Primordial proteins and HIV-Part II

Nanobacteria are suspected to be responsible for a number of diseases, i.e., kidney stones, heart disease, ovarian cancer, peripheral neuropathy, and reduced bone mineral density. Being protected by a mineral shell consisting of apatite, the nanovesicles can enter eukaryotic cells. Depending on the host's stress level, nanobacteria may carry a substantial layer of a protein based slime, instrumental in collecting calcium phosphate from the environment. Calcium phosphate is known to mediate the uptake of nucleic acids by eukaryotic cells. Surprisingly, a pathogenic effect of nanobacteria in HIV can be derived primarily from the trafficking of calcium phosphate in HIV infected cells, performed by primordial proteins. The inescapable conclusion is that nanobacteria could promote genetic diversity in HIV.     

Peripheral neuropathy and light-preliminary report indicating prevalence of nanobacteria in HIV

Peripheral neuropathy is a common condition in HIV-positive patients and is often experienced in diabetes mellitus. The primary mechanism of the disease, which can considerably aggravate the patient's state, is unknown. The perineurium of patients with peripheral neuropathy is frequently enveloped by apatite. Nanobacteria (NB) are protectd by a mineral shell consisting of apatite. Light has been shown to elevate the vitality level of cells, and was predicted to inhibit deposition of stressed NB in the cardiovascular system. Results indicate that light can durably restore the condition of patients with severe peripheral neuropathy.     

Could reduced bone mineral densities in HIV be caused by nanobacteria?

From the observations of different research groups reporting on reduced bone mineral density (BMD) and on a pronounced tendency for kidney stone formation, both in HIV-infected patients, and from results achieved in the treatment of severest peripheral neuropathy with lasers, it is concluded that nanobacteria (NB) could actively contribute to the reduction of BMD. A reduced BMD could primarily stem from NB, extracting calcium and phosphate from blood, affecting the calcium and phosphate homeostasis in humans.     

The therapeutic effect of lipo PGE1 on diabetic neuropathy-changes in endothelin and various angiopathic factors

A high blood concentration of endothelin (ET)-1 may participate in the onset and progress of diabetic microangiopathy, resulting in neuropathy. We examined the therapeutic effects of prostaglandin E1 (PGE1), which possesses both a peripheral vasodilating action and inhibition of platelet aggregation, on diabetic microangiopathy. Increases in both skin temperature and peripheral never conduction velocity in diabetic patients were recorded four weeks after Lipo PGE1 administration. A quantitative decrease in urinary albumin concentration was also observed, suggesting its efficacy of action was on diabetic nephropathy. Lipo PGE1 administration reduced the elevated circulating plasma ET-1 levels in the diabetic patients. As an increase in ET-1 concentrations is thought to correlate with the onset and progress of diabetic microangiopathy, the reduction of plasma ET-1 concentration by Lipo PGE1 administration may be one reason for the improvement in diabetic neuropathy and nephropathy.     

Characterization of Granulations of Calcium and Apatite in Serum as Pleomorphic Mineralo-Protein Complexes and as Precursors of Putative Nanobacteria

Calcium and apatite granulations are demonstrated here to form in both human and fetal bovine serum in response to the simple addition of either calcium or phosphate, or a combination of both. These granulations are shown to represent precipitating complexes of protein and hydroxyapatite (HAP) that display marked pleomorphism, appearing as round, laminated particles, spindles, and films. These same complexes can be found in normal untreated serum, albeit at much lower amounts, and appear to result from the progressive binding of serum proteins with apatite until reaching saturation, upon which the mineralo-protein complexes precipitate. Chemically and morphologically, these complexes are virtually identical to the so-called nanobacteria (NB) implicated in numerous diseases and considered unusual for their small size, pleomorphism, and the presence of HAP. Like NB, serum granulations can seed particles upon transfer to serum-free medium, and their main protein constituents include albumin, complement components 3 and 4A, fetuin-A, and apolipoproteins A1 and B100, as well as other calcium and apatite binding proteins found in the serum. However, these serum mineralo-protein complexes are formed from the direct chemical binding of inorganic and organic phases, bypassing the need for any biological processes, including the long cultivation in cell culture conditions deemed necessary for the demonstration of NB. Thus, these serum granulations may result from physiologically inherent processes that become amplified with calcium phosphate loading or when subjected to culturing in medium. They may be viewed as simple mineralo-protein complexes formed from the deployment of calcification-inhibitory pathways used by the body to cope with excess calcium phosphate so as to prevent unwarranted calcification. Rather than representing novel pathophysiological mechanisms or exotic lifeforms, these results indicate that the entities described earlier as NB most likely originate from calcium and apatite binding factors in the serum, presumably calcification inhibitors, that upon saturation, form seeds for HAP deposition and growth. These calcium granulations are similar to those found in organisms throughout nature and may represent the products of more general calcium regulation pathways involved in the control of calcium storage, retrieval, tissue deposition, and disposal.     

Treatment of symptomatic diabetic neuropathy by surgical decompression of multiple peripheral nerves.

Symptomatic diabetic sensorimotor polyneuropathy is considered progressive and irreversible. The hypothesis that symptoms of diabetic neuropathy may be due to entrapment of peripheral nerves was investigated in a prospective study from 1982 to 1988 in which diabetics (38 type I, 22 type II) had surgical decompression of 154 peripheral nerves in 51 upper extremities and 31 lower extremities. Mean postoperative follow-up was 30 months (range 6 to 83 months). Considering the entire series, an excellent final result was noted for motor function in 44 percent and for sensory function in 67 percent of the decompressed nerves. Ten percent of the patients were not improved, and 2 percent were worse in sensorimotor function. Upper extremity nerve decompressions achieved better results than lower extremity nerve decompressions. Improvement in postoperative electrodiagnostic studies varied in relationship to the preoperative electrodiagnosis. Improvement was noted in 100 percent of those nerves with the preoperative diagnosis of "localized entrapment," 80 percent for "peripheral neuropathy with superimposed entrapment," and 50 percent for "peripheral neuropathy." Progressive neuropathy occurred in a nontreated limb of 50 percent of those patients whose surgically treated limb maintained improvement. The results of this study suggest that symptoms of sensorimotor diabetic neuropathy may be due partly to compression of multiple peripheral nerves. The results further suggest that surgical decompression of such nerves may result in symptomatic improvement.     

Pain modality and spinal glia expression by streptozotocin induced diabetic peripheral neuropathy in rats

Pain symptoms are a common complication of diabetic peripheral neuropathy or an inflammatory condition. In the most experiments, only one or two evident pain modalities are observed at diabetic peripheral neuropathy according to experimental conditions. Following diabetic peripheral neuropathy or inflammation, spinal glial activation may be considered as an important mediator in the development of pain. For this reason, the present study was aimed to address the induction of pain modalities and spinal glial expression after streptozotocin injection as compared with that of zymosan inflammation in the rat. Evaluation of pain behavior by either thermal or mechanical stimuli was performed at 3 weeks or 5 hours after either intravenous streptozotocin or zymosan. Degrees of pain were divided into 4 groups: severe, moderate, mild, and non-pain induction. On the mechanical allodynia test, zymosan evoked predominantly a severe type of pain, whereas streptozotocin induced a weak degree of pain (severe+moderate: 57.1%). Although zymosan did not evoke cold allodynia, streptozotocin evoked stronger pain behavior, compared with zymosan (severe+moderate: 50.0%). On the other hand, the high incidence of thermal hyperalgesia (severe+moderate: 90.0%) and mechanical hyperalgesia (severe+moderate: 85.7%) by streptozotocin was observed, as similar to that of zymosan. In the spinal cord, the increase of microglia and astrocyte was evident by streptozotocin, only microglia was activated by zymosan. Therefore, it is recommended that the selection of mechanical and thermal hyperalgesia is suitable for the evaluation of streptozotocin induced diabetic peripheral neuropathy. Moreover, spinal glial activation may be considered an important factor.     

Clodronate changes neurobiological effects of pulsed magnetic field on diabetic rats with peripheral neuropathy

Several studies have reported that pulsed magnetic fields (PMFs) can be a choice of therapy for diabetic peripheral neuropathy. However, the exact underlying mechanism of PMF is still not known. The purpose of this study was, therefore, to investigate the effects of clodronate encapsulated with liposome, a specific agent depleting macrophage, on PMF-treated streptozotocin-induced type I diabetic rats with peripheral neuropathy. Effects of PMF, liposome-encapsulated clodronate (LEC) or their combined treatments were investigated in diabetic rats by measuring the thermal latencies, mechanical thresholds, whole blood glucose levels, serum insulin level, and body mass. In diabetic rats, PMF exhibited a decrease in the blood glucose levels but did not change the serum insulin level. Both mechanical thresholds and thermal latencies of diabetic rats enhanced throughout the PMF treatment. During the PMF treatment, the administration of LEC suppressed the PMF-induced decrease in blood glucose level, PMF-induced increase in mechanical threshold and thermal latencies in diabetic animals. In addition, PMF reduced the LEC-induced increase in insulin levels of diabetic rats. Findings demonstrated that although effects of both PMF alone and LEC alone on diabetic animals are mostly positive, LEC may remove the therapeutic efficacies of PMF in combined treatment.     

Establishment of a Convenient System for the Culture and Study of Perineurium Barrier In Vitro

The perineurium serves as a selective, metabolically active diffusion barrier in the peripheral nervous system, which is composed of perineurial cells joined together by tight junctions (TJs). Not only are these junctions known to play an essential role in maintaining cellular polarity and tissue integrity, but also limit the paracellular diffusion of certain molecules and ions, whereas loss of TJs barrier function is imperative for tumour growth, invasion and metastasis. Hence, a detailed study on the barrier function of perineurial cells may provide insights into the molecular mechanism of perineural invasion (PNI). In this study, we aimed to develop an efficient procedure for the establishment of perineurial cell lines as a tool for investigating the physiology and pathophysiology of the peripheral nerve barriers. Herein, the isolation, expansion, characterization and maintenance of perineurial cell lines under favourable conditions are presented. Furthermore, the analysis of the phenotypic features of these perineurial cells as well as the barrier function for the study of PNI are described. Such techniques may provide a valuable means for the functional and molecular investigation of perineurial cells, and in particular may elucidate the pathogenesis and progression of PNI, and other peripheral nerve disorders.

     

Reversible suppression of in vitro biomineralization by activation of protein kinase A

Parathyroid hormone (PTH-(1-34)) potently suppresses apatite deposition in osteoblastic cultures. These inhibitory effects are mediated through signaling events following PTH receptor binding. Using both selective inhibitors and activators of protein kinase A (PKA), this study shows that a transient activation of PKA is sufficient to account for PTH's inhibition of apatite deposition. This inhibition is not a result of reduced cell proliferation, reduced alkaline phosphatase activity, increased collagenase production, or lowering medium pH. Rather, data suggest a functional relationship between matrix assembly and apatite deposition in vitro. Bone sialoprotein (BSP) and apatite co-localize in the extracellular matrix of mineralizing cultures, with matrix deposition of BSP temporally preceding that of apatite. Transient activation of PKA by either PTH-(1-34) or short term cAMP analog treatment blocks the deposition of BSP in the extracellular matrix without a significant reduction in the total amount of BSP synthesized and secreted. This effect is reversible after allowing the cultures to recover in the absence of PKA activators for several days. Thus, a transient activation of PKA may suppress mineral deposition in vitro as a consequence of altering the assembly of an extracellular matrix permissive for apatite formation.     

The TRPV1 receptor is associated with preferential stress in large dorsal root ganglion neurons in early diabetic sensory neuropathy

Chronic diabetic neuropathy is associated with peripheral demyelination and degeneration of nerve fibers. The mechanism(s) underlying neuronal injury in diabetic sensory neuropathy remain poorly understood. Recently, we reported increased expression and function of transient receptor potential vanilloid 1 (TRPV1) in large dorsal root ganglion (DRG) neurons in diabetic sensory neuropathy. In this study, we examined the effects of TRPV1 activation on cell injury pathways in this subpopulation of neurons in the streptozotocin-induced diabetic rat model. Large DRG neurons from diabetic (6–8 weeks) rats displayed increased oxidative stress and activation of cell injury markers compared with healthy controls. Capsaicin (CAP) treatment induced decreased labeling of MitoTracker Red and increased cytosolic cytochrome c and activation of caspase 3 in large neurons isolated from diabetic rats. CAP treatment also induced oxidative stress in large diabetic DRG neurons, which was blocked by pre-treatment with caspase or calpain inhibitor. In addition, both μ-calpain expression and calpain activity were significantly increased in DRG neurons from diabetic rats after CAP treatment. Treatment with capsazepine, a competitive TRPV1 antagonist, markedly reduced these abnormalities in vitro and prevented activation of cell injury in large DRG neurons in diabetic rats in vivo . These results suggest that activation of the TRPV1 receptor activates pathways associated with caspase-dependent and calpain-dependent stress in large DRG neurons in STZ-diabetic rats. Activation of the TRPV1 receptor may contribute to preferential neuronal stress in large DRG neurons relatively early in diabetic sensory neuropathy.     

An Early Diagnostic Tool for Diabetic Peripheral Neuropathy in Rats

The skin’s rewarming rate of diabetic patients is used as a diagnostic tool for early diagnosis of diabetic neuropathy. At present, the relationship between microvascular changes in the skin and diabetic neuropathy is unclear in streptozotocin (STZ) diabetic rats. The aim of this study was to investigate whether the skin rewarming rate in diabetic rats is related to microvascular changes and whether this is accompanied by changes observed in classical diagnostic methods for diabetic peripheral neuropathy. Computer-assisted infrared thermography was used to assess the rewarming rate after cold exposure on the plantar skin of STZ diabetic rats’ hind paws. Peripheral neuropathy was determined by the density of intra-epidermal nerve fibers (IENFs), mechanical sensitivity, and electrophysiological recordings. Data were obtained in diabetic rats at four, six, and eight weeks after the induction of diabetes and in controls. Four weeks after the induction of diabetes, a delayed rewarming rate, decreased skin blood flow and decreased density of IENFs were observed. However, the mechanical hyposensitivity and decreased motor nerve conduction velocity (MNCV) developed 6 and 8 weeks after the induction of diabetes. Our study shows that the skin rewarming rate is related to microvascular changes in diabetic rats. Moreover, the skin rewarming rate is a non-invasive method that provides more information for an earlier diagnosis of peripheral neuropathy than the classical monofilament test and MNCV in STZ induced diabetic rats.     

Prevalence and clinical characteristics of diabetic peripheral neuropathy in hospital patients with Type 2 diabetes in Korea

Diabet. Med. 29, e290-e296 (2012) ABSTRACT: Aims Diabetic peripheral neuropathy is a common complication of diabetes. This cross-sectional study investigated the prevalence and clinical characteristics of this neuropathy in patients with Type?2 diabetic mellitus treated at hospitals in Korea. Methods Questionnaires and medical records were used to collect data on 4000 patients with Type?2 diabetes from the diabetes clinics of 40 hospitals throughout Korea. Diabetic peripheral neuropathy was diagnosed based on a review of medical records or using the Michigan Neuropathy Screening Instrument score and monofilament test. Results The prevalence of neuropathy was 33.5% (n?=?1338). Multivariate analysis revealed that age, female sex, diabetes duration, lower glycated haemoglobin, treatment with oral hypoglycaemic agents or insulin, presence of retinopathy, history of cerebrovascular or peripheral arterial disease, presence of hypertension or dyslipidaemia, and history of foot ulcer were independently associated with diabetic peripheral neuropathy. Of the patients with neuropathy, 69.8% were treated for the condition and only 12.6% were aware of their neuropathy. Conclusion There was a high prevalence of peripheral neuropathy in patients with Type?2 diabetes in Korea and those patients were far more likely to have complications or co-morbidities. The proper management of diabetic peripheral neuropathy deserves attention from clinicians to ensure better management of diabetes in Korea.     

Insulin-Induced Hypoglycemic Peripheral Motor Neuropathy in Spontaneously Diabetic WBN/Kob Rats

Intensive insulin therapy can lead to hypoglycemia, with patients sometimes developing hypoglycemic neuropathy. Spontaneously diabetic Wistar Bonn Kobori (WBN/Kob) rats develop diabetic peripheral motor neuropathy characterized by segmental demyelination and axonal degeneration. We examined the short-term effects of hypoglycemia on neuropathic changes in these rats. Spontaneous diabetic WBN/Kob rats received insulin implants for 40 d and were divided into 3 groups based on blood glucose levels: group N, normoglycemic to slightly hyperglycemic (150 to 250 mg/dL); group H, hypoglycemic to slightly hyperglycemic (50 to 200 mg/dL); and group D, nontreated spontaneously diabetic (350 to 420 mg/dL). Conduction velocity was measured in sciatic–tibial motor nerves; these nerves also underwent qualitative and quantitative histomorphologic analysis. Conduction velocity was not significantly different in N, D, and H groups. Morphologic analysis of the sciatic nerves of H rats showed severe changes, including axonal degeneration, myelin distention, and endoneurial fibrosis, that tended to occur in large, myelinated fibers. N and D rats showed relatively mild changes. The degree and distribution of degenerated nerve fibers in H rats were significantly higher than in N and D rats. These results suggest that hypoglycemia of less than 50 mg/dL induced severe peripheral neuropathy. Hypoglycemic lesions differed from the hyperglycemic lesions in diabetic WBN/Kob rats. This rat strain is an appropriate model for investigating the hypoglycemic peripheral neuropathy that can be associated with a diabetic condition.Peripheral neuropathy is a leading complication of diabetes mellitus. Although its exact pathogenesis is not fully understood, chronic hyperglycemia and resultant microenvironmental changes in peripheral nerve tissue contribute to the development of neuropathy.⁵ Therefore, intensive insulin therapy is needed to prevent such complications in patients with type 1 diabetes. However, intensive insulin therapy can lead to hypoglycemia, with patients sometimes developing hypoglycemic peripheral neuropathy.⁸Although experimental hypoglycemic peripheral neuropathy has been studied by using animal models of type 1 diabetes, few studies have included morphologic analyses.^4,7,14,15 These studies showed that hypoglycemia causes axonopathy involving both degenerative and regenerative events. However, hyperglycemic peripheral neuropathy characterized by axonal atrophy has also been induced in diabetic animal models, such that the hyperglycemic changes in these models were similar to hypoglycemic changes. Diabetic WBN/Kob rats spontaneously develop diabetic peripheral motor neuropathy characterized by segmental demyelination and secondary axonal degeneration.^12,13,19 Morphologic changes in diabetic peripheral motor neuropathy are characterized by various degenerative and regenerative changes in myelin sheath, demyelination, and a shift toward axons of smaller diameter. Therefore, WBN/Kob rats may be useful for distinguishing hyperglycemic from hypoglycemic changes. In addition, the threshold of hypoglycemia that induces the morphologic and clinical changes characteristic of peripheral neuropathy in diabetic animals remains unclear.¹⁴ In the present study, we investigated the effects of short-term hypoglycemia on peripheral neuropathic changes in diabetic WBN/Kob rats.     

Suffocation of nerve fibers by living nanovesicles: a model simulation

A model using nanospheres to allow the simulation of the nonspecific interaction of nanobacteria (NB), one with another or with body tissues, is established. Depending primarily on their concentrations and stress levels, these apatite nanovesicles may nucleate thrombogenic conglomerates in blood, or self-assemble to dense nanoclay layers on surfaces in the body. Partial or total encapsulation of nerve fiber bundles by such mineral layers may interrupt the metabolic exchanges between the surrounded tissue and its immediate environment and may restrict signaling processes. The presented model could provide detailed insight into plaque formation triggered by NB, and the parameters encouraging it.     

Effect of various nerve decompression procedures on the functions of distal limbs in streptozotocin-induced diabetic rats: further optimism in diabetic neuropathy

It is known that diabetic neuropathy is the result of endoneurial edema caused by various biochemical reactions triggered by hyperglycemia. This sequence of events can cause cessation of circulation at the perineurial level, or the tough layer, which is not resilient enough to spread intraneural pressure. Internal and external limiting structures create a double crush phenomenon to the nerve structure. Decompression of the nerve trunk at separate levels is one of the adjuncts to the overall treatment plan for diabetic neuropathy. In this study, the right sciatic nerves of 30 rats with streptozotocin-induced diabetes were used; three groups were created. In the control group, the sciatic nerves were explored and dissected only. In group II, tarsal tunnel release was performed and accompanied by epineurotomy of the sciatic nerve and its peroneal and tibial extensions. In group III, in addition to the procedures performed in group II, perineural sheaths, exposed through the epineurotomy sites at both the peroneal and tibial nerves, were incised for decompression of the fascicles. Improvement in diabetic neuropathy was evaluated by using footprint parameters. The last print length values, estimated according to the 38-month measurements, were 26.1 +/- 0.12 mm in the control group, 23.2 +/- 0.07 mm in group II, and 22.2 +/- 0.1 mm in group III. The toe spread and intermediate toe spread values of the groups were parallel to improvements in print lengths throughout the study. The best improvement was observed in the perineurotomy group. Finally, an electron microscopic study revealed variable degenerative changes in all groups, but they were milder in groups II and III. This experimental study reveals that adding internal decompression to external release doubled the effect in reducing derangement in the sciatic nerves of the rats and, in the authors' opinion, offers cause for further optimism in the treatment of diabetic neuropathy.     

Role of Neuropoietic Cytokines in Development and Progression of Diabetic Polyneuropathy: From Glucose Metabolism to Neurodegeneration

Diabetic neuropathy develops as a result of hyperglycemia- induced local metabolic and microvascular changes in both type I and type II diabetes mellitus. Diabetic neuropathy shows slower impulse conduction, axonal degeneration, and impaired regeneration. Diabetic neuropathy affects peripheral, central, and visceral sensorimotor and motor nerves, causing improper locomotor and visceral organ dysfunctions. The pathogenesis of diabetic neuropathy is complex and involves multiple pathways. Lack of success in preventing neuropathy, even with successful treatment of hyperglycemia, suggests the presence of early mediators between hyperglycemia-induced metabolic and enzymatic changes and functional and structural properties of Schwann cells (SCs) and axons. It is feasible that once activated, such mediators can act independently of the initial metabolic stimulus to modulate SC-axonal communication. Neuropoietic cytokines, including interleukin-1 (IL-1), interleukin-6 (IL-6), leukemia inhibitory factor (LIF), ciliary neurotrophic factor (CNTF), tumor necrosis factor alpha (TNF-α), and transforming growth factor beta (TGF- β), exhibit pleiotrophic effects on homeostasis of glia and neurons in central, peripheral, and autonomic nervous system. These cytokines are produced locally by resident and infiltrating macrophages, lymphocytes, mast cells, SCs, fibroblasts, and sensory neurons. Metabolic changes induced by hyperglycemia lead to dysregulation of cytokine control. Moreover, their regulatory roles in nerve degeneration and regeneration may potentially be utilized for the prevention and/or therapy of diabetic neuropathy.     

Results of decompression of peripheral nerves in diabetics: a prospective, blinded study

Diabetic neuropathy traditionally is considered progressive and irreversible and will result in lower extremity ulceration and amputation in a segment of the diabetic population, despite the best efforts to control serum glucose levels. Restoration of sensation to the diabetic may prevent these complications of neuropathy. The present study was designed to evaluate whether decompression of a peripheral nerve at a known site of anatomic narrowing can restore sensibility to that nerve in the diabetic. Twenty diabetic patients ( 14 type I, 6 type II, with a mean duration of diabetes of 14.8 years) had surgical decompression of a median nerve at the wrist and an ulnar nerve at the elbow, or a decompression of the posterior tibial nerve at the ankle (total of 31 nerves). A therapist, in a manner blind to the operative site, evaluated two-point discrimination in the pulp of the appropriate digit. The postoperative sensibility was compared with that of the nontreated, contralateral extremity. At a mean of 23.3 months, 69 percent of the lower-extremity nerves and 88 percent of the upper-extremity nerves (79 percent overall) had improvement in sensibility. In comparison, 32 percent of the control (not decompressed) contralateral nerves had measurable progression of neuropathy. The hypothesis that decompression of a peripheral nerve in the diabetic will improve sensibility was confirmed at the p < 0.001 level.     

Pupillary signs in diabetic autonomic neuropathy.

Pupillary function was investigated in 36 insulin-dependent diabetics and 36 controls matched for age and sex. About half of the diabetics had evidence of peripheral somatic or autonomic neuropathy, or both. The diabetic patients had abnormally small pupil diameters in the dark and less fluctuation in pupil size (hippus) during continuous illumination than the controls. They also had reduced reflex responses to light flashes of an intensity adjusted for individual retinal sensitivities. The pupillary findings were compared with results of five tests of cardiovascular function and five tests of peripheral sensory and motor nerve function. Almost all the patients with autonomic neuropathy had pupillary signs, which we therefore conclude are a common manifestation of diabetic autonomic neuropathy.     

VEGF 164 gene transfer by electroporation improves diabetic sensory neuropathy in mice

BACKGROUND: Diabetic neuropathy is the most common cause of peripheral neuropathy and a serious complication of diabetes. Vascular endothelial growth factor (VEGF) stimulates angiogenesis and has neurotrophic and neuroprotective activities. To examine the efficiency of VEGF 164 electro-gene therapy for neuropathy, intramuscular VEGF 164 gene transfer by electroporation was performed to treat sensory neuropathy in diabetic mice. METHODS: VEGF 164 was overexpressed in the tibial anterior (TA) muscles of streptozotocin-induced diabetic mice with hypoalgesia, using a VEGF 164 plasmid injection with electroporation. From 2 weeks after electro-gene transfer, the nociceptive threshold was measured weekly using the paw-pressure test. The TA muscles, sciatic nerve, liver and spleen were histochemically examined at 4 weeks after electro-gene transfer. RESULTS: Two weeks after electro-gene transfer into the bilateral TA muscles, the elevated nociceptive threshold was decreased to a normal level in all treated mice. Improvement of the hypoalgesia continued for 14 weeks. When the VEGF 164 plasmid was injected with electroporation into a unilateral TA muscle, recovery from hypoalgesia was observed in not only the ipsilateral hindpaw, but also the contralateral one, suggesting that VEGF circulates in the blood. No increase in the number of endoneurial vessels in the sciatic nerve was found in the VEGF 164 plasmid-electroporated mice. CONCLUSIONS: These findings suggest that VEGF 164 electro-gene therapy completely recovered the sensory deficits, i.e. hypoalgesia, in the diabetic mice through mechanisms other than angiogenesis in the endoneurium of the peripheral nerve, and may be useful for treatment for diabetic sensory neuropathy in human subjects.