|Year : 2018 | Volume
| Issue : 6 | Page : 689-695
Glehnia littoralis Extract Promotes Neurogenesis in the Hippocampal Dentate Gyrus of the Adult Mouse through Increasing Expressions of Brain-Derived Neurotrophic Factor and Tropomyosin-Related Kinase B
Joon Ha Park1, Bich Na Shin2, Ji Hyeon Ahn1, Jeong Hwi Cho2, Tae-Kyeong Lee2, Jae-Chul Lee2, Yong Hwan Jeon3, Il Jun Kang4, Ki-Yeon Yoo5, In Koo Hwang6, Choong Hyun Lee7, Yoo Hun Noh8, Sung-Su Kim8, Moo-Ho Won2, Jong Dai Kim9
1 Department of Biomedical Science and Research Institute for Bioscience and Biotechnology, Hallym University, Chuncheon 24252, Korea
2 Department of Neurobiology, School of Medicine, Kangwon National University, Chuncheon 24341, Korea
3 Department of Radiology, School of Medicine, Kangwon National University, Chuncheon 24341, Korea
4 Department of Food Science and Nutrition, Hallym University, Chuncheon 24252, Korea
5 Department of Oral Anatomy, College of Dentistry and Research Institute of Oral Biology, Gangneung-Wonju National University, Gangneung 25457, Korea
6 Department of Anatomy and Cell Biology, College of Veterinary Medicine, and Research Institute for Veterinary Science, Seoul National University, Seoul 08826, Korea
7 Department of Pharmacy, College of Pharmacy, Dankook University, Cheonan 31116, Korea
8 Famenity Biomedical Research Center, Famenity, Inc., Gyeonggi 13837, Korea
9 Division of Food Biotechnology, School of Biotechnology, Kangwon National University, Chuncheon 24341, Korea
|Date of Submission||16-Nov-2017|
|Date of Web Publication||9-Mar-2018|
Prof. Jong Dai Kim
Division of Food Biotechnology, School of Biotechnology, Kangwon National University, Chuncheon 24341
Prof. Moo-Ho Won
Department of Neurobiology, School of Medicine, Kangwon National University, Chuncheon 24341
Source of Support: None, Conflict of Interest: None
Background: Glehnia littoralis has been used for traditional Asian medicine, which has diverse therapeutic activities. However, studies regarding neurogenic effects of G. littoralis have not yet been considered. Therefore, in this study, we examined effects of G. littoralis extract on cell proliferation, neuroblast differentiation, and the maturation of newborn neurons in the hippocampus of adult mice.
Methods: A total of 39 male ICR mice (12 weeks old) were randomly assigned to vehicle-treated and 100 and 200 mg/kg G. littoralis extract-treated groups (n = 13 in each group). Vehicle and G. littoralis extract were orally administrated for 28 days. To examine neurogenic effects of G. littoralis extract, we performed immunohistochemistry for 5-bromo-2-deoxyuridine (BrdU, an indicator for cell proliferation) and doublecortin (DCX, an immature neuronal marker) and double immunofluorescence staining for BrdU and neuronal nuclear antigen (NeuN, a mature neuronal marker). In addition, we examined expressional changes of brain-derived neurotrophic factor (BDNF) and its major receptor tropomyosin-related kinase B (TrkB) using Western blotting analysis.
Results: Treatment with 200 mg/kg, not 100 mg/kg, significantly increased number of BrdU-immunoreactive (+) and DCX+ cells (48.0 ± 3.1 and 72.0 ± 3.8 cells/section, respectively) in the subgranular zone (SGZ) of the dentate gyrus (DG) and BrdU+/NeuN+ cells (17.0 ± 1.5 cells/section) in the granule cell layer as well as in the SGZ. In addition, protein levels of BDNF and TrkB (about 232% and 244% of the vehicle-treated group, respectively) were significantly increased in the DG of the mice treated with 200 mg/kg of G. littoralis extract.
Conclusion: G. littoralis extract promots cell proliferation, neuroblast differentiation, and neuronal maturation in the hippocampal DG, and neurogenic effects might be closely related to increases of BDNF and TrkB proteins by G. littoralis extract treatment.
Keywords: Brain-Derived Neurotrophic Factor; Cell Proliferation; Glehnia littoralis; Neuroblast Differentiation; Tropomyosin-Related Kinase B
|How to cite this article:|
Park JH, Shin BN, Ahn JH, Cho JH, Lee TK, Lee JC, Jeon YH, Kang IJ, Yoo KY, Hwang IK, Lee CH, Noh YH, Kim SS, Won MH, Kim JD. Glehnia littoralis Extract Promotes Neurogenesis in the Hippocampal Dentate Gyrus of the Adult Mouse through Increasing Expressions of Brain-Derived Neurotrophic Factor and Tropomyosin-Related Kinase B. Chin Med J 2018;131:689-95
|How to cite this URL:|
Park JH, Shin BN, Ahn JH, Cho JH, Lee TK, Lee JC, Jeon YH, Kang IJ, Yoo KY, Hwang IK, Lee CH, Noh YH, Kim SS, Won MH, Kim JD. Glehnia littoralis Extract Promotes Neurogenesis in the Hippocampal Dentate Gyrus of the Adult Mouse through Increasing Expressions of Brain-Derived Neurotrophic Factor and Tropomyosin-Related Kinase B. Chin Med J [serial online] 2018 [cited 2018 Dec 10];131:689-95. Available from: http://www.cmj.org/text.asp?2018/131/6/689/226894
Joon Ha Park and Bich Na Shin contributed equally to this work.
| Introduction|| |
Neurogenesis in the adult brain is a normal process to generate new neurons and occurs throughout life in restricted brain regions, which is called neurogenic regions, such as the subgranular zone (SGZ) of the dentate gyrus (DG) of the hippocampus and the subventricular zone of the lateral ventricle in mammals., Neural progenitor cells within the SGZ of the DG proliferate and differentiate into mature neurons in the granule cell layer, and newly generated neurons in the DG integrate into functional hippocampal network that may be crucial for learning and memory., It has been demonstrated that neurogenesis in the DG is deceased with age and diverse neurodegenerative diseases including Alzheimer's and Parkinson's diseases, which result in cognitive impairment.,, Thus, neurogenesis in the DG has received great clinical attention as a potential therapeutic target for the treatment of neurodegenerative diseases.,
Traditional medicinal plants and their components possess diverse biological properties and have been widely used as attractive resources for the prevention or treatment of neurodegenerative diseases.,Glehnia littoralis, a perennial member of the Glehnia genus belonging to the family Umbelliferae, is distributed in Korea, China, and Japan and has been used in traditional oriental medicine as diaphoretics, antipyretics, analgesics, and expectorant., It has been reported that G. littoralis has antioxidative constituents such as quercetin, isoquercetin, rutin, chlorogenic acid, and caffeic acid. Recent studies have proven that G. littoralis has a broad spectrum of biological properties such as antibacterial, antifungal, antioxidant, and anti-inflammatory effects.,, In addition, it has been recently reported that G. littoralis displaysbeneficial effects against transient global cerebral ischemia.
To the best of our knowledge, few studies regarding effects of G. littoralis on neurogenesis in the adult brain have been conducted. Herein, we assessed effects of G. littoralis on adult neurogenesis in the DG of the adult mouse hippocampus using 5-bromo-2-deoxyuridine (BrdU, an indicator for cell proliferation) labeling and immunohistochemistry for doublecortin (DCX, an immature neuronal marker), which has been commonly used to investigate the proliferation of neuroblast., In addition, we examined expressional changes of brain-derived neurotrophic factor (BDNF) and its major receptor tropomyosin-related kinase B (TrkB), which are well known to be involved in the neurogenic process.,
| Methods|| |
Adult male ICR mice (body weight 25–30 g, 12 weeks of age) were purchased from Orient Bio Inc. (Seongnam, South Korea), and they were handled by NIH Guide for the Care and Use of Laboratory Animals (NIH Publication No. 85–23, 1985, revised 1996). The protocol used in this experiment was reviewed and approved by the Kangwon National University-Institutional Animal Care and Use Committee (Approval No.: KW-160802-3) based on ethical procedures and scientific care. All of the experiments were conducted to minimize the number of animals used and the suffering caused by the procedures used in the present study.
Extraction of plant material
G. littoralis was collected in Kangwon Province in October 2015 by Dr. Jong Dai Kim. For the preparation of the ethanol extract of G. littoralis (GLe), roots and rhizomes of G. littoralis were washed with distilled water, air-dried at 60°C, and ground into fine powder by a grinder (IKA M20, IKA, Staufen, Germany). The powder of the GLe was refluxed with 10 vol (v/w) of 70% ethanol at 70°C for 24 h. The extraction procedure was repeated three times. The extract was filtered through Whatman No. 1 filter paper (Whatman Ltd., Maidstone, Kent, UK), concentrated with a vacuum evaporator, and completely dried with a freeze-drier. The extraction yield was 9.24%.
Treatment with ethanol extract of Glehnia littoralis and 5-bromo-2-deoxyuridine
Mice were assigned to three groups (n = 13 in each group): (1) vehicle-treated group, which was treated with sterile saline (0.9% sodium chloride), (2 and 3) 100 and 200 mg/kg GLe-treated groups, which were treated with 100 and 200 mg/kg of GLe, respectively. GLe was dissolved in sterile saline. GLe or saline was fed using a feeding needle once daily for 28 days before sacrifice because it has been reported that DCX is expressed by immature newborn cells up to 28 days of cell age.
To examine newly generated neurons, BrdU (Sigma, USA) was dissolved in saline just before injection. Mice were intraperitoneally injected with BrdU (50 mg/kg) solution on day 8, 15, 22, and 27 according to our published procedure., All animals were weighed once per week during the experimental period. There were no significant differences in body weight between the experimental groups (data not shown).
Tissue processing for histology
To conduct histological analysis, mice (n = 7 in each group) were anesthetized with 30 mg/kg of Zoletil 50 (Virbac, Carros, France) and perfused by the aorta with 4% paraformaldehyde in 0.1 mol/L phosphate buffered (PB, pH 7.4). Their brains were removed and postfixed in the same fixative for 6 h. The brain tissues were cryoprotected by infiltration with 30% sucrose for 12 h and serially cut into 30 μm thickness of coronal sections in a cryostat (Leica, Wetzlar, Germany). The sections were kept in 6-well plates containing PB saline (PBS, pH 7.4) for the next process.
To examine neurogenic effects of GLe in the DG, the prepared sections were carefully processed under the same conditions. Six sections per animal were selected with 150 μm interval according to anatomical landmarks corresponding to −1.46 and −2.46 mm posterior to the bregma with a reference to the mouse brain atlas. As previously described, in short, the sections were treated with 10% normal donkey serum (in 0.05 mol/L PBS) for 30 min and incubated with rat anti-BrdU (1:200, BioSource International, Camarillo, CA, USA) and goat anti-DCX (1:500, Santa Cruz Biotechnology, Santa Cruz, CA, USA) for 12 h at 4°C. The reacted sections were exposed to biotinylated goat anti-rat or rabbit anti-goat immunoglobulin G (IgG, 1:200, Vector, Burlingame, CA, USA) and streptavidin-peroxidase complex (1:200, Vector) for 2 h at room temperature. Finally, the reacted sections were visualized with 3,3'-diaminobenzidine tetrahydrochloride (in 0.1 mol/L Tris-hydrochloric acid buffer, pH 7.2). For reference, DNA denaturation was required for BrdU immunohistochemistry. The DNA denaturation was conducted by incubating the sections in 50% formamide/2X SSC (0.3 mol/L sodium chloride and 0.03 mol/L sodium citrate) and then incubated in 2 mol/L hydrochloric acid and in 0.1 mol/L boric acid. To examine the stained sections, the sections were dehydrated and mounted in Canada balsam (Kanto Chemical, Japan).
Negative control tests were conducted using preimmune serum instead of primary antibodies for establishing the specificity of the immunostaining. Negative controls resulted in no immunoreactivity in the tissues conducted (data not shown).
To examine the differentiation of newly generated cells to mature neurons, five sections per animal were chosen with 150 μm interval, and the sections were stained by double immunofluorescence staining with BrdU and neuronal nuclear antigen (NeuN, a mature neuronal marker) according to a published procedure. Briefly, DNA denaturation was conducted like the above-mentioned method. The denatured sections were incubated in a mixture of rat anti-BrdU (1:100, BioSource International, Camarillo, CA, USA) and rabbit anti-NeuN (1: 500, Chemicon, International Temecula, USA) 12 h at 4°C. They were then incubated in a mixture of both FITC-conjugated anti-rat IgG (1:200; Jackson ImmunoResearch, West Grove, PA, USA) and Cy3-conjugated anti-rabbit IgG (1:500; Jackson ImmunoResearch) for 3 h at room temperature.
Western blotting analysis
To observe changes in expression levels of BDNF and TrkB proteins in the DG, six mice from each group were anesthetized with Zoletil 50® (30 mg/kg) and sacrificed by cervical dislocation. Western blotting analysis was conducted by a published protocol. Briefly, brains of the mice were removed and serially cut into coronal sections of 400 μm thickness by a vibratome (Leica Camera AG, Wetzlar, Germany). Hippocampal tissues containing the DG were dissected with a surgical blade. The tissues were homogenized in 50 mmol/L PBS (pH 7.4) containing ethylene glycol tetraacetic acid (pH 8.0), 0.2% Nonidet P-40, 10 mmol/L ethylenediaminetetraacetic acid (pH 8.0), 15 mmol/L sodium pyrophosphate, 100 mmol/L β-glycerophosphate, 50 mmol/L sodium fluoride, 150 mmol/L sodium chloride, 2 mmol/L sodium orthovanadate, 1 mmol/L phenylmethylsulfonyl fluoride, and 1 mmol/L dithiothreitol (DTT). The homogenized tissues were centrifuged at 15,000 ×g for 25 min at 4°C. Protein levels in the supernatants were determined using a Micro Bicinchoninic Acid Protein Assay Kit with bovine serum albumin as a standard (Pierce Chemical, Rockford, IL, USA). The aliquots containing 50 μg total protein were boiled in the loading buffer that contained 250 mmol/L Tris (pH 6.8), 10 mmol/L DTT, 10% sodium dodecyl sulfate, 0.5% bromophenol blue, and 50% Glycerol, and they were subsequently loaded onto a 10% polyacrylamide gel (SigmaAldrich). After the electrophoresis, the gels were transferred onto nitrocellulose membranes (Pall Corp., Pittsburgh, PA, USA). The membranes were incubated with 5% non-fat dry milk in TBS (pH 7.4) containing 0.1% Tween 20 for 50 min to reduce background staining. The membranes were incubated with rabbit anti-BDNF (1:500, Abcam), rabbit anti-TrkB (1:500, Santa Cruz Biotechnology, Inc.), and rabbit anti-β-actin (1:5,000, Sigma-Aldrich, MO, USA) 12 h at 4°C, and they were exposed to peroxidase-conjugated goat anti-rabbit IgG (1:4,000, Santa Cruz Biotechnology, Inc.) and an enhanced chemiluminescence kit (GE Healthcare Life Sciences, Chalfont, UK).
The quantitative analysis of numbers of BrdU-immunoreactive (+) and DCX + cells was conducted by our published procedure. Briefly, images of all BrdU + and DCX + structures were captured from immunostained sections of the DG using a light microscope (BX53, Olympus, Germany), which was equipped with a digital camera (DP72, Olympus) that was connected to a PC monitor. A total number of BrdU + or DCX + cells were counted in six sections/each mouse using an image analyzing system equipped with a computer-based CCD camera (Optimas 6.5, CyberMetrics, Scottsdale, AZ, USA). Each cell count was conducted by averaging the total cell numbers of each mouse. In addition, for calculating a number of BrdU +/NeuN + cells in the DG, the double immunoreaction of BrdU/NeuN was observed using a confocal microscope (LSM 510 META NLO; Carl Zeiss, Jena, Germany) and the cell count was conducted as described above.
Western blotting analysis was conducted according to our published method. Shortly, bands of the Western blot were scanned, and a densitometric analysis was performed for the quantification of the bands. Scion Image 4.0.2 software (Scion Corp., Frederick, MD, USA) was used to calculate a relative optical density (ROD). Each ratio of the ROD was calibrated as a percent, and the ratio was compared with the vehicle-treated group, designated as 100%.
The data shown in this study represent the means ± standard error of mean. All statistical analyses were conducted using GraphPad Prism (version 5.0; GraphPad Software, La Jolla, CA, USA). Statistical analyses of differences between the groups were performed using one-way analysis of variance (ANOVA) with Duncan's post hoc test with SPPS software version 17.0 (SPSS, Inc., Chicago, IL, USA). A P < 0.05 was considered to indicate a statistically significant difference.
| Results|| |
In the vehicle-treated group, BrdU + cells were mainly found in the SGZ of the DG [Figure 1]A and [Figure 1]a, and the mean number of BrdU + cells in the SGZ was 16.0 ± 4.7 cells per se ction [Figure 1]D. In the 100 mg/kg GLe-treated group, the distribution pattern and a mean number of BrdU + cells in the DG were not significantly different from those in the vehicle-treated group [Figure 1]B, [Figure 1]b, and [Figure 1]D. However, in the 200 mg/kg GLe-treated group, BrdU + cells were significantly increased in the SGZ and GCL compared with those in the vehicle-treated group [Figure 1]C and [Figure 1]c, and the mean number of BrdU + cells was 48.0 ± 3.1 cells per se ction [Figure 1]D.
|Figure 1: Representative images of immunohistochemistry for BrdU in the DG of the vehicle-treated (A and a), 100 mg/kg GLe-treated (B and b), and 200 mg/kg GLe-treated (C and c) groups. In the vehicle-treated group, BrdU+ cells (arrows) are mainly located in the SGZ. BrdU+ cells are significantly increased only in the 200 mg/kg GLe-treated group. GCL: Granule cell layer; ML: Molecular layer; PL: Polymorphic layer. Scale bar = 200 (A, B, and C) and 40 (a, b, and c) μm. (D) The mean number of BrdU+ cells per section (n = 7 per group; *P < 0.05 vs. the vehicle-treated group). The bars indicate mean ± SEM. SEM: Standard error of the mean; BrdU: 5-bromo-2-deoxyuridine; DG: Dentate gyrus; GLe: Ethanol extract of Glehnia littoralis; SGZ: Subgranular zone.|
Click here to view
In the vehicle-treated group, DCX + cells (29.0 ± 4.5 cells) as neuroblasts were easily found in the SGZ of the DG [Figure 2]A. Some of them revealed poorly developed processes [Figure 2]a. In the 100 mg/kg GLe-treated group, there were no significant differences in the morphology and mean number of DCX + cells in the SGZ compared with those in the vehicle-treated group [Figure 2]B, [Figure 2]b, and [Figure 2]D. However, in the 200 mg/kg GLe-treated group, a number of DCX + cells were significantly increased (72.0 ± 3.8 cells/section) in the SGZ, and most of them had long and thick processes compared with those in the vehicle-treated group [Figure 2]C, [Figure 2]c, and [Figure 2]D.
|Figure 2: Representative images of DCX immunohistochemistry in the DG of the vehicle-treated (A and a), 100 mg/kg GLe-treated (B and b) and 200 mg/kg GLe-treated (C and c) groups. In the vehicle-treated group, DCX+ cells are found in the SGZ, and some of them show poorly developed processes (arrowheads). A significant increase in the number of DCX+ cells with well-developed processes (arrows) is observed only in the 200 mg/kg GLE-treated group. GCL: Granule cell layer; ML: Molecular layer; PL: Polymorphic layer. Scale bar = 200 (A, B, and C) and 40 (a, b, and c) μm. (D) The mean number of DCX+ cells per section (n = 7 per group; *P < 0.05 vs. the vehicle-treated group). The bars indicate mean ± SEM. SEM: Standard error of the mean; GLe: Ethanol extract of Glehnia littoralis; SGZ: Subgranular zone; DG: Dentate gyrus; DCX: Doublecortin.|
Click here to view
In the vehicle-treated group, cells co-labeled with BrdU and NeuN immunoreaction, as newly generated neurons, were mainly detected in the SGZ of the DG [Figure 3]a, [Figure 3]b, [Figure 3]c, and the mean number of BrdU +/NeuN + cells was 7.0 ± 1.1 cells per se ction [Figure 3]J. In the 100 mg/kg GLe-treated group, the distribution pattern and mean number of BrdU +/NeuN + cells were not different from the vehicle-treated group [Figure 3]d, [Figure 3]e, [Figure 3]f and [Figure 3]j. However, in the 200 mg/kg GLe-treated group, a significant increase in number of BrdU +/NeuN + cells (17.0 ± 1.5 cells/section) was observed in the SGZ, and some of them were detected in the granule cell layer [Figure 3]g, [Figure 3]h, [Figure 3]i, [Figure 3]j.
|Figure 3: Representative confocal images of cells double-labeled with BrdU (green; a, d, and g), NeuN (red; b, e, and h) and merged images (c, f, and i) in the DG of the vehicle-treated (a-c), 100 mg/kg GLe-treated (d-f), and 200 mg/kg GLe-treated (g-i) groups. In all groups, BrdU+/NeuN+ cells (arrows) are mainly distributed in the SGZ. BrdU+/NeuN+ cells are significantly increased only in the 200 mg/kg GLe-treated group. GCL: Granule cell layer; PL: Polymorphic layer. Scale bar = 40 μm. (j) The mean number of BrdU+/NeuN+ cells per section (n = 7 per group; *P < 0.05 vs. the vehicle-treated group). The bars indicate mean ± SEM. SEM: Standard error of mean; GLe: Ethanol extract of Glehnia littoralis; DG: Dentate gyrus; BrdU: 5-bromo-2-deoxyuridine; NeuN: Neuronal nuclear antigen.|
Click here to view
Protein levels of brain-derived neurotrophic factor and tropomyosin-related kinase B
Protein levels of BDNF and TrkB in the 100 mg/kg GLe-treated group were not significantly different from those in the vehicle-treated group [Figure 4]. However, protein levels of BDNF and TrkB in the 200 mg/kg GLe-treated group were significantly increased (about 232% and 244% of the vehicle-treated group, respectively) compared with the vehicle-treated group [Figure 4].
|Figure 4: Western blotting analysis of BDNF and TrkB in the DG derived from the vehicle-treated, 100 mg/kg GLe-treated, and 200 mg/kg GLe-treated groups. ROD as mean percentage values of immunoblot band is represented (n = 6 per group; *P < 0.05 vs. the vehicle-treated group). The bars indicate mean ± SEM. BDNF: Brain-derived neurotrophic factor; TrkB: Tropomyosin-related kinase B; DG: Dentate gyrus; GLe: Ethanol extract of Glehnia littoralis; ROD: Relative optical density.|
Click here to view
| Discussion|| |
Until now, many researchers have been trying to find new medical plants and their components, which can promote neurogenesis in the neurogenic regions, as a potential therapeutic agent of neurodegenerative diseases and many studies have demonstrated that some plant extracts and their components have the capacity to promote neurogenesis., Although some researchers recently showed that extracts of plants in the family Umbelliferae including Oenanthe javanica and Angelica sinensis improved cell proliferation and neuroblast differentiation in the SGZ of the hippocampal DG,, neurogenic effects of GLein the brainhave not yet been investigated. Therefore, in the present study, we examined effects of GLe treatment on cell proliferation, neuronal differentiation, and maturation of neurons to neural progenitor cells. Our results revealed that the number of BrdU + and DCX + cells only in the 200 mg/kg GLe-treated mice, not 100 mg/kg GLe, were significantly increased in the SGZ of the DG compared with the vehicle-treated mice; especially, increased DCX + cells in the 200 mg/kg GLe-treated mice showed a well-developed dendritic complexity, which is an important marker of neuronal development  and is crucial for the functional integration of newborn neurons into hippocampal neuronal circuitry., In addition, we found a significant increase in a number of BrdU +/NeuN + cells in the SGZ and GCL of the 200 mg/kg GLe-treated mice, which means neuronal maturation increased by GLe treatment. Therefore, these results indicate that treatment with GLe can promote adult neurogenesis in the hippocampal DG.
It has been reported that the neurogenic process is controlled by numerous neurotrophic factors., Among the neurotrophic factors, BDNF is a representative neurotrophic factor in the brain and binds its high-affinity receptor TrkB, which may act as a positive regulator of neurogenesis in the hippocampus. Specifically, it was reported that deletion of BDNF or TrkB-impaired neurogenesis in the DG of mice,, while exogenous BDNF or increases of BDNF and TrkB expressions in the hippocampus following exercise and treatment with diverse agents including natural materials and pharmacological drugs significantly promoted neurogenesis in the mouse and rat DG.,,, In this study, we found that protein levels of BDNF and TrkB in the hippocampal DG were significantly increased in the 200 mg/kg GLe-treated mice compared with the vehicle-treated mice. This result was consistent with our previous study that showed that treatment with 200 mg/kg of GLe significantly increased BDNF expression in the cornu ammonis 1 region of gerbil hippocampus, suggesting that increased BDNF expression was closely involved in neuronal survival after cerebral ischemic insult. Therefore, on the basis these reports as well as our results, we suggest that increased BDNF and TrkB expressions in the DG following GLe treatment might contribute to promoting adult hippocampal neurogenesis.
In summary, the results of this study revealed that treatment with GLe resulted in significant increases of cell proliferation, neuroblast differentiation, and neuronal maturation as well as BDNF and TrkB expressions in the hippocampal DG of adult mice. These results indicate that GLe can promote adult neurogenesis in the DG of the hippocampus and that increases of BDNF and TrkB expressions in the DG following GLe treatment might be closely associated with neurogenic effects of GLe. Thus, we suggest that G. littoralis can be used as a therapeutic potential candidate to prevent and treat neurodegenerative diseases, which involve the impairment of neurogenesis.
Financial support and sponsorship
This work was supported by the grants from Bio-Synergy Research Project (No. NRF-2015M3A9C4076322) of the Ministry of Science, ICT, and Future Planning through the National Research Foundation (NRF) of Korea, the Bio and Medical Technology Development Program of the NRF funded by the Korean government, MSIP (No. NRF-2015M3A9B6066835), Basic Science Research Program through the NRF of Korea funded by the Ministry of Education (No. NRF-2017R1D1A1B03033271).
Conflicts of interest
There are no conflicts of interest.
| References|| |
Eriksson PS, Perfilieva E, Björk-Eriksson T, Alborn AM, Nordborg C, Peterson DA, et al.
Neurogenesis in the adult human hippocampus. Nat Med 1998;4:1313-7. doi: 10.1038/3305.
Whalley K. Adult neurogenesis: Encouraging integration. Nat Rev Neurosci 2016;17:669. doi: 10.1038/nrn.2016.136.
Clelland CD, Choi M, Romberg C, Clemenson GD Jr., Fragniere A, Tyers P, et al.
A functional role for adult hippocampal neurogenesis in spatial pattern separation. Science 2009;325:210-3. doi: 10.1126/science.1173215.
Sahay A, Scobie KN, Hill AS, O'Carroll CM, Kheirbek MA, Burghardt NS, et al.
Increasing adult hippocampal neurogenesis is sufficient to improve pattern separation. Nature 2011;472:466-70. doi: 10.1038/nature09817.
Hollands C, Tobin MK, Hsu M, Musaraca K, Yu TS, Mishra R, et al.
Depletion of adult neurogenesis exacerbates cognitive deficits in Alzheimer's disease by compromising hippocampal inhibition. Mol Neurodegener 2017;12:64. doi: 10.1186/s13024-017-0207-7.
Kohl Z, Ben Abdallah N, Vogelgsang J, Tischer L, Deusser J, Amato D, et al.
Severely impaired hippocampal neurogenesis associates with an early serotonergic deficit in a BAC α-synuclein transgenic rat model of Parkinson's disease. Neurobiol Dis 2016;85:206-17. doi: 10.1016/j.nbd.2015.10.021.
Mathews KJ, Allen KM, Boerrigter D, Ball H, Shannon Weickert C, Double KL, et al.
Evidence for reduced neurogenesis in the aging human hippocampus despite stable stem cell markers. Aging Cell 2017;16:1195-9. doi: 10.1111/acel.12641.
Abdipranoto A, Wu S, Stayte S, Vissel B. The role of neurogenesis in neurodegenerative diseases and its implications for therapeutic development. CNS Neurol Disord Drug Targets 2008;7:187-210.
Sailor KA, Ming GL, Song H. Neurogenesis as a potential therapeutic strategy for neurodegenerative diseases. Expert Opin Biol Ther 2006;6:879-90. doi: 10.2174/187152708784083858.
de Rus Jacquet A, Timmers M, Ma SY, Thieme A, McCabe GP, Vest JHC, et al.
Lumbee traditional medicine: Neuroprotective activities of medicinal plants used to treat Parkinson's disease-related symptoms. J Ethnopharmacol 2017;206:408-25. doi: 10.1016/j.jep.2017.02.021.
Howes MR, Fang R, Houghton PJ. Effect of Chinese herbal medicine on Alzheimer's disease. Int Rev Neurobiol 2017;135:29-56. doi: 10.1016/bs.irn.2017.02.003.
Wiart C. Medicinal plants of China, Korea, and Japan: Bioresources for Tomorrow's Drugs and Cosmetics. Boca Raton, FL: CRC Press; 2012. p. 432.
Yuan Z, Tezuka Y, Fan W, Kadota S, Li X. Constituents of the underground parts of Glehnia littoralis
. Chem Pharm Bull (Tokyo) 2002;50:73-7. doi: 10.1248/cpb.50.73.
Matsuura H, Saxena G, Farmer SW, Hancock RE, Towers GH. Antibacterial and antifungal polyine compounds from Glehnia littoralis
ssp. leiocarpa. Planta Med 1996;62:256-9. doi: 10.1055/s-2006-957872.
Ng TB, Liu F, Wang HX. The antioxidant effects of aqueous and organic extracts of Panax quinquefolium
, Panax notoginseng
, Codonopsis pilosula
, Pseudostellaria heterophylla
and Glehnia littoralis
. J Ethnopharmacol 2004;93:285-8. doi: 10.1016/j.jep.2004.03.040.
Yoon T, Lee DY, Lee AY, Choi G, Choo BK, Kim HK, et al.
Anti-inflammatory effects of Glehnia littoralis
extract in acute and chronic cutaneous inflammation. Immunopharmacol Immunotoxicol 2010;32:663-70. doi: 10.3109/08923971003671108.
Park JH, Lee TK, Yan BC, Shin BN, Ahn JH, Kim IH, et al.
Pretreated Glehnia littoralis
extract prevents neuronal death following transient global cerebral ischemia through increases of superoxide dismutase 1 and brain-derived neurotrophic factor expressions in the gerbil hippocampal cornu ammonis 1 area. Chin Med J 2017;130:1796-803. doi: 10.4103/0366-6999.211554.
] [Full text]
Couillard-Despres S, Winner B, Schaubeck S, Aigner R, Vroemen M, Weidner N, et al.
Doublecortin expression levels in adult brain reflect neurogenesis. Eur J Neurosci 2005;21:1-4. doi: 10.1111/j.1460-9568.2004.03813.x.
Kee N, Sivalingam S, Boonstra R, Wojtowicz JM. The utility of Ki-67 and BrdU as proliferative markers of adult neurogenesis. J Neurosci Methods 2002;115:97-105. doi: 10.1016/s0165-0270(02)00007-9.
Bergami M, Rimondini R, Santi S, Blum R, Götz M, Canossa M, et al.
Deletion of TrkB in adult progenitors alters newborn neuron integration into hippocampal circuits and increases anxiety-like behavior. Proc Natl Acad Sci U S A 2008;105:15570-5. doi: 10.1073/pnas.0803702105.
Li Y, Luikart BW, Birnbaum S, Chen J, Kwon CH, Kernie SG, et al.
TrkB regulates hippocampal neurogenesis and governs sensitivity to antidepressive treatment. Neuron 2008;59:399-412. doi: 10.1016/j.neuron.2008.06.023.
Chen BH, Park JH, Cho JH, Kim IH, Lee JC, Lee TK, et al.
Tanshinone I enhances neurogenesis in the mouse hippocampal dentate gyrus via increasing Wnt-3, phosphorylated glycogen synthase kinase-3β and β-catenin immunoreactivities. Neurochem Res 2016;41:1958-68. doi: 10.1007/s11064-016-1906-0.
Cho JH, Park JH, Ahn JH, Lee JC, Hwang IK, Park SM, et al.
Vanillin and 4-hydroxybenzyl alcohol promotes cell proliferation and neuroblast differentiation in the dentate gyrus of mice via the increase of brain-derived neurotrophic factor and tropomyosin-related kinase B. Mol Med Rep 2016;13:2949-56. doi: 10.3892/mmr.2016.4915.
Franklin KB, Paxinos G. The Mouse Brain in Stereotaxic Coordinates. San Diego: Academic Press; 1997. p. 22, 186.
Lee TH, Lee CH, Kim IH, Yan BC, Park JH, Kwon SH, et al.
Effects of ADHD therapeutic agents, methylphenidate and atomoxetine, on hippocampal neurogenesis in the adolescent mouse dentate gyrus. Neurosci Lett 2012;524:84-8. doi: 10.1016/j.neulet.2012.07.029.
Bae JS, Han M, Shin HS, Shon DH, Lee ST, Shin CY, et al.
Lycopersicon esculentum extract enhances cognitive function and hippocampal neurogenesis in aged mice. Nutrients 2016;8. pii: E679. doi: 10.3390/nu8110679.
Nakai M, Iizuka M, Matsui N, Hosogi K, Imai A, Abe N, et al.
Bangle (Zingiber purpureum
) improves spatial learning, reduces deficits in memory, and promotes neurogenesis in the dentate gyrus of senescence-accelerated mouse P8. J Med Food 2016;19:435-41. doi: 10.1089/jmf.2015.3562.
Chen BH, Park JH, Cho JH, Kim IH, Shin BN, Ahn JH, et al.
Ethanol extract of Oenanthe javanica
increases cell proliferation and neuroblast differentiation in the adolescent rat dentate gyrus. Neural Regen Res 2015;10:271-6. doi: 10.4103/1673-5374.152382.
] [Full text]
Xin J, Zhang J, Yang Y, Deng M, Xie X. Radix angelica sinensis that contains the component Z-ligustilide promotes adult neurogenesis to mediate recovery from cognitive impairment. Curr Neurovasc Res 2013;10:304-15. doi: 10.2174/15672026113109990023.
Cohen D, Segal M, Reiner O. Doublecortin supports the development of dendritic arbors in primary hippocampal neurons. Dev Neurosci 2008;30:187-99. doi: 10.1159/000109862.
Ge S, Yang CH, Hsu KS, Ming GL, Song H. A critical period for enhanced synaptic plasticity in newly generated neurons of the adult brain. Neuron 2007;54:559-66. doi: 10.1016/j.neuron.2007.05.002.
Plümpe T, Ehninger D, Steiner B, Klempin F, Jessberger S, Brandt M, et al.
Variability of doublecortin-associated dendrite maturation in adult hippocampal neurogenesis is independent of the regulation of precursor cell proliferation. BMC Neurosci 2006;7:77. doi: 10.1186/1471-2202-7-77.
Hagg T. From neurotransmitters to neurotrophic factors to neurogenesis. Neuroscientist 2009;15:20-7. doi: 10.1177/1073858408324789.
Lee E, Son H. Adult hippocampal neurogenesis and related neurotrophic factors. BMB Rep 2009;42:239-44. doi: 10.5483/bmbrep.2009.42.5.239.
Lee J, Duan W, Mattson MP. Evidence that brain-derived neurotrophic factor is required for basal neurogenesis and mediates, in part, the enhancement of neurogenesis by dietary restriction in the hippocampus of adult mice. J Neurochem 2002;82:1367-75. doi: 10.1046/j.1471-4159.2002.01085.x.
Kim BK, Shin MS, Kim CJ, Baek SB, Ko YC, Kim YP, et al.
Treadmill exercise improves short-term memory by enhancing neurogenesis in amyloid beta-induced Alzheimer disease rats. J Exerc Rehabil 2014;10:2-8. doi: 10.12965/jer.140086.
Scharfman H, Goodman J, Macleod A, Phani S, Antonelli C, Croll S, et al.
Increased neurogenesis and the ectopic granule cells after intrahippocampal BDNF infusion in adult rats. Exp Neurol 2005;192:348-56. doi: 10.1016/j.expneurol.2004.11.016.
[Figure 1], [Figure 2], [Figure 3], [Figure 4]