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Introduction: Monosodium glutamate (MSG), an umami substance, stimulates the gut-brain axis communication via gut umami receptors and the subsequent vagus nerves. However, the brain mechanism underlying the effect of MSG ingestion during the developmental period on aggression has not yet been clarified. We first tried to establish new experimental conditions to be more appropriate for detailed analysis of the brain, and then investigated the effects of MSG ingestion on aggressive behavior during the developmental stage of an ADHD rat model. Methods: Long-Evans, WKY/Izm, SHR/Izm, and SHR-SP/Ezo were individually housed from postnatal day 25 for 5 weeks. Post-weaning social isolation (PWSI) was given to escalate aggressive behavior. The resident-intruder test, that is conducted during the subjective night, was used for a detailed analysis of aggression, including the frequency, duration, and latency of anogenital sniffing, aggressive grooming, and attack behavior. Immunohistochemistry of c-Fos expression was conducted in all strains to predict potential aggression-related brain areas. Finally, the most aggressive strain, SHR/Izm, a known model of attention-deficit hyperactivity disorder (ADHD), was used to investigate the effect of MSG ingestion (60 mM solution) on aggression, followed by c-Fos immunostaining in aggression-related areas. Bilateral subdiaphragmatic vagotomy was performed to verify the importance of gut-brain interactions in the effect of MSG. Results: The resident intruder test revealed that SHR/Izm rats were the most aggressive among the four strains for all aggression parameters tested. SHR/Izm rats also showed the highest number of c-Fos + cells in aggression-related brain areas, including the central amygdala (CeA). MSG ingestion significantly decreased the frequency and duration of aggressive grooming and attack behavior and increased the latency of attack behavior. Furthermore, MSG administration successfully increased c-Fos positive cell number in the intermediate nucleus of the solitary tract (iNTS), a terminal of the gastrointestinal sensory afferent fiber of the vagus nerve, and modulated c-Fos positive cells in the CeA. Interestingly, vagotomy diminished the MSG effects on aggression and c-Fos expression in the iNTS and CeA. Conclusion: MSG ingestion decreased PWSI-induced aggression in SHR/Izm, which was mediated by the vagus nerve related to the stimulation of iNTS and modulation of CeA activity.
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We previously demonstrated that orally supplemented Bifidobacterium breve MCC1274 (B. breve MCC1274) mitigated Alzheimer's disease (AD) pathologies in both 7-month-old AppNL-G-F mice and wild-type mice; thus, B. breve MCC1274 supplementation might potentially prevent the progression of AD. However, the possibility of using this probiotic as a treatment for AD remains unclear. Thus, we investigated the potential therapeutic effects of this probiotic on AD using 17-month-old AppNL-G-F mice with memory deficits and amyloid beta saturation in the brain. B. breve MCC1274 supplementation ameliorated memory impairment via an amyloid-cascade-independent pathway. It reduced hippocampal and cortical levels of phosphorylated extracellular signal-regulated kinase and c-Jun N-terminal kinase as well as heat shock protein 90, which might have suppressed tau hyperphosphorylation and chronic stress. Moreover, B. breve MCC1274 supplementation increased hippocampal synaptic protein levels and upregulated neuronal activity. Thus, B. breve MCC1274 supplementation may alleviate cognitive dysfunction by reducing chronic stress and tau hyperphosphorylation, thereby enhancing both synaptic density and neuronal activity in 17-month-old AppNL-G-F mice. Overall, this study suggests that B. breve MCC1274 has anti-AD effects and can be used as a potential treatment for AD.
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Enfermedad de Alzheimer , Bifidobacterium breve , Aplicaciones Móviles , Ratones , Animales , Enfermedad de Alzheimer/metabolismo , Péptidos beta-Amiloides/metabolismo , Bifidobacterium breve/metabolismo , Ratones Transgénicos , Modelos Animales de Enfermedad , Trastornos de la Memoria/tratamiento farmacológico , Precursor de Proteína beta-Amiloide/genética , Precursor de Proteína beta-Amiloide/metabolismoRESUMEN
Amyloid-ß (Aß) accumulation caused by an imbalance of the production and clearance of Aß in the brain is associated with the development of Alzheimer's disease (ad). Apolipoprotein E (ApoE) (the strongest genetic risk factor) enhances Aß clearance, preventing Aß deposition. Sirtuin 2 (Sirt2) is an NAD+-dependent histone deacetylase and its inhibition has been reported to ameliorate memory impairment in ad-like model mice. However, the role of Sirt2 in ApoE secretion is unknown. Here, we found that inhibition of Sirt2 activity in primary cultured astrocytes and BV2 cells decreased ApoE secretion, resulting in the accumulation of intracellular ApoE and inhibiting extracellular Aß degradation. However, the reduction of Sirt2 protein level by Sirt2 siRNA decreased ApoE protein level, which ultimately reduces ApoE secretion. In addition, the knockdown of Sirt2 in the HEK293-APP cells also decreased levels of intracellular ApoE leading to reduction of its secretion, which is accompanied by increased Aß levels without altering APP and APP processing enzymes. Our findings provide a novel role of Sirt2 in ApoE secretion.
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Enfermedad de Alzheimer , Sirtuina 2 , Animales , Humanos , Ratones , Enfermedad de Alzheimer/genética , Péptidos beta-Amiloides/metabolismo , Precursor de Proteína beta-Amiloide/metabolismo , Apolipoproteínas E/genética , Apolipoproteínas E/metabolismo , Astrocitos , Encéfalo/metabolismo , Células HEK293 , Ratones Transgénicos , Microglía/metabolismo , Sirtuina 2/metabolismoRESUMEN
We previously demonstrated that the Alzheimer's disease (AD)-like model mice, Tg2576, housed at a high ambient temperature of 30 °C for 13 months, exhibited increased body temperature, which increased amyloid-ß (Aß) levels and tau stability, leading to tau phosphorylation and ultimately inducing memory impairment. Here, we aimed to exclude the possible effect of environmental factors associated with the difference in ambient temperature (23 °C vs. 30 °C) and to further clarify the effects of elevated body temperature on AD-like pathologies. We generated uncoupling protein 1 (UCP1) deletion in Tg2576 mice, Tg2576/UCP1-/-, because UCP1 deletion mice show a sustained rise in body temperature at normal room temperature. As expected, the body temperature in Tg2576/UCP1-/- mice was higher than that in Tg2576/ UCP1+/+ mice at 23 °C, which was accompanied by upregulated Aß levels due to increased ß-secretase (BACE1) and decreased neprilysin (NEP) protein levels in the brains of Tg2576/UCP1-/- mice compared with those in the Tg2576/ UCP1+/+ mice. Elevated body temperature also increased total tau levels, leading to enhanced phosphorylation, heat shock protein induction, and activated tau kinases. Furthermore, elevated body temperature enhanced glial activation and decreased synaptic protein levels in the brain. Taken together, these findings demonstrate that elevated body temperatures exacerbate AD-like pathologies.
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Enfermedad de Alzheimer , Ratones , Animales , Enfermedad de Alzheimer/metabolismo , Secretasas de la Proteína Precursora del Amiloide/metabolismo , Temperatura Corporal , Proteína Desacopladora 1/metabolismo , Ratones Transgénicos , Ácido Aspártico Endopeptidasas/metabolismo , Péptidos beta-Amiloides/genética , Péptidos beta-Amiloides/metabolismo , Encéfalo/metabolismo , Precursor de Proteína beta-Amiloide/genética , Precursor de Proteína beta-Amiloide/metabolismo , Modelos Animales de EnfermedadRESUMEN
Background: Tooth loss is closely associated with Alzheimer's disease (AD). Previously, we reported that tooth loss induced memory impairment in amyloid precursor protein knock-in mice by decreasing neuronal activity and synaptic protein levels and increasing glial activation, neuroinflammation, and pyramidal neuronal cell loss without altering amyloid-ß levels in the hippocampus. However, the effects of tooth loss in young wild-type mice have not been explored yet. Objective: We investigated the effects of tooth loss on memory impairment, neuronal activity, synaptic protein levels, glial activation, and pyramidal neuronal cell loss in young wild-type mice. Methods: Two-month-old wild-type mice were randomly divided into control and tooth loss groups. In the tooth loss group, maxillary molar teeth on both sides were extracted, whereas no teeth were extracted in the control group. Two months after tooth extraction, we performed a novel object recognition test to evaluate memory function. Glial activation, neuronal activity, synaptic protein levels, and the number of pyramidal neurons were evaluated using immunofluorescence staining, immunohistochemistry, and western blotting. Results: The tooth loss group exhibited memory impairment and decreased neuronal activity and the levels of synaptic proteins in both the hippocampus and cortex. Moreover, tooth loss increased the activation of phosphorylated c-Jun N-terminal kinase (JNK), heat shock protein 90 (HSP90), and glial activation and reduced the number of pyramidal neurons in the hippocampus. Conclusion: Tooth loss in the young wild-type mice will attenuate neuronal activity, decrease synaptic protein levels, and induce pyramidal neuronal loss, and eventually lead to memory impairment.
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BACKGROUND: We previously reported the effects of a probiotic strain, Bifidobacterium breve MCC1274, in improving cognitive function in preclinical and clinical studies. Recently, we demonstrated that supplementation of this strain led to decreased amyloid-ß production, attenuated microglial activation, and suppressed inflammation reaction in the brain of APP knock-in (AppNL - G - F) mice. OBJECTIVE: In this study, we investigated the plasma metabolites to reveal the mechanism of action of this probiotic strain in this Alzheimer's disease (AD)-like model. METHODS: Three-month-old mice were orally supplemented with B. breve MCC1274 or saline for four months and their plasma metabolites were comprehensively analyzed using CE-FTMS and LC-TOFMS. RESULTS: Principal component analysis showed a significant difference in the plasma metabolites between the probiotic and control groups (PERMANOVA, pâ=â0.03). The levels of soy isoflavones (e.g., genistein) and indole derivatives of tryptophan (e.g., 5-methoxyindoleacetic acid), metabolites with potent anti-oxidative activities were significantly increased in the probiotic group. Moreover, there were increased levels of glutathione-related metabolites (e.g., glutathione (GSSG)_divalent, ophthalmic acid) and TCA cycle-related metabolites (e.g., 2-Oxoglutaric acid, succinic acid levels) in the probiotic group. Similar alternations were observed in the wild-type mice by the probiotic supplementation. CONCLUSION: These results suggest that the supplementation of B. breve MCC1274 enhanced the bioavailability of potential anti-oxidative metabolites from the gut and addressed critical gaps in our understanding of the gut-brain axis underlying the mechanisms of the probiotic action of this strain in the improvement of cognitive function.
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Bifidobacterium breve , Animales , Bifidobacterium breve/metabolismo , Suplementos Dietéticos , Genisteína/metabolismo , Glutatión/metabolismo , Disulfuro de Glutatión/metabolismo , Indoles , Ácidos Cetoglutáricos/metabolismo , Ratones , Ácido Succínico/metabolismo , TriptófanoRESUMEN
Global warming is a serious public health threat to people worldwide. High body temperature is one of the important risk factors for Alzheimer's disease (AD), and the body temperature of AD patients has been found to be significantly higher than that of elderly control subjects. However, the effects of high body temperature on cognitive function and AD pathologies have not been completely elucidated. We report here that Tg2576 mice housed at a high ambient temperature of 30 °C for 13 months showed an increase in the body temperature, which is accompanied by memory impairment and an enhancement of amyloid-ß peptides (Aß) generation through the upregulation of ß-site APP cleaving enzyme 1 (BACE1) level and decrease in the level of an Aß-degrading enzyme, neprilysin (NEP) in the brain, compared with those of Tg2576 mice at 23 °C. High body temperature also increased the levels of heat shock proteins (HSPs), stress-stimulated kinases such as JNK, and total tau, leading to the enhancement of tau phosphorylation at 30 °C. Taken together, our findings suggest that high body temperature exacerbates cognitive function and AD pathologies, which provides a mechanistic insight for its prevention.
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Enfermedad de Alzheimer , Enfermedad de Alzheimer/metabolismo , Secretasas de la Proteína Precursora del Amiloide/metabolismo , Péptidos beta-Amiloides/metabolismo , Precursor de Proteína beta-Amiloide/metabolismo , Animales , Ácido Aspártico Endopeptidasas/metabolismo , Temperatura Corporal , Encéfalo/metabolismo , Cognición , Modelos Animales de Enfermedad , Humanos , Ratones , Ratones TransgénicosRESUMEN
Accumulating evidence suggests that insulin deficiency is a risk factor for Alzheimer's disease (AD); however, the underlying molecular mechanisms are not completely understood. Here, we investigated the effects of insulin deficiency on AD-like pathologies using an insulin-deficient amyloid-ß (Aß) precursor protein (APP) transgenic mouse model (Tg2576 mice). Female Tg2576 mice were injected intraperitoneally with streptozotocin (STZ) to induce insulin deficiency, and their body weights, serum glucose levels, and serum insulin levels were evaluated. STZ-treated mice showed exacerbated Aß accumulation, tau hyperphosphorylation, glial activation, neuroinflammation, and increased Sirt2 protein levels in the brain, as determined by two-dimensional gel electrophoresis (2-DE) coupled with liquid chromatography-tandem mass spectrometry (LC-MS/MS) and Western blotting. Furthermore, our in vitro experiments revealed that insulin depletion or interleukin-6 treatment increased Sirt2 protein levels in both Neuro2a and Neuro2a-P301L cells. The overexpression of Sirt2 in these cells induced tau hyperphosphorylation through extracellular signal-regulated kinase (ERK) activation. Conversely, Sirt2 knockdown reversed tau hyperphosphorylation in these cells. We showed for the first time that Sirt2 is upregulated in the brains of STZ-treated Tg2576 mice and is involved in tau phosphorylation through ERK activation. Our findings suggest that Sirt2 is a promising therapeutic target for the treatment of AD.
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Enfermedad de Alzheimer , Enfermedad de Alzheimer/patología , Péptidos beta-Amiloides/metabolismo , Precursor de Proteína beta-Amiloide/metabolismo , Animales , Cromatografía Liquida , Modelos Animales de Enfermedad , Quinasas MAP Reguladas por Señal Extracelular/metabolismo , Femenino , Insulina/metabolismo , Ratones , Ratones Transgénicos , Fosforilación , Sirtuina 2/metabolismo , Estreptozocina , Espectrometría de Masas en Tándem , Proteínas tau/metabolismoRESUMEN
Probiotics improve brain function, including memory and cognition, via the microbiome-gut-brain axis. Oral administration of Bifidobacterium breve MCC1274 (B. breve MCC1274) improves cognitive function in AppNL-G-F mice and mild cognitive impairment (MCI) subjects, and mitigates Alzheimer's disease (AD)-like pathologies. However, its effects on wild-type (WT) mice have not yet been explored. Thus, the effects of B. breve MCC1274 on AD-like pathologies in two-month-old WT mice were investigated, which were orally administered B. breve MCC1274 for four months. Aß levels, amyloid precursor protein (APP), APP processing enzymes, phosphorylated tau, synaptic protein levels, glial activity, and cell proliferation in the subgranular zone of the dentate gyrus were evaluated. Data analysis was performed using Student's t-test, and normality was tested using the Shapiro-Wilk test. Oral administration of B. breve MCC1274 in WT mice decreased soluble hippocampal Aß42 levels by reducing presenilin1 protein levels, and reduced phosphorylated tau levels. It also activated the protein kinase B (Akt)/glycogen synthase kinase-3ß (GSK-3ß) pathway, which may be responsible for the reduction in presenilin1 levels and inhibition of tau phosphorylation. B. breve MCC1274 supplementation attenuated microglial activation and elevated synaptic protein levels in the hippocampus. These findings suggest that B. breve MCC1274 may mitigate AD-like pathologies in WT mice by decreasing Aß42 levels, inhibiting tau phosphorylation, attenuating neuroinflammation, and improving synaptic protein levels.
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Enfermedad de Alzheimer , Bifidobacterium breve , Probióticos , Enfermedad de Alzheimer/metabolismo , Péptidos beta-Amiloides/metabolismo , Precursor de Proteína beta-Amiloide/metabolismo , Animales , Bifidobacterium breve/metabolismo , Modelos Animales de Enfermedad , Glucógeno Sintasa Quinasa 3 beta/metabolismo , Humanos , Ratones , Ratones Transgénicos , FosforilaciónRESUMEN
BACKGROUND: Probiotic supplementation reestablishes microbiome diversity and improves brain function in Alzheimer's disease (AD); their molecular mechanisms, however, have not yet been fully illustrated. OBJECTIVE: We investigated the effects of orally supplemented Bifidobacterium breve MCC1274 on cognitive function and AD-like pathologies in AppNL-G-F mice. METHODS: Three-month-old AppNL-G-F mice were orally supplemented with B. breve MCC1274 for four months. The short-term memory function was evaluated using a novel object recognition test. Amyloid plaques, amyloid-ß (Aß) levels, Aß fibril, amyloid-ß protein precursor and its processing enzymes, its metabolic products, glial activity, and cell proliferation in the subgranular zone of the dentate gyrus were evaluated by immunohistochemistry, Aß ELISA, western blotting, and immunofluorescence staining. The mRNA expression levels of pro- and anti-inflammatory cytokines were determined by qRT-PCR analysis. RESULTS: We found that the oral B. breve MCC1 274 supplementation prevented memory impairment in AppNL-G-F mice and decreased hippocampal Aß levels through the enhancement of the a-disintegrin and metalloproteinase 10 (ADAM10) level. Moreover, administration of the probiotic activated the ERK/HIF-1α signaling pathway responsible for increasing the ADAM10 level and also attenuated microglial activation, which in turn led to reduction in the mRNA expression levels of pro-inflammatory cytokines in the brain. In addition, B. breve MCC1274 supplementation increased the level of synaptic proteins in the hippocampus. CONCLUSION: Our findings support the possibility that oral B. breve MCC1274 supplementation might be used as a potential preventive therapy for AD progression.
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Péptidos beta-Amiloides/metabolismo , Bifidobacterium breve/metabolismo , Trastornos de la Memoria/prevención & control , Microglía/metabolismo , Probióticos , Animales , Encéfalo/patología , Modelos Animales de Enfermedad , Hipocampo/patología , Trastornos de la Memoria/metabolismo , Ratones , Ratones TransgénicosRESUMEN
BACKGROUND: Epidemiological studies have shown that tooth loss is associated with Alzheimer's disease (AD) and dementia. However, the molecular and cellular mechanisms by which tooth loss causes AD remain unclear. OBJECTIVE: We investigated the effects of tooth loss on memory impairment and AD pathogenesis in AppNL-G-F mice. METHODS: Maxillary molar teeth on both sides were extracted from 2-month-old AppNL-G-F mice, and the mice were reared for 2 months. The short- and long-term memory functions were evaluated using a novel object recognition test and a passive avoidance test. Amyloid plaques, amyloid-ß (Aß) levels, glial activity, and neuronal activity were evaluated by immunohistochemistry, Aß ELISA, immunofluorescence staining, and western blotting. The mRNA expression levels of neuroinflammatory cytokines were determined by qRT-PCR analysis. RESULTS: Tooth loss induced memory impairment via an amyloid-cascade-independent pathway, and decreased the neuronal activity, presynaptic and postsynaptic protein levels in both the cortex and hippocampus. Interestingly, we found that tooth loss induced glial activation, which in turn leads to the upregulation of the mRNA expression levels of the neuroinflammation cytokines tumor necrosis factor-α (TNF-α), interleukin-6 (IL-6), and IL-1ß in the hippocampus. We also found that tooth loss activated a stress-activated protein kinase, c-Jun N-terminal kinase (JNK), and increased heat shock protein 90 (HSP90) levels in the hippocampus, which may lead to a glial activation. CONCLUSION: Our findings suggest that taking care of teeth is very important to preserve a healthy oral environment, which may reduce the risk of cognitive dysfunction.
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Enfermedad de Alzheimer/metabolismo , Péptidos beta-Amiloides/metabolismo , Gliosis/metabolismo , Trastornos de la Memoria/metabolismo , Placa Amiloide/metabolismo , Pérdida de Diente/complicaciones , Enfermedad de Alzheimer/patología , Enfermedad de Alzheimer/psicología , Animales , Corteza Cerebral/metabolismo , Corteza Cerebral/patología , Modelos Animales de Enfermedad , Femenino , Gliosis/patología , Gliosis/psicología , Hipocampo/metabolismo , Hipocampo/patología , Humanos , Masculino , Trastornos de la Memoria/patología , Trastornos de la Memoria/psicología , Ratones , Ratones Endogámicos C57BL , Ratones Transgénicos , Placa Amiloide/patología , Placa Amiloide/psicología , Pérdida de Diente/patologíaRESUMEN
BACKGROUND: The accumulation of aggregated α-synuclein (αSyn) is known as one of the critical reasons to exhibit their variable molecular pathologies and phenotypes in synucleinopathies. Recent studies suggested that the real-time quaking-induced conversion (RT-QuIC) assay is one of the potential methods to detect these αSyn aggregates and could detect the aggregated αSyn in the brain tissue and cerebrospinal fluid (CSF) using the propensity of the prion-like oligomerization. OBJECTIVE: We tried to optimize the αSyn RT-QuIC assay based on the aggregation of αSyn in brain samples of synucleinopathies by comparing the conditions of the recently reported αSyn RTQuIC assays. METHODS: This study applied a highly sensitive RT-QuIC assay using recombinant αSyn (rαSyn) to detect aggregated αSyn in the brain tissue from dementia with Lewy bodies (DLB). RESULTS: This study compared αSyn RT-QuIC assays under conditions such as beads, rαSyn as a substrate, reaction buffers, and fluorescence detectors. We observed that the addition of beads and the use of 6x His-tagged rαSyn as a substrate help to obtain higher positive responses from αSyn RT-QuIC assay seeding with brain homogenate (BH) of DLB and phosphate buffer-based reaction showed higher positive responses than HEPES buffer-based reaction on both fluorescent microplate readers. We also observed that the DLB BHs gave positive responses within 15-25h, which is faster high positive responses than recently reported assays. CONCLUSION: This established αSyn RT-QuIC assay will be able to apply to the early clinical diagnosis of αSyn aggregates-related diseases in various biofluids such as CSF.
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Bioensayo , Encéfalo/metabolismo , Enfermedad por Cuerpos de Lewy/líquido cefalorraquídeo , Agregado de Proteínas , alfa-Sinucleína/líquido cefalorraquídeo , Femenino , Humanos , MasculinoRESUMEN
Lactoferrin (LF) is present in senile plaques and neurofibrillary tangles in the brains of Alzheimer's disease (AD) patients and amyloid-ß protein precursor transgenic (AßPP-Tg) mice. LF has anti-inflammatory and antioxidant functions, which exert neuroprotective effects against AD. However, its effects on memory impairment and AD pathogenesis have not been fully examined. In this study, we examined the effects of LF on memory impairment and AD pathogenesis in AßPP-Tg mice (J20 mice). Nine-month-old J20 mice were fed with control, 2% lactoferrin-containing (LF), and 0.5% pepsin-hydrolyzed lactoferrin-containing (LF-hyd) diets for 3 months. We found that both the LF and LF-hyd diets attenuated memory impairment in J20 mice and decreased brain Aß40 and Aß42 levels through the inhibition of amyloidogenic processing of AßPP, as it decreased ß-site amyloid protein precursor cleaving enzyme 1 (BACE1) levels. Furthermore, we found for the first time that LF and LF-hyd treatments increased both ApoE secretion and ATP-binding cassette A1 (ABCA1) protein levels in the brains of J20 mice and in primary astrocyte cultures. Moreover, LF and LF-hyd promoted extracellular degradation of Aß in primary astrocyte cultures. These findings indicate that the reduction in Aß levels in the brains of mice fed with both the LF and LF-hyd diets may also be mediated by increased ApoE secretion and ABCA1 protein levels, which in turn leads to the enhanced degradation of Aß in the brains of J20 mice. Our findings suggest that LF and LF-hyd can be used for the treatment and/or prevention of the development of AD.
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Péptidos beta-Amiloides/biosíntesis , Suplementos Dietéticos , Lactoferrina/uso terapéutico , Trastornos de la Memoria/prevención & control , Transportador 1 de Casete de Unión a ATP/metabolismo , Secretasas de la Proteína Precursora del Amiloide/metabolismo , Péptidos beta-Amiloides/genética , Péptidos beta-Amiloides/metabolismo , Animales , Apolipoproteínas E/metabolismo , Ácido Aspártico Endopeptidasas/metabolismo , Astrocitos/metabolismo , Química Encefálica/efectos de los fármacos , Dieta , Humanos , Sistema de Señalización de MAP Quinasas/efectos de los fármacos , Trastornos de la Memoria/psicología , Ratones , Ratones Transgénicos , Fragmentos de Péptidos/metabolismo , Cultivo Primario de Células , Ratas , Ratas WistarRESUMEN
Mitochondrial dysfunctions and oxidative stress play important roles in the early pathogenesis of Alzheimer's disease (AD), which also involves the aberrant expression levels of mitochondrial proteins. However, the molecular mechanisms underlying the aberrant expression levels of these proteins in the pathogenesis of AD are still not completely understood. Tid1 (DnaJA3/mtHsp40), a mammalian homolog of the Drosophila tumor suppressor Tid56, is reported to induce mitochondrial fragmentation associated with an increase in reactive oxygen species (ROS) levels, resulting in cell death in some cancer cells. However, the involvement of Tid1 in AD pathogenesis is as yet unknown. In this study, we found that the Tid1 protein levels were upregulated in the hippocampus of AD patients and Tg2576 mice. Our in vitro studies showed that Aß42 increased the expression levels of Tid1 in primary rat cortical neurons. The knockdown of Tid1 protected against neuronal cell death induced by Aß42, and Tid1-mediated neuronal cell death, was dependent on the increased ROS generation and caspase-3 activity. The overexpression of Tid1 in HEK293-APP cells increased the BACE1 levels, resulting in increased Aß production. Conversely, Tid1 knockdown in HEK293-APP cells and primary cultured neurons decreased Aß production through the reduction in the BACE1 levels. We also found that the overexpression of Tid1 activated c-Jun N-terminal kinase (JNK) leading to increased Aß production. Taken together, our results suggest that upregulated Tid1 levels in the hippocampus of patients with AD and Tg2576 mice induce apoptosis and increase Aß production, and Tid1 may therefore be a suitable target in therapeutic interventions for AD.
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Enfermedad de Alzheimer/metabolismo , Péptidos beta-Amiloides/metabolismo , Ácido Aspártico Endopeptidasas/metabolismo , Proteínas del Choque Térmico HSP40/metabolismo , Anciano , Anciano de 80 o más Años , Enfermedad de Alzheimer/patología , Secretasas de la Proteína Precursora del Amiloide/metabolismo , Precursor de Proteína beta-Amiloide/metabolismo , Hipocampo/metabolismo , Humanos , Neuronas/metabolismoRESUMEN
Hypoxia-ischemia (H-I) in rats at postnatal day 3 causes disorganization of oligodendrocyte development in layers II/III of the sensorimotor cortex without apparent neuronal loss, and shows mild hindlimb dysfunction with imbalanced motor coordination. However, the mechanisms by which mild motor dysfunction is induced without loss of cortical neurons are currently unclear. To reveal the mechanisms underlying mild motor dysfunction in neonatal H-I model, electrical responsiveness and dendrite morphology in the sensorimotor cortex were investigated at 10 weeks of age. Responses to intracortical microstimulation (ICMS) revealed that the cortical motor map was significantly changed in this model. The cortical area related to hip joint movement was reduced, and the area related to trunk movement was increased. Sholl analysis in Golgi staining revealed that layer I-III neurons on the H-I side had more dendrite branches compared with the contralateral side. To investigate whether changes in the motor map and morphology appeared at earlier stages, ICMS and Sholl analysis were also performed at 5 weeks of age. The minimal ICMS current to evoke twitches of the hip area was higher on the H-I side, while the motor map was unchanged. Golgi staining revealed more dendrite branches in layer I-III neurons on the H-I side. These results revealed that alterations of both dendrite morphology and ICMS threshold of the hip area occurred before the rearrangement of the motor map in the neonatal H-I model. They also suggest that altered dendritic morphology and altered ICMS responsiveness may be related to mild motor dysfunction in this model.
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We previously established neonatal white matter injury (WMI) model rat that is made by right common carotid artery dissection at postnatal day 3, followed by 6% hypoxia for 60 min. This model has fewer oligodendrocyte progenitor cells and reduced myelin basic protein (MBP) positive areas in the sensorimotor cortex, but shows no apparent neuronal loss. However, how motor deficits are induced in this model is unclear. To elucidate the relationship between myelination disturbance and concomitant motor deficits, we first performed motor function tests (gait analysis, grip test, horizontal ladder test) and then analyzed myelination patterns in the sensorimotor cortex using transmission electron microscopy (TEM) and Contactin associated protein 1 (Caspr) staining in the neonatal WMI rats in adulthood. Behavioral tests revealed imbalanced motor coordination in this model. Motor deficit scores were higher in the neonatal WMI model, while hindlimb ladder stepping scores and forelimb grasping force were comparable to controls. Prolonged forelimb swing times and decreased hindlimb paw angles on the injured side were revealed by gait analysis. TEM revealed no change in myelinated axon number and the area g-ratio in the layer II/III of the cortex. Electromyographical durations and latencies in the gluteus maximus in response to electrical stimulation of the brain area were unchanged in the model. Caspr staining revealed fewer positive dots in layers II/III of the WMI cortex, indicating fewer and/or longer myelin sheath. These data suggest that disorganization of oligodendrocyte development in layers II/III of the sensorimotor cortex relates to imbalanced motor coordination in the neonatal WMI model rat.
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Axones/metabolismo , Vaina de Mielina/metabolismo , Oligodendroglía/metabolismo , Sustancia Blanca/metabolismo , Animales , Animales Recién Nacidos , Modelos Animales de Enfermedad , Hipoxia-Isquemia Encefálica/metabolismo , Masculino , Ratas WistarRESUMEN
Fast-scan cyclic voltammetry (FSCV) is an established method for measuring dopamine (DA) levels in the brain in real time. However, it is difficult to discriminate DA from other monoamines such as serotonin (5-hydroxytryptamine, 5-HT) and norepinephrine (NE). We report a novel DA-specific biosensor consisting of a carbon-fiber electrode coated with an ion-exchange membrane, a layer containing monoamine oxidase B, and a cellulose membrane. We performed FSCV using the probe to monitor the amount of DA in vitro and in vivo. First, we measured currents in vitro in phosphate-buffered saline as we added one micromole each of DA, 5-HT, and NE. The results confirmed that the biosensor selectively detected DA. Next, we implanted the probe in the striatum of male rats to investigate whether it could selectively detect changes in the DA content in vivo. The probe detected both the tonic change induced by methamphetamine administration and the phasic change induced by electrical stimulation of the medial forebrain bundle. In contrast, the electrode in the 6-hydroxydopamine-lesioned striatum did not respond to systemic selective serotonin or serotonin/norepinephrine reuptake inhibitors, confirming its selectivity. Furthermore, the probe in the striatum could still detect changes in the DA level 1 week after electrode implantation. The results suggest that the novel biosensor can measure real-time changes in DA levels in vivo with a relatively high signal-to-noise ratio.
Asunto(s)
Técnicas Biosensibles/instrumentación , Cuerpo Estriado/química , Dopamina/análisis , Técnicas Electroquímicas/instrumentación , Animales , Fibra de Carbono , Cuerpo Estriado/efectos de los fármacos , Estimulación Eléctrica/métodos , Técnicas Electroquímicas/métodos , Electrodos , Análisis de Inyección de Flujo/instrumentación , Análisis de Inyección de Flujo/métodos , Masculino , Metanfetamina/farmacología , Monoaminooxidasa/química , Norepinefrina/análisis , Oxidopamina/farmacología , Ratas , Ratas Wistar , Serotonina/análisis , Relación Señal-RuidoRESUMEN
BACKGROUND: Pathological stage and grade have limited ability to predict the outcomes of superficial urothelial bladder carcinoma at initial transurethral resection (TUR). AT-motif binding factor 1 (ATBF1) is a tumor suppressive transcription factor that is normally localized to the nucleus but has been detected in the cytoplasm in several cancers. Here, we examined the diagnostic value of the intracellular localization of ATBF1 as a marker for the identification of high risk urothelial bladder carcinoma. METHODS: Seven anti-ATBF1 antibodies were generated to cover the entire ATBF1 sequence. Four human influenza hemagglutinin-derived amino acid sequence-tagged expression vectors with truncated ATBF1 cDNA were constructed to map the functional domains of nuclear localization signals (NLSs) with the consensus sequence KR[X10-12]K. A total of 117 samples from initial TUR of human bladder carcinomas were analyzed. None of the patients had received chemotherapy or radiotherapy before pathological evaluation. RESULTS: ATBF1 nuclear localization was regulated synergistically by three NLSs on ATBF1. The cytoplasmic fragments of ATBF1 lacked NLSs. Patients were divided into two groups according to positive nuclear staining of ATBF1, and significant differences in overall survival (P = 0.021) and intravesical recurrence-free survival (P = 0.013) were detected between ATBF1+ (n = 110) and ATBF1- (n = 7) cases. Multivariate analysis revealed that ATBF1 staining was an independent prognostic factor for intravesical recurrence-free survival after adjusting for cellular grading and pathological staging (P = 0.008). CONCLUSIONS: Cleavage of ATBF1 leads to the cytoplasmic localization of ATBF1 fragments and downregulates nuclear ATBF1. Alterations in the subcellular localization of ATBF1 due to fragmentation of the protein are related to the malignant character of urothelial carcinoma. Pathological evaluation using anti-ATBF1 antibodies enabled the identification of highly malignant cases that had been overlooked at initial TUR. Nuclear localization of ATBF1 indicates better prognosis of urothelial carcinoma.
Asunto(s)
Biomarcadores de Tumor/metabolismo , Carcinoma de Células Transicionales/metabolismo , Proteínas de Homeodominio/metabolismo , Neoplasias de la Vejiga Urinaria/metabolismo , Adulto , Anciano , Anciano de 80 o más Años , Animales , Western Blotting , Células COS , Carcinoma de Células Transicionales/patología , Línea Celular Tumoral , Núcleo Celular/metabolismo , Chlorocebus aethiops , Citoplasma/metabolismo , Progresión de la Enfermedad , Femenino , Células HEK293 , Humanos , Inmunohistoquímica , Estimación de Kaplan-Meier , Masculino , Persona de Mediana Edad , Análisis Multivariante , Neoplasias de la Vejiga Urinaria/patologíaRESUMEN
BACKGROUND AND OBJECTIVE: Previous studies have reported that tooth loss is a risk factor of Alzheimer's disease (AD). However, the association between tooth loss and cognition and the impact of tooth loss on the molecular pathogenesis of AD remain elusive. In this study, we tested the effect of tooth loss on learning and memory and on the molecular pathogenesis of AD in an aged AD model mice. MATERIALS AND METHODS: We divided 14-month-old amyloid precursor protein (APP) transgenic mice, an AD model mouse line, into upper molar extracted group (experimental) and molar intact group (control). At 18 months old, we analysed not only the changes of amyloid-beta (Aß), pyramidal cells in the brain but also the learning and memory ability with step-through passive avoidance test. RESULTS: The amount of Aß and the number of pyramidal cells in the hippocampus were not significantly different between the experimental and control group. Similarly, the difference of learning and memory ability could not be distinguished between the groups. CONCLUSION: Neither molecular pathogenesis of AD nor associated learning and memory were aggravated by tooth loss in these mice. The limited results of this study which used the aged mice may help the dental profession to plan and explain treatments to patients with AD, which must be designed while taking into account the severity of the AD symptoms.