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1.
Behav Brain Res ; : 115147, 2024 Jul 17.
Artigo em Inglês | MEDLINE | ID: mdl-39029628

RESUMO

Early life adversity has been linked with a higher probability of developing behavioral impairments and environmental manipulation is a strategy that may reduce the negative effects of exposure to adversity in early life. Here, we focused on exploring the influence of environmental enrichment (EE) as a protective factor in the context of early life adversity. We hypothesized that 24hours of maternal deprivation (MD), in the second week of life, could induce anxiety-like behavior alterations and that exposure to EE could induce resilience to these behaviors due to alterations in the serotonergic system. Male Wistar rats were exposed to MD, on postnatal days 11 and 13, and to EE, after weaning. In adulthood, we performed a series of behavioral tests for fear, anxiety, and locomotor activity. We also measured the levels of serotonin in the amygdala and dorsal raphe nucleus. Our results revealed that MD does not impact fear behavior or the levels of serotonin, while EE decreases locomotor activity in a novel environment and enhances exploration in the predator odor test. EE also decreases serotonin in the amygdala and increases its turnover rate levels. Our findings provide insights into the critical timeframe during which stress exposure impacts the development and confirm that exposure to EE has an independent and protective effect for anxiety-like behaviors later in life.

2.
Cereb Cortex ; 27(1): 544-553, 2017 01 01.
Artigo em Inglês | MEDLINE | ID: mdl-26494801

RESUMO

The impact of nicotine (NIC) on plasticity is thought to be primarily determined via calcium channel properties of nicotinic receptor subtypes, and glutamatergic plasticity is likewise calcium-dependent. Therefore glutamatergic plasticity is likely modulated by the impact of nicotinic receptor-dependent neuronal calcium influx. We tested this hypothesis for transcranial direct current stimulation (tDCS)-induced long-term potentiation-like plasticity, which is abolished by NIC in nonsmokers. To reduce calcium influx under NIC, we blocked N-methyl-d-aspartate (NMDA) receptors. We applied anodal tDCS combined with 15 mg NIC patches and the NMDA-receptor antagonist dextromethorphan (DMO) in 3 different doses (50, 100, and 150 mg) or placebo medication. Corticospinal excitability was monitored by single-pulse transcranial magnetic stimulation-induced motor-evoked potential amplitudes after plasticity induction. NIC abolished anodal tDCS-induced motor cortex excitability enhancement, which was restituted under medium dosage of DMO. Low-dosage DMO did not affect the impact of NIC on tDCS-induced plasticity and high-dosage DMO abolished plasticity. For DMO alone, the low dosage had no effect, but medium and high dosages abolished tDCS-induced plasticity. These results enhance our knowledge about the proposed calcium-dependent impact of NIC on plasticity in humans and might be relevant for the development of novel nicotinic treatments for cognitive dysfunction.


Assuntos
Dextrometorfano/farmacologia , Antagonistas de Aminoácidos Excitatórios/farmacologia , Plasticidade Neuronal/efeitos dos fármacos , Nicotina/farmacologia , Agonistas Nicotínicos/farmacologia , Estimulação Transcraniana por Corrente Contínua , Adulto , Análise de Variância , Relação Dose-Resposta a Droga , Potencial Evocado Motor/efeitos dos fármacos , Potencial Evocado Motor/fisiologia , Feminino , Humanos , Masculino , Córtex Motor/efeitos dos fármacos , Córtex Motor/fisiologia , Plasticidade Neuronal/fisiologia , Receptores de N-Metil-D-Aspartato/antagonistas & inibidores , Receptores de N-Metil-D-Aspartato/metabolismo , Fatores de Tempo
3.
Brain Stimul ; 6(3): 261-9, 2013 May.
Artigo em Inglês | MEDLINE | ID: mdl-22878259

RESUMO

BACKGROUND: Extensive evidence supports the notion that modulation of PFC excitability using low-intensity electrical stimulation is a promising modality for treating neuropsychiatric diseases and improving cognitive function. OBJECTIVE: This study examined the effects of epidural direct current stimulation (eDCS), a method providing smaller shunting of current and more focal stimulation, on spatial working memory. METHODS: Male Wistar rats that were well trained in an 8-arm radial maze and in which 5-mm round electrodes were implanted over the left medial prefrontal cortex (mPFC) received anodal eDCS (400 µA during 11 min) (n = 9) or sham procedure (n = 9) five minutes before delayed tests in the radial maze. RESULTS: Animals that received eDCS over the left mPFC had significantly fewer errors in the post-delay performance on the 1-h (P < 0.01), 4-h (P < 0.001), and 10-h (P < 0.001) delayed tests compared with sham-treated animals. General locomotor activity was unaffected because time spent in each visited arm did not change significantly by eDCS. There was no evidence of neuronal lesions in the mPFC underneath the eDCS. CONCLUSIONS: Our results suggest that epidural direct current stimulation over the mPFC facilitates spatial working memory in rats, an effect that persisted over the long term.


Assuntos
Estimulação Encefálica Profunda/métodos , Memória de Curto Prazo/fisiologia , Córtex Pré-Frontal/fisiologia , Percepção Espacial/fisiologia , Análise de Variância , Animais , Eletrodos Implantados , Masculino , Aprendizagem em Labirinto/fisiologia , Ratos , Ratos Wistar , Fatores de Tempo
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