The therapeutic effects of 4-methylcatechol, a stimulator of endogenous nerve growth factor synthesis, on experimental diabetic neuropathy in rats

Morphogenetic theory of mental and cognitive disorders: the role of neurotrophic and guidance molecules

Mental illness and cognitive disorders represent a serious problem for the modern society. Many studies indicate that mental disorders are polygenic and that impaired brain development may lay the ground for their manifestation. Neural tissue development is a complex and multistage process that involves a large number of distant and contact molecules. In this review, we have considered the key steps of brain morphogenesis, and the major molecule families involved in these process. The review provides many indications of the important contribution of the brain development process and correct functioning of certain genes to human mental health. To our knowledge, this comprehensive review is one of the first in this field. We suppose that this review may be useful to novice researchers and clinicians wishing to navigate the field.

Ameliorative Effects of Isoeugenol and Eugenol against Impaired Nerve Function and Inflammatory and Oxidative Mediators in Diabetic Neuropathic Rats

Diabetic polyneuropathy is characterized by structural abnormalities, oxidative stress, and neuroinflammation. The current study aimed to determine the antinociceptive effects of isoeugenol and eugenol and their combinations in neuropathic pain resulting from streptozotocin (STZ)-induced diabetes and neuroinflammation. Female SD rats were categorized into normal control, diabetic control, and treatment groups. On the 28th day and 45th day, behavioral studies (allodynia and hyperalgesia) were performed to analyze the development and protection of diabetic polyneuropathy. The levels of inflammatory and oxidative mediators, such as superoxide dismutase (SOD), tumor necrosis factor-α (TNF-α), catalase, reduced glutathione, and thiobarbituric acid reactive substances (TBARS), were estimated. In addition, the level of nerve growth factor (NGF) was estimated at the end of the study in different groups. The anti-NGF treatment decreased its upregulation in the dorsal root ganglion significantly. The results showed that isoeugenol, eugenol, and their combination have therapeutic potential against neuronal and oxidative damage induced by diabetes. In particular, both compounds significantly affected behavioral function in treated rats and showed neuroprotection against diabetic neuropathy, and their combination had synergistic effects.

Nerve Growth Factor transfer from cardiomyocytes to innervating sympathetic neurons activates TrkA receptors at the neuro-cardiac junction

The integration of ex vivo and in vitro data, described in this manuscript, together with our previous demonstration that sympathetic neurons (SNs) contact target cardiomyocytes (CMs) at the neuro-cardiac junction (NCJ), which underlies intercellular synaptic communication (Prando et al., 47), demonstrate that: CMs are the cell source of Nerve Growth Factor (NGF), required to sustain innervating cardiac SNs; NCJ is the place of the intimate liaison, between SNs and CMs, allowing on the one hand neurons to peremptorily control CM activity, and on the other, CMs to adequately sustain the contacting, everchanging, neuronal actuators; alterations in NCJ integrity may compromise the efficiency of 'CM-to-SN' signaling, thus representing a potentially novel mechanism of sympathetic denervation in cardiac diseases. ABSTRACT: Background Sympathetic neurons densely innervate the myocardium with non-random topology and establish structured contacts (i.e. neuro-cardiac junctions, NCJ) with cardiomyocytes, allowing synaptic intercellular communication. Establishment of heart innervation is regulated by molecular mediators released by myocardial cells. The mechanisms underlying maintenance of cardiac innervation in the fully developed heart, are, however, less clear. Notably, several cardiac diseases, primarily affecting cardiomyocytes, are associated to sympathetic denervation, supporting that retrograde 'cardiomyocyte-to-sympathetic neuron' communication is essential for heart cellular homeostasis. Objective We aimed to determine whether cardiomyocytes provide Nerve Growth Factor (NGF) to sympathetic neurons, and the role of the NCJ in supporting such retrograde neurotrophic signaling. Methods and Results Immunofluorescence on murine and human heart slices shows that NGF and its receptor, Tropomyosin-receptor-kinase-A, accumulate respectively in the pre- and post-junctional sides of the NCJ. Confocal immunofluorescence, scanning ion conductance microscopy and molecular analyses, in co-cultures, demonstrate that cardiomyocytes feed NGF to sympathetic neurons, and that such mechanism requires a stable intercellular contact at the NCJ. Consistently, cardiac fibroblasts, devoid of NCJ, are unable to sustain SN viability. ELISA assay and competition binding experiments suggest that this depends on the NCJ being an insulated microenvironment, characterized by high [NGF]. In further support, real-time imaging of Tropomyosin-receptor-kinase-A-vesicle movements demonstrate that efficiency of neurotrophic signaling parallels the maturation of such structured intercellular contacts. Conclusions Altogether, our results demonstrate the mechanisms which link sympathetic neuron survival to neurotrophin release by directly innervated cardiomyocytes, conceptualizing sympathetic neurons as cardiomyocyte-driven heart drivers. Abstract figure legend Sympathetic neuron (SN, green) varicosities establish synaptic contacts with target cardiomyocytes (CMs, pink), which we previously called Neuro-Cardiac Junction (NCJ, Prando et al. J Physiol 47). At NCJs, CMs release selectively NGF, which by activating TrkA signaling, is key to sustain neuronal survival. This article is protected by copyright. All rights reserved.

[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.

The interaction of ASAH1 and NGF gene involving in neurotrophin signaling pathway contributes to schizophrenia susceptibility and psychopathology

The neurodevelopmental hypothesis of schizophrenia has been widely accepted. In light of our previous microarray data, two neurodevelopment-related genes were focused on inclduing the N-acylsphingosine amidohydrolase 1 gene (ASAH1) and the nerve growth factor gene (NGF). The evidence that ASAH1 and NGF are associated with schizophrenia is far from conclusive. Furthermore, their interactions in schizophrenia have not been investigated. Total 413 patients and 578 controls were included. Eleven single-nucleotide polymorphisms (SNPs) in ASAH1 and NGF were selected. A multifactor dimensionality reduction (MDR) was applied to investigate gene-gene interactions in schizophrenia, and the traditional odds ratio methods was applied to validate it. The effects of ASAH1, NGF and their interaction on the severity of the disease were analyzed by 3 × 3 covariance analysis of (ANCOVA). The biological interaction between ASAH1 and NGF was examined. KEGG was used to identify the related signaling pathways. After correction by Bonferroni, there were no differences in the genotypic, allelic, or haplotypic frequencies of 11 SNPs between patients and controls. However, the interaction of certain SNPs had effect on susceptibility to schizophrenia, including two high-risk and one low-risk genotypic combinations (OR = 1.49 [1.11-2.00]; OR = 1.45 [1.09-1.92], and OR = 0.64 [0.41-0.98]). ASAH1-rs7830490 and its interaction with NGF-rs4332358 were associated with the general psychopathological subscale score (F _adjusted = 3.94, p _adjusted = 0.01; F _adjusted = 2.36, p _adjusted = 0.03). We also found that ASAH1 and NGF interacted with CaMK2B involving in the neurotrophin signaling pathway. Our results suggest that the interaction of ASAH1 and NGF with CaMK2B involved in neurotrophin signaling pathway may contribute to schizophrenia susceptibility and psychopathology.

Aroma compounds of non-alcoholic fermented beverage: Gilaburu juice

The present research was planned to characterize the aroma composition of Viburnum opulus L. which is one important members of the Caprifoliaceae family. Volatile components of Viburnum opulus L. were extracted by use of the purge and trap technique with dichloromethane and analyzed by gas chromatography-mass spectrometry (GC-MS). The extraction method gave highly representative aromatic extract of the studied sample. A total of 47 aroma compounds were found including acids, alcohols, ketones, volatile phenols, aldehydes, furans, lactones, an ester a terpene and a pyranone. Among all aroma compounds, isovaleric acid was found as the most abundant aroma compound in the fermented GR juice, having a 30% of total aroma concentration. Butanoic acid, 4-methyl catechol and propanoic acid were other aroma compounds found in higher concentrations (18%, 11% and 6% respectively).

[Basic Research on Neurotrophic Factors and Its Application to Medical Uses]

The author has studied nerve growth factor (NGF) and its family of neurotrophic factors (neurotrophins) for over 40 years. During the first 20 years, my laboratory established a highly sensitive enzyme immunoassay for NGF and analyzed the regulatory mechanism of NGF synthesis in cultured primary cells. Fibroblast cells cultured from peripheral organs such as the heart and astrocytes from the brain produced a substantial amount of NGF in a growth-dependent manner. Furthermore, synthesis of NGF in these cells could be upregulated by catechol compounds including catecholamines. This observation might explain a physiological relation between the level of NGF mRNA and the density of innervation in the peripheral sympathetic nervous systems. Over the subsequent 20 years, my laboratory investigated the physiological functions of neurotrophic factors, including neurotrophins, during development or post-injury and found that brain-derived neurotrophic factor (BDNF) plays a role in the formation of the laminar structure of the cerebral cortex. In addition, my laboratory discovered that endogenous glial cell line-derived neurotrophic factor (GDNF) contributes to the amelioration of motor activity after spinal cord injury. Therefore we aimed to develop low-molecular weight compounds that generate neurotrophic factor-like intracellular signals to protect or ameliorate neurological/psychiatric diseases. 2-Decenoic acid derivatives and other similar molecules could protect or ameliorate in animal models of mood disorders such as depression and enhance recovery from spinal cord injury-induced motor paralysis. Compounds that can generate neurotrophin-like signals in neurons are expected to be developed as therapeutic drugs for certain neurological or psychiatric disorders.

Antinociceptive and neuropharmacological activities of methanol extract of Phoenix sylvestris fruit pulp

Fruits of Phoenix sylvestris Roxb. (Arecaceae) are used to treat back pain, toothache, headache, arthritis, nervous debility and as sedative. The aim of this study was to evaluate the antinociceptive and neuropharmacological activities of methanol extract of P. sylvestris fruit pulp (MEPS). The antinociceptive activity of MEPS was evaluated by heat-induced (hot plate, tail immersion test) and chemical-induced pain models (acetic acid-induced writhing, formalin-induced nociception, glutamate-induced nociception and paw edema test). The effect of MEPS on central nervous system (CNS) was studied using hole cross test, open field test, sodium thiopental-induced sleeping time and elevated plus maze test. MEPS showed strong, significant and dose-dependent antinociceptive activity in all heat-induced and chemical-induced pain models at all experimental doses. Involvement of opioid receptor mediated analgesia was evident from the reversal of analgesic effect by naloxone. MEPS also showed reduced locomotor activity in both hole cross and open field tests. The increase in sleeping time in sodium thiopental-induced sleeping test and anxiolytic activity in elevated plus maze test were also significant. So, it is evident that MEPS possesses strong central and peripheral antinociceptive activity as well as CNS depressant, sedative and anxiolytic activity. The results justify the ethnomedicinal use of P. sylvestris fruit in different painful conditions and CNS disorders.

Neurotropin(®) ameliorates chronic pain via induction of brain-derived neurotrophic factor

Neurotropin (NTP)(®), a non-protein extract isolated from the inflamed skin of rabbits inoculated with vaccinia virus, is used clinically for the treatment of neuropathic pain. Moreover, NTP may activate the descending pain inhibitory system. Depression-like behavior is often complicated by chronic pain. However, little is known about NTP-mediated prevention of mood disorders in chronic pain and its molecular mechanisms. We aimed to investigate the effects of NTP on brain-derived neurotrophic factor (BDNF)-mediated signaling and gene expression in chronic pain. In addition, these effects of NTP were compared with pregabalin which is an anticonvulsant, anxiolytic analgesic used to treat neuropathic pain and fibromyalgia. A chronic constriction injury model was established in Sprague-Dawley rats. The pain response was assessed using a paw withdrawal latency (PWL) test and depression was assessed by the immobility time in a forced swim test (FST). NTP was orally administered in two doses of 50 NU (Neurotropin Unit) and 100 NU/kg for 7 days from day 7 after injury. To measure the analgesic and anti-depressant effects of NTP, either K252a (a tyrosine kinase inhibitor), or 5,7-dihydroxy tryptamine (5,7-DHT, a selective toxin for 5-HTergic neurons) was administered by intracerebroventricular injection. Changes in pERK1/2 and pCREB (immunohistochemistry), 5-HT, and BDNF protein level (ELISA) and BDNF mRNA (RT-PCR) were measured in the anterior cingulate cortex (ACC) and in the rostral ventromedial medulla (RVM) 14 days after injury. After injury, the rats showed a decrease in PWL associated with the increase in time of immobility in FST. In this injury model, NTP blocked both the decrease in PWL and the increase in the FST, while pregabalin (10 mg/kg, po.) did not affect the increase in the FST. These effects of NTP were reversed by K252a, and 5,7-DHT. The analgesic effects of pregabalin were not reversed by K252a. NTP normalized the injury-induced excessive activation of pERK1/2 associated with decreased pCREB and BDNF mRNA in the ACC and in the RVM, and these changes were reversed by 5,7-DHT. In contrast, pregabalin did not affect either pCREB or BDNF levels in the chronic pain model. NTP ameliorated chronic pain and pain-related depression by normalizing the induction of BDNF associated with the 5-HTergic system. Pregabalin showed the analgesic effects but had no effects on either depression or the BDNF pathway. These results suggest that NTP may represent an additional drug strategy for chronic pain associated with depression.

The effects of Ginkgo biloba extract (GBe) on axonal transport microvasculature and morphology of sciatic nerve in streptozotocin-induced diabetic rats

To evaluate the protective effects ofGinkgo biloba extract (GBe) which has antioxidant activity against peripheral neuropathy due to diabetes mellitus, slow axonal transport and morphology of sciatic nerve including endoneurial microvessels were examined in 12 rats with diabetes mellitus induced by streptozotocin (STZ, 60mg/kg, b.w., i.p.). Six of the diabetic rats were treated with 0.1 % of GBe for 6 weeks from one week after the STZ injection. Serum glucose and lipid peroxide levels in GBe-treated diabetic rats were significantly lower than those in untreated diabetic rats (p<0.01, respectively), though the serum glucose level was higher than that in the control rats. L-[(35)S] methionine pulse radiolabeling with subsequent gel fluorography demonstrated that mean velocities (Vmean) of actin and β-tubulin, i.e. slow component b (SCb) transport in untreated diabetic rats were significantly lower than those in control rats (p<0.05, respectively); mean diameter of axons in the former rats was significantly smaller than that in the latter (p<0.01). Vmean of actin transport in GBe-treated diabetic rats was significantly faster than that in untreated diabetic rats (p<0.05). Vmean of slow axonal transport was significantly correlated with mean diameter of axons in the three groups of rats combined (p<0.01). On electron microscopy, severe altered endoneurial microvessels decreasing in luminal area together with endothelial cell degeneration or hypertrophy, pericyte debris and basement membrane thickening were observed in untreated diabetic rats; on the other hand these findings were less prominent in the diabetic rats treated with GBe. It is suggested that GBe treatment may protect disturbed slow axonal transport and pathological alterations of peripheral nerve with abnormal endoneurial microvasculature from diabetes mellitus by antioxidant activity.

Intracerebroventricular 4-methylcatechol (4-MC) ameliorates chronic pain associated with depression-like behavior via induction of brain-derived neurotrophic factor (BDNF)

Neuropathic pain concurrent with mood disorder from peripheral nerve injury is a serious clinical problem that significantly affects quality of life. Recent studies have suggested that a lack of brain-derived neurotrophic factor (BDNF) in the limbic system may cause this pain-emotion. BDNF is induced in cultured neurons by 4-methylcatechol (4-MC), but the role of 4-MC-induced BDNF in pain-emotion is poorly understood. Thus, we assessed the possible involvement of BDNF in brain in depression-like behavior during chronic pain following peripheral nerve injury. In addition, we examined whether intracerebroventricular (i.c.v.) 4-MC prevents chronic pain in rats and produces an antidepressant effect. Sprague-Dawley rats implanted intracerebroventricularly with a PE-10 tube were subjected to chronic constriction injury (CCI). Pain was assessed by a reduction in paw withdrawal latency (PWL) to heat stimuli after CCI. We also used a forced swimming testing (FST; time of immobility, in seconds) from day 14 to day 21 after CCI. Modulation of pain and emotional behavior was performed by injection of PD0325901 (a MEK1/2 inhibitor). 4-MC (100 nM) was continuously administered i.c.v. for 3 days during the period from day 14 to day 21 after CCI. To block analgesic and antidepressant effects, anti-BDNF antibody or K252a (a TrkB receptor inhibitor) was injected in combination with 4-MC. Naloxone was also coadministered to confirm the analgesic effect of 4-MC. During the chronic stage after CCI, the rats showed a sustained decrease in PWL (thermal hyperalgesia) associated with extension of the time of immobility (depression-like behavior). PD0325901 significantly reduced the decrease in PWL and the increased time of immobility after CCI. The decreased PWL and increased time of immobility were also reduced by 4-MC and by treatment with an ERK1/2 inhibitor. These effects of 4-MC i.c.v. were reversed by anti-BDNF and K252a. The analgesic effect of 4-MC i.c.v. was also antagonized by naloxone. Based on these results, we suggest that a lack of BDNF and activation of ERK1/2 in the pain-emotion network in the CNS may be involved in depression-like behavior during chronic pain. 4-MC i.c.v. ameliorates chronic pain and depression-like behavior by producing of BDNF and normalization of ERK1/2 activation. Therefore, enhancement of BDNF may be a new treatment strategy for chronic pain associated with depression.

Vascular risk factors and Alzheimer's disease

Vascular cognitive impairment risk factors include stroke, hypertension, diabetes and atherosclerosis. In the elderly, vascular risk factors occur in the presence of high levels of amyloid in the aging brain. Stroke alters the clinical expression of a given load of Alzheimer's disease (AD) pathology. Experimentally, large vessel infarcts or small striatal infarcts are larger in the presence of amyloid. Patients with minor cerebral infarcts and moderate AD lesions will develop the clinical manifestations of dementia. Moreover, there is also an association between other vascular risk factors and the clinical expression of cognitive decline and dementia. The risk of AD is increased in subjects with adult-onset diabetes mellitus, hypertension, atherosclerotic disease and atrial fibrillation. Experimentally, small striatal infarcts in the presence of high levels of amyloid in the brain exhibit a progression in infarct size over time with enhanced degree of cognitive impairment, AD-type pathology and neuroinflammation compared with striatal infarcts or high amyloid levels alone.

Interleukin-6 attenuates the development of experimental diabetes-related neuropathy

Neuropathy is the most severe and the least understood complication of diabetes. We investigated the potential neuroprotective effect of IL-6 therapy in an experimental model of diabetic neuropathy. A single i.v. injection of streptozotocin (STZ, 55 mg/kg) was used to induce experimental diabetes in adult males. IL-6 (1, 10 or 30 microg/kg) was administrated either intraperitoneally on a daily basis or subcutaneously (s.c.) on a daily, on a three times or one time per week basis, starting at day 10 post-STZ. A decrease in sensory nerve conduction velocity (SNCV), indicative of neuropathy, is seen in STZ rats as early as day 10 post-STZ, a time at which blood glycaemia is already maximal. At later time points, this electrophysiological impairment became severe and clinically apparent by affecting tail flick latency. Motor dysfunction defined by a significant increase in compound muscle action potential (CMAP) latency was also recorded. At the completion of the study (day 40 post-STZ), histological examination revealed significant axonopathy and myelin loss, along with an increase in the proportion of fibers with abnormal appearance in sciatic nerves of STZ rats. These changes were not observed in non-diabetic rats and were significantly prevented by IL-6 treatment. The optimal dose appeared to be 10 microg/kg s.c. three injections per week, which showed a better effect in most of the parameters studied than 4-methylcatechol, a NGF-like neuroprotective compound. Once weekly and three times weekly administrations of IL-6 were as effective as daily treatment. Taken together, these results support the potential neuroprotective actions of IL-6. The fact that the half-life of IL-6 is only approximately 5 h while weekly dosing was neuroprotective strongly suggests activation by IL-6 of effector molecule(s) with longer duration of action.

Protection of sensory function in diabetic rats by Neotrofin

We investigated the ability of Neotrofin, an agent that enhances endogenous nerve growth factor (NGF) levels, to prevent phenotypic, functional and structural changes that occur in the peripheral nerve of streptozotocin-diabetic rats. Eight weeks of Neotrofin treatment prevented depletion of NGF protein in plantar foot skin and sciatic nerve of diabetic rats and increased NGF protein in associated skeletal muscles. These effects were accompanied by maintenance of normal nerve levels of the neuropeptides substance P and calcitonin gene related peptide. Thermal hypoalgesia and conduction slowing of large sensory fibres in diabetic rats were ameliorated by Neotrofin treatment, whereas there was no effect on conduction slowing in large motor fibres or on reduced myelinated fibre axonal calibre. Enhancing endogenous production of neurotrophic factors using small molecules may be an alternative to either exogenous treatment with neurotrophic factors or gene therapy as a therapeutic approach to treating diabetic neuropathy.

4-Methylcatechol stimulates phosphorylation of Trk family neurotrophin receptors and MAP kinases in cultured rat cortical neurons

Effects of 4-methycatechol (4MC), a potent stimulator of nerve growth factor and brain-derived neurotrophic factor (BDNF) synthesis, on phosphorylation of cellular molecules in cultured rat cortical neurons were examined. 4MC stimulated tyrosine phosphorylation of various proteins of molecular weight from 10-300 kDa including Trks, which are high-affinity neurotrophin receptors. Moreover, 4MC enhanced the phosphorylation of serine 133 of mitogen-activated protein kinase (MAPK/ERK) in a dose-dependent manner. Pretreatment of cultures with PD98059, a selective inhibitor of MAPK kinase (MEK-1), inhibited 4MC-induced phosphorylation of ERKs, demonstrating MEK-1-mediated activation. Therefore, it seems that 4MC triggered the phosphorylation of Trks, resulting in the activation of the subsequent MAPK/ERK signal cascade, or perhaps the involvement of BDNF action as 4MC can stimulate neuronal BDNF synthesis. The phosphorylation of MAPK/ERK was unaffected, however, in the presence of cycloheximide, a protein synthesis inhibitor, and K252a, a selective inhibitor of Trks, suggesting that the effect of newly synthesized BDNF was negligible on this event, and that primary sites of 4MC actions are not limited only to Trks. These results suggest that 4MC primarily activates multiple signal transduction molecules such as tyrosine kinases, including Trks. A significant increase in the survival rate of cortical neurons in the presence of 10 or 100 nM 4MC supported this idea, because the concentrations were much lower than those for stimulation of BDNF synthesis. Our results strongly suggest that the neurotrophic actions of 4MC found so far are mediated predominantly by direct activation of some intracellular signals including MAPK/ERK rather than by neurotrophin synthesis.

Synthesis of water-soluble polymeric prodrugs possessing 4-methylcatechol derivatives by mechanochemical solid-state copolymerization and nature of drug release

In this study we synthesized the water-soluble polymeric prodrugs possessing a 4-methylcatechol (4MC) derivative as a side chain by mechanochemical solid-state copolymerization. 1-benzoyl-4-methylcatechol (Bz4MC) was selected as a model compound of 4MC, and its methacryloyl derivative (1) was synthesized. 6-O-methacryloyl-D-galactose (2) was also prepared as a water-soluble monomer. The mechanochemical solid-state copolymerization of 1 and 2 was carried out to obtain the water-soluble polymeric prodrug possessing the Bz4MC as a side chain. The mechanochemical copolymerization of 1 and 2 proceeded to completion, and the polymeric prodrug produced possessed a narrow molecular weight distribution. Three kinds of polymeric prodrugs, whose compositions were different from one another, were hydrolyzed in vitro. The hydrolysis of these polymeric prodrugs proceeded to completion. The rate constants of hydrolysis decreased with increasing the mole fraction of 1 in polymeric prodrug. It was suggested that the rate constant of hydrolysis could be controlled by the composition, the mole fraction of 1 in the polymeric prodrug.

Diabetic neuropathies in brain are induced by deficiency of BDNF

Diabetes is known to be one of the risk factors for dementia; however, neuropathic changes in the brain of patients with the disease have not been completely revealed. So in the present study, we investigated the brain function of rats with diabetes induced by streptozotocin (STZ), one of the most commonly used animal models for diabetes. In the diabetic rats, immediately working memory performance was impaired in the Y-maze task and neuronal cytoskeleton proteins such as calbindin, synaptophysin, and syntaxin were reduced. Furthermore, morphological observation by Golgi staining showed a decrease in the number of basal dendrites and abnormality of spine structure. Next, we measured the content of brain-derived neurotrophic factor (BDNF) in the diabetic brain, because BDNF is one of the essential proteins for the maintenance of neuronal functions including synapse function and neuronal transmissions. In the diabetic brains, both protein and mRNA levels of BDNF were severely reduced. These results suggest that, in diabetes, synapse dysfunction is, at least in part, caused by a failure of BDNF synthesis in the brain.

Accumulation of nerve growth factor protein at both rostral and caudal stumps in the transected rat spinal cord

Changes in the nerve growth factor (NGF) content in the rat spinal cord during development or after traumatic spinal cord injury were examined by using a two-site enzyme immunoassay (EIA) system and an immunohistochemical technique. From embryonic day (E) 14 to postnatal day (P) 70, the spinal cord contained 200-300 pg NGF/g of wet tissue evenly in all regions tested. After complete spinal cord transection of P49 rats, the NGF level started to increase in the rostral and caudal stumps nearest to the injury site at 2 and 4 days, respectively. The NGF level of the caudal side returned to the original level by 2 weeks, but that of the rostral side remained high even 3 weeks, after the injury. At 4 days after the injury, NGF-like immunoreactivity in both stumps was predominantly localized in the axon-like structures of the white matter and in cells morphologically resembling immune cells. These observations suggest that the NGF was transported within the spinal tracts, and that NGF secreted from immune cells that had invaded into the injured spinal cord had accumulated around the transection site. Increased NGF at the injury site may be advantageous for injured neurons and involved in mechanisms directing to axonal regeneration of the injured spinal cord.

Tissue nerve growth factor concentrations in neuromuscular diseases

In order to investigate the possible influences of pathological processes on muscle NGF levels in human subjects, we measured the NGF concentrations in muscle biopsies from 35 male and 16 female subjects (controls, n = 14; amyotrophic lateral sclerosis, n = 20; inflammatory myopathy, n = 6; muscular dystrophy, n = 11). The NGF concentration in each group was as follows: controls, 1.73 +/- 0.3 pg/mg protein (mean +/- S.E.M.); muscular dystrophies, 1.73 +/- 0.48 pg/mg protein; inflammatory myopathies, 2.28 +/- 1.45 pg/mg protein; amyotrophic lateral sclerosis, 4.15 +/- 0.79 pg/mg protein. The tissue NGF concentrations were significantly (140%) higher in patients with ALS than in the control subjects (P < 0.05, Wilcoxon signed rank test). Age and gender had no influence on tissue NGF concentrations. We conclude that the NGF increases observed here in affected muscle in amyotrophic lateral sclerosis can best be explained in terms of rapidly progressing denervation processes. Copyright 1998 Lippincott Williams & Wilkins

Therapeutic effects of aldose reductase inhibitor on experimental diabetic neuropathy through synthesis/secretion of nerve growth factor

We investigated alterations in nerve growth factor (NGF) and ciliary neurotrophic factor (CNTF) contents during treatment with epalrestat, an aldose reductase inhibitor (ARI), on streptozotocin (STZ)-induced diabetic neuropathy in rats. Diabetic rats showed a statistically significant reduction in H-wave-related sensory nerve conduction velocity (HSNCV) and in NGF content in sciatic nerves during the experiment of 8 weeks. No reduction in the CNTF content in sciatic nerves was seen in the diabetic rats. The epalrestat treatment, which started 4 weeks after STZ injection, resulted in a significantly greater NGF content and faster HSNCV than those in untreated diabetic rats. But no statistically significant alterations of motor nerve conduction velocity (MNCV) or CNTF content were seen during the treatment. ARI showed the stimulating effect for NGF synthesis/secretion in rat Schwann cell culture in vitro. These findings suggest that decreased levels of NGF in diabetic sciatic nerves may be involved in the pathogenesis of diabetic neuropathy in these rats and further show that epalrestat treatment can be useful for the treatment of diabetic neuropathy through NGF-induction in Schwann cells and/or inhibition of the polyol pathway.

Pharmacology of neurotrophic factors

The field of neurotrophic factor pharmacology emerged during the past decade with the discovery that these proteins can counteract neuronal atrophy and death in the adult nervous system. These concepts are being tested in clinical trials. Therapeutic use of neurotrophic proteins seems practical for diseases of the peripheral nervous system (PNS), where they can be given by systemic administration. For diseases of the CNS, special administration strategies will have to be developed to deliver the neurotrophic factors into the brain. The development of small molecule mimetics represents an alternative approach that is actively pursued to provide brain-penetrant neurotrophics.

Synthesis and evaluation of brain-targeted chemical delivery systems for the neurotrophomodulator 4-methylcatechol

Since various 4-alkylcatechols stimulate nerve growth factor (NGF) biosynthesis both in-vitro and in-vivo, delivery of these agents to the brain may provide beneficial effect for the treatment of neurodegenerative diseases such as Alzheimer's. Several dihydropyridine-pyridinium salt type redox chemical delivery systems (CDS) of 4-methylcatechol (4-methylcatechol) were prepared as potential brain selective targetry forms for 4-methylcatechol. After preliminary evaluation by in-vitro stability studies in various buffer solutions and biological media, a selected CDS was further investigated in the rat to determine its in-vivo distribution. Selective and sustained delivery of the compound of interest to the rat brain was achieved. Furthermore, the NGF stimulatory activity in the rat brain after peripheral administration of the selected CDS was evaluated by measuring the levels of pre-pro-NGF mRNA in the rat hippocampus and frontal cortex, by dot blot hybridization and analysis. Results showed the peripheral administration of the CDS to achieve a 1.7-fold increase in NGF mRNA compared to control in the rat hippocampus, and an approximately 1.4-fold increase in the frontal cortex.

Peripheral neuropathies and neurotrophic factors: animal models and clinical perspectives

A large body of data exists showing that a wide variety of neurotrophic factors can promote the survival or growth of different neuronal populations in vitro. More recently, several studies have been published on the survival-promoting effects of particular factors in animal models of peripheral neuropathies. Thus, the effect of axotomy on neuropeptide expression in dorsal root ganglion cells is partially reversed by nerve growth factor treatment, and the effect on choline acetyltransferase expression in motoneurones is partially reversed by glial-derived neurotrophic factor, neurotrophin-4/5 and brain-derived neurotrophic factor. Nerve growth factor also ameliorates some of the changes seen in sensory neurones in animal models of diabetic neuropathy and small fibre cytostatic drug neuropathy, whereas neurotrophin-3 has been found to reverse some changes in large sensory neurones associated with cisplatin neurotoxicity. The results of these studies provide grounds for optimism in the clinical uses of such factors, and, indeed, several clinical studies are now under way.