Streptozotocin induced Alzheimer's disease like changes and the underlying neural degeneration and regeneration mechanism

Alzheimer’s disease（AD）is a neurodegenerative disorder which is remarkably characterized by pathological hallmarks that include neurofibrillary tangles,neuronal loss extracellular senile plaques containing aggregated amyloid beta（Aβ）,and neurofibrillary tangles composed of the hyperphosphorylated form of the microtubule protein tau.It is the most common form of dementia which is characterized by severe neurodegenerative changes such as loss of neurons and synapses in brain（Kamat et al.,2014）.

The biochemical pathways of central nervous system neural degeneration in niacin deficiency

Neural degeneration is a very complicated process. In spite of all the advancements in the molecular chemistry, there are many unknown aspects of the phenomena of neurodegeneration which need to be put together. It is a common sequela of the conditions of niacin deficiency. Neural degeneration in Pellagra manifests as chromatolysis mainly in pyramidal followed by other neurons and glial cells. However, there is a gross lack of understanding of biochemi- cal mechanisms of neurodegeneration in niacin deficiency states. Because of the necessity of niacin or its amide derivative NAD in a number of biochemical pathways, it is understandable that several of these pathways may be involved in the common outcome of neural degener- ation. Here, we highlight five pathways that could be involved in the neuraldegeneration for which evidence has accumulated through several studies. These pathways are： 1） the trypto- phan-kyneurenic acid pathway, 2） the mitochondrial ATP generation related pathways, 3） the poly （ADP-ibose） polymerase （PARP） pathway, 4） the BDNF-TRKB Axis abnormalities, 5） the genetic influences of niacin deficiency.

Gait deterioration due to neural degeneration of the corticoreticular pathway:a case report

The corticoreticular pathway（CRP）mainly mediates proximal and axial muscles and therefore it is an important neural tract for walking（Miyai et al.,2002;Matsuyama et al.,2004;Mendoza and Foundas,2007）.Diffusion tensor tractography（DTT）,derived from diffusion tensor imaging（DTI）,

Zhichan decoction induces differentiation of dopaminergic neurons in Parkinson's disease rats after neural stem cell transplantation

The goal of this study was to increase the dopamine content and reduce dopaminergic metabolites in the brain of Parkinson’s disease rats. Using high-performance liquid chromatography, we found that dopamine and dopaminergic metabolite（dihydroxyphenylacetic acid and homovanillic acid） content in the midbrain of Parkinson’s disease rats was increased after neural stem cell transplantation ＋ Zhichan decoction, compared with neural stem cell transplantation alone. Our genetic algorithm results show that dihydroxyphenylacetic acid and homovanillic acid levels achieve global optimization. Neural stem cell transplantation ＋ Zhichan decoction increased dihydroxyphenylacetic acid levels up to 10-fold, while transplantation alone resulted in a 3-fold increment. Homovanillic acid levels showed no apparent change. Our experimental findings show that after neural stem cell transplantation in Parkinson’s disease rats, Zhichan decoction can promote differentiation of neural stem cells into dopaminergic neurons.

Ouabain-Induced Auditory Nerve Degeneration in Congenic Ly5.1 Mice

The Ly5.1 mouse,also termed B6.SJL-Ptprca Pepcb/BoyJ,is a congenic strain widely used as a recipient in animal studies of bone marrow transplant.Our previous study documented that a majority of type I spiral ganglion neurons (SGNs) in the apical turns of Ly5.1 mice are unmyelinated and aggregate into neuronal clusters,similar to the spiral ganglion in the human ear.Ouabain,a well known Na-K ATPase inhibitor,has been shown to induce neuronal degeneration in a variety of neural tissues including the adult gerbil and CBA/CaJ mouse spiral ganglion.Here,functional and pathological changes of the auditory nerves in young-adult Ly5.1 mice were examined at 3,7 and 14 days after ouabain exposure.Similar to observations in CBA/CaJ mice,ouabain application selectively removed type I SGNs,resulting in an immense decline of the auditory nerve function.Hyperplasia of glial cells was seen in the injured auditory nerves at 7 days after ouabain exposure.Our data indicate that the 'human-like' features of unmyelinated type I SGNs have no protective impact on the fate of SGNs after ouabain exposure.Cells incorporating bromodeoxyuridine (BrdU) and expressing Sox2 were also counted in the auditory nerves of control and ouabain-treated ears.The number of Sox2+ glial cells significantly increased at 3 and 7 days post-treatment.Interestingly,the highest density of BrdU+ cells appeared in the apical turn of the injured auditory nerve shortly after ouabain exposure,suggesting that the pattern of SGN loss at the apical turn in Ly5.1 mouse may have some impact on the reaction of non-neuronal cells in response to acute ototoxic drug exposure in the auditory nerve.

Mechanical properties of nerve roots and rami radiculares isolated from fresh pig spinal cords

No reports have described experiments designed to determine the strength characteristics of spinal nerve roots and rami radiculares for the purpose of explaining the complexity of symptoms of medullary cone lesions and cauda equina syndrome. In this study, to explain the pathogenesis of cauda equina syndrome, monoaxial tensile tests were performed to determine the strength characteristics of spinal nerve roots and rami radiculares, and analysis was conducted to evaluate the stress-strain relationship and strength characteristics. Using the same tensile test device, the nerve root and ramus radiculares isolated from the spinal cords of pigs were subjected to the tensile test and stress relaxation test at load strain rates of 0.1, 1, 10, and 100 s-1 under identical settings. The tensile strength of the nerve root was not rate dependent, while the ramus radiculares tensile strength tended to decrease as the strain rate increased. These findings provide important insights into cauda equina symptoms, radiculopathy, and clinical symptoms of the medullary cone.

Changes in the blood-nerve barrier after sciatic nerve cold injury:indications supporting early treatment

Severe edema in the endoneurium can occur after non-freezing cold injury to the peripheral nerve, which suggests damage to the blood-nerve barrier. To determine the effects of cold injury on the blood-nerve barrier, the sciatic nerve on one side of Wistar rats was treated with low tem- peratures （3-5℃） for 2 hours. The contralateral sciatic nerve was used as a control. We assessed changes in the nerves using Evans blue as a fluid tracer and morphological methods. Excess fluid was found in the endoneurium 1 day after cold injury, though the tight junctions between cells remained closed. From 3 to 5 days after the cold injury, the fluid was still present, but the tight junctions were open. Less tracer leakage was found from 3 to 5 days after the cold injury compared with 1 day after injury. The cold injury resulted in a breakdown of the blood-nerve barrier func- tion, which caused endoneurial edema. However, during the early period, the breakdown of the blood-nerve barrier did not include the opening of tight junctions, but was due to other factors. Excessive fluid volume produced a large increase in the endoneurial fluid pressure, prevented liquid penetration into the endoneurium from the microvasculature. These results suggest that drug treatment to patients with cold injuries should be administered during the early period after injury because it may be more difficult for the drug to reach the injury site through the microcirculation after the tissue fluid pressure becomes elevated.

Blockade of transient receptor potential cation channel subfamily V member 1 promotes regeneration after sciatic nerve injury

The transient receptor potential cation channel subfamily V member 1（TRPV1） provides the sensation of pain（nociception）. However, it remains unknown whether TRPV1 is activated after peripheral nerve injury, or whether activation of TRPV1 affects neural regeneration. In the present study, we established rat models of unilateral sciatic nerve crush injury, with or without pretreatment with AMG517（300 mg/kg）, a TRPV1 antagonist, injected subcutaneously into the ipsilateral paw 60 minutes before injury. At 1 and 2 weeks after injury, we performed immunofluorescence staining of the sciatic nerve at the center of injury, at 0.3 cm proximal and distal to the injury site, and in the dorsal root ganglia. Our results showed that Wallerian degeneration occurred distal to the injury site, and neurite outgrowth and Schwann cell regeneration occurred proximal to the injury. The number of regenerating myelinated and unmyelinated nerve clusters was greater in the AMG517-pretreated rats than in the vehicle-treated group, most notably 2 weeks after injury. TRPV1 expression in the injured sciatic nerve and ipsilateral dorsal root ganglia was markedly greater than on the contralateral side. Pretreatment with AMG517 blocked this effect. These data indicate that TRPV1 is activated or overexpressed after sciatic nerve crush injury, and that blockade of TRPV1 may accelerate regeneration of the injured sciatic nerve.