P≤0.04). Vitamin D supplementation therapy decreased pain and increased quality of life without significantly affecting nerve conduction in patients with CWP.

Selected Risk Nutritional Factors for Chemotherapy-Induced Polyneuropathy

The present study seeks to identify the nutritional risk factors involved in the development of neuropathies induced by chemotherapeutic treatments. Unlike the gastrointestinal or hematological adverse effects of chemotherapy there is no protective treatment strategy for polyneuropathy. The aim of this study was to find possible deficiencies in nutritional factors, which can be used for supplementation in the future for prevention of chemotherapy-induced neuropathy development. We analyzed 70 patients undergoing paclitaxel chemotherapy and evaluated the risk factors involved in chemotherapy-induced peripheral neuropathy (CIPN). Several risk factors were considered in the development of CIPN, including deficiency of vitamin B1, B6, and D and fatty acids. The occurrence of CIPN complication in 60% cases was observed. We found significant differences in vitamin D and saturated fatty acid concentration. Vitamin D levels in the group without CIPN were estimated to be 38.2 (24.95, 47.63) nmol/L, whereas in the group with CIPN it was determined to be 25.6 (19.7, 32.55) nmol/L, p = 0.008. The level of total saturated fatty acids in the group without CIPN was of 32.613 Area % (31.322; 36.262), whereas in the group with CIPN it was of 34.209 Area % (32.86; 39.386), p = 0.01. The obtained results suggest a diet lower in saturated fatty acid content during chemotherapy. The most significant finding was that supplementation of vitamin D before chemotherapy could be an efficient neuroprotective in CIPN prophylaxis, as significantly lower levels 25OH derivative of vitamin D were observed in the CIPN group throughout the study period.

Serum protein changes in a rat model of chronic pain show a correlation between animal and humans

In previous works we showed the overexpression of some proteins in biological fluids from patients suffering chronic pain. In this proteomic study we analysed serum from a rat model of neuropathic pain obtained by the chronic constriction injury (CCI) of sciatic nerve, at two time intervals, 2 and 5 weeks after the insult, to find proteins involved in the expression or mediation of pain. Sham-operated and CCI rats were treated with saline or indomethacin. Two weeks after ligation, we identified three serum proteins overexpressed in CCI rats, two of which, alpha-1-macroglobulin and vitamin D-binding protein (VDBP), remained increased 5 weeks post-surgery; at this time interval, we found increased levels of further proteins, namely apolipoprotein A-I (APOA1), apolipoprotein E (APOE), prostaglandin-H2 D-isomerase (PTGDS) and transthyretin (TTR), that overlap the overexpressed proteins found in humans. Indomethacin treatment reversed the effects of ligation. The qPCR analysis showed that transcript levels of APOA1, APOE, PTGDS and VDBP were overexpressed in the lumbar spinal cord (origin of sciatic nerve), but not in the striatum (an unrelated brain region), of CCI rats treated with saline 5 weeks after surgery, demonstrating that the lumbar spinal cord is a possible source of these proteins.

Evaluation of cognitive subdomains, 25-hydroxyvitamin D, and 1,25-dihydroxyvitamin D in the European Male Ageing Study

PURPOSE

Although lower levels of vitamin D have been related to poor cognitive functioning and dementia in older adults, evidence from longitudinal investigations is inconsistent. The objective of this study was to determine whether 25-hydroxyvitamin D [25(OH)D] and 1,25-dihydroxyvitamin D [1,25(OH)₂D] levels are associated with specified measures of cognitive decline in ageing men.

METHODS

The European Male Ageing Study (EMAS) followed 3369 men aged 40-79 over 4.4 years. 25(OH)D levels at baseline were measured by radioimmunoassay, and 1,25(OH)₂D levels were obtained with liquid chromatography-tandem mass spectrometry. Visuoconstructional abilities, visual memory, and processing speed at baseline and follow-up were assessed using the Rey-Osterrieth Complex Figure Test (ROCF), Camden Topographical Recognition Memory (CTRM), and the Digit Symbol Substitution Test (DSST).

RESULTS

Following attritions, a total of 2430 men with a mean (SD) age of 59.0 (10.6) were included in the analyses. At baseline, the mean 25(OH)D concentration was 64.6 (31.5) nmol/l, and mean 1,25(OH)₂D level was 59.6 (16.6) pmol/l. In age-adjusted linear regression models, high 25(OH)D concentrations were associated with a smaller decline in the DSST (β = 0.007, p = 0.020). Men with low 25(OH)D levels (<50 nmol/l) showed a greater decline in the CTRM compared to men with higher (≥75 nmol/l) levels (β = -0.41, p = 0.035). However, these associations disappeared after adjusting for confounders such as depressive symptoms, BMI, and comorbidities. There was no indication of a relationship between 1,25(OH)₂D and decline in cognitive subdomains.

CONCLUSION

We found no evidence for an independent association between 25(OH)D or 1,25(OH)₂D levels and visuoconstructional abilities, visual memory, or processing speed over on average 4.4 years in this sample of middle-aged and elderly European men.

A Systematic Review of the Role of Vitamin D on Neuromuscular Remodelling Following Exercise and Injury

Vitamin D is important for skeletal muscle health and deficiency is associated with clinical neuromuscular symptoms of poor strength and gait. Supplementation can independently increase muscle strength in chronically deficient populations. However, the regulatory role of vitamin D on neuromuscular remodelling and adaptation subsequent to exercise conditioning or injury has not been systematically reviewed.

OBJECTIVE

to systematically review the available evidence of the role of vitamin D on neuromuscular remodelling following exercise conditioning, exercise- or experimentally induced injury. We searched Medline (OVID platform), PubMed, Embase and Web of Science for randomised controlled trials (RCTs) including measures of neuromuscular function, injury and/or inflammation; a physiologically stressful intervention involving exercise conditioning, exercise- or experimentally induced injury and; vitamin D supplementation. Nine RCTs met the inclusion criteria. Significant heterogeneity of methodological approaches and outcomes meant that meta-analysis of data was limited. Qualitative findings indicated that vitamin D may be an effective accelerant of neuromuscular remodelling in animal models (24-140 % improved recovery vs. control); the effects in humans are inconclusive and likely influenced by baseline vitamin D and supplementation strategy. Results of the meta-analyses indicated no effect of vitamin D supplementation on muscle strength adaptation following resistance training [standardised mean difference (SMD): 0.74, P = 0.42] or muscle damage (SMD: -0.03, P = 0.92), although inflammatory markers were elevated in the latter (SMD: 0.56, P = 0.04). Data from animal models offer promising and plausible mechanisms for vitamin D as an agent for neuromuscular adaptation. Further high-quality research is needed to offer clearer insight into the influential role of vitamin D in human populations.

Cholecalciferol (vitamin D₃) improves functional recovery when delivered during the acute phase after a spinal cord trauma

In a previous study, based on a rat model of thoracic spinal cord compression, we demonstrated that cholecalciferol (Vitamin D3), delivered at the dose of 200 IU/kg/day, significantly improved ventilatory frequency and spasticity. In order to confirm the restorative potential of vitamin D, we performed a new study, using a rat model of left cervical hemisection (C2). From Day 1 or Day 7, animals received, during three months, a weekly oral bolus of either cholecalciferol, at the dose of 500 IU/kg/day, or vehicle, namely triglycerides. Rats were assessed every month, using a ladder test for sensori-locomotor ability and neuromuscular capacity. Three months after injury, H-reflex was recorded from left extensor digitorum muscle in order to measure the reflexivity of the sub-lesional region. Ventilatory frequency was also monitored during an electrically induced muscle fatigue of the hindlimb known to enhance muscle metaboreflex and increase respiratory rate. After recording the phrenic nerve activity, ipsilateral to the lesion, during spontaneous breathing, animals were artificially ventilated while paralyzed with a neuromuscular blocking agent and then the brainstem respiratory centres were provoked to maximal output by temporarily stopping the ventilator. Spinal cords were immunostained with an anti-neurofilament antibody to evaluate axon numbers. We show here that vitamin D-treated animals display i) an enhanced locomotor activity, ii) an improved breathing when hindlimb muscle was electrically stimulated to induce fatigue, iii) an H-reflex depression similar to control animals, iv) a phrenic nerve activity response to a temporary asphyxial stress and v) a non significant decreased number of axons in the proximal stump when compared with the Sham group. This new set of data confirms that vitamin D is a potent molecule that could be tested in clinical trials assessing functional recovery in para-/tetra-plegic patients, shortly after a trauma.

Vitamin D and the brain: key questions for future research

Over the last decade a convergent body of evidence has emerged from epidemiology, animal experiments and clinical trials which links low vitamin D status with a range of adverse neuropsychiatric outcomes. This research demonstrates that the timing of exposure to low vitamin D influences the nature of brain phenotypes, as exposures during gestation versus adulthood result in different phenotypes. With respect to early life exposures, there is robust evidence from rodent experiments indicating that transient developmental vitamin D (DVD) deficiency is associated with changes in brain structure, neurochemistry, gene and protein expression and behavior. In particular, DVD deficiency is associated with alterations in the dopaminergic neurotransmitter systems. In contrast, recently published animal experiments indicate that adult vitamin D (AVD) deficiency is associated with more subtle neurochemical and behavioral phenotypes. This paper explores key issues that need to be addressed in future research. There is a need to define the timing and duration of the 'critical window' during which low vitamin D status is associated with differential and adverse brain outcomes. We discuss the role for 'two-hit hypotheses', which propose that adult vitamin D deficiency leaves the brain more vulnerable to secondary adverse exposures, and thus may exacerbate disease progression. Finally, we explore the evidence implicating a role for vitamin D in rapid, non-genomic mechanisms that may involve L-type calcium channels and brain function. This article is part of a Special Issue entitled '17th Vitamin D Workshop'.

Effects of vitamin D supplementation on neuroplasticity in older adults: a double-blinded, placebo-controlled randomised trial

Vitamin D can improve muscle function and reduce falls, but whether it can strengthen neural connections within the brain and nervous system is not known. This 10-week randomised controlled trial indicates that treatment with 2,000 IU/day vitamin D3 does not significantly alter neuroplasticity relative to placebo in older adults.

INTRODUCTION

The purpose of this study was to examine the effects of vitamin D supplementation on neuroplasticity, serum brain-derived neurotrophic factor (BDNF) and muscle strength and function in older adults.

METHODS

This was a 10-week double-blinded, placebo-controlled randomised trial in which 26 older adults with 25-hydroxyvitamin D [25OHD] concentrations 25-60 nmol/L were randomised to 2,000 IU/day vitamin D3 or matched placebo. Single- and paired-pulse transcranial magnetic stimulation applied over the motor cortex was used to assess changes in motor-evoked potentials (MEPs) and short-interval intracortical inhibition (SICI), as measures of corticospinal excitability and inhibition respectively, by recording electromyography (EMG) responses to stimulation from the wrist extensors. Changes in muscle strength, stair climbing power, gait (timed-up-and-go), dynamic balance (four square step test), serum 25(OH)D and BDNF concentrations were also measured.

RESULTS

After 10 weeks, mean 25(OH)D levels increased from 46 to 81 nmol/L in the vitamin D group with no change in the placebo group. The vitamin D group experienced a significant 8-11% increase in muscle strength and a reduction in cortical excitability (MEP amplitude) and SICI relative to baseline (all P < 0.05), but these changes were not significantly different from placebo. There was no effect of vitamin D on muscle power, function or BDNF.

CONCLUSIONS

Daily supplementation with 2,000 IU vitamin D3 for 10 weeks had no significant effect on neuroplasticity compared to placebo, but the finding that vitamin D treatment alone was associated with a decrease in corticospinal excitability and intracortical inhibition warrants further investigation as this suggests that it may improve the efficacy of neural transmission within the corticospinal pathway.

Role of inflammatory cytokines in peripheral nerve injury

Inflammatory events occurring in the distal part of an injured peripheral nerve have, nowadays, a great resonance. Investigating the timing of action of the several cytokines in the important stages of Wallerian degeneration helps to understand the regenerative process and design pharmacologic intervention that promotes and expedites recovery. The complex and synergistic action of inflammatory cytokines finally promotes axonal regeneration. Cytokines can be divided into pro- and anti-inflammatory cytokines that upregulate and downregulate, respectively, the production of inflammatory mediators. While pro-inflammatory cytokines are expressed in the first phase of Wallerian degeneration and promote the recruitment of macrophages, anti-inflammatory cytokines are expressed after this recruitment and downregulate the production of all cytokines, thus determining the end of the process. In this review, we describe the major inflammatory cytokines involved in Wallerian degeneration and the early phases of nerve regeneration. In particular, we focus on interleukin-1, interleukin-2, interleukin-6, tumor necrosis factor-β, interleukin-10 and transforming growth factor-β.

Stem cell-based approaches to improve nerve regeneration: potential implications for reconstructive transplantation?

Reconstructive transplantation has become a viable option to restore form and function after devastating tissue loss. Functional recovery is a key determinant of overall success and critically depends on the quality and pace of nerve regeneration. Several molecular and cell-based therapies have been postulated and tested in pre-clinical animal models to enhance nerve regeneration. Schwann cells remain the mainstay of research focus providing neurotrophic support and signaling cues for regenerating axons. Alternative cell sources such as mesenchymal stem cells and adipose-derived stromal cells have also been tested in pre-clinical animal models and in clinical trials due to their relative ease of harvest, rapid expansion in vitro, minimal immunogenicity, and capacity to integrate and survive within host tissues, thereby overcoming many of the challenges faced by culturing of human Schwann cells and nerve allografting. Induced pluripotent stem cell-derived Schwann cells are of particular interest since they can provide abundant, patient-specific autologous Schwann cells. The majority of experimental evidence on cell-based therapies, however, has been generated using stem cell-seeded nerve guides that were developed to enhance nerve regeneration across "gaps" in neural repair. Although primary end-to-end repair is the preferred method of neurorrhaphy in reconstructive transplantation, mechanistic studies elucidating the principles of cell-based therapies from nerve guidance conduits will form the foundation of further research employing stem cells in end-to-end repair of donor and recipient nerves. This review presents key components of nerve regeneration in reconstructive transplantation and highlights the pre-clinical studies that utilize stem cells to enhance nerve regeneration.

Hypovitaminosis D in widespread pain: its effect on pain perception, quality of life and nerve conduction studies

The aim of the study was to investigate the effects of hypovitaminosis D on pain, quality of life (QoL) and nerve conduction studies (NCSs) in patients with chronic widespread pain (CWP). We randomly selected 83 female patients with CWP according to their vitamin D levels in this cross-sectional study. Patients were divided into two groups as sufficient vitamin D level (above 20 ng/ml) and deficient vitamin D level (below 20 ng/ml, hypovitaminosis D). Various pain scales and Nottingham Health Profile (NHP) were used. NCSs were also done. In patients with hypovitaminosis D, there were significantly higher pain scores for all scales (p value range 0.002-0.027). The subscale and total NHP scores were significantly higher in hypovitaminosis D group (p = 0.048-0.001) except social isolation subscale (p = 0.553). Vitamin D levels were in negative correlation with right and left median and/or ulnar motor nerve amplitudes, left tibial motor amplitude. This study confirm that hypovitaminosis D is related with higher pain intensity and lower QoL scores in patients with CWP when compared with control group. Additionally, we identified for the first time that there were negative correlations between vitamin D levels and some findings of NCSs.

Vitamin D levels and microvascular complications in type 2 diabetes

BACKGROUND

Vitamin D has important actions on glucose metabolism. These include improved insulin exocytosis, direct stimulation of insulin receptor, improved uptake of glucose by peripheral tissues, improving insulin resistance. It has got various pleiotropic effects like suppression of cell mediated immunity, regulation of cell proliferation, stimulation of neurotropic factors such as nerve growth factor, Glial cell line-derived neurotrophic factor, neurotropin, suppression of RAAS, reduction of albuminuria, immunomodulatory effects, and anti-inflammatory effects. Thus, vitamin D is implicated in many ways in the pathogenesis of retinopathy, neuropathy and nephropathy.

OBJECTIVES

To study the correlation of vitamin D levels with microvascular complications in type 2 diabetes.

MATERIALS AND METHODS

Cross-sectional case-control study of 18 patients (18-70 years), who met the American Diabetes Association 2011 criteria for type 2 diabetes, was conducted. Age and sex matched healthy controls were taken. Subjects were evaluated for the presence of microvascular complications by clinical evaluation, urine examination, fundus examination, nerve conduction studies, and various biochemical tests. 25-OH cholecalciferol levels were done for each. Cut off level for vitamin D deficiency was 20 ng/ml.

RESULTS

Mean vitamin D was lower in type 2 diabetics than healthy subjects (19.046 vs. 27.186 ng/ml). Prevalence of vitamin D deficiency and insufficiency was found to significantly higher in diabetics when compared to healthy subjects (P = 0.0001). Vitamin D deficiency was found to be significantly associated with neuropathy (χ(2) = 5.39, df = 1, P = 0.020), retinopathy, (χ(2) = 6.6, df = 1, P = 0.010) and nephropathy (χ(2) = 10. 52, df = 1, P = 0.001). Lower levels of vitamin D were found to be associated with increasing prevalence of combinations of microvascular complications namely neuropathy with retinopathy (P = 0.036), neuropathy with nephropathy (P = 0.029), retinopathy with nephropathy (P = 0.022) and neuropathy with retinopathy with nephropathy (P = 0.0001).

[Repairing the spinal cord with vitamin D: a promising strategy]

In 2014, a phase II randomised, double blind clinical trial assessing the efficacy of cholecalciferol (vitamin D3) in patients with a cervical trauma will be set up. This trial stems from previous studies showing that vitamin D supplementation improves functional recovery in rat models of peripheral or central nerve injury. In a first series of experiments, we used a rat model of peripheral nerve trauma to demonstrate the therapeutic efficiency of vitamin D. We first demonstrated that ergocalciferol (vitamin D2) increases the number and the diameter of newly formed axons and improves the response of metabosensitive fibers from tibialis muscle, in a model of transected peroneal nerve. Then, we compared vitamin D2 and vitamin D3 and observed that the latter is more efficient. At the dose of 500 IU/kg/day, vitamin D3 induces a dramatic functional recovery. We also demonstrated that vitamin D3 increases the number of preserved or newly formed axons in the proximal end, the mean axon diameter in the distal end, neurite myelination in both the distal and proximal ends as well as the expression of genes involved in axogenesis and myelination. In parallel, we assessed the therapeutic role of vitamin D on the central nervous system. In a first study, using a rat model of spinal cord compression at the T10 thoracic level, we delivered vitamin D3 (cholecalciferol) orally at the dose of 50 IU/kg/day or 200 IU/kg/day. When compared to control animals, vitamin D-treated rats displayed, three months after injury, a significant improvement of ventilatory frequency and a reduction of H reflex indicating functional improvements at three months post-injury. In a second study, we used a rat model of cervical hemisection (C2) with a higher dose of oral vitamin D3 (500 IU/kg/day) delivered weekly, during 12 weeks. We observed an improved locomotor recovery, a reduced spasticity and a significantly higher rate of axons crossing the lesion site in treated animals. However, it must be pointed out that the functional improvement is reduced when vitamin D is provided one week after the trauma.

The Influence of Vitamin D Treatment on the Inducible Nitric Oxide Synthase (INOS) Expression in Primary Hippocampal Neurons

INTRODUCTION

Neurodegeneration is a process that is characterized by the loss of neuronal structure and function and eventually ends with neuronal death. An elevated level of inducible nitric oxide synthase (iNOS) is suggested to accompany this process by inducing oxidative and nitrosative damage. Vitamin D is reported to protect glial cells against neurotoxicity via suppressing iNOS synthesis. Though there was no data about whether iNOS is regulated by vitamin D in hippocampal neurons. In this study our aim was to determine any alteration in iNOS expression of hippocampal neurons in response to vitamin D treatment.

METHOD

Twenty four and 48 hours of vitamin D treatments were performed on primary hippocampal neuron cultures that were prepared from Sprague dawley rat embryos (E18). The alterations in the iNOS mRNA expression were determined with quantative real time polymerase chain reaction (qRT-PCR). The cytotoxicity levels of each group were investigated by the measurement of lactate dehydrogenase (LDH) that is released to culture medium.

RESULTS

No difference was observed between groups in 24 hours of treatment regarding the iNOS expression. Though the iNOS mRNA level of vitamin D treated group was significantly lower than that of control group on the 48th hours of treatment (p<.001). Vitamin D treatment also attenuated the LDH release which is an indicator of cytotoxicity (p<.001).

CONCLUSION

Our results indicated that vitamin D has the potential to prevent oxidative damage by suppressing iNOS expression.

Vitamin D and neurocognitive function

In recent years, emerging evidence has linked vitamin D not only to its known effects on calcium and bone metabolism, but also to many chronic illnesses involving neurocognitive decline. The importance of vitamin D₃ in reducing the risk of these diseases continues to increase due to the fact that an increasing portion of the population in developed countries has a significant vitamin D deficiency. The older population is at an especially high risk for vitamin D deficiency due to the decreased cutaneous synthesis and dietary intake of vitamin D. Recent studies have confirmed an association between cognitive impairment, dementia, and vitamin D deficiency. There is a need for well-designed randomized trials to assess the benefits of vitamin D and lifestyle interventions in persons with mild cognitive impairment and dementia.

Mechano- and metabosensitive alterations after injection of botulinum toxin into gastrocnemius muscle

This study was designed to investigate effects of motor denervation by Clostridium botulinum toxin serotype A (BoNT/A) on the afferent activity of fibers originating from the gastrocnemius muscle of rats. Animals were randomized in two groups, 1) untreated animals acting as control and 2) treated animals in which the toxin was injected in the left muscle. Locomotor activity was evaluated once per day during 12 days with a test based on footprint measurements of walking rats (sciatic functional index). At the end of the functional assessment period, electrophysiological tests were used to measure muscle properties, metabosensitive afferent fiber responses to chemical (KCl and lactic acid) injections, electrically induced fatigue (EIF), and mechanosensitive responses to tendon vibrations. Additionally, ventilatory response was recorded during repetitive muscle contractions. Then, rats were sacrificed, and the BoNT/A-injected muscles were weighed. Twelve days postinjection we observed a complete motor denervation associated with a significant muscle atrophy and loss of force to direct muscle stimulation. In the BoNT/A group, the metabosensitive responses to KCl injections were unaltered. However, we observed alterations in responses to EIF and to 1 mM of lactic acid (which induces the greatest activation). The ventilatory adjustments during repetitive muscle activation were abolished, and the mechanosensitive fiber responses to tendon vibrations were reduced. These results indicate that BoNT/A alters the sensorimotor loop and may induce insufficient motor and physiological adjustments in patients in whom a motor denervation with BoNT/A was performed.

Vitamin D deficiency intensifies deterioration of risk factors, such as male sex and absence of vision, leading to increased postural body sway

INTRODUCTION

Due to inconsistent findings, the influence of vitamin D on postural body sway (PBS) is currently under debate. This study evaluated the impact of vitamin D on PBS with regards to different foot positions and eye opening states in community-dwelling older individuals.

METHODS

In a cross-sectional study, we assessed PBS in 342 older individuals (264 females [average age (± SD): 68.3 ± 9.0 years], 78 males [65.7 ± 9.6 years]). A detailed medical history and vitamin D level were obtained for each individual. Fall risk was evaluated using the New York-Presbyterian Fall Risk Assessment Tool (NY PFRA). PBS parameters (area, distance, velocity, frequency) were evaluated on a pressure plate with feet in closed stance (CS) or hip-width stance (HWS), open eyes and closed eyes. Statistical analysis included logarithmic mixed models for repeated measures with the MIXED model procedure to test the influence of vitamin D (categorized in <10 μg/l, 10-20 μg/l, 21-30 μg/l, >30 μg/l), foot position, eye opening state, age, sex and frequency of physical activity on PBS.

RESULTS

Vitamin D was not an independent risk factor for falls experienced in the last 12 months. Nonetheless, PBS was higher in patients with vitamin D deficiency (<10 μg/l) in HWS (A/P p=0.028 and area p=0.037). Additionally, vitamin D deficiency intensified the deleterious effects of male sex (distance p=0.002) and absence of vision (area p<0.001) on PBS.

CONCLUSION

Independent risk factors for increased PBS like male sex and absence of vision are additionally compromised by vitamin D deficiency.