RESUMO
Cranial irradiation with (56)Fe, a form of space radiation, causes hippocampus-dependent cognitive changes. (56)Fe irradiation also increases reactive oxygen species (ROS) levels, which may contribute to these changes. Therefore, we investigated the effects of the antioxidant alpha lipoic acid (ALA) on cognition following sham-irradiation and irradiation. Male mice were irradiated (brain only) with (56)Fe (3 Gy) or sham-irradiated at 6-9 months of age. Half of the mice remained fed a regular chow and the other half of the mice were fed a caloric-matched diet containing ALA starting two-weeks prior to irradiation and throughout cognitive testing. Following cognitive testing, levels of 3-nitrotyrosine (3NT), a marker of oxidative protein stress, and levels of microtubule-associated protein (MAP-2), a dendritic protein important for cognition, were assessed using immunohistochemistry and confocal microscopy. ALA prevented radiation-induced impairments in spatial memory retention in the hippocampal and cortical dependent water maze probe trials following reversal learning. However, in sham-irradiated mice, ALA treatment impaired cortical-dependent novel object recognition and amygdala-dependent cued fear conditioning. There was a trend towards lower 3NT levels in irradiated mice receiving a diet containing ALA than irradiated mice receiving a regular diet. In the hippocampal dentate gyrus of mice on regular diet, irradiated mice had higher levels of MAP-2 immunoreactivity than sham-irradiated mice. Thus, ALA might have differential effects on the brain under normal physiological conditions and those involving environmental challenges such as cranial irradiation.
Assuntos
Irradiação Craniana/psicologia , Ferro/toxicidade , Transtornos da Memória/dietoterapia , Memória/efeitos dos fármacos , Memória/efeitos da radiação , Lesões Experimentais por Radiação/dietoterapia , Ácido Tióctico/farmacologia , Animais , Antioxidantes/farmacologia , Antioxidantes/uso terapêutico , Encéfalo/efeitos dos fármacos , Encéfalo/metabolismo , Encéfalo/efeitos da radiação , Condicionamento Psicológico/efeitos dos fármacos , Condicionamento Psicológico/efeitos da radiação , Irradiação Craniana/métodos , Giro Denteado/efeitos dos fármacos , Giro Denteado/metabolismo , Giro Denteado/efeitos da radiação , Masculino , Aprendizagem em Labirinto/efeitos dos fármacos , Aprendizagem em Labirinto/efeitos da radiação , Transtornos da Memória/induzido quimicamente , Camundongos , Camundongos Endogâmicos C57BL , Proteínas Associadas aos Microtúbulos/metabolismo , Lesões Experimentais por Radiação/induzido quimicamente , Ácido Tióctico/uso terapêutico , Tirosina/análogos & derivados , Tirosina/metabolismoRESUMO
Female mice are more susceptible to radiation-induced cognitive changes than male mice. Previously, we showed that, in female mice, androgens antagonize age-related cognitive decline in aged wild-type mice and androgens and selective androgen receptor modulators (SARMs) antagonize cognitive changes induced by human apolipoprotein E4, a risk factor for developing age-related cognitive decline. In this study, the potential effects of the SARM ACP-105 were assessed in female mice that were either sham-irradiated or irradiated with ¹³7Cesium at a dose of 10Gy. Behavioral testing started 2 weeks following irradiation. Irradiation impaired sensorimotor function in vehicle-treated mice but not in ACP-105-treated mice. Irradiation impaired cued fear conditioning and ACP-105 enhanced fear conditioning in sham-irradiated and irradiated mice. When immunoreactivity for microtubule-associated protein 2 was assessed in the cortex of sham-irradiated mice, there was a brain area × ACP-105 interaction. While ACP-105 reduced MAP-2 immunoreactivity in the sensorimotor cortex, there was a trend towards increased MAP-2 immunoreactivity in the enthorhinal cortex. No effect on MAP-2 immunoreactivity was seen in the irradiated cortex or sham-irradiated or irradiated hippocampus. Thus, there are relatively early radiation-induced behavioral changes in female mice and reduced MAP-2 levels in the sensorimotor cortex following ACP-105 treatment might contribute to enhanced rotorod performance.
Assuntos
Compostos Azabicíclicos/farmacologia , Condicionamento Clássico/efeitos dos fármacos , Medo/efeitos dos fármacos , Atividade Motora/efeitos dos fármacos , Análise de Variância , Animais , Córtex Cerebral/efeitos dos fármacos , Córtex Cerebral/metabolismo , Córtex Cerebral/efeitos da radiação , Condicionamento Clássico/efeitos da radiação , Medo/efeitos da radiação , Feminino , Imuno-Histoquímica , Camundongos , Proteínas Associadas aos Microtúbulos/metabolismo , Atividade Motora/efeitos da radiação , Teste de Desempenho do Rota-Rod , Sinaptofisina/metabolismoRESUMO
Previously we found apoE isoform-dependent effects of (137)Cs irradiation on cognitive function of female mice 3 months following irradiation. Alterations in the number of immature neurons and in the levels of the dendritic marker microtubule-associated protein 2 (MAP-2) might contribute to the cognitive changes following irradiation. Therefore, in the present study we determined if, following (137)Cs irradiation, there are apoE isoform-dependent effects on loss of doublecortin-positive neuroprogenitor cells or MAP-2 immumonoreactivity. In the dentate gyrus, CA1 and CA3 regions of the hippocampus, enthorhinal and sensorimotor cortex, and central and basolateral nuclei of the amygdala of apoE3 female mice, MAP-2 immunoreactivity increased 3 months following (137)Cs irradiation. In addition, at 8 h following irradiation, the number of doublecortin-positive cells was higher in apoE3 than apoE2 or apoE4 mice. Together, these data indicate that brains of apoE3 mice respond differently to (137)Cs irradiation than those of apoE2 or apoE4 mice.
Assuntos
Apolipoproteínas E/metabolismo , Proteínas Associadas aos Microtúbulos/imunologia , Neurônios/metabolismo , Neurônios/efeitos da radiação , Neuropeptídeos/metabolismo , Animais , Radioisótopos de Césio , Proteínas do Domínio Duplacortina , Feminino , Humanos , Camundongos , Proteínas Associadas aos Microtúbulos/metabolismo , Neurônios/citologia , Isoformas de Proteínas/metabolismo , Células-Tronco/citologia , Células-Tronco/efeitos da radiaçãoRESUMO
Metabotropic glutamate receptors (mGluRs) modulate glutamatergic and GABAergic neurotransmission. mGluR8 is generally located presynaptically where it regulates neurotransmitter release. Previously we reported that 6-month-old mGluR8(-/-) male mice show higher measures of anxiety in anxiety tests involving avoidable anxiety-provoking stimuli than age-matched wild-type male mice. In wild-type mice, middle-aged females and males show higher measures of anxiety in such tests and reduced spatial learning than young adults. In this study we evaluated in middle-aged mice the effects of mGluR8 deficiency on measures of anxiety involving avoidable and unavoidable anxiety-provoking stimuli and on cognitive performance and whether these effects are sex-dependent. Female and male mGluR8(-/-) mice showed increased measures of anxiety in the open field. In contrast, male mGluR8(-/-) mice showed increased but female mGluR8(-/-) mice decreased measures of anxiety in the elevated plus maze and the acoustic startle response. mGluR8 deficiency impaired novel location recognition and spatial memory retention in the water maze. The impairment in spatial memory retention in the water maze, but not in novel location recognition, was more pronounced in female than male mice. Thus, potential sex differences in the therapeutic effects of mGluR8 modulation to reduce measures of anxiety and improve cognitive performance should be carefully considered.
Assuntos
Cognição/fisiologia , Fenótipo , Receptores de Glutamato Metabotrópico/deficiência , Caracteres Sexuais , Estimulação Acústica/métodos , Análise de Variância , Animais , Ansiedade/genética , Comportamento Exploratório/fisiologia , Feminino , Masculino , Aprendizagem em Labirinto/fisiologia , Transtornos da Memória/genética , Camundongos , Camundongos Endogâmicos C57BL , Camundongos Knockout , Atividade Motora/genética , Reconhecimento Psicológico/fisiologia , Reflexo de Sobressalto/genéticaRESUMO
OBJECTIVE: Mice subjected to traumatic brain injury at postnatal day 21 show emerging cognitive deficits that coincide with hippocampal neuronal loss. Here we consider glutathione peroxidase (GPx) activity as a determinant of recovery in the injured immature brain. METHODS: Wild-type and transgenic (GPxTg) mice overexpressing GPx were subjected to traumatic brain injury or sham surgery at postnatal day 21. Animals were killed acutely (3 or 24 hours after injury) to assess oxidative stress and cell injury in the hippocampus or 4 months after injury after behavioral assessments. RESULTS: In the acutely injured brains, a reduction in oxidative stress markers including nitrotyrosine was seen in the injured GPxTg group relative to wild-type control mice. In contrast, cell injury, with marked vulnerability in the dentate gyrus, was apparent despite no differences between genotypes. Magnetic resonance imaging demonstrated an emerging cortical lesion during brain maturation that was also indistinguishable between injured genotypes. Stereological analyses of cortical volumes likewise confirmed no genotypic differences between injured groups. However, behavioral tests beginning 3 months after injury demonstrated improved spatial memory learning in the GPxTg group. Moreover, stereological analysis within hippocampal subregions demonstrated a significantly greater number of neurons within the dentate of the GPx group. INTERPRETATION: Our results implicate GPx in recovery of spatial memory after traumatic brain injury. This recovery may be attributed, in part, to a reduction in early oxidative stress and selective, long-term sparing of neurons in the dentate.
Assuntos
Lesões Encefálicas/fisiopatologia , Glutationa Peroxidase/metabolismo , Recuperação de Função Fisiológica/fisiologia , Animais , Animais Recém-Nascidos , Comportamento Animal , Lesões Encefálicas/genética , Lesões Encefálicas/patologia , Modelos Animais de Doenças , Fluoresceínas , Regulação da Expressão Gênica/genética , Glutationa Peroxidase/genética , Hipocampo/crescimento & desenvolvimento , Hipocampo/patologia , Hipocampo/fisiopatologia , Marcação In Situ das Extremidades Cortadas/métodos , Imageamento por Ressonância Magnética/métodos , Masculino , Camundongos , Camundongos Endogâmicos BALB C , Camundongos Transgênicos , Compostos Orgânicos , Estresse Oxidativo/genética , Técnicas Estereotáxicas , Superóxido Dismutase/metabolismoRESUMO
With the rise in methamphetamine (MA) use among women of childbearing age, the potential consequences of MA exposure to the developing brain for cognition in adulthood is a major concern. Histamine might mediate these MA effects. Following MA administration in neonatal mice, histamine levels in brain were elevated and the hypothalamic-pituitary-adrenal axis was activated. Co-administration of MA with the H3 receptor agonist immepip antagonized these effects. The effects of MA on histamine levels and on hypothalamic-pituitary-adrenal axis activation at P20 were more pronounced in female than male mice. These sex differences could have contributed to the increased susceptibility of female mice to the detrimental long-term cognitive effects of MA and the H3/H4 antagonist thioperamide. Following behavioral testing, mice neonatally treated with MA or thioperamide showed reduced levels of the dendritic marker microtubule-associated protein 2 in the CA3 region of the hippocampus and the enthorhinal cortex. This was not seen in mice neonatally treated with immepip and MA who did not show cognitive impairments, suggesting that these brain areas might be particularly important for the long-term effects of MA on cognitive function. These data support a role for histamine in the effects of MA on the developing brain.
Assuntos
Encéfalo/efeitos dos fármacos , Encéfalo/crescimento & desenvolvimento , Estimulantes do Sistema Nervoso Central/farmacologia , Histamina/metabolismo , Metanfetamina/farmacologia , Fatores Etários , Animais , Animais Recém-Nascidos , Encéfalo/anatomia & histologia , Corticosterona/metabolismo , Ensaio de Imunoadsorção Enzimática/métodos , Feminino , Antagonistas dos Receptores Histamínicos H3/farmacologia , Sistema Hipotálamo-Hipofisário/efeitos dos fármacos , Imidazóis/farmacologia , Masculino , Metanfetamina/sangue , Camundongos , Camundongos Endogâmicos C57BL , Proteínas Associadas aos Microtúbulos/metabolismo , Piperidinas/farmacologia , Sistema Hipófise-Suprarrenal/efeitos dos fármacos , Fatores Sexuais , Fatores de TempoRESUMO
The immature brain may be particularly vulnerable to injury during critical periods of development. To address the biologic basis for this vulnerability, mice were subjected to traumatic brain injury at postnatal day 21, a time point that approximates that of the toddler-aged child. After motor and cognitive testing at either 2 weeks (juveniles) or 3 months (adults) after injury, animals were euthanized and the brains prepared for quantitative histologic assessment. Brain-injured mice exhibited hyperactivity and age-dependent anxiolysis. Cortical lesion volume and subcortical neuronal loss were greater in brain-injured adults than in juveniles. Importantly, cognitive decline was delayed in onset and coincided with loss of neurons in the hippocampus. Our findings demonstrate that trauma to the developing brain results in a prolonged period of pathogenesis in both cortical and subcortical structures. Behavioral changes are a likely consequence of regional-specific neuronal degeneration.
Assuntos
Lesões Encefálicas/fisiopatologia , Encéfalo/patologia , Encéfalo/fisiopatologia , Transtornos Cognitivos/fisiopatologia , Deficiências do Desenvolvimento/fisiopatologia , Degeneração Neural/fisiopatologia , Agitação Psicomotora/fisiopatologia , Envelhecimento/fisiologia , Animais , Encéfalo/crescimento & desenvolvimento , Lesões Encefálicas/complicações , Morte Celular/fisiologia , Diferenciação Celular/fisiologia , Transtornos Cognitivos/etiologia , Deficiências do Desenvolvimento/etiologia , Modelos Animais de Doenças , Progressão da Doença , Comportamento Exploratório/fisiologia , Hipocampo/crescimento & desenvolvimento , Hipocampo/patologia , Hipocampo/fisiopatologia , Humanos , Lactente , Masculino , Transtornos da Memória/etiologia , Transtornos da Memória/fisiopatologia , Camundongos , Camundongos Endogâmicos C57BL , Degeneração Neural/etiologia , Neurônios/patologia , Agitação Psicomotora/etiologia , Células-Tronco/metabolismo , Células-Tronco/patologia , TempoRESUMO
Multipotential bone marrow stromal cells (MSCs) from wild-type (Wt) or apolipoprotein E deficient (Apoe(-/-)) mice were implanted into the cerebral ventricles of Apoe(-/-) mice. MSCs from Wt mice continued expressing apoE up to 6 months after implantation and were associated with enhanced novel object recognition and increased microtubule-associated protein 2 (MAP2) immunoreactivity in the dentate gyrus. These data show that MSCs can be used to distinguish developmental from post-developmental effects of a gene knockout and support their therapeutic potential for neurodegenerative diseases.
Assuntos
Apolipoproteínas E/metabolismo , Células Estromais/transplante , Células-Tronco Totipotentes/transplante , Animais , Animais Recém-Nascidos , Apolipoproteínas E/genética , Células da Medula Óssea/citologia , Células da Medula Óssea/metabolismo , Transplante de Medula Óssea/métodos , Ventrículos Cerebrais/metabolismo , Ventrículos Cerebrais/cirurgia , Giro Denteado/metabolismo , Feminino , Imuno-Histoquímica , Masculino , Camundongos , Camundongos Endogâmicos C57BL , Camundongos Knockout , Proteínas Associadas aos Microtúbulos/metabolismo , Células Estromais/citologia , Células Estromais/metabolismo , Células-Tronco Totipotentes/citologia , Células-Tronco Totipotentes/metabolismoRESUMO
The role of histamine in brain function has been studied using histidine decarboxylase (HDC) deficient male mice. As the effects of HDC deficiency on brain function might be sex-dependent, we behaviorally analyzed Hdc(-/-) and control female mice. Compared to female control mice, Hdc(-/-) female mice showed hypoactivity, increased measures of anxiety, impairments in water-maze performance, but enhanced passive avoidance memory retention. Following behavioral testing, arginine vasopression (AVP) immunoreactivity was higher in the dorsal hypothalamus and central and basolateral nuclei of the amygdala of Hdc(-/-) than Hdc(+/+) mice. Finally, MAP2 immunoreactivity in the hippocampal CA1 region correlated positively with measures of anxiety in the open-field and light-dark tests and negatively with performance during the hidden sessions of the water-maze. As the effects of HDC deficiency on object recognition, water-maze, and rotorod performance, were sex-dependent, it is important to consider potential effects of sex in the interpretation of the role of histaminergic neurotransmission in brain function.
Assuntos
Ansiedade/genética , Ansiedade/psicologia , Cognição/fisiologia , Histidina Descarboxilase/genética , Histidina Descarboxilase/fisiologia , Animais , Arginina Vasopressina/metabolismo , Aprendizagem da Esquiva/fisiologia , Escuridão , Dendritos/metabolismo , Dendritos/fisiologia , Comportamento Exploratório/fisiologia , Feminino , Imuno-Histoquímica , Luz , Masculino , Aprendizagem em Labirinto/fisiologia , Camundongos , Camundongos Knockout , Proteínas Associadas aos Microtúbulos/metabolismo , Equilíbrio Postural/fisiologia , Reconhecimento Psicológico/fisiologia , Caracteres SexuaisRESUMO
Compared with apoE2 and E3, apoE4 increases the risk of cognitive impairments and of developing Alzheimer's disease (AD). ApoE4 interacts with female sex, further increasing AD risk. Previously, we showed that female Apoe-/- mice are more susceptible to apoE4-induced cognitive deficits than male mice. Androgens protect against these deficits and apoE4 male mice are more sensitive to acute blockade of androgen receptors than apoE3 male mice. To determine the chronic effects of reduced circulating androgen levels on susceptibility to the effects of apoE4 on cognitive function in males, we castrated and sham-castrated apoE4, apoE3, and Apoe-/- male mice and behaviorally compared them 3 months later. Castration impaired novel location recognition in apoE4, but not apoE3 or Apoe-/-, mice. In contrast, castration impaired novel object recognition and spatial memory retention in the water maze in Apoe-/-, but not apoE3 or apoE4, mice. On the contrary, castrated, but not sham-castrated, apoE4 mice showed improved acquisition over the first two hidden platform sessions and spatial memory retention in the first probe trial. While apoE3 and Apoe-/- mice increased their exploratory times with the objects in the trial with the novel object, apoE4 mice did not. ApoE4 mice required more trials than apoE3 or Apoe-/- mice to reach criterion during passive avoidance training, but castration did not modulate passive avoidance learning or memory. Thus, androgens have differential roles in object recognition and spatial learning and memory in the water maze, depending on whether or not apoE4 is present.
Assuntos
Androgênios/metabolismo , Apolipoproteínas E/fisiologia , Cognição/fisiologia , Análise de Variância , Animais , Apolipoproteína E3 , Apolipoproteínas E/deficiência , Aprendizagem da Esquiva/fisiologia , Comportamento Animal , Castração/métodos , Comportamento Exploratório/fisiologia , Lateralidade Funcional , Masculino , Aprendizagem em Labirinto/fisiologia , Camundongos , Camundongos Knockout , Fosfopiruvato Hidratase/metabolismo , Análise de Componente Principal , Desempenho Psicomotor/fisiologia , Tempo de Reação/genética , Reconhecimento Psicológico/fisiologia , Teste de Desempenho do Rota-Rod/métodos , Fatores de TempoRESUMO
To study the role of the metabotropic glutamate receptor 8 (mGluR8), mice lacking this receptor were generated by homologous recombination. Homozygous mGluR8-deficient mice are about 8% heavier than their wild-type age-matched controls after reaching 4 weeks of age. This weight difference is not caused by an altered food intake and is not exacerbated by feeding the animals a high-fat diet. Moreover, mGluR8-/- mice are mildly insulin resistant, possibly as a result of being overweight. Behavioral testing revealed a reduced locomotor activity of mGluR8-/- mice compared with wild-type mice during the first 3 days in a novel enclosed environment. However after 3 days, the locomotor activities of wild-type and mGluR8-/- mice were similar, suggesting a reduced exploratory behavior of mGluR8-/- mice in a novel enclosed environment. By contrast, there were no genotype differences in locomotor activity in the open field, plus maze, or in total time spent exploring objects during object recognition tests, indicating that there is a dissociation between effects of mGluR8 deficiency in exploratory activity in a novel safe enclosed environment vs. a more anxiogenic novel open environment. The absence of mGluR8 also leads to increased measures of anxiety in the open field and elevated plus maze. Whether the diverse phenotypic differences observed in mGluR8-/- mice result from the misregulation of a unique neural pathway, possibly in the thalamus or hypothalamus, or whether they are the consequence of multiple developmental and functional alterations in synaptic transmission, remains to be determined.
Assuntos
Ansiedade/genética , Camundongos Knockout/fisiologia , Receptores de Glutamato Metabotrópico/deficiência , Projetos de Pesquisa , Aumento de Peso/genética , Absorciometria de Fóton/métodos , Fatores Etários , Animais , Aprendizagem da Esquiva/fisiologia , Comportamento Animal/fisiologia , Glicemia/genética , Western Blotting/métodos , Composição Corporal/genética , Tolerância a Medicamentos/genética , Ingestão de Alimentos/genética , Comportamento Exploratório/fisiologia , Genótipo , Insulina/farmacologia , Aprendizagem em Labirinto/fisiologia , Camundongos , Biologia Molecular/métodos , Atividade Motora/genética , Desempenho Psicomotor/fisiologia , Tempo de Reação/genética , Receptores de Glutamato Metabotrópico/genética , Reconhecimento Psicológico/fisiologia , Fatores de TempoRESUMO
Increased anxiety may occur in up to 70% of AD patients during the course of their illness. Here we show that human apoE isoforms, which differ in AD risk, have differential effects on measures of anxiety in adult Apoe-/- male mice expressing human apoE3 or apoE4 in their brains and male probable AD (PRAD) patients. Compared with wild-type mice, Apoe-/- mice without human apoE or with apoE4, but not apoE3, showed increased measures of anxiety. These behavioral alterations were associated with reduced microtubule-associated protein 2-positive neuronal dendrites in the central nucleus of the amygdala. Consistent with the mouse data, male and female PRAD patients with epsilon4/epsilon4 showed higher anxiety scores than those with epsilon3/epsilon3. We conclude that human apoE isoforms have differential effects on measures of anxiety.