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No description available.

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Dorsal root ganglion (DRG) neurons are responsive to altered neuromuscular activity and play a role in diabetic peripheral neuropathy (DPN). We present evidence that small and large DRG neurons are differentially affected by exercise and diabetes. We examined gene expression in samples of small and large neurons of rat L4/L5 DRG, and the specific responses after exercise and diabetes, to identify potential molecular processes involved in activity-dependent changes. Small and large DRG neurons were collected using laser capture microdissection. Relative mRNA levels were determined using real-time polymerase chain reaction experiments. In study 1, healthy adult rats received treadmill exercise for 1 or 17 weeks, or voluntary wheel exercise for 16 weeks. In study 2, STZ-induced diabetic rats received 15 weeks of sedentary treatment or voluntary wheel exercise. Behavioural testing of thermal latency response was performed on all animals in study 2. In study 1, there were no significant changes in small or large DRG neuron gene expression after acute treadmill exercise. After chronic treadmill exercise, mRNA levels changed relative to healthy sedentary rats in small (↑ 5HT1D; ↓5HT1F) and large (↓ 5HT1A, TrkC, SYN1) DRG neurons. After chronic voluntary wheel exercise, mRNA levels changed relative to healthy sedentary rats in small (↓ 5HT1D, OPRD1, TrkA; ↑ GAP43) and large (↓ 5HT1D, Nav1.6, OPRD1, TrkA, TrkC, SYN1; ↑ 5HT3A, GAP43) DRG neurons. In study 2, there were no significant changes in large DRG neuron gene expression. In small DRG neurons, mRNA levels were changed in the diabetic sedentary group (↓TrkB; ↑5HT1F) as well as the diabetic wheel group (↓ CGRP) relative to healthy sedentary rats. 5HT1A receptor mRNA levels were higher in diabetic sedentary rats relative to diabetic wheel rats. Our results demonstrate that small and large DRG neurons respond, but in different ways, to the duration and intensity of exercise. DRG neurons show a greater response to voluntary compared to forced exercise, and chronic compared to acute exercise. The genetic changes in small DRG neurons of rats with DPN that exercise may be correlated with the positive change in progression of thermal hypoalgesia associated with exercise. / May 2016

Several molecular changes occur following axotomy, such as gene up-regulation and down-regulation. In our previous study using Affymetrix arrays, it was found that after the axotomy of sciatic nerve, there were many novel genes with significant expression changes. Among such genes was neuronatin, whose expression was significantly up-regulated. Neuronatin was identified as a gene selectively expressed in the neonatal brain and is involved in neuronal differentiation during brain development, and markedly reduced in adult brains. The present study investigated whether the expression of neuronatin correlates with symptoms of neuropathic pain in adult rats with transected sciatic nerve. Adult male Sprague-Dawley rats weighting 230 to 280 g were used. The rats were grouped into two: those that were sham operated and those that had sciatic nerve axotomy. The specimens-L4,5 dorsal root ganglians(DRG) and their corresponding spinal cords-were collected at post-axotomy day 1, day 3, and day 5. The neuronatin protein contents were analyzed by western blotting and immunohisto- chemistry. Changes in the mRNA levels were evaluated using RT-PCR. Randall and Selitto test was performed to reveal changes in the animal behaviors. The subcellular co-localization of neuronatin with neuronal cell type specific markers were also investigated in correlation with pain-related animal behavior. It was found that after sciatic nerve injury, the expression of neuronatin in dorsal root ganglians was increased in protein extracts. Furthermore, the results of immunohistochemistry revealed that the cell numbers of DRGs were relatively increased. Unmyelinated C-fiber and thinly myelinated A-£_ fiber in adult DRGs were also among the principal sub-population of primary afferent neurons with distributed neuronatin. The increased expression of neuronatin and its subcellular localization were related to mechanical hyperalgesia. The results indicated that there was a following significant correlation between mechanical allodynia axotomy of sciatic nerve and the increased expression of neuronatin in C-fiber and A-£_ fiber of DRG neurons.

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Spinal root avulsion leads to paralysis and loss of sensory function. Surgical methods can improve motor function and ameliorate pain but sensory recovery in adults is poor. Previous studies have shown that cell transplantation or treatment with trophic factors can improve functional outcome in rodents after dorsal root transection or crush. Here, a dorsal root injury model, more similar to human avulsion injuries, was used. The aims of this thesis were to investigate the behaviour of different stem cells following transplantation to avulsed dorsal roots and asses their potential to serve as possible regenerative therapy. In paper I, different murine stem cell types were transplanted to avulsed dorsal roots in rats. Murine embryonic stem cells remained outside the spinal cord and were surrounded by glutamatergic terminals. Boundary cap neural crest stem cells (bNCSC) formed elongated bands outside the spinal cord and migrated to the spinal cord as single cells. In paper II, transplanted bNCSC were further characterized. bNCSC remaining outside the spinal cord expressed glial markers and were associated with different types of sensory fibres. bNCSC that migrated into the injured spinal cord expressed different neuronal markers. In paper III, effects of bNCSC transplantation on local vasculature and glial scar formation were studied. bNCSC increase angiogenesis in a non dose response manner and participate in boundary glial scar formation. In paper IV, bNCSC spinal migration was analysed using two different injury models - dorsal root transection and dorsal root avulsion. In addition, bNCSC capacity to support sensory regeneration was assessed and the results suggest that bNCSC do not support robust regeneration of avulsed afferents. In paper V, an in vitro stem cell model system was used to assess the possibility of using artificial nanomaterials to deliver differentiation factors. Cells treated with either soluble factors or particle-delivered factors showed similar differentiation patterns. Stem cell transplantation offers several opportunities following dorsal root avulsion, including cell replacement and regenerative support. By elucidating the mechanisms by which stem cells can assist regeneration of avulsed afferents will allow for more targeted or combinatorial approaches, including growth factor treatment.

Background: Multiple sclerosis (MS) is a chronic, neurological disease characterized by targeted destruction on central nervous system (CNS) myelin. The autoimmune theory is the most widely accepted explanation of disease pathology. Circulating Th-1 cells become activated by exposure to CNS-specific antigens such as myelin basic protein. The activated Th-1 cells secrete inflammatory cytokines, which are pivotal for inflammatory responses. We hypothesize that enhanced production of inflammatory cytokines triggers cellular events within the dorsal root ganglia (DRG) and/or spinal cord, facilitating the development of neuropathic pain (NPP) in MS. NPP, the second worst disease-induced symptom suffered by patients with MS, is normally regulated by DRG and/or spinal cord. Objective: To determine gene and protein expression levels of tumor necrosis factor-alpha (TNF ) within DRG and/or spinal cord in an animal model of MS. Methods: Experimental autoimmune encephalomyelitis (EAE) was induced in adolescent female Lewis rats. Animals were sacrificed every 3 days post-disease induction. DRG and spinal cords were harvested for protein and gene expression analysis. Results: We show significant increases in TNF expression in the DRG and of EAE animals at peak disease stage, as assessed by clinical symptoms. Conclusion: Antigen-induced production of inflammatory cytokines such as TNF within the DRG identifies a potential noel mechanism for MS-induced NPP.

Background: Multiple sclerosis (MS) is a chronic, neurological disease characterized by targeted destruction on central nervous system (CNS) myelin. The autoimmune theory is the most widely accepted explanation of disease pathology. Circulating Th-1 cells become activated by exposure to CNS-specific antigens such as myelin basic protein. The activated Th-1 cells secrete inflammatory cytokines, which are pivotal for inflammatory responses. We hypothesize that enhanced production of inflammatory cytokines triggers cellular events within the dorsal root ganglia (DRG) and/or spinal cord, facilitating the development of neuropathic pain (NPP) in MS. NPP, the second worst disease-induced symptom suffered by patients with MS, is normally regulated by DRG and/or spinal cord. Objective: To determine gene and protein expression levels of tumor necrosis factor-alpha (TNF ) within DRG and/or spinal cord in an animal model of MS. Methods: Experimental autoimmune encephalomyelitis (EAE) was induced in adolescent female Lewis rats. Animals were sacrificed every 3 days post-disease induction. DRG and spinal cords were harvested for protein and gene expression analysis. Results: We show significant increases in TNF expression in the DRG and of EAE animals at peak disease stage, as assessed by clinical symptoms. Conclusion: Antigen-induced production of inflammatory cytokines such as TNF within the DRG identifies a potential noel mechanism for MS-induced NPP.