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Journal of Korean Neurosurgical Society > Volume 54(1); 2013 > Article
Bang, Kim, Cho, Kim, and Sung: Valproic Acid Increases Expression of Neuronal Stem/Progenitor Cell in Spinal Cord Injury

Abstract

Objective

This study investigates the effect of valproic acid (VPA) on expression of neural stem/progenitor cells (NSPCs) in a rat spinal cord injury (SCI) model.

Methods

Adult male rats (n=24) were randomly and blindly allocated into three groups. Laminectomy at T9 was performed in all three groups. In group 1 (sham), only laminectomy was performed. In group 2 (SCI-VPA), the animals received a dose of 200 mg/kg of VPA. In group 3 (SCI-saline), animals received 1.0 mL of the saline vehicle solution. A modified aneurysm clip with a closing force of 30 grams was applied extradurally around the spinal cord at T9, and then rapidly released with cord compression persisting for 2 minutes. The rats were sacrificed and the spinal cord were collected one week after SCI. Immunohistochemistry (IHC) and western blotting sample were obtained from 5 mm rostral region to the lesion and prepared. We analyzed the nestin immunoreactivity from the white matter of ventral cord and the ependyma of central canal. Nestin and SOX2 were used for markers for NSPCs and analyzed by IHC and western blotting, respectively.

Results

Nestin and SOX2 were expressed significantly in the SCI groups but not in the sham group. Comparing SCI groups, nestin and SOX2 expression were much stronger in SCI-VPA group than in SCI-saline group.

Conclusion

Nestin and SOX2 as markers for NSPCs showed increased expression in SCI-VPA group in comparison with SCI-saline group. This result suggests VPA increases expression of spinal NSPCs in SCI.

INTRODUCTION

Spinal cord injury (SCI) can cause clinically irreversible disability and result in much comorbidity. The primary SCI is direct injury from an initial mechanical trauma, and the secondary injury results from progressive processes that augment the injury resulting in a protracted period of tissue destruction1,2,29). These cascading injuries make recovery from SCI hard or irreversible. However, recent studies demonstrated that spontaneous neuronal regeneration can occur in rat models of SCI15,16,19). Existence of neural stem/progenitor cells (NSPCs) in adult stage was proven in adult mammals, including humans11,17). In particular, there were many reports that SCIs induce proliferation and expression of spinal NSPCs. These observations suggest that adult NSPCs may work for neuronal regeneration in adult mammals following SCI.
Valproic acid (VPA) is widely used for the treatment of seizures and bipolar disorders. In addition, VPA is a potent histone deacetylase (HDACs) inhibitor, which is critical to cellular inflammatory and repair processes8). In many animal model studies of neurodegenerative diseases, VPA has beneficial effectsin treatment of stroke, amyotrophic lateral sclerosis, spinal muscular atrophy, Parkinson's disease and Alzheimer's disease7,10,20,27,28,32,33). Recently, VPA was shown to be important for expression and self-renewal of hematopoietic stem cells6). We hypothesized that VPA can stimulate expression of NSPCs. Therefore, this study is intended to investigate the effects of VPA on NSPCs expression in a rat SCI model.

MATERIALS AND METHODS

Animal surgery and administration of VPA

All animal experiments were performed in accordance with the National Institutes of Health guidelines on animal care, and were approved by the Institutional Animal Care Committee. All efforts were made to minimize the number of animals used and animal suffering. Adult male Sprague-Dawley rats (n=30) weighing 290-310 grams (Samtako Bio, Osan, Korea) were randomly and blindly allocated into three groups. In group 1 (sham, n=8), laminectomy was performed. In group 2 (SCI-VPA, n=11), the animals received a dose of 200 mg/kg of VPA (Sigma-Aldrich, St. Louis, MO, USA). In group 3 (SCI-saline, n=11), animals received 1.0 mL of the saline vehicle solution. Rats were anesthetized intraperitoneally with a mixture of xylazine (10 mg/kg) and ketamine (60 mg/kg). After laminectomy at T9, the extradural plane between the dura and adjacent vertebrae was carefully dissected. A modified aneurysm clip with a closing force of 30 grams (Aesculap, Tuttlingen, Germany) was held in an applicator in the open position. The clip was rapidly released from the applicator and applied vertically onto the exposed spinal cord for a 2-minute compression. For the sham controls the same surgical procedure was followed, but clip compression was not applied. After surgery, the muscle, fascia, and skin were sutured using a 4-0 silk suture. Rectal temperature was maintained at 37.0±0.5℃ by a thermostatically-regulated heating pad during surgery, and during recovery, animals were placed overnight in a temperature and humidity controlled chamber. To reduce post-surgery isolation-induced stress, rats were housed in pairs at an ambient temperature of 22-25℃ in an alternating 12-hour light/dark cycle. Bladders were manually emptied twice daily until spontaneous voiding occurred. At three days after surgery, we checked functional deficit using the open locomotor rating scale by Basso, Beattie, and Bresnahan (the BBB score)3). All rats showed 4 or 5 BBB score, indicating proper cord damage in SCI model. A dose of 200 mg/kg of VPA or normal saline as a vehicle control was intraperitoneally injected twice daily at 12 hours intervals for 7 days. The total daily VPA dose of 400 mg/kg/day was similar to doses used in previous studies9,34). To evaluate histological changes, the animals were sacrificed and the spinal cords were collected 1 week after SCI. For immunohistochemistry analysis, samples were prepared from the sham group (n=5), SCI-saline group (n=7), and SCI-VPA group (n=7). Samples for western blotting analysis were prepared from rats in the three groups (group 1=3 rats, group 2, 3=4 rats).

Immunohistochemistry of nestin

Rats were deeply anesthetized by an intraperitoneal injection of ketamine and were perfused intracardially with 4% paraformaldehyde in 0.1 M sodium phosphate buffer (PB, pH=7.4). The thoracic spinal cord was excised, postfixed for 24 hours, and maintained overnight in 30% sucrose in 0.1 M PB. Spinal cord tissues were sectioned at a thickness of 30 µm on a cryostat, and sections were floated on the surface of 0.1 M PB. A 5 and 6 mm section rostral to the center of injury was selected. To detect nestin (marker for neural stem cell), spinal cord sections were blocked with 4% normal serum in 0.5% Triton X-100 for 1 hour at room temperature and incubated overnight at 4℃ with a 1 : 2000 dilution of mouse monoclonal anti-nestin (R&D Systems Inc., Minneapolis, MN, USA), and rinsed for 3×10 min in 0.1 M PB. Sections were then incubated in 0.1 M PB containing 4% normal serum and 0.5% Triton X-100 for 2 hours at 25℃ on a shaker, and then in primary antiserum in 0.1 M PB containing 4% normal serum and 0.5% Triton X-100 for 12 hours at 25℃. After rinsing (3×10 min) in 0.1 M PB, sections were incubated in a 1 : 200 dilution of biotinylated anti-mouse IgG (Sigma, St. Louis, MO, USA) in 0.1 M PB containing 4% normal serum and 0.5% Triton X-100 at 25℃ for 2 hours. The sections were then incubated in a 1 : 50 dilution of avidin-biotinylated horseradish peroxidase (Vector Laboratory) in 0.1 M PB for 2 hours and rinsed (3×10 min) in 0.25 M Tris. Finally, staining was visualized by reaction with 3, 3'-diaminobenzidine tetrahydrochloride (DAB) and hydrogen peroxide in 0.25 M Tris for 3-10 min using a DAB reagent set (Kierkegaard&Perry, Gaithersburg, MD, USA). All sections were rinsed in 0.1 M PB and mounted on Superfrost Plus slides (Fisher, Pittsburgh, PA, USA) and dried overnight at 37℃. The mounted sections were dehydrated with alcohol, cleared with xylene, and cover slipped with Permount mounting medium (Fisher). The labeled cells were identified and counted with separation of antibody at three tissues in each different animal. The labeled tissues were photographed using a Zeiss Axiopan microscope with high power DIC optics (Carl Zeiss Meditec Incorporation, Jena, Germany). The images were viewed on a computer monitor using a Zeiss Plan-Apochromat 40x objective (Carl Zeiss) and photographs of the central canal region and ventral side of white matter of left and right sides were taken with a Zeiss AxioCam HRc digital camera (Carl Zeiss). Enumeration of immune-positive cells used a Labworks, version 4.5, computer-assisted image analyzer (UVP, Upland, CA, USA).

Western blotting of SOX2

Rats in three groups were decapitated rapidly under anesthesia. The thoracic spinal cord was rapidly dissected and then immediately frozen in liquid nitrogen. Frozen tissue was mixed with RIPA buffer (25 mM Tris-Cl pH 7.6, 150 mM NaCl, 1% NP-40, 1% sodium deoxycholate, 0.1% SDS) containing protease inhibitor cocktail (Roche, Mannheim, Germany) and immediately homogenized. The homogenate was centrifuged at 13000 rpm for 30 min at 4℃ and the supernatants were determined using the BCA protein assay (Sigma, St. Louis, MO, USA). Proteins were separated by 10% SDS-PAGE gel and transferred to a nitrocellulose membrane. After incubation in a blocking solution of 5% non-fat dry milk in Tris-buffered saline containing 0.1% Tween-20 for 1 h at room temperature. The membrane was incubated with a 1 : 1000 dilution of mouse monoclonal anti-SOX2 (cell signaling) and mouse monoclonal anti-β-actin (Sigma-Aldrich), and overnight at 4℃, and then with a horseradish peroxidase (HRP)-conjugated secondary antibody for 1 h at room temperature. The proteins were detected with chemiluminescence reagents. Immune-positive bands used an image J, version 1.46r, computer-assisted image analyzer (National Institutes of Health, USA).

Statistical analysis

All statistical comparisons were computed using SPSS 17.0 (SPSS, Inc., an IBM Company, Chicago, IL, USA). Data are expressed as mean±standard error of the mean. Repeated measure ANOVA was used to compare groups. Null hypotheses of no difference were rejected if p-values were less than 0.05.

RESULTS

Nestin expression in SCI

We analyzed the nestin immunoreactivity from two different sites of the spinal cord based on methods from Sibuya et al.32). One site is the white matter of ventral side and the other is the ependyma of central canal in a cross-section of spinal cord. We used ANOVA analysis for confirmation of density areas of nestin.
In the white matter of ventral side, nestin immunoreactivity was almost undetectable in the sham group (Fig. 1A, D). SCI groups showed remarkable nestin immunoreactivity compared with sham group. In the SCI-saline group, nestin immunoreactivity extended in arboroid processes from the pial surface toward the spinal cord center (Fig. 1B, E). In the SCI-VPA group, nestin immunoreactivity was much stronger than in SCI-saline group (Fig. 1C, F). Density areas of nestin expression in the white matter of ventral side differed significantly between the SCI and sham group (Fig. 2). The SCI group showed significantly large density area compared with sham group and within SCI groups, the SCI-VPA group had a much larger density area of nestin than the SCI-saline group.
In the ependyma of the central canal, nestin immunoreactivity also was strongest in the SCI-VPA group (Fig. 3C). In sham group, nestin immunoreactivity was observed in some cells (Fig. 3A). SCI groups had significant nestin immunoreactivity compared to the sham group and extended in processes from the whole ependymal area (Fig. 3B, C). The density areas of nestin expression in the ependyma of the central canal were similar to the white matter of ventral side. The SCI groups had significantly large density areas of nestin compared to the sham group, and SCI-VPA group had a much larger density area of nestin than SCI-saline group (Fig. 4).
To sum up, VPA increased expression of nestin, a marker for NSPCs, in the white matter of the ventral side and ependyma of the central canal.

SOX2 analysis in SCI

SOX2 was detectable in SCI groups and undetectable in sham group. Besides, in SCI groups, VPA significantly increased the SOX2 positive band than in the SCI-saline group (Fig. 5). This difference was confirmed by ANOVA analysis. SOX2 protein levels were highest in SCI-VPA group, followed by SCI-saline (Fig. 6).

DISCUSSION

Recovery from SCI is a major goal of neurosurgeons. Early decompressive surgery or high-dose steroid therapy, while long-standing treatments of choice, do not provide recovery from critical sequelae after SCI. Efforts to minimize secondary injury of SCI have included drug management as a neuroprotective effect in many recent studies, including minocycline, erythropoietin, and Nogo-66 receptor antagonist13,23,24). VPA also was investigated35). These drugs are efficacious for minimizing scarring and cavitation caused by SCI13,23,24,35). However, the so-called "neuroprotective effect" was not enough for radical management of SCI. The ultimate goal of management for SCI is regeneration of injured neural tissues, so numerous studies of neural stem cell therapy have been reported.
Embryonic stem cells are pluripotent and self-replicating. Transplantation of human embryonic stem cells to injured rat spinal cord could result in recovery26). Despite several limitations to be overcome, including differentiation to purified neural cell type5,18,26) and teratoma formation4), human embryonic stem cell therapy is an attractive method for recovery from SCI. This strategy has been recently validated21). The existence of NSPCs at the embryonic stage and at the adult stage is already proven11,17). Reported adult NSPCs so far are the ependymal cells and subependymal cells of the cerebral ventricles and glial fibrillary acidic protein-positive cells in the subventricular zone. Interestingly, SCI induces expression of NSPCs and this phenomenon may be associated with neuronal repair and regeneration after SCI30).
Various markers for NSPCs are reported, and among these we used nestin and SOX2. Nestin, an intermediate filament protein, is a widely employed marker of multipotent neural stem cells in adult CNS. In an experiment on an SCI rat model, nestin expression increased time-dependently, and peaked in the 5-mm rostral region to the injury center at 1 week after SCI30). SOX2, sex-determining region Y-box 2, is a transcription factor that is essential for regulation of self-renewal and potency of embryonic and adult neural stem cells and express in the adult multipotent NSPCs22). In an experiment using SOX2 as NSPC's marker on SCI rat model, it is observed that SOX2 expression reaches a peak at 1-2 weeks after SCI22). Based on this prior research, we selected the killing time and the region of transection, at one week after injury and 5-mm rostral to injury.
VPA, 2-propylpentanoic acid, is an HDAC inhibitors. HDAC enzymes can be classified into four major classes according to their homology to yeast HDACs8). VPA inhibits HDAC8, a class 1 HDAC8). HDAC inhibitors are involved in normalization of histone hypoacetylation and transcriptional dysfunction of various neurodegenerative conditions8). The neuroprotective effects of treatment with VPA as HDAC inhibitor are proven in various animal models of neurodegenerative diseases, such as stroke, amyotrophic lateral sclerosis, spinal muscular atrophy, Parkinson's disease and Alzheimer's disease7,10,20,27,28,32,33). Furthermore, we reported that VPA minimizes secondary injury of SCI by diminishing cavitation volume inflammatory reactions, and restoring the hisone acetylations in injured spinal cords after SCI in our previous study35). A recent study demonstrated that VPA as HDAC inhibitor has the ability to stimulate proliferation and self-renewal of hematopoietic stem cells (HSCs)6). In above study, it was reported that VPA increases the proliferation of human CD 34+ HSCs but does not induce differentiation. In addition, VPA activates glycogen synthase kinase 3β (GSK3β)-dependent signaling pathways necessary for the self-renewal potential of HSC. VPA induces proliferation of neural progenitor cell by activation of Wnt/GSK3β/β-catenin pathway in rat brain12). These findings prompted to us to investigate the effect of VPA on expression of NSPCs in SCI rat model. In our study, VPA increases the expression of NSPCs after SCI. This result is similar to previous studies6,12), but, in another study, activation of GSK3β by phosphorylation promotes differentiation of NSPCs and reduces proliferation of NSPCs in rat subventricular zone25). Weighing this evidence, it is certain that the GSK3β signaling pathway is important for proliferation of NSPCs. Therefore, we guess that the effect of activated GSK3β signaling pathway by VPA may be different according to circumstance. There have been no studies so far about VPA effect on NSPCs expression in SCI model as in our study. Further studies are needed to investigate how VPA causes expression of NSPCs by GSK3β signaling pathway.
Furthermore, there is one thing to be concerned about. As known by previous studies, VPA contributes to an anti-inflammatory reaction by down-regulation of various inflammatory genes31) and this anti-inflammatory reaction is conducive to migration of adult NSPCs to the injury site14). Consequently, we can draw a hypothesis that the above sequential steps cause VPA to negatively affect the reaction for migration of NSPCs to the injury site. However, in our study, we cannot tell how much VPA affects migration of NSPCs to the injury site. According to our results, it is certain that VPA can increase expression of NSPCs around the injury site. Because existence of endogenous NSPCs were already proved in the spinal cord by a previous study30), we would suggest one hypothesis : a higher proportion of assignment for NSPCs expression may at increased proliferation of endogenous NSPCs more than at decreased migration of NSPCs by VPA in the case of SCI.
There is no previous in vivo study about the VPA effect on migration of NSPCs to the injury site. In a future study, we have to launch an in vivo SCI model study using VPA for investigation of the effect on migration of NSPCs.

CONCLUSION

In our study, nestin and SOX2 as markers for NSPCs showed increased expression in the SCI-VPA group in comparison with the SCI-saline group. This result indicates that VPA increases expression of spinal NSPCs in SCI. In future research, we should evaluate the GSK3β signaling pathway in spinal cord and phenomenon between proliferation and differentiation of NSPCs in SCI and launch an in vivo SCI model study using VPA for investigation of the effect on migration of NSPCs.

Acknowledgements

This research was supported by Basic Science Research Program through the National Research Foundation of Korea (NRF) funded by the Ministry of Education, Science and Technology (2012R1A1A1014361).

References

1. Balentine JD : Pathology of experimental spinal cord trauma. I. The necrotic lesion as a function of vascular injury. Lab Invest 39 : 236-253, 1978
pmid
2. Balentine JD : Pathology of experimental spinal cord trauma. II. Ultrastructure of axons and myelin. Lab Invest 39 : 254-266, 1978
pmid
3. Basso DM, Beattie MS, Bresnahan JC : Graded histological and locomotor outcomes after spinal cord contusion using the NYU weight-drop device versus transection. Exp Neurol 139 : 244-256, 1996
crossref pmid
4. Brederlau A, Correia AS, Anisimov SV, Elmi M, Paul G, Roybon L, et al : Transplantation of human embryonic stem cell-derived cells to a rat model of Parkinson's disease : effect of in vitro differentiation on graft survival and teratoma formation. Stem Cells 24 : 1433-1440, 2006
crossref pmid
5. Brüstle O, Jones KN, Learish RD, Karram K, Choudhary K, Wiestler OD, et al : Embryonic stem cell-derived glial precursors : a source of myelinating transplants. Science 285 : 754-756, 1999
crossref pmid
6. Bug G, Gül H, Schwarz K, Pfeifer H, Kampfmann M, Zheng X, et al : Valproic acid stimulates proliferation and self-renewal of hematopoietic stem cells. Cancer Res 65 : 2537-2541, 2005
crossref pmid
7. Chen PS, Peng GS, Li G, Yang S, Wu X, Wang CC, et al : Valproate protects dopaminergic neurons in midbrain neuron/glia cultures by stimulating the release of neurotrophic factors from astrocytes. Mol Psychiatry 11 : 1116-1125, 2006
crossref pmid
8. Chuang DM, Leng Y, Marinova Z, Kim HJ, Chiu CT : Multiple roles of HDAC inhibition in neurodegenerative conditions. Trends Neurosci 32 : 591-601, 2009
crossref pmid pmc
9. Dash PK, Orsi SA, Zhang M, Grill RJ, Pati S, Zhao J, et al : Valproate administered after traumatic brain injury provides neuroprotection and improves cognitive function in rats. PLoS One 5 : e11383, 2010
crossref pmid pmc
10. Feng HL, Leng Y, Ma CH, Zhang J, Ren M, Chuang DM : Combined lithium and valproate treatment delays disease onset, reduces neurological deficits and prolongs survival in an amyotrophic lateral sclerosis mouse model. Neuroscience 155 : 567-572, 2008
crossref pmid pmc
11. Gage FH, Coates PW, Palmer TD, Kuhn HG, Fisher LJ, Suhonen JO, et al : Survival and differentiation of adult neuronal progenitor cells transplanted to the adult brain. Proc Natl Acad Sci U S A 92 : 11879-11883, 1995
crossref pmid pmc
12. Go HS, Kim KC, Choi CS, Jeon SJ, Kwon KJ, Han SH, et al : Prenatal exposure to valproic acid increases the neural progenitor cell pool and induces macrocephaly in rat brain via a mechanism involving the GSK-3β/β-catenin pathway. Neuropharmacology 63 : 1028-1041, 2012
crossref pmid
13. Gorio A, Gokmen N, Erbayraktar S, Yilmaz O, Madaschi L, Cichetti C, et al : Recombinant human erythropoietin counteracts secondary injury and markedly enhances neurological recovery from experimental spinal cord trauma. Proc Natl Acad Sci U S A 99 : 9450-9455, 2002
crossref pmid pmc
14. Imitola J, Raddassi K, Park KI, Mueller FJ, Nieto M, Teng YD, et al : Directed migration of neural stem cells to sites of CNS injury by the stromal cell-derived factor 1alpha/CXC chemokine receptor 4 pathway. Proc Natl Acad Sci U S A 101 : 18117-18122, 2004
crossref pmid pmc
15. Inoue T, Kawaguchi S, Kurisu K : Spontaneous regeneration of the pyramidal tract after transection in young rats. Neurosci Lett 247 : 151-154, 1998
crossref pmid
16. Iseda T, Nishio T, Kawaguchi S, Yamanoto M, Kawasaki T, Wakisaka S : Spontaneous regeneration of the corticospinal tract after transection in young rats : a key role of reactive astrocytes in making favorable and unfavorable conditions for regeneration. Neuroscience 126 : 365-374, 2004
crossref pmid
17. Johansson CB, Momma S, Clarke DL, Risling M, Lendahl U, Frisén J : Identification of a neural stem cell in the adult mammalian central nervous system. Cell 96 : 25-34, 1999
crossref pmid
18. Keirstead HS, Nistor G, Bernal G, Totoiu M, Cloutier F, Sharp K, et al : Human embryonic stem cell-derived oligodendrocyte progenitor cell transplants remyelinate and restore locomotion after spinal cord injury. J Neurosci 25 : 4694-4705, 2005
crossref pmid
19. Kikukawa S, Kawaguchi S, Mizoguchi A, Ide C, Koshinaga M : Regeneration of dorsal column axons after spinal cord injury in young rats. Neurosci Lett 249 : 135-138, 1998
crossref pmid
20. Kim HJ, Rowe M, Ren M, Hong JS, Chen PS, Chuang DM : Histone deacetylase inhibitors exhibit anti-inflammatory and neuroprotective effects in a rat permanent ischemic model of stroke : multiple mechanisms of action. J Pharmacol Exp Ther 321 : 892-901, 2007
crossref pmid
21. Lee H, Shamy GA, Elkabetz Y, Schofield CM, Harrsion NL, Panagiotakos G, et al : Directed differentiation and transplantation of human embryonic stem cell-derived motoneurons. Stem Cells 25 : 1931-1939, 2007
crossref pmid
22. Lee HJ, Wu J, Chung J, Wrathall JR : SOX2 expression is upregulated in adult spinal cord after contusion injury in both oligodendrocyte lineage and ependymal cells. J Neurosci Res 91 : 196-210, 2013
crossref pmid
23. Lee SM, Yune TY, Kim SJ, Park DW, Lee YK, Kim YC, et al : Minocycline reduces cell death and improves functional recovery after traumatic spinal cord injury in the rat. J Neurotrauma 20 : 1017-1027, 2003
crossref pmid
24. Li S, Strittmatter SM : Delayed systemic Nogo-66 receptor antagonist promotes recovery from spinal cord injury. J Neurosci 23 : 4219-4227, 2003
crossref pmid
25. Maurer MH, Brömme JO, Feldmann RE Jr, Järve A, Sabouri F, Bürgers HF, et al : Glycogen synthase kinase 3beta (GSK3beta) regulates differentiation and proliferation in neural stem cells from the rat subventricular zone. J Proteome Res 6 : 1198-1208, 2007
crossref pmid
26. Nistor GI, Totoiu MO, Haque N, Carpenter MK, Keirstead HS : Human embryonic stem cells differentiate into oligodendrocytes in high purity and myelinate after spinal cord transplantation. Glia 49 : 385-396, 2005
crossref pmid
27. Qing H, He G, Ly PT, Fox CJ, Staufenbiel M, Cai F, et al : Valproic acid inhibits Abeta production, neuritic plaque formation, and behavioral deficits in Alzheimer's disease mouse models. J Exp Med 205 : 2781-2789, 2008
crossref pmid pmc
28. Ren M, Leng Y, Jeong M, Leeds PR, Chuang DM : Valproic acid reduces brain damage induced by transient focal cerebral ischemia in rats : potential roles of histone deacetylase inhibition and heat shock protein induction. J Neurochem 89 : 1358-1367, 2004
crossref pmid
29. Rowland JW, Hawryluk GW, Kwon B, Fehlings MG : Current status of acute spinal cord injury pathophysiology and emerging therapies : promise on the horizon. Neurosurg Focus 25 : E2, 2008
crossref
30. Shibuya S, Miyamoto O, Auer RN, Itano T, Mori S, Norimatsu H : Embryonic intermediate filament, nestin, expression following traumatic spinal cord injury in adult rats. Neuroscience 114 : 905-916, 2002
crossref pmid
31. Sinn DI, Kim SJ, Chu K, Jung KH, Lee ST, Song EC, et al : Valproic acid-mediated neuroprotection in intracerebral hemorrhage via histone deacetylase inhibition and transcriptional activation. Neurobiol Dis 26 : 464-472, 2007
crossref pmid
32. Sugai F, Yamamoto Y, Miyaguchi K, Zhou Z, Sumi H, Hamasaki T, et al : Benefit of valproic acid in suppressing disease progression of ALS model mice. Eur J Neurosci 20 : 3179-3183, 2004
crossref pmid
33. Sumner CJ, Huynh TN, Markowitz JA, Perhac JS, Hill B, Coovert DD, et al : Valproic acid increases SMN levels in spinal muscular atrophy patient cells. Ann Neurol 54 : 647-654, 2003
crossref pmid
34. Wang Z, Leng Y, Tsai LK, Leeds P, Chuang DM : Valproic acid attenuates blood-brain barrier disruption in a rat model of transient focal cerebral ischemia : the roles of HDAC and MMP-9 inhibition. J Cereb Blood Flow Metab 31 : 52-57, 2011
crossref pmid
35. Yu SH, Cho DC, Kim KT, Nam KH, Cho HJ, Sung JK : The neuroprotective effect of treatment of valproic Acid in acute spinal cord injury. J Korean Neurosurg Soc 51 : 191-198, 2012
crossref pmid pmc
Fig. 1
Nestin expression in the white matter of spinal cord 1week after surgery at 5-mm rostral region to injury. A and D : Sham group-operated. B and E : SCI-saline group operated. C and F : SCI-VPA group operated. Scale bar=500 µm (A, B and C) and 50 µm (D, E and F). SCI : spinal cord injury, VPA : valproic acid.
jkns-54-8-g001.jpg
Fig. 2
Density areas of nestin expression (µm2) in the white matter of ventral side in a cross section of spinal cord 1 week after surgery at 5-mm rostral region to injury (**p<0.05). SCI : spinal cord injury, VPA : valproic acid.
jkns-54-8-g002.jpg
Fig. 3
Nestin expression in the ependyma of central canal 1 week after surgery at 5-mm rostral region to injury. A : Sham group-operated. B : SCI-saline group operated. C : SCI-VPA group operated. SCI : spinal cord injury, VPA : valproic acid.
jkns-54-8-g003.jpg
Fig. 4
Density areas of nestin expression (µm2) in the ependyma of central canal 1 week after surgery at 5-mm rostral region to injury (**p<0.05). SCI : spinal cord injury, VPA : valproic acid.
jkns-54-8-g004.jpg
Fig. 5
Western blot band of SOX2 and β-catenin. SCI : spinal cord injury, VPA : valproic acid.
jkns-54-8-g005.jpg
Fig. 6
SOX2 protein levels relative to sham group (*p<0.1, **p<0.05).
jkns-54-8-g006.jpg
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