[Search for Neuroprotective Compounds -From 4-Methycatechol to Citrus Compounds].

In the 1980s, the authors developed the enzyme immunoassay (EIA) system for mouse nerve growth factor (NGF) to clarify its important physiological roles. Our EIA system was a new and powerful tool for measurement of extremely low levels of NGF in vitro and in vivo, and it contributed to investigation into the regulatory mechanism of NGF synthesis. After that, we demonstrated that the compounds with a low molecular weight, such as 4-methylcatechol, which elicit stimulatory activity toward NGF synthesis, were useful and practical for therapeutic purposes; as NGF has potent activity on neuronal degeneration in both the central nervous system (CNS) and the peripheral nervous system. Since 2008, we have been searching for and isolating neuroprotective component(s) from citrus peels. As a result, our study revealed that 1) 3,5,6,7,8,3',4'-heptamethoxyflavone (HMF) has neuroprotective ability in the CNS by inducing brain-derived neurotrophic factor (BDNF) and by suppressing inflammation; 2) auraptene (AUR) also has neuroprotective ability in the CNS by suppressing inflammation and by probably inducing neurotrophic factor(s). As the content of AUR in the peels of Kawachi Bankan is exceptionally high, 1) we found this peel powder to exert neuroprotective effects in the brain of various pathological model mice; 2) some of the AUR transited from the peel to the juice during the squeezing process to obtain the juice. Therefore, K. Bankan juice, which is enriched in AUR by adding peel paste to the raw juice, was shown to be practical for suppression of cognitive dysfunction of aged healthy volunteers.

Involvement of Oxidative Stress and Nerve Growth Factor in Behavioral and Biochemical Deficits of Experimentally Induced Musculoskeletal Pain in Mice: Ameliorative Effects of Heraclin.

Musculoskeletal pain is a widespread complex regional pain syndrome associated with altered emotional and cognitive functioning along with heightened physical disability that has become a global health concern. Effective management of this disorder and associated disabilities includes accurate diagnosis of its biomarkers and instituting mechanism-based therapeutic interventions. Herein, we explored the role of heraclin, a plant-derived molecule, in musculoskeletal pain and its underlying mechanistic approaches in an experimental mouse model. Reserpine (0.5 mg/kg) for 3 consecutive days evoked hyperalgesia, motor incoordination, lack of exploratory behavior, anxiety, and cognition lapse in mice. Reserpine-challenged mice displayed higher serum cytokine level, altered brain neurotransmitter content, elevated brain and muscle oxidative stress, and upregulated brain nerve growth factor receptor expression. Treatment with heraclin (10 mg/kg for 5 consecutive days) exerted analgesic effect and improved motor coordination and memory deficits in mice. Heraclin arrested serum cytokine rise, normalized brain neurotransmitter content, reduced tissue oxidative stress, and downregulated the nerve growth factor receptor expression. Therefore, it may be suggested that heraclin exerts beneficial effects against reserpine-induced musculoskeletal pain disorder possibly through the attenuation of NGFR-mediated pain and inflammatory signaling. Graphical Abstract.

The Mixture of Gotu Kola, Cnidium Fruit, and Goji Berry Enhances Memory Functions by Inducing Nerve-Growth-Factor-Mediated Actions Both In Vitro and In Vivo.

Nerve growth factor (NGF), a typical neurotrophin, has been characterized by the regulation of neuronal cell differentiation and survival involved in learning and memory functions. NGF has a main role in neurite extension and synapse formation by activating the cyclic adenosine monophosphate-response-element-binding protein (CREB) in the hippocampus. The purpose of this study was to determine whether a mixture of Gotu Kola, Cnidium fruit, and Goji berry (KYJ) enhances memory function by inducing NGF-mediated actions both in vitro and in vivo. The KYJ combination increased NGF concentration and neurite length in C6 glioma and N2a neuronal cells, respectively. Additionally, we discovered memory-enhancing effects of KYJ through increased NGF-mediated synapse maturation, CREB phosphorylation, and cell differentiation in the mouse hippocampus. These findings suggest that this combination may be a potential nootropic cognitive enhancer via the induction of NGF and NGF-dependent activities.

Benefits of Gardening Activities for Cognitive Function According to Measurement of Brain Nerve Growth Factor Levels.

The objective of this study was to determine the effects of gardening activities in senior individuals on brain nerve growth factors related to cognitive function. Forty-one senior individuals (age 76.6 ± 6.0 years) were recruited from the local community in Gwangjin-gu, Seoul, South Korea. A 20-min low-to-moderate intensity gardening activity intervention, making a vegetable garden, was performed by the subjects in a garden plot located on the Konkuk University (Seoul, South Korea) campus. The gardening involved six activities including cleaning a garden plot, digging, fertilizing, raking, planting/transplanting, and watering. To determine the effects of the gardening activities on brain nerve growth factors related to memory, blood samples were drawn twice from each subject before and after the gardening activity by professional nurses. The levels of brain nerve growth factors, including brain-derived neurotrophic factor (BDNF), vascular endothelial growth factor (VEGF) and platelet derived growth factor (PDGF), were analyzed. Levels of BDNF and PDGF were significantly increased after the gardening activity. This study revealed a potential benefit of gardening activities for cognitive function in senior individuals.

Negletein as a neuroprotectant enhances the action of nerve growth factor and induces neurite outgrowth in PC12 cells.

Negletein has been shown to have therapeutic potential for inflammation-associated diseases, but its effect on neurite outgrowth is still unknown. The present study showed that negletein alone did not trigger PC12 cells to differentiate and extend neurites. When compared with the cells in the untreated control, a significant (P < 0.05) induction and a higher neurite outgrowth activity was observed when the cells were cotreated with negletein (10 µM) and a low dose of nerve growth factor (NGF; 5 ng/mL). The neurite outgrowth process was blocked by the tyrosine kinase receptor (Trk) inhibitor, K252a, suggesting that the neuritogenic effect was NGF-dependent. Negletein (10 µM) together with NGF (5 ng/mL) enhanced the phosphorylation of extracellular signal-regulated kinases (ERKs), protein kinase B (Akt), and cAMP response element-binding protein (CREB). The growth associated protein-43 (GAP-43) and the NGF level were also upregulated by negletein (10 µM) and a low dose of NGF (5 ng/mL). Negletein at nanomolar concentration also was found to be sufficient to mediate the survival of serum-deprived PC12 cells up to 72 h. Taken together, negletein might be useful as an efficient bioactive compound to protect neurons from cell death and promote neuritogenesis. © 2016 BioFactors, 42(6):591-599, 2016.

Organotypic Spinal Cord Culture: a Proper Platform for the Functional Screening.

Recent improvements in organotypic slice culturing and its accompanying technological innovations have made this biological preparation increasingly useful ex vivo experimental model. Among organotypic slice cultures obtained from various central nervous regions, spinal cord slice culture is an absorbing model that represents several unique advantages over other current in vitro and in vivo models. The culture of developing spinal cord slices, as allows real-time observation of embryonic cells behaviors, is an instrumental platform for developmental investigation. Importantly, due to the ability of ex vivo models to recapitulate different aspects of corresponding in vivo conditions, these models have been subject of various manipulations to derive disease-relevant slice models. Moreover spinal cord slice cultures represent a potential platform for screening of different pharmacological agents and evaluation of cell transplantation and neuroregenerative materials. In this review, we will focus on studies carried out using the ex vivo model of spinal cord slice cultures and main advantages linked to practicality of these slices in both normal and neuropathological diseases and summarize them in different categories based on application.

Elucidation of pathophysiology and treatment of neuropathic pain.

Neuropathic pain, pain arising as a direct consequence of a lesion or disease affecting the somatosensory system, is relatively common, occurring in about 1% of the population. Studies in animal models describe a number of peripheral and central pathophysiological processes after nerve injury that would be the basis of underlying neuropathic pain mechanism. Additionally, neuro-imaging (positron emission tomography and functional magnetic resonance imaging) provides insights in brain mechanisms corresponding with mechanistic processes including allodynia, hyperalgesia, altered sensation, and spontaneous pain. A change in function, chemistry, and structures of neurons (neural plasticity) underlie the production of the altered sensitivity characteristics of neuropathic pain. Peripheral processes in neuropathic pain involve production of mediators (cytokines, protons, nerve growth factor), alterations in calcium channels, sodium channels, hyperpolarisation-activated nucleotide-gated ion channels, and potassium channels, phenotypic switches and sprouting of nerves endings, and involvement of the sympathetic nervous system. Stimulation of the N-Methyl-D-Aspartate receptor, activation of microglia, oligodendrocytes, and astrocytes, increased production of nerve growth factor and brain-derived neurotrophic factor together with loss of spinal inhibitory control are responsible for central neuron hyperexcitability and maintenance of neuropathic pain. Recent advances, including functional imaging techniques, in identification of peripheral and central sensitization mechanisms related to nervous system injury have increased potential for affecting pain research from both diagnostic as well as therapeutic view. Key brain regions involved in generating pharmacologically induced analgesia may be identified. Despite the progress in pain research, neuropathic pain is challenge to manage. Although numerous treatment options are available for relieving neuropathic pain, there is no consensus on the most appropriate treatment. However, recommendations can be proposed for first-line, second-line, and third-line pharmacological treatments based on the level of evidence for the different treatment strategies. Available therapies shown to be effective in managing neuropathic pain include opioids and tramadol, anticonvulsants, antidepressants, topical treatments (lidocaine patch, capsaicin), and ketamine. Tricyclic antidepressants are often the first drugs selected to alleviate neuropathic pain (first-line pharmacological treatment). Although they are very effective in reducing pain in several neuropathic pain disorders, treatment may be compromised (and outweighed) by their side effects. In patients with a history of cardiovascular disorders, glaucoma, and urine retention, pregabalin and gabapentine are emerging as first-line treatment for neuropathic pain. In addition these anti-epileptic drugs have a favourable safety profile with minimal concerns regarding drug interactions and showing no interference with hepatic enzymes. Alternatively, opioids (oxycodone and methadone) and tramadol may alleviate nociceptive and neuropathic pain. Despite the numerous treatment options available for relieving neuropathic pain, no more than half of patients experience clinically meaningful pain relief, which is almost always partial but not complete relief. In addition, patients frequently experience burdensome adverse effects and as a consequence are often unable to tolerate the treatment. In the remaining patients, combination therapies using two or more analgesics with different mechanisms of action may also offer adequate pain relief. Although combination treatment is clinical practice and may result in greater pain relief, trials regarding different combinations of analgesics (which combination to use, occurrence of additive or supra-additive effects, sequential or concurrent treatment, adverse-event profiles of these analgesics, alone and in combination) are scarce. If medical treatments have failed, invasive therapies such as intrathecal drug administration and neurosurgical stimulation techniques (spinal cord stimulation, deep brain stimulation, and motor cortex stimulation) may be considered.

Sesquiterpenoids and lignans from the roots of Valeriana officinalis L.

Two new guaiane-type sesquiterpenoids, valerol A (1) and kessyl 3-acetate (2), together with nine known compounds, valeracetate (3), anismol A (4), orientalol C (5), spatulenol (6), 4α,10α-epoxyaromadendrane (7), (+)-8-hydroxypinoresinol (8), pinorespiol (9), pinoresinol 4-O-ß-D-glucopyranoside (10), and 8-hydroxypinoresinol 4'-O-ß-D-glucopyranoside (11) were isolated from the roots of Valeriana officinalis. The structures and relative configurations of 1 and 2 were elucidated on the basis of spectroscopic methods (1D- and 2D-NMR, MS, UV, and IR). These compounds were evaluated for inhibitory activity on acetylcholinesterase (AChE) and enhancing activity on nerve growth factor (NGF)-mediated neurite outgrowth in PC12 cells.

A dual mechanism linking NGF/proNGF imbalance and early inflammation to Alzheimer's disease neurodegeneration in the AD11 anti-NGF mouse model.

The neurotrophin Nerve Growth Factor (NGF) is essential for the maintenance and differentiation of basal forebrain cholinergic neurons. Since basal forebrain cholinergic neurons represent one major neuronal population affected and progressively degenerating in Alzheimer's disease (AD), interest has grown for NGF as a potential therapeutic agent in neurodegenerative disorders linked to aging, particularly for AD. However, no evidence was available, to link, in a cause-effect manner, deficits in NGF signalling to the broader activation in the Alzheimer's cascade, besides cholinergic deficits. The phenotypic analysis of the AD11 anti-NGF transgenic mouse, obtained by the "neuroantibodies" phenotypic protein knock out strategy, allowed demonstrating a direct causal link between NGF deprivation and AD pathology. Since then, extensive mechanistic studies on the AD11 model provided a new twist to the concept that alterations in NGF transport and signalling play a crucial role in sporadic Alzheimer's neurodegeneration, leading to the hypothesis of "Neurotrophic imbalance" as an upstream driver for sporadic AD. The results obtained with the AD11 anti-NGF mice highlight the fact that the particular mode of NGF neutralization, with an NGF antibody expressed in the brain, selectively interfering with mature NGF versus unprocessed proNGF, plays a major role in the mechanism of neurodegeneration, and could lead to new insights into the mechanisms of human sporadic AD. Here, we will review (1) the renewed neurotrophic imbalance hypothesis for AD and (2) the mechanisms underlying the neurodegenerative phenotype of AD11 anti-NGF mice.

[Effects of ethanol extracts of herbal medicines on dermatitis in an atopic dermatitis mouse model].

Atopic dermatitis is a chronic and relapsing inflammatory skin disease that is characterized by highly pruritic, eczematous skin lesions. Our previous study elucidated that nerve growth factor (NGF) plays an important role in the pathogenesis of skin lesions and inhibition of the physiological effects of NGF can moderate skin lesions in atopic dermatitis. In this study, we investigated the effects of ethanol extracts of herbal medicines on neuritic outgrowth induced by NGF. Four herbal extracts (Geranium thunbergii, Humulus lupulus, Rosmarinus officinalis and Salvia officinalis L.) inhibited NGF-induced neuritic outgrowth in PC12 cells. We also investigated the effects of each herbal extract on dermatitis in NC/Nga, an atopic dermatitis mouse model. The skin lesions of the NC/Nga mice were significantly inhibited by repeated applications of each herbal extract. These results suggested that the four herbal extracts can prevent and moderate the symptoms of atopic dermatitis, and these effects might be appeared by inhibiting the effect of NGF on neuritic outgrowth in lesional skin.

Green tea polyphenols potentiate the action of nerve growth factor to induce neuritogenesis: possible role of reactive oxygen species.

Exogenously administered nerve growth factor (NGF) repairs injured axons, but it does not cross the blood-brain barrier. Thus, agents that could potentiate the neuritogenic ability of endogenous NGF would be of great utility in treating neurological injuries. Using the PC12 cell model, we show here that unfractionated green tea polyphenols (GTPP) at low concentrations (0.1 µg/ml) potentiate the ability of low concentrations of NGF (2 ng/ml) to induce neuritogenesis at a level comparable to that induced by optimally high concentrations of NGF (50 ng/ml) alone. In our experiments, GTPP by itself did not induce neuritogenesis or increase immunofluorescent staining for ß-tubulin III; however, it increased expression of mRNA and proteins for the neuronal markers neurofilament-L and GAP-43. Among the polyphenols present in GTPP, epigallocatechin-3-gallate (EGCG) alone appreciably potentiated NGF-induced neurite outgrowth. Although other polyphenols present in GTPP, particularly epigallocatechin and epicatechin, lack this activity, they synergistically promoted this action of EGCG. GTPP also induced an activation of extracellular signal-regulated kinases (ERKs). PD98059, an inhibitor of the ERK pathway, blocked the expression of GAP-43. K252a, an inhibitor of TrkA-associated tyrosine kinase, partially blocked the expression of these genes and ERK activation. Antioxidants, catalase (cell-permeable form), and N-acetylcysteine (both L and D-forms) inhibited these events and abolished the GTPP potentiation of NGF-induced neuritogenesis. Taken together, these results show for the first time that GTPP potentiates NGF-induced neuritogenesis, likely through the involvement of sublethal levels of reactive oxygen species, and suggest that unfractionated GTPP is more effective in this respect than its fractionated polyphenols.

Cutaneous sensory nerves: mediators of phototherapeutic effects?

Exposures to ultraviolet radiation (UVR) during accidental or voluntary sun exposure or treatment with phototherapy or photochemotherapy have a significant impact on the skin. Many skin diseases such as psoriasis, atopic dermatitis, or cutaneous T-cell lymphoma significantly improve by photo(chemo)therapy, though the mechanisms behind the therapeutic effects of photo(chemo)therapy are still far from understood. Various pathways and means through which the energy of UVR from natural or artificial sources is ultimately transformed into biologic effects within the skin have been suggested and cutaneous sensory nerves, neuropeptides, neurotrophins, and certain nerve-related receptors have been among them. In fact a three-dimensional network of sensory nerve fibers derived from dorsal root ganglia intersperses all layers of the skin including the epidermis. In this forefront of defense against environmental impacts (including UVR) on the skin, sensory nerve fibers become targets by itself and closely contact resident and infiltrating cutaneous cells. Thus, terminals of cutaneous sensory nerve fibers, and neuropeptides within these fibers, are in a central position to participate in mediating therapeutic effects of photo(chemo)therapy.

Nerve growth factor promotes differentiation of odontoblast-like cells.

Contemporary strategies in tooth repair markedly rely on the newest findings on the cellular and biological components of dental development. Among several identified bioactive molecules, neurotrophins were recently proposed to affect tooth germ cell proliferation, differentiation, and cell-extracellular matrix interactions. The present study attempted to explore the effect of nerve growth factor (NGF) on a spontaneously immortalized dental papilla mesenchymal cell line. NGF induced differentiation of odontoblast-lineage cells with subsequent biomineralization in vitro. Here we showed that normalized transcript levels of tissue-specific markers such as DSPP and DMP1 were elevated significantly, indicating cell differentiation and maturation processes. We performed innovative gene expression analysis of TM14, a matricellular protein and novel member of the fibulin family. TM14 expression followed a pattern similar to that of DMP1, which suggests its important role in cell-matrix and intercellular interactions during dentin calcification. Alkaline phosphatase enzyme assay confirmed the extracellular matrix calcifications in NGF-supplemented groups. Thus, NGF was characterized as a potent promoter of mineralization during dentin formation. For the first time, we included TM14 in odontoblast genotype analysis and proved that NGF also promotes in vitro odontoblast differentiation. Collectively, these results highlight the importance of NGF during tooth morphogenesis, as well as urge the elaboration of complex epithelial-mesenchymal tissue cultures, where further elucidation of the signaling factor network could be completed.

[Prurigo]. / Les prurigos.

Prurigo is a medical term which includes several clinical, pathological and etiologic entities. Diagnostic and therapeutic management is different depending on if we face acute prurigo or chronic prurigo. Acute prurigo is almost always linked to parasites or insects. Chronic prurigo can be linked to dermatologic diseases or may reveal internal pathologies. Complementary exams we should ask for are focused on these diseases. Idiopathic chronic prurigo, without underlying disease, is the most frequent one. It needs regular survey, as it can reveal cutaneous or internal diseases after months or even years. Treatment of prurigo is treatment of the underlying disease. Symptomatic treatment against pruritus, topic or systemic, must be added.

Intravesical botulinum toxin A injections plus hydrodistension can reduce nerve growth factor production and control bladder pain in interstitial cystitis.

OBJECTIVES: To investigate the level of nerve growth factor (NGF) mRNA in bladder tissue and the effect of botulinum toxin A (BTX-A) treatment in patients with interstitial cystitis (IC). METHODS: A total of 19 patients with IC were treated with 100 U or 200 U of intravesical BTX-A injections followed by cystoscopic hydrodistension 2 weeks later. Bladder mucosa biopsies were performed before BTX-A injection and immediately after hydrodilation and in 12 controls. The NGF mRNA and protein levels in bladder tissues were assessed by real-time polymerase chain reaction and immunohistochemistry studies to determine differences in NGF expression between patients with IC before and after BTX-A treatment and compare with controls. RESULTS: At 3 months, 14 patients had symptomatic improvement (responders) and 5 did not (nonresponders). The NGF mRNA levels at baseline in the overall IC patient group were significantly greater than those in the controls (0.65 +/- 0.33 versus 0.42 +/- 0.25, P = 0.046). At 2 weeks after BTX-A treatment, the NGF mRNA levels had decreased to 0.47 +/- 0.23 (P = 0.002, compared with baseline) and were no longer significantly different from those of the controls. The NGF mRNA levels decreased significantly in responders and were significantly decreased after BTX-A in 11 patients with a visual analog pain scale reduction of 2 or more. The immunoreactivity study of bladder tissue from patients with IC showed greater NGF density at baseline compared with controls, but the difference was no longer significant after successful BTX-A treatment. CONCLUSIONS: Intravesical BTX-A injections plus hydrodistension reduce bladder pain in patients with IC. The NGF levels in the bladder tissue were significantly increased in patients with IC and decreased to normal level after treatment in responders.

The neuropeptide pituitary adenylate cyclase activating protein stimulates human monocytes by transactivation of the Trk/NGF pathway.

Transactivation is a process whereby stimulation of G-protein-coupled receptors (GPCR) activates signaling from receptors tyrosine kinase (RTK). In neuronal cells, the neuropeptide pituitary adenylate cyclase-activating polypeptide (PACAP) acting through the GPCR VPAC-1 exerts trophic effects by transactivating the RTK TrkA receptor for the nerve growth factor (NGF). Both PACAP and NGF have pro-inflammatory activities on monocytes. We have tested the possibility that in monocytes, PACAP, as reported in neuronal cells, uses NGF/TrkA signaling pathway. In these cells, PACAP increases TrkA tyrosine phosphorylations through a PI-3kinase dependent but phospholipase C independent pathway. K252a, an inhibitor of TrkA decreases PACAP-induced Akt and ERK phosphorylation and calcium mobilisation resulting in decreases in intracellular H2O2 production and membrane upregulation of CD11b expression, both functions being inhibited after anti-NGF or anti-TrkA antibody treatment. K252a also inhibits PACAP-associated NF-KB activity. Monocytes increase in NGF production is seen after micromolar PACAP exposure while nanomolar treatment which desensitizes cells to high dose of PACAP prevents PACAP-induced TrkA phosphorylation, H2O2 production and CD11b expression. Finally, NGF-dependent ERK activation and H2O2 production is pertussis toxin sensitive. Altogether these data indicate that in PACAP-activated monocytes some pro-inflammatory activities occur through transactivation mechanisms involving VPAC-1, NGF and TrkA-associated tyrosine kinase activity.

Three-membered ring sesquiterpenoids with NGF-potentiating activity from the roots of Valeriana fauriei.

Three novel three-membered ring sesquiterpenoids, named kissoone A (1), kissoone B (2), and its acetylated product, kissoone C (3), were isolated from the roots of Valeriana fauriei. Their structures were elucidated on the basis of spectroscopic analysis. Compounds 2 and 3 showed enhancing activity on nerve growth factor (NGF)-mediated neurite outgrowth in PC 12D cells.

NGF rapidly increases membrane expression of TRPV1 heat-gated ion channels.

Nociceptors, or pain-sensitive receptors, are unique among sensory receptors in that their sensitivity is increased by noxious stimulation. This process, called sensitization or hyperalgesia, is mediated by a variety of proinflammatory factors, including bradykinin, ATP and NGF, which cause sensitization to noxious heat stimuli by enhancing the membrane current carried by the heat- and capsaicin-gated ion channel, TRPV1. Several different mechanisms for sensitization of TRPV1 have been proposed. Here we show that NGF, acting on the TrkA receptor, activates a signalling pathway in which PI3 kinase plays a crucial early role, with Src kinase as the downstream element which binds to and phosphorylates TRPV1. Phosphorylation of TRPV1 at a single tyrosine residue, Y200, followed by insertion of TRPV1 channels into the surface membrane, explains most of the rapid sensitizing actions of NGF.

Acetylated flavonoid glycosides potentiating NGF action from Scoparia dulcis.

Three new acetylated flavonoid glycosides, 5,6,4'-trihydroxyflavone 7-O-alpha-L-2,3-di-O-acetylrhamnopyranosyl-(1-->6)-beta-D-glucopyranoside (1), apigenin 7-O-alpha-L-3-O-acetylrhamnopyranosyl-(1-->6)-beta-D-glucopyranoside (2), and apigenin 7-O-alpha-L-2,3-di-O-acetylrhamnopyranosyl-(1-->6)-beta-D-glucopyranoside (3), were isolated from Scoparia dulcis together with the known compound eugenyl beta-D-glucopyranoside (4). Their structures were elucidated by spectroscopic analyses. Compounds 2 and 3 showed an enhancing activity of nerve growth factor-mediated neurite outgrowth in PC12D cells.