INJ Search

CLOSE


Int Neurourol J > Volume 23(2); 2019 > Article
Shin, Kim, Park, Ko, Kim, Kim, Roh, Kim, and Kim: Long-term Surgical and Chemical Castration Deteriorates Memory Function Through Downregulation of PKA/CREB/BDNF and c-Raf/MEK/ERK Pathways in Hippocampus

ABSTRACT

Purpose

Goserelin is a drug used for chemical castration. In a rat model, we investigated whether surgical and chemical castration affected memory ability through the protein kinase A (PKA)/cyclic adenosine monophosphate response element-binding protein (CREB)/brain-derived neurotrophic factor (BDNF) and c-Raf/mitogen-activated protein kinases-extracellular signal–regulated kinases (MEK)/extracellular signal–regulated kinases (ERK) pathways in the hippocampus.

Methods

Orchiectomy was performed for surgical castration and goserelin acetate was subcutaneously transplanted into the anterior abdominal wall for chemical castration. Immunohistochemistry was done to quantify neurogenesis. To assess the involvement of the PKA/CREB/BDNF and c-Raf/MEK/ERK pathways in the memory process, western blots were used.

Results

The orchiectomy group and the goserelin group showed less neurogenesis and impaired short-term and spatial memory. Phosphorylation of PKA/CREB/BDNF and phosphorylation of c-Raf/MEK/ERK decreased in the orchiectomy and goserelin groups.

Conclusions

Short-term memory and spatial memory were affected by surgical and chemical castration via the PKA/CREB/BDNF and c-Raf/MEK/ERK signaling pathways.

• HIGHLIGHTS

- Surgical and chemical castration decreased neurogenesis and impaired short-term and spatial memory.
- Phosphorylation of the PKA/CREB/BDNF pathway decreased after surgical castration and chemical castration.
- Phosphorylation of the c-Raf/MEK/ERK pathway decreased after surgical castration and chemical castration.

INTRODUCTION

Chemical castration using luteinizing hormone-releasing hormone (LHRH) agonists is an alternative method to surgical castration. Goserelin, a synthetic long-acting agonist of LHRH, has been used in the treatment of prostate cancer, metastatic breast cancer, and uterine fibromas. This agent has similar effects to surgical castration [1]. Chronic orchiectomy has been found to result in deficits in spatial learning, which were reversed by testosterone replacement at physiological levels [2]. It was also reported that surgical castration of male rats impaired their performance on a working memory task during acquisition of an 8-arm maze task [3].
Newly formed neurons in the hippocampus play a significant role in hippocampal-dependent learning and memory [4]. Removal of testicular hormones by castration reduces the number of newly generated neurons in adult rodents, leading to a decline in memory [5,6]. Testosterone enhances neurogenesis in adult animals, while in contrast, low testosterone decreases hippocampal neurogenesis and neuronal survival [5]. Testosterone deprivation impairs spatial working memory and cognitive function in male rats [7].
The category of neurotrophins includes brain-derived neurotrophic factor (BDNF), nerve growth factor, neurotrophin-3 (NT-3), NT-4/5, NT-6, and NT-7. Of these, BDNF is known to be responsible for neurogenesis, neuroprotection, and synaptic plasticity [8]. Cyclic adenosine monophosphate response element-binding protein (CREB) acts as a transcription factor and plays an important role in neuronal survival, neurogenesis, and synaptic plasticity. Increased phosphorylated CREB (p-CREB) expression leads to increased activation of protein kinase A (PKA) [9]. The CREB signal, including BDNF, controls the expression of genes that promote synaptic and neuronal plasticity [10]. CREB-BDNF signaling has been associated with many neurobiological phenomena, including cell survival and synaptic plasticity [11]. In the hippocampus, the PKA-CREB-BDNF pathway has been suggested to be closely associated with cognitive function [12]. We sought to explore the relationship between cognitive function after castration and the PKA-CREB-BDNF signaling pathway.
Mitogen-activated protein kinases (MAPKs), including serine and threonine protein kinases, are involved in synaptic plasticity, learning, and memory [13]. Of these, extracellular signal–regulated kinases (ERKs) are activated by c-Raf serine/threonine kinases. c-Raf activates MAPK-ERK kinase (MEK), which then activates ERK1/2 [14]. The c-Raf/MEK/ERK pathway has been suggested to play a crucial role in the hippocampal memory acquisition process [15]. Therefore, we also sought to explore the relationship between memory processes after castration and the c-Raf/MEK/ERK signaling pathway.
PKA/CREB/BDNF and c-Raf/MEK/ERK signaling is closely related to memory formation processes. In a rat model, we investigated whether surgical and chemical castration influenced memory capability through the PKA/CREB/BDNF and c-Raf/MEK/ERK pathways in the hippocampus.

MATERIALS AND METHODS

Animals Treatments

The Institutional Animal Care and Ethics Committee (KHUASP [SE]-18-150) of Kyung Hee University reviewed and approved this experimental procedure. Male Sprague-Dawley rats were purchased commercially (Orient Co., Seoul, Korea); their weight was 300±10 g and their age was 8 weeks. The rats were equally divided into 3 groups: the sham-operation group, the orchiectomy group, and the goserelin group (n=10 in each group).

Surgical Castration

Bilateral orchiectomy was performed as described elsewhere [16]. Briefly, using 3% isoflurane in 20% O2 and 77 % N2, the rats were anesthetized. After an incision was made on the center of the scrotum, the arteries, veins, and ductus deferens were isolated, ligated, and severed. We removed the testicles and epididymis in the same manner.

Chemical Castration with Goserelin

Goserelin acetate in a biodegradable cylinder (1 mm wide ×5 mm long, 3.6 mg) (Zoladex, AstraZeneca, Bedfordshire, UK) was subcutaneously transplanted into the anterior abdominal wall of the rats in the goserelin treatment group. The transplantation of goserelin was repeated 3 times at intervals of 4 weeks, and the total application of the drug lasted 84 days.

Step-Down Avoidance Test

Following a previously described method [17], the step-down avoidance test was conducted to assess short-term memory. Eighty-three days after the start of the experiment, the rats were placed on a 7×25-cm platform and the time taken for them to descend was measured. The platform faced a 42×25-cm grid, and stainless steel bars measuring 0.1 cm in diameter were placed 1 cm apart at a height of 2.5 cm. Twenty-four hours before determining latency, the animals were immediately shocked with a 0.5-mA scramble for 3 seconds as they reached the ground. The latency time was determined 24 hours after the training session. Latency was defined as the time interval between the time the rat descended and when its four legs were placed on the grid. A latency time of 5 minutes or longer was considered as 5 minutes.

Eight-Arm Radial Maze Test

Following methods described elsewhere [18], the eight-arm radial maze test was conducted 82 days after the start of the experiment. Starting 24 hours before the test, the rats were deprived of water. The maze consisted of an octagonal stage with eight arms, which were 50 cm long and 10 cm wide. A water cup measuring 1 cm in depth and 3 cm in diameter was placed at the end of each of the eight arms. The maze was placed 1 m above the floor. When the rat had drunk all of the water in the 8 arms, or when more than 5 minutes had elapsed in the experiment, then the test was completed. Re-entering a previously visited arm was considered to be an error, and the error number was tabulated. The number of correct choices before the first error was recorded as the correct number.

Testosterone Detection

From a cardiac puncture, blood from each rat was collected and assayed for serum testosterone. A SpectraMax 190 enzymelinked immunosorbent assay (ELISA) reader (Molecular Devices, Sunnyvale, CA, USA) was used at a wavelength of 450 nm, with commercially available testosterone ELISA kits (IBL International GmbH, Hamburg, Germany).

Tissue Preparation

Zoletil 50 (10 mg/kg, intraperitoneally; Vibac Laboratories, Carros, France) was used to induce anesthesia, and then the rats received a transcardial perfusion of 50mM phosphate-buffered saline (PBS). Next, the rats were infused with a solution containing 4% paraformaldehyde in 100mM phosphate buffer (pH, 7.4). After that, fixed brains were cryoprotected in a 30% sucrose solution for 3 days, and the sections were cut into 40-μm coronal sections using a freezing microtome (Leica, Nussloch, Germany). On average, eight sections including the hippocampus were obtained.

BrdU Immunohistochemistry

Following a previously described method [18], 5-bromo-2′-deoxyuridine (BrdU) immunohistochemistry was carried out. First, the sections were infiltrated with 0.5% Triton X-100 in PBS for 20 minutes, and then they were pretreated with 50% formamide-2 X standard saline citrate for 2 hours at 65℃. Next, the sections were incubated with 2 N HCl for 1 hour, neutralized with 0.1M sodium borate buffer (pH, 8.5) for 30 minutes, and treated with mouse monoclonal anti-BrdU primary antibody (1:600, Roche Applied Science, Mannheim, Germany) at 4℃ overnight. After washing 3 times, these sections were treated with a biotinylated mouse secondary antibody (1:200; Vector Laboratories, Burlingame, CA, USA) for 1 hour, followed by treatment with avidin–peroxidase complex (1:100; Vector Laboratories) for 1 hour. The sections were then visualized in 50mM Tris-HCl (pH, 7.6) containing 0.03% hydrogen peroxide, 0.03% 3,3′-diaminobenzidine (DAB), and 40-mg/mL nickel chloride for immunostaining.
The same sections were counterstained using mouse antineuronal nuclei antibody (1:300; Chemicon International, Temecula, CA, USA). After washing 3 times, the sections were treated with a biotinylated mouse secondary antibody (1:200; Vector Laboratories) for 1 hour, followed by another hour of treatment with avidin-peroxidase complex (1:100; Vector Laboratories) at 4℃. These slides were dehydrated by alcohol and mounted using Permount coverslips (Thermo Fisher Scientific Inc., Fair Lawn, NJ, USA).

DCX Immunohistochemistry

Following a method described elsewhere [18], doublecortin (DCX) immunohistochemistry was performed. After the sections were incubated in 3% H2O2 for 30 minutes at room temperature, they were blocked by 10% normal rabbit serum in PBS with 0.2% Triton X-100 and 1% bovine serum albumin for 1 hour. The section was incubated in goat anti-DCX antibody (1:500; Santa Cruz Biotechnology, Santa Cruz, CA, USA) at 4℃ overnight. After washing 3 times, the sections were treated with a biotinylated goat secondary antibody (1:200; Vector Laboratories) for 1 hour, followed by another hour with avidin–peroxidase complex (1:100; Vector Laboratories). The sections were visualized in 50mM Tris-HCl (pH, 7.6) containing 0.03% hydrogen peroxide and 0.03% DAB for immunostaining. The slides were dehydrated by alcohol and mounted using Permount coverslips (Thermo Fisher Scientific Inc.).

Western Blot Analysis

Following a method described elsewhere [18], western blotting analysis was conducted. The hippocampal tissues were homogenized in lysis buffer (1% Triton X-100, 150mM NaCl, 10% glycerol, 100mM sodium fluoride, 1mM sodium orthovanadate, 1mM PMSF [phenylmethylsulfonyl fluoride], 1.5mM MgCl2 ·6H2O, 1mM EGTA [ethyleneglycol-bis-(b-aminoethylether)- N,N,N’,N’-tetraacetic acid], and 50mM HEPES [N-2-hydroxyethylpiperazine-N-2-ethanesulfonic acid]). After centrifugation for 15 minutes at 4℃ (14,000 rpm), the supernatant was collected. Using a Bio-Rad protein assay kit (Hercules, CA, USA), protein content was measured. Protein (40 μg) was electrophoresed on sodium dodecyl sulfate-polyacrylamide gel electrophoresis gel, and then transferred to nitrocellulose membranes. The membranes were blocked with 5% skim milk powder at 4℃ for 1 hour, and then treated with mouse actin antibody (Santa Cruz Biotechnology; 1:500), rabbit BDNF antibody (Santa Cruz Biotechnology; 1:1,000), rabbit tropomyosin receptor kinase B (TrkB) antibody (Santa Cruz Biotechnology; 1:1,000), rabbit total PKA antibody (Santa Cruz Biotechnology; 1:1,000), rabbit p-PKA antibody (Santa Cruz Biotechnology; 1:1,000), rabbit total c-Raf antibody (Santa Cruz Biotechnology; 1:1,000), rabbit p-c-Raf antibody (Santa Cruz Biotechnology; 1:1,000), rabbit total MEK 1/2 antibody (Santa Cruz Biotechnology; 1:1,000), rabbit p-MEK 1/2 antibody (Santa Cruz Biotechnology; 1:1,000), rabbit total ERK 1/2 antibody (Santa Cruz Biotechnology; 1:1,000), p-ERK 1/2 antibody (1:1, 000; Cell Signaling Technology, Danvers, MA, USA). The membranes were treated with horseradish peroxidase-conjugated secondary rabbit antibody (1:2,000) at room temperature for 1 hour. Bands were visualized using an enhanced chemiluminescence detection system (Santa Cruz Biotechnology).

Data Analysis

After determining the area of the hippocampal dentate gyrus using the Image-Pro Plus image analyzer (Media Cybernetics Inc., Silver Spring, MD, USA), the numbers of BrdU-positive and DCX-positive cells were expressed as the numbers of cells per square millimeter of the granular cell layer in the hippocampal dentate gyrus. Bands were densitometrically quantified using ImagePro Plus software (Media Cybernetics) to compare protein expression levels.
The results are presented as the mean±standard error of the mean. One-way analysis of variance and the Duncan post hoc test were performed for comparisons among the groups. P-values<0.05 were considered to indicate statistical significance.

RESULTS

Testosterone Concentration

Data on testosterone concentration are shown in Fig. 1. Serum concentrations of testosterone were lower in the orchiectomy group and in the goserelin group than in the sham-operation group (P<0.05).

Short-term Memory

Fig. 2A presents data on the latency time of the step-down avoidance task. The latency time was shorter in the orchiectomy group and in the goserelin group than in the sham-operation group (P<0.05).

Spatial Memory

Fig. 2B and C show the correct choice number and error number from the 8-arm radial maze task. The rats in the orchiectomy group and in the goserelin group showed higher error numbers than those in the sham-operation group (P<0.05). The correct number, in contrast, exhibited no significant differences among the 3 groups.

Neurogenesis

Fig. 3 presents photomicrographs of BrdU-positive cells and DCX-positive cells in the hippocampal dentate gyrus. Hippocampal neurogenesis was suppressed in the orchiectomy group and in the goserelin group relative to the sham-operation group (P<0.05). DCX-positive cells were suppressed in the orchiectomy group and in the goserelin group relative to the sham-operation group (P<0.05).

BDNF, TrkB, p-PKA, p-CREB Expressions in Hippocampus

Fig. 4 shows the relative expression levels of BDNF, TrkB, p-PKA, and p-CREB in the hippocampus. The expression of BDNF, TrkB, p-PKA, and p-CREB was suppressed in the orchiectomy group and in the goserelin group relative to the shamoperation group (P<0.05 for all).

p-c-Raf, p-MEK, p-ERK Expression in Hippocampus

Fig. 5 shows the relative expression levels of p-c-Raf, p-MEK, and p-ERK in the hippocampus, all of which were suppressed in the orchiectomy group and in the goserelin group relative to the sham-operation group (P<0.05 for all).

DISCUSSION

Plasma testosterone mainly originates in the testicles, and orchiectomized rats have been shown to have very low testosterone levels. LHRH agonists cause chemical castration equivalent to surgical castration [19]. In the current study, testosterone levels were similarly low in goserelin-treated and orchiectomized rats.
Beer et al. [20] reported that prostate cancer treatment resulted in androgen deficiency, leading to long-term memory impairment. Cognitive deficits can be a symptom of orchiectomy, which is associated with a decrease in the expression of hippocampal androgen receptors [21]. In the current study, orchiectomy and goserelin treatment reduced short-term memory and worsened spatial memory.
The hippocampus is a target of androgen action, as testosterone improves hippocampal neurogenesis through an androgendependent mechanism [5]. Orchiectomy-induced reduction of testicular hormone levels leads to a decrease in new cell formation in the hippocampus [5,6]. Testosterone supplementation, in contrast, improves the castration-induced decrease in new cell formation [5,6]. In the current study, orchiectomy and goserelin treatment suppressed new cell formation in the hippocampal dentate gyrus.
Activation of the CREB cascade is regulated by PKA, ERK, and phosphatidylinositol-3 kinase [22]. Inhibition of CREB decreased neurogenesis and hippocampal plasticity, whereas expression of CREB may contribute to the number of new neurons and memory ability [23]. The downstream actions of CREB involve effects on synaptic plasticity and hippocampaldependent long-term memory [24]. PKA can directly activate CREB by phosphorylation of CREB [25]. In the adult brain, CREB participates in neuronal plasticity and potentiates learning and memory processes [26]. Learning and memory capacity is known to be enhanced through the PKA-CREB-BDNF signaling pathway [27]. In the current study, orchiectomy and goserelin reduced the level of phosphorylated PKA-CREBBDNF signaling. These results indicate that orchiectomy or goserelin treatment exacerbates memory impairment by reducing PKA/CREB/BDNF/signaling.
The most important upstream activator of c-Raf-MEK-ERK is the Raf protein [14]. Phosphorylation of c-Raf at threonine and serine residues activates c-Raf, which in turn activates MEK. Furthermore, activated MEK activates MAPK. The MAPK pathway is a series of intracellular phosphorylation cascades that play important roles in transducing extracellular stimuli, ultimately leading to cell differentiation, proliferation, survival, or death [28]. The ERK signaling pathway modulates hippocampal-dependent learning and long-term synaptic plasticity [29]. MAPK/ERK activation is necessary for memory consolidation and synaptic plasticity [30].
The ERK pathway is a major signaling pathway within the MAPK signaling pathway. Activation of ERK has been strongly implicated in the differentiation, survival, and adaptive responses of neurons during development and in the adult brain [31]. MAPKs regulate the transcription of specific genes through activation of the transcription factor CREB [32]. In the present study, orchiectomy and goserelin inhibited the levels of phosphorylated c-Raf, MEK 1/2, and ERK 1/2. These results indicate that orchiectomy or goserelin treatment exacerbates memory impairment by reducing the phosphorylation of c-Raf/MEK/ERK.
Downregulation of the PKA/CREB/BDNF and c-Raf/MEK/ERK pathways may result in reduced neurogenesis, which is an important mechanism underlying the spatial memory dysfunction caused by long-term surgical and chemical castration.

NOTES

Fund/Grant Support
This research was supported by the grants from the National Research Foundation of Korea (NRF-2013R1A1A1063509).
Research Ethics
The experimental procedure was approved by the Kyung Hee University Institutional Animal Care and Ethics Committee (KHUASP[SE]-18-150).
Conflict of Interest
KHK, an associate editor of International Neurourology Journal, is the corresponding author of this article. However, he played no role whatsoever in the editorial evaluation of this article or the decision to publish it. Except for that, no potential conflict of interest relevant to this article was reported.
AUTHOR CONTRIBUTION STATEMENT
·Full access to all the data in the study and takes responsibility for the integrity of the data and the accuracy of the data analysis: SMS, CJK
·Study concept and design: SMS, KHK
·Acquisition of data: TWK, SSP, IGK
·Analysis and interpretation of data: MK, SYR
·Drafting of the manuscript: SMS
·Critical revision of the manuscript for important intellectual content: CJK
·Statistical analysis: TWK, SSP, IGK
·Administrative, technical, or material support: MK, SYR
·Study supervision: CJK, KHK

REFERENCES

1. Lehmusvaara S, Erkkilä T, Urbanucci A, Waltering K, Seppälä J, Larjo A, et al. Chemical castration and anti-androgens induce differential gene expression in prostate cancer. J Pathol 2012;227:336-45. PMID: 22431170
crossref pmid
2. Kritzer MF, McLaughlin PJ, Smirlis T, Robinson JK. Gonadectomy impairs T-maze acquisition in adult male rats. Horm Behav 2001;39:167-74. PMID: 11243744
crossref pmid
3. Daniel JM, Winsauer PJ, Moerschbaecher JM. Castration in rats impairs performance during acquisition of a working memory task and exacerbates deficits in working memory produced by scopolamine and mecamylamine. Psychopharmacology (Berl) 2003;170:294-300. PMID: 12898124
crossref pmid pdf
4. Shin MS, Ko IG, Kim SE, Kim BK, Kim TS, Lee SH, et al. Treadmill exercise ameliorates symptoms of methimazole-induced hypothyroidism through enhancing neurogenesis and suppressing apoptosis in the hippocampus of rat pups. Int J Dev Neurosci 2013;31:214-23. PMID: 23328696
crossref pmid
5. Spritzer MD, Galea LA. Testosterone and dihydrotestosterone, but not estradiol, enhance survival of new hippocampal neurons in adult male rats. Dev Neurobiol 2007;67:1321-33. PMID: 17638384
crossref pmid
6. Hamson DK, Wainwright SR, Taylor JR, Jones BA, Watson NV, Galea LA. Androgens increase survival of adult-born neurons in the dentate gyrus by an androgen receptor-dependent mechanism in male rats. Endocrinology 2013;154:3294-304. PMID: 23782943
crossref pmid pdf
7. Pintana H, Pongkan W, Pratchayasakul W, Chattipakorn N, Chattipakorn SC. Testosterone replacement attenuates cognitive decline in testosterone-deprived lean rats, but not in obese rats, by mitigating brain oxidative stress. Age (Dordr) 2015;37:84. PMID: 26277724
crossref pmid pmc pdf
8. Begni V, Riva MA, Cattaneo A. Cellular and molecular mechanisms of the brain-derived neurotrophic factor in physiological and pathological conditions. Clin Sci (Lond) 2017;131:123-38. PMID: 28011898
crossref pmid
9. Xue W, Wang W, Gong T, Zhang H, Tao W, Xue L, et al. PKACREB-BDNF signaling regulated long lasting antidepressant activities of Yueju but not ketamine. Sci Rep 2016;6:26331. PMID: 27197752
crossref pmid pmc
10. Yi JH, Park HJ, Beak SJ, Lee S, Jung JW, Kim BC, et al. Danggui-Jakyak-San enhances hippocampal long-term potentiation through the ERK/CREB/BDNF cascade. J Ethnopharmacol 2015;175:481-9. PMID: 26453932
crossref pmid
11. Karege F, Bondolfi G, Gervasoni N, Schwald M, Aubry JM, Bertschy G. Low brain-derived neurotrophic factor (BDNF) levels in serum of depressed patients probably results from lowered platelet BDNF release unrelated to platelet reactivity. Biol Psychiatry 2005;57:1068-72. PMID: 15860348
crossref pmid
12. Wang C, Guo J, Guo R. Effect of XingPiJieYu decoction on spatial learning and memory and cAMP-PKA-CREB-BDNF pathway in rat model of depression through chronic unpredictable stress. BMC Complement Altern Med 2017;17:73. PMID: 28118829
crossref pmid pmc pdf
13. Sweatt JD. The neuronal MAP kinase cascade: a biochemical signal integration system subserving synaptic plasticity and memory. J Neurochem 2001;76:1-10. PMID: 11145972
crossref pmid
14. Roberts PJ, Der CJ. Targeting the Raf-MEK-ERK mitogen-activated protein kinase cascade for the treatment of cancer. Oncogene 2007;26:3291-310. PMID: 17496923
crossref pmid pdf
15. Sweatt JD. Mitogen-activated protein kinases in synaptic plasticity and memory. Curr Opin Neurobiol 2004;14:311-7. PMID: 15194111
crossref pmid
16. Han JH, Shin MS, Lee JM, Kim TW, Jin JJ, Ko IG, et al. Long-term chemical castration induces depressive symptoms by suppressing serotonin expression in rats. Anim Cells Syst 2018;1:29-36. crossref
17. Jung SY, Kim DY. Treadmill exercise improves motor and memory functions in cerebral palsy rats through activation of PI3K-Akt pathway. J Exerc Rehabil 2017;13:136-42. PMID: 28503524
crossref pmid pmc pdf
18. Lee JM, Ji ES, Kim TW, Kim CJ, Shin MS, Lim BV, et al. Treadmill exercise improves memory function by inhibiting hippocampal apoptosis in pilocarpine-induced epileptic rats. J Exerc Rehabil 2018;14:713-23. PMID: 30443515
crossref pmid pmc pdf
19. de Jong IJ, Eaton A, Bladou F. LHRH agonists in prostate cancer: frequency of treatment, serum testosterone measurement and castrate level: consensus opinion from a roundtable discussion. Curr Med Res Opin 2007;23:1077-80. PMID: 17519074
crossref pmid
20. Beer TM, Bland LB, Bussiere JR, Neiss MB, Wersinger EM, Garzotto M, et al. Testosterone loss and estradiol administration modify memory in men. J Urol 2006;175:130-5. PMID: 16406889
crossref pmid
21. Hawley WR, Grissom EM, Martin RC, Halmos MB, Bart CL, Dohanich GP. Testosterone modulates spatial recognition memory in male rats. Horm Behav 2013;63:559-65. PMID: 23481590
crossref pmid
22. Hashimoto K, Shimizu E, Iyo M. Critical role of brain-derived neurotrophic factor in mood disorders. Brain Res Brain Res Rev 2004;45:104-14. PMID: 15145621
crossref pmid
23. Zhu DY, Lau L, Liu SH, Wei JS, Lu YM. Activation of cAMP-response-element-binding protein (CREB) after focal cerebral ischemia stimulates neurogenesis in the adult dentate gyrus. Proc Natl Acad Sci U S A 2004;101:9453-7. PMID: 15197280
crossref pmid pmc
24. Shi YQ, Huang TW, Chen LM, Pan XD, Zhang J, Zhu YG, et al. Ginsenoside Rg1attenuates amyloid-β content, regulates PKA/CREB activity, and improves cognitive performance in SAMP8 mice. J Alzheimers Dis 2010;19:977-89. PMID: 20157253
crossref pmid
25. Wang H, Zhang M. The role of Ca²+-stimulated adenylyl cyclases in idirectional synaptic plasticity and brain function. Rev Neurosci 2012;23:67-78. PMID: 22718613
pmid
26. Ortega-Martínez S. A new perspective on the role of the CREB family of transcription factors in memory consolidation via adult hippocampal neurogenesis. Front Mol Neurosci 2015;8:46. PMID: 26379491
crossref pmid pmc
27. Talarowska M, Florkowski A, Zboralski K, Berent D, Wierzbiński P, Gałecki P. Auditory-verbal declarative and operating memory among patients suffering from depressive disorders- preliminary study. Adv Med Sci 2010;55:317-27. PMID: 21163755
crossref pmid pdf
28. Chang L, Karin M. Mammalian MAP kinase signalling cascades. Nature 2001;410:37-40. PMID: 11242034
crossref pmid pdf
29. Alonso M, Medina JH, Pozzo-Miller L. ERK1/2 activation is necessary for BDNF to increase dendritic spine density in hippocampal CA1 pyramidal neurons. Learn Mem 2004;11:172-8. PMID: 15054132
crossref pmid pmc
30. Schafe GE, Atkins CM, Swank MW, Bauer EP, Sweatt JD, LeDoux JE. Activation of ERK/MAP kinase in the amygdala is required for memory consolidation of pavlovian fear conditioning. J Neurosci 2000;20:8177-87. PMID: 11050141
crossref pmid
31. Cavanaugh JE, Ham J, Hetman M, Poser S, Yan C, Xia Z. Differential regulation of mitogen-activated protein kinases ERK1/2 and ERK5 by neurotrophins, neuronal activity, and cAMP in neurons. J Neurosci 2001;21:434-43. PMID: 11160424
crossref pmid
32. Adams JP, Sweatt JD. Molecular psychology: roles for the ERK MAP kinase cascade in memory. Annu Rev Pharmacol Toxicol 2002;42:135-63. PMID: 11807168
crossref pmid

Fig. 1.
Testosterone concentrations. SH, sham-operation group; ORX, orchiectomy group; GOS, goserelin group. *P<0.05 compared to the sham-operation group.
inj-1938103-052f1.jpg
Fig. 2.
Effects of surgical and chemical castration on short-term memory and spatial memory. (A) Latency in the step-down avoidance test. (B) The time required to accomplish eight successful performances. (C) The number of errors made before eight successful performances. SH, sham-operation group; ORX, orchiectomy group; GOS, goserelin group. *P<0.05 compared to the sham-operation group.
inj-1938103-052f2.jpg
Fig. 3.
Effects of surgical and chemical castration on cell proliferation and doublecortin (DCX) expression in the hippocampal dentate gyrus. (A) Photomicrographs of 5-bromo-2′-deoxyuridine (BrdU)-positive cells. The scale bar represents 100 μm. (B) Photomicrographs of DCX-positive cells. The scale bar represents 100 μm. (C) The number of BrdU-positive cells in the hippocampal dentate gyrus. (D) The number of DCX-positive cells in the hippocampal dentate gyrus. SH, sham-operation group; ORX, orchiectomy group; GOS, goserelin group. *P<0.05 compared to the sham-operation group.
inj-1938103-052f3.jpg
Fig. 4.
Effects of surgical and chemical castration on the expression of PKA-CREB-BDNF signaling in the hippocampus. (A) Representative western blot images of PKA, CREB, BDNF, and TrkB. (B) Ratio of phosphorylated PKA (p-PKA) to total PKA (t-PKA). (C) Ratio of phosphorylated CREB (p-CREB) to total CREB (t-CREB) (D) Relative expression levels of BDNF. (E) Relative expression levels of TrkB. PKA, protein kinase A; CREB, cyclic adenosine monophosphate response element-binding protein; BDNF, brain-derived neurotrophic factor; TrkB, tropomyosin receptor kinase B; SH, sham-operation group; ORX, orchiectomy group; GOS, goserelin group. *P<0.05 compared to the sham-operation group.
inj-1938103-052f4.jpg
Fig. 5.
Effects of surgical and chemical castration on the expression of c-Raf/MEK/ERK signaling in the hippocampus. (A) Representative western blot images of c-Raf, MEK, and ERK. (B) Ratio of phosphorylated c-Raf (p-c-Raf) to total c-Raf (t-c-Raf). (C) Ratio of phosphorylated MEK 1/2 (p-MEK 1/2) to total MEK 1/2 (t-MEK 1/2). (D) Ratio of phosphorylated ERK 1/2 (p-ERK 1/2) to total ERK 1/2 (t-ERK 1/2). MEK, mitogen-activated protein kinases-extracellular signal–regulated kinases; ERK, extracellular signal–regulated kinases; SH, sham-operation group; ORX, orchiectomy group; GOS, goserelin group. *P<0.05 compared to the sham-operation group.
inj-1938103-052f5.jpg
TOOLS
Share :
Facebook Twitter Linked In Google+
METRICS Graph View
  • 0 Crossref
  • 1 Scopus
  • 544 View
  • 32 Download
We recommend


ARTICLE & ORGAN
Article Category

Browse all articles >

Organ

Browse all articles >

ISSUES
DISEASES & TOPICS
Diseases

Browse all articles >

Topics

Browse all articles >

AUTHOR
INFORMATION

Editorial Office
Department of Urology, Kangbuk Samsung Medical Center, Sungkyunkwan University School of Medicine,
29 Saemunan-ro, Jongno-gu, Seoul 03181, Korea
Tel: +82-2-2001-2237     Fax: +82-2-2001-2247    E-mail: choys1011@naver.com

Copyright © 2019 by Korean Continence Society. All rights reserved.

Powerd by M2community

Close layer
prev next