RESUMEN
The metabotropic glutamate receptor subtype 1 (mGluR1, Grm1) in cerebellar Purkinje cells (PCs) is essential for motor coordination and motor learning. At the synaptic level, mGluR1 has a critical role in long-term synaptic depression (LTD) at parallel fiber (PF)-PC synapses, and in developmental elimination of climbing fiber (CF)-PC synapses. mGluR1a, a predominant splice variant in PCs, has a long carboxyl (C)-terminal domain that interacts with Homer scaffolding proteins. Cerebellar roles of the C-terminal domain at both synaptic and behavior levels remain poorly understood. To address this question, we introduced a short variant, mGluR1b, which lacks this domain into PCs of mGluR1-knock-out (KO) mice (mGluR1b-rescue mice). In mGluR1b-rescue mice, mGluR1b showed dispersed perisynaptic distribution in PC spines. Importantly, mGluR1b-rescue mice exhibited impairments in inositol 1,4,5-trisphosphate receptor (IP3R)-mediated Ca(2+) release, CF synapse elimination, LTD induction, and delay eyeblink conditioning: they showed normal transient receptor potential canonical (TRPC) currents and normal motor coordination. In contrast, PC-specific rescue of mGluR1a restored all cerebellar defects of mGluR1-KO mice. We conclude that the long C-terminal domain of mGluR1a is required for the proper perisynaptic targeting of mGluR1, IP3R-mediated Ca(2+) release, CF synapse elimination, LTD, and motor learning, but not for TRPC currents and motor coordination.
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Plasticidad Neuronal/fisiología , Células de Purkinje/metabolismo , Receptores de Glutamato Metabotrópico/metabolismo , Sinapsis/metabolismo , Animales , Cerebelo/metabolismo , Técnica del Anticuerpo Fluorescente , Inmunohistoquímica , Inmunoprecipitación , Hibridación in Situ , Ratones , Ratones Endogámicos C57BL , Ratones Noqueados , Técnicas de Placa-Clamp , Estructura Terciaria de Proteína , Desempeño Psicomotor/fisiología , Transducción de Señal/fisiologíaRESUMEN
Eyeblink conditioning is associated with motor learning, which requires the cerebellum and the brainstem. This article provides behavioral data on whether JNJ16259685, a selective metabotropic glutamate receptor type 1 (mGluR1) antagonist, affects eyeblink conditioning in wild-type mice (C57BL/6 J strain). The dataset contains four types of behavioral outputs pertinent to eyeblink conditioning. We used a t-test and an analysis of variance (ANOVA) to analyze the percentage of conditioned responses (CR%), peak CR latencies, onset CR latencies, and electromyography (EMG) amplitudes. The information obtained in this dataset adds to our knowledge of the molecular mechanisms underlying eyeblink conditioning and can prove beneficial for investigators studying the pharmacological effects of mGluR1 on motor learning. Future research might use this dataset as a basis for conducting experiments with different JNJ16259685 doses, administration methods, and durations than the ones used in the described procedures.
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Since the early 2000s, Japan has been frequently noted as being the only country among about 20 major countries where the publication of academic papers has stagnated. During this period, there have been major changes especially with regards to the Japanese pharmacy schools, such as the shift to a six-year schooling system and the rapid increase in the number of private pharmacy schools. However, few studies have focused on academic productivity specifically among pharmacy schools. Therefore, this study analyzed the outputs associated with the publication of peer-reviewed scholarly articles in Scopus search engine per faculty member in pharmacy schools nationwide in 2020. Professors, associate professors, and lecturers were considered as faculty members. The average number of papers published per the faculty member was 3.13 for national and public universities and 1.15 for private universities, with a significant difference between these universities. Dividing the pharmacy schools of private universities into schools established in and after 2003 and schools established before that, the production coefficient of the former was 0.98 and that of the latter was 1.33. Newly established pharmacy schools were thus found to be slightly less productive in terms of published papers than traditional schools. The paper productivity of private university pharmacy schools is stagnant; the increase in the number of private schools that have adopted a six-year schooling system has contributed to large extent to the creation of clinically competent pharmacists, but it has also brought to light concerns related to the decline in basic research capabilities of Japanese pharmaceutical academia.
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Educación en Farmacia , Facultades de Farmacia , Humanos , Bibliometría , Docentes , JapónRESUMEN
Mutations of the myosin Va gene cause the neurological diseases Griscelli syndrome type 1 and Elejalde syndrome in humans and dilute phenotypes in rodents. To understand the pathophysiological mechanisms underlying the neurological disorders in myosin Va diseases, we conducted an integrated analysis at the molecular, cellular, electrophysiological, and behavioral levels using the dilute-neurological (d-n) mouse mutant. These mice manifest an ataxic gait and clonic seizures during postnatal development, but the neurological disorders are ameliorated in adulthood. We found that smooth endoplasmic reticulum (SER) rarely extended into the dendritic spines of Purkinje cells (PCs) of young d-n mice, and there were few, if any, IP(3) receptors. Moreover, long-term depression (LTD) at parallel fiber-PC synapses was abolished, consistent with our previous observations in juvenile lethal dilute mutants. Young d-n mice exhibited severe impairment of cerebellum-dependent motor learning. In contrast, adult d-n mice showed restoration of motor learning and LTD, and these neurological changes were associated with accumulation of SER and IP(3) receptors in some PC spines and the expression of myosin Va proteins in the PCs. RNA interference-mediated repression of myosin Va caused a reduction in the number of IP(3) receptor-positive spines in cultured PCs. These findings indicate that myosin Va function is critical for subsequent processes in localization of SER and IP(3) receptors in PC spines, LTD, and motor learning. Interestingly, d-n mice had defects of motor coordination from young to adult ages, suggesting that the role of myosin Va in PC spines is not sufficient for motor coordination.
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Cerebelo/fisiología , Aprendizaje/fisiología , Actividad Motora/fisiología , Cadenas Pesadas de Miosina/metabolismo , Miosina Tipo V/metabolismo , Plasticidad Neuronal/fisiología , Neuronas/fisiología , Análisis de Varianza , Animales , Western Blotting , Condicionamiento Clásico/fisiología , Condicionamiento Palpebral/fisiología , Espinas Dendríticas/metabolismo , Electrofisiología , Retículo Endoplásmico Liso/metabolismo , Inmunohistoquímica , Receptores de Inositol 1,4,5-Trifosfato/metabolismo , Ratones , Ratones Mutantes Neurológicos , Cadenas Pesadas de Miosina/genética , Miosina Tipo V/genética , Prueba de Desempeño de Rotación con Aceleración Constante , Sinapsis/fisiologíaRESUMEN
Group I metabotropic glutamate receptors (mGluRs) include mGluR1 and mGluR5, which are coupled to the Gq family of heterotrimeric G-proteins and readily activated by their selective agonist 3,5-dihydroxyphenilglycine (DHPG). mGluR1 and mGluR5 exhibit nearly complementary distributions spatially or temporally in the central nervous system (CNS). In adult cerebellar Purkinje cells (PCs), mGluR1 is a dominant group I mGluR and mGluR5 is undetectable. mGluR1 expression increases substantially during the first three weeks of postnatal development and remains high throughout adulthood. On the other hand, mGluR5 expression is observed during the first two postnatal weeks and then decreases. However, functional differences between mGluR1 and mGluR5 in the CNS remains to be elucidated. To address this issue, we generated "mGluR5-rescue" mice in which mGluR5 is specifically expressed in PCs in global mGluR1-knockout (KO) mice. mGluR5-rescue mice exhibited apparently normal motor coordination, developmental elimination of redundant climbing fiber (CF)-PC synapses, and delay eyeblink conditioning, which were severely impaired in mGluR1-KO mice. We concluded that mGluR5 is functionally comparable with mGluR1 in cerebellar PCs.
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Células de Purkinje , Receptor del Glutamato Metabotropico 5/metabolismo , Sinapsis , Animales , Ratones , Ratones Noqueados , Células de Purkinje/fisiología , Receptores de Glutamato Metabotrópico , Sinapsis/metabolismoRESUMEN
We herein present behavioral data on whether memantine, an adamantane derivative and medical NMDA-receptor antagonist, improves spatial and latent learning deficits in amyloid precursor protein/presenilin 2 double-transgenic mice (PS2Tg2576 mice). In PS2Tg2576 mice, early amyloid-ß protein (Aß) deposition at 2-3 months of age and progressive accumulation at about 5 months of age has been shown. Thus, PS2Tg2576 mice were subjected to Morris water maze (MWM) test for spatial memory and the water-finding test for latent memory testing at ages 3 and 5-6 months. In addition, memantine (30 mg/kg/day, p.o.) was administered 3-4 weeks before commencing the behavioral tasks to check for effects on cognitive function. The information provided in this paper adds to the literature and can be used for the selection of animal models and behavioral paradigms for Alzheimer's disease (AD) research.
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Prion protein (PrPC) knockout mice, named as the "Ngsk" strain (Ngsk Prnp0/0 mice), show late-onset cerebellar Purkinje cell (PC) degeneration because of ectopic overexpression of PrPC-like protein (PrPLP/Dpl). Our previous study indicated that the mutant mice also exhibited alterations in cerebellum-dependent delay eyeblink conditioning, even at a young age (16 weeks of age) when neurological changes had not occurred. Thus, this electrophysiological study was designed to examine the synaptic function of the cerebellar cortex in juvenile Ngsk Prnp0/0 mice. We showed that Ngsk Prnp0/0 mice exhibited normal paired-pulse facilitation but impaired long-term depression of excitatory synaptic transmission at synapses between parallel fibres and PCs. GABAA-mediated inhibitory postsynaptic currents recorded from PCs were also weakened in Ngsk Prnp0/0 mice. Furthermore, we confirmed that Ngsk Prnp0/0 mice (7-8-week-old) exhibited abnormalities in delay eyeblink conditioning. Our findings suggest that these alterations in both excitatory and inhibitory synaptic transmission to PCs caused deficits in delay eyeblink conditioning of Ngsk Prnp0/0 mice. Therefore, the Ngsk Prnp0/0 mouse model can contribute to study underlying mechanisms for impairments of synaptic transmission and neural plasticity, and cognitive deficits in the central nervous system.
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Cerebelo/fisiopatología , Depresión Sináptica a Largo Plazo/fisiología , Proteínas PrPC/genética , Transmisión Sináptica/fisiología , Ácido gamma-Aminobutírico/metabolismo , Animales , Cerebelo/metabolismo , Condicionamiento Palpebral/fisiología , Potenciales Postsinápticos Inhibidores/fisiología , Ratones , Ratones Noqueados , Plasticidad Neuronal/fisiología , Proteínas PrPC/metabolismoRESUMEN
AIM: Fear conditioning tests are intended to elucidate a subject's ability to associate a conditioned stimulus with an aversive, unconditioned stimulus, such as footshock. Among these tests, a paradigm related to precise cortical functions would be increasingly important in drug screening for disorders such as schizophrenia and dementia. Therefore, we established a new fear conditioning paradigm using a visual cue in mice. In addition, the validity of the test was evaluated using a genetically engineered mouse, heterozygous deficient in Mdga1 (Mdga1+/-), which is related to schizophrenia. RESULTS: Mice were given footshocks associated with a visual cue of moving gratings at training in 25-minute sessions. The mice showed the conditioned response of freezing behavior to the visual stimulus at testing 24 hours after the footshocks. In the test for validation, the Mdga1+/- deficient mice showed significantly less freezing than wild-type mice. CONCLUSION: The visually cued fear conditioning paradigm with moving gratings has been established, which is experimentally useful to evaluate animal cortical functions. The validity of the test was confirmed for Mdga1-deficient mice with possible deficiency in cortical functions.
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Condicionamiento Operante/fisiología , Señales (Psicología) , Miedo/fisiología , Trastornos de la Memoria/fisiopatología , Percepción de Movimiento/fisiología , Corteza Visual/fisiología , Animales , Estimulación Eléctrica/efectos adversos , Miedo/psicología , Femenino , Trastornos de la Memoria/psicología , Ratones , Ratones Endogámicos C57BL , Ratones Transgénicos , Estimulación Luminosa/métodosRESUMEN
Intracellular Ca2+ levels are changed by influx from extracellular medium and release from intracellular stores. In the central nervous systems, Ca2+ release is involved in various physiological events, such as neuronal excitability and transmitter release. Although stable Ca2+ release in response to stimulus is critical for proper functions of the nervous systems, regulatory mechanisms relating to Ca2+ release are not fully understood in central neurons. Here, we demonstrate that ShcB, an adaptor protein expressed in central neurons, has an essential role in functional maintenance of Ca2+ store in cerebellar Purkinje cells (PCs). ShcB-knockout (KO) mice showed defects in cerebellar-dependent motor function and long-term depression (LTD) at cerebellar synapse. The reduced LTD was accompanied with an impairment of intracellular Ca2+ release. Although the expression of Ca2+ release channels and morphology of Ca2+ store looked intact, content of intracellular Ca2+ store and activity of sarco/endoplasmic reticular Ca2+-ATPase (SERCA) were largely decreased in the ShcB-deficient cerebellum. Furthermore, when ShcB was ectopically expressed in the ShcB-KO PCs, the Ca2+ release and its SERCA-dependent component were restored. These data indicate that ShcB plays a key role in the functional maintenance of ER Ca2+ store in central neurons through regulation of SERCA activity.
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Cerebelo/metabolismo , Depresión Sináptica a Largo Plazo/genética , ATPasas Transportadoras de Calcio del Retículo Sarcoplásmico/genética , Proteína Transformadora 2 que Contiene Dominios de Homología 2 de Src/genética , Sinapsis/genética , Animales , Calcio/metabolismo , Señalización del Calcio/genética , Cerebelo/patología , Retículo Endoplásmico/genética , Humanos , Ratones , Ratones Noqueados , Trastornos Motores/genética , Trastornos Motores/fisiopatología , Plasticidad Neuronal/genética , Células de Purkinje/metabolismo , Células de Purkinje/patologíaRESUMEN
MDGA1 (MAM domain-containing glycosylphosphatidylinositol anchor) has recently been linked to schizophrenia and bipolar disorder. Dysregulation of dopamine (DA) and serotonin (5-HT) systems has long been associated with schizophrenia and other neuropsychiatric disorders. Here, we measured prepulse inhibition (PPI) of the startle response and ex vivo tissue content of monoamines and their metabolites in the frontal cortex, striatum and hippocampus of Mdga1 homozygous (Mdga1-KO), Mdga1 heterozygous (Mdga1-HT) and wild-type (WT) male mice. We found that Mdga1-KO mice exhibited statistically significant impairment of PPI, and had higher levels of homovanillic acid in all three brain regions studied compared with Mdga1-HT and WT mice (P < 0.05), while levels of norepinephrine, DA and its metabolites 3,4-dihydroxyphenylacetic acid and 3-methoxytyramine remained unchanged. Mdga1-KO mice also had a lower 5-hydroxyindoleacetic acid level in the striatum (P < 0.05) compared with WT mice. 5-HT levels remained unchanged with the exception of a significant increase in the level in the cortex. These data are the first evidence suggesting that MDGA1 deficiency leads to a pronounced deficit in PPI and plays an important role in perturbation of DA and 5-HT metabolism in mouse brain; such changes may contribute to a range of neuropsychiatric disorders.
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Encéfalo/metabolismo , Dopamina/metabolismo , Moléculas de Adhesión de Célula Nerviosa/metabolismo , Inhibición Prepulso/fisiología , Serotonina/metabolismo , Animales , Cromatografía Líquida de Alta Presión , Ratones , Ratones Endogámicos C57BL , Ratones Noqueados , Reflejo de Sobresalto/fisiologíaRESUMEN
There has been growing awareness of the correlation between an episode of traumatic brain injury (TBI) and the development of Alzheimer's disease (AD) later in life. It has been reported that TBI accelerated amyloid-ß (Aß) pathology and cognitive decline in the several lines of AD model mice. However, the short-term and long-term effects of TBI by the weight-drop method on amyloid-ß pathology and cognitive performance are unclear in wild-type (WT) mice. Hence, we examined AD-related histopathological changes and cognitive impairment after TBI in wild-type C57BL6J mice. Five- to seven-month-old WT mice were subjected to either TBI by the weight-drop method or a sham treatment. Seven days after TBI, the WT mice exhibited significantly lower spatial learning than the sham-treated WT mice. However, 28 days after TBI, the cognitive impairment in the TBI-treated WT mice recovered. Correspondingly, while significant amyloid-ß (Aß) plaques and amyloid precursor protein (APP) accumulation were observed in the TBI-treated mouse hippocampus 7 days after TBI, the Aß deposition was no longer apparent 28 days after TBI. Thus, TBI induced transient amyloid-ß deposition and acute cognitive impairments in the WT mice. The present study suggests that the TBI could be a risk factor for acute cognitive impairment even when genetic and hereditary predispositions are not involved. The system might be useful for evaluating and developing a pharmacological treatment for the acute cognitive deficits.
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Péptidos beta-Amiloides/metabolismo , Lesiones Traumáticas del Encéfalo/metabolismo , Trastornos del Conocimiento/patología , Disfunción Cognitiva/patología , Enfermedad de Alzheimer/metabolismo , Enfermedad de Alzheimer/patología , Precursor de Proteína beta-Amiloide/metabolismo , Animales , Lesiones Traumáticas del Encéfalo/patología , Cognición/fisiología , Trastornos del Conocimiento/metabolismo , Disfunción Cognitiva/metabolismo , Modelos Animales de Enfermedad , Masculino , Ratones Endogámicos C57BLRESUMEN
Classical eyeblink conditioning is a representative associative motor learning that requires both the cerebellar cortex and the deep cerebellar nucleus (DCN). Metabotropic glutamate receptor subtype 1 (mGluR1) is richly expressed in Purkinje cells (PCs) of the cerebellar cortex. Global mGluR1 knock-out (KO) mice show a significantly lower percentage of conditioned response (CR%) than wild-type mice in eyeblink conditioning, and the impaired CR% is restored by the introduction of mGluR1 in PCs. However, the specific roles of mGluR1 in major memory processes, including formation, storage and expression have not yet been defined. We thus examined the role of mGluR1 in these processes of eyeblink conditioning, using mGluR1 conditional KO (cKO) mice harboring a selective and reversible expression of mGluR1 in PCs. We have found that eyeblink memory is not latently formed in the absence of mGluR1 in adult mouse PCs. However, once acquired, eyeblink memory is expressed even after the depletion of mGluR1 in PCs. We thus conclude that mGluR1 in PCs is indispensable for the formation of eyeblink memory, while it is not required for the expression of CR.
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Parpadeo , Células de Purkinje/metabolismo , Receptores de Glutamato Metabotrópico/metabolismo , Animales , Condicionamiento Clásico , Memoria , Ratones Endogámicos C57BL , Ratones Noqueados , Receptores de Glutamato Metabotrópico/genéticaRESUMEN
The endocannabinoid system modulates synaptic transmission, controls neuronal excitability, and is involved in various brain functions including learning and memory. 2-arachidonoylglycerol, a major endocannabinoid produced by diacylglycerol lipase-α (DGLα), is released from postsynaptic neurons, retrogradely activates presynaptic CB1 cannabinoid receptors, and induces short-term or long-term synaptic plasticity. To examine whether and how the endocannabinoid system contributes to reward-based learning of a motor sequence, we subjected male CB1-knockout (KO) and DGLα-KO mice to three types of operant lever-press tasks. First, we trained mice to press one of three levers labeled A, B, and C for a food reward (one-lever task). Second, we trained mice to press the three levers in the order of A, B, and C (three-lever task). Third, the order of the levers was reversed to C, B, and A (reverse three-lever task). We found that CB1-KO mice and DGLα-KO mice exhibited essentially the same deficits in the operant lever-press tasks. In the one-lever task, both strains of knockout mice showed a slower rate of learning to press a lever for food. In the three-lever task, both strains of knockout mice showed a slower rate of learning of the motor sequence. In the reverse three-lever task, both strains of knockout mice needed more lever presses for reversal learning. These results suggest that the endocannabinoid system facilitates reward-based learning of a motor sequence by conferring the flexibility with which animals can switch between strategies.
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Ácidos Araquidónicos/deficiencia , Endocannabinoides/fisiología , Glicéridos/deficiencia , Aprendizaje/fisiología , Receptor Cannabinoide CB1/deficiencia , Recompensa , Animales , Endocannabinoides/deficiencia , Masculino , Ratones , Ratones Endogámicos C57BL , Ratones NoqueadosRESUMEN
We herein present behavioral data regarding whether COA-Cl, a novel adenosine-like nucleic acid analog that promotes angiogenesis and features neuroprotective roles, improves cognitive and behavioral deficits in a murine model for Alzheimer׳s disease (AD). COA-Cl induced significant spatial memory improvement in the amyloid precursor protein/presenilin 2 double-transgenic mouse model of AD (PS2Tg2576 mice). Correspondingly, non-spatial novel object cognition test performance also significantly improved in COA-Cl-treated PS2Tg2576 mice; however, these mice demonstrated no significant changes in physical activity or motor performance. COA-Cl did not change the spontaneous activities and cognitive ability in the wild-type mice.
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Cannabinoids exert their psychomotor actions through the CB1 cannabinoid receptor in the brain. Genetic deletion of CB1 in mice causes various symptoms, including changes in locomotor activity, increased ring catalepsy, supraspinal hypoalgesia, and impaired memory extinction. Although the cerebellar cortex contains the highest level of CB1, severe cerebellum-related functional deficits have not been reported in CB1 knock-out mice. To clarify the roles of CB1 in cerebellar function, we subjected CB1 knock-out mice to a delay version of classical eyeblink conditioning. This paradigm is a test for cerebellum-dependent discrete motor learning, in which conditioned stimulus (CS) (352 ms tone) and unconditioned stimulus (US) (100 ms periorbital electrical shock) are coterminated. We found that delay eyeblink conditioning performance was severely impaired in CB1 knock-out mice. In contrast, they exhibited normal performance in a trace version of eyeblink conditioning with 500 ms stimulus-free interval intervened between the CS offset and the US onset. This paradigm is a test for hippocampus-dependent associative learning. Sensitivity of CB1 knock-out mice to CS or US was normal, suggesting that impaired delay eyeblink conditioning is attributable to defects in association of responses to CS and US. We also found that intraperitoneal injection of the CB1 antagonist SR141716A [N-piperidino-5-(4-chlorophenyl)-1-(2,4-dichlorophenyl)-4-methyl-3-pyrazole carboxamide] to wild-type mice caused severe impairment in acquisition but not extinction of delay eyeblink conditioning. SR141716A treatment had no effect on trace eyeblink conditioning with a 500 or 750 ms trace interval. These results indicate that endogenous cannabinoid signaling through CB1 is essential for cerebellum-dependent discrete motor learning, especially for its acquisition.
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Moduladores de Receptores de Cannabinoides/metabolismo , Cerebelo/fisiología , Aprendizaje/fisiología , Actividad Motora/fisiología , Receptor Cannabinoide CB1/metabolismo , Transducción de Señal/fisiología , Estimulación Acústica , Animales , Parpadeo/fisiología , Moduladores de Receptores de Cannabinoides/antagonistas & inhibidores , Condicionamiento Clásico/efectos de los fármacos , Condicionamiento Clásico/fisiología , Electrochoque , Extinción Psicológica , Aprendizaje/efectos de los fármacos , Ratones , Ratones Noqueados , Destreza Motora/efectos de los fármacos , Piperidinas/farmacología , Pirazoles/farmacología , Receptor Cannabinoide CB1/antagonistas & inhibidores , Rimonabant , Sensación/efectos de los fármacos , Factores de TiempoRESUMEN
Classical conditioning of the eyeblink reflex is a simple form of associative learning for motor responses. To examine the involvement of hippocampal CA3 NMDA receptors (NRs) in nonspatial associative memory, mice lacking an NR1 subunit selectively in adult CA3 pyramidal cells [CA3-NR1 knock-out (KO) mice] were subjected to eyeblink conditioning paradigms. Mice received paired presentations of an auditory conditioned stimulus (CS) and a periorbital shock unconditioned stimulus (US). With repeated presentation of the CS followed by the US, wild-type mice learned to blink in anticipation of the US before its onset. We first confirmed that wild-type mice require an intact hippocampus in the trace version of eyeblink conditioning in which the CS and US do not overlap, creating a stimulus-free time gap of 500 ms. Under the same condition, CA3-NR1 KO mice successfully acquired conditioned responses (CRs) during the 10 d acquisition sessions, whereas the extinction of CRs was impaired on the first day of extinction sessions. Importantly, CA3-NR1 KO mice were impaired in the formation of an adaptively timed CR during the first five trials in the daily acquisition sessions. The aberrantly timed CR was also observed in the extinction sessions in accordance with the impaired extinction of CRs. These results indicate that CA3-NR1 KO mice are unable to rapidly retrieve adaptive CR timing, suggesting that CA3 NRs play a crucial role in the memory of adaptive CR timing in trace conditioning.
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Condicionamiento Palpebral , Hipocampo/fisiología , Células Piramidales/fisiología , Receptores de N-Metil-D-Aspartato/fisiología , Adaptación Fisiológica , Animales , Parpadeo , Electromiografía , Extinción Psicológica , Hipocampo/citología , Cinética , Ratones , Ratones Noqueados , Receptores de N-Metil-D-Aspartato/genéticaRESUMEN
Presenilin 1 and presenilin 2 (PS1 and PS2) play a critical role in γ-secretase-mediated cleavage of amyloid-ß precursor protein (APP) and the subsequent generation of ß-amyloid peptides. The purpose of the present study was to test whether PS2 mutation accelerates the onset of contextual fear memory deficits in a mouse model of AD that expresses a mutation (K670N/M671L) of the human APP with the Swedish mutation (Tg2576 mice). In the present study, an APP/PS2 double-transgenic mouse model (PS2Tg2576) was generated by crossbreeding transgenic mice carrying the human mutant PS2 (N141I) with Tg2576 mice. Contextual fear conditioning was tested in PS2Tg2576 mice aged 3, 4, 6, and 10-12 months. PS2Tg2576 mice showed a tendency of lower freezing behavior as early as 3 months of age, but significant memory impairment was observed from the age of 4 months. The cognitive impairment was more prominent at ages of 6 and 10-12 months. In contrast, Tg2576 mice aged 3 and 4 months exhibited successful acquisition of contextual fear learning, but Tg2576 mice aged 6 months or older showed significantly impaired fear memory. These results show that PS2 mutation significantly accelerates the onset of fear memory deficits in the APP AD model mice.
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Synaptopathies contributing to neurodevelopmental disorders are linked to mutations in synaptic organizing molecules, including postsynaptic neuroligins, presynaptic neurexins, and MDGAs, which regulate their interaction. The role of MDGA1 in suppressing inhibitory versus excitatory synapses is controversial based on in vitro studies. We show that genetic deletion of MDGA1 in vivo elevates hippocampal CA1 inhibitory, but not excitatory, synapse density and transmission. Furthermore, MDGA1 is selectively expressed by pyramidal neurons and regulates perisomatic, but not distal dendritic, inhibitory synapses. Mdga1-/- hippocampal networks demonstrate muted responses to neural excitation, and Mdga1-/- mice are resistant to induced seizures. Mdga1-/- mice further demonstrate compromised hippocampal long-term potentiation, consistent with observed deficits in spatial and context-dependent learning and memory. These results suggest that mutations in MDGA1 may contribute to cognitive deficits through altered synaptic transmission and plasticity by loss of suppression of inhibitory synapse development in a subcellular domain- and cell-type-selective manner.
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Cognición , Red Nerviosa/metabolismo , Moléculas de Adhesión de Célula Nerviosa/metabolismo , Inhibición Neural , Sinapsis/metabolismo , Animales , Región CA1 Hipocampal/patología , Eliminación de Gen , Potenciación a Largo Plazo , Ratones Endogámicos C57BL , Ratones Noqueados , Moléculas de Adhesión de Célula Nerviosa/deficiencia , Sinapsis/ultraestructura , Transmisión SinápticaRESUMEN
Several pathological and epidemiological studies have demonstrated a possible relationship between traumatic brain injury (TBI) and Alzheimer's disease (AD). However, the exact contribution of TBI to AD onset and progression is unclear. Hence, we examined AD-related histopathological changes and cognitive impairment after TBI in triple transgenic (3×Tg)-AD model mice. Five- to seven-month-old 3×Tg-AD model mice were subjected to either TBI by the weight-drop method or a sham treatment. In the 3×Tg-AD mice subjected to TBI, the spatial learning was not significantly different 7 days after TBI compared to that of the sham-treated 3×Tg-AD mice. However, 28 days after TBI, the 3×Tg-AD mice exhibited significantly lower spatial learning than the sham-treated 3×Tg-AD mice. Correspondingly, while a few amyloid-ß (Aß) plaques were observed in both sham-treated and TBI-treated 3×Tg-AD mouse hippocampus 7 days after TBI, the Aß deposition was significantly greater in 3×Tg-AD mice 28 days after TBI. Thus, we demonstrated that TBI induced a significant increase in hippocampal Aß deposition 28 days after TBI compared to that of the control animals, which was associated with worse spatial learning ability in 3×Tg-AD mice. The present study suggests that TBI could be a risk factor for accelerated AD progression, particularly when genetic and hereditary predispositions are involved.
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Enfermedad de Alzheimer/patología , Enfermedad de Alzheimer/psicología , Péptidos beta-Amiloides/metabolismo , Lesiones Traumáticas del Encéfalo/patología , Lesiones Traumáticas del Encéfalo/psicología , Aprendizaje Espacial , Enfermedad de Alzheimer/complicaciones , Enfermedad de Alzheimer/metabolismo , Precursor de Proteína beta-Amiloide/metabolismo , Animales , Lesiones Traumáticas del Encéfalo/complicaciones , Lesiones Traumáticas del Encéfalo/metabolismo , Disfunción Cognitiva/complicaciones , Modelos Animales de Enfermedad , Hipocampo/metabolismo , Hipocampo/patología , Ratones , Ratones Endogámicos C57BL , Ratones TransgénicosRESUMEN
This data article contains supporting information regarding the research article entitled "Traumatic brain injury accelerates amyloid-ß deposition and impairs spatial learning in the triple-transgenic mouse model of Alzheimer׳s disease" (H. Shishido, Y. Kishimoto, N. Kawai, Y. Toyota, M. Ueno, T. Kubota, Y. Kirino, T. Tamiya, 2016) [1]. Triple-transgenic (3×Tg)-Alzheimer׳s disease (AD) model mice exhibited significantly poorer spatial learning than sham-treated 3×Tg-AD mice 28 days after traumatic brain injury (TBI). Correspondingly, amyloid-ß (Aß) deposition within the hippocampus was significantly greater in 3×Tg-AD mice 28 days after TBI. However, data regarding the short-term and long-term influences of TBI on amyloid precursor protein (APP) accumulation in AD model mice remain limited. Furthermore, there is little data showing whether physical activity and motor learning are affected by TBI in AD model mice. Here, we provide immunocytochemistry data confirming that TBI induces significant increases in APP accumulation in 3×Tg-AD mice at both 7 days and 28 days after TBI. Furthermore, 3×Tg-AD model mice exhibit a reduced ability to acquire conditioned responses (CRs) during delay eyeblink conditioning compared to sham-treated 3×Tg-AD model mice 28 days after TBI. However, physical activity and motor performance are not significantly changed in TBI-treated 3×Tg-AD model mice.