Visualization and Genetic Manipulation of Dendrites and Spines in the Mouse Cerebral Cortex and Hippocampus using <em>In utero</em> Electroporation

In utero electroporation (IUE) has become a powerful technique to study the development of different regions of the embryonic nervous system 1-5. To date ...

Université de Bordeaux

Nicotine, the neuroactive compound responsible for tobacco addiction, is primarily believed to have beneficial effects on the adult brain. However, in heavy smokers, abstinence from nicotine is accompanied by cognitive impairments that suggest adverse effects of nicotine on brain plasticity. For this reason, we studied changes in plasticity-related processes in the dentate gyrus (DG) of the hippocampal formation of animals trained to self-administer nicotine. The DG was chosen because it undergoes profound plastic rearrangements, many of which have been related to memory and learning performances. In this region, we examined the expression of the polysialylated (PSA) forms of neural cell adhesion molecule (NCAM), PSA-NCAM, neurogenesis, and cell death by measuring the number of pyknotic cells. It was found that nicotine self-administration profoundly decreased, in a dose-dependent manner, the expression of PSA-NCAM in the DG; a significant effect was observed at all the doses tested (0.02, 0.04, and 0.08 mg/kg per infusion). Neurogenesis was also decreased in the DG, but a significant effect was observed only for the two highest doses of nicotine. Finally, the same doses that decreased neurogenesis also increased cell death. These results raise an important additional concern for the health consequences of nicotine abuse and open new insight on the possible neural mechanisms of tobacco addiction.

Nicotine self-administration impairs hippocampal plasticity.

The role of the hippocampus in pavlovian fear conditioning is controversial. Although lesion and pharmacological inactivation studies have suggested a key role for the dorsal hippocampus in contextual fear conditioning, the involvement of the ventral part is still uncertain. Likewise, the debate is open with regard to the putative implication of each hippocampal subdivision in fear conditioning to a discrete conditioned stimulus. We explored the potential existence of dissociations occurring in the dorsal versus ventral hippocampus at the cellular level while dealing with either contextual or cued fear conditioning and focused in a molecular "signature" linked to structural plasticity, the polysialylated form of the neural cell adhesion molecule (PSA-NCAM). We found an upregulation of PSA-NCAM expression in the dorsal (but not ventral) dentate gyrus at 24 h after contextual (but not tone) fear conditioning. Specific removal of PSA through microinfusion of the enzyme endoneuraminidase-N in the dorsal (but not ventral) hippocampus reduced freezing responses to the conditioned context. Therefore, we present evidence for a specific role of PSA-NCAM in the dorsal hippocampus in the plasticity processes occurring during consolidation of the context representation after "standard" contextual fear conditioning. Interestingly, we also found that exposing animals just to the context induced an activation of PSA-NCAM in both dorsal and ventral dentate gyrus. Altogether, these findings highlighting the distinctive occurrence of these neuroplastic processes in the dorsal hippocampus during the standard contextual fear-conditioning task enlighten the ongoing debate about the involvement of these hippocampal subdivisions in pavlovian fear conditioning.

Upregulation of polysialylated neural cell adhesion molecule in the dorsal hippocampus after contextual fear conditioning is involved in long-term memory formation.

Nei mammiferi, i nuovi neuroni vengono aggiunti al bulbo olfattivo (OB) per tutta la vita. La maggior parte di questi nuovi neuroni, cellule granulo e periglomerular provengono dalla zona subventricolare (SVZ) fodera i ventricoli laterali e migrare via rostrale migratori verso OB. migliaia di nuovi neuroni appaiono ogni giorno, ma la funzione di questa continua neurogenesi rimane poco chiara.

Effetti cellulari e comportamentali di irradiazione cranica della zona subventricolare in topi adulti.

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In mammals, new neurons are added to the olfactory bulb (OB) throughout life. Most of these new neurons, granule and periglomerular cells originate from the subventricular zone (SVZ) lining the lateral ventricles and migrate via the rostral migratory stream toward the OB. Thousands of new neurons appear each day, but the function of this ongoing neurogenesis remains unclear.

Cellular and behavioral effects of cranial irradiation of the subventricular zone in adult mice.

Chez les mammif&#xE8;res, de nouveaux neurones sont ajout&#xE9;s au bulbe olfactif (OB) tout au long de la vie. La plupart de ces nouveaux neurones, les cellules granulaires et p&#xE9;riglom&#xE9;rulaire proviennent de la zone sous-ventriculaire (ZSV) qui tapisse les ventricules lat&#xE9;raux et de migrer via le courant de migration rostrale vers l&#x26;#39;OB. Des milliers de nouveaux neurones apparaissent chaque jour, mais la fonction de cette neurogen&#xE8;se continue reste incertaine.

Les effets cellulaires et comportementaux de l&#x26;#39;irradiation cr&#xE2;nienne de la zone sous-ventriculaire chez la souris adulte

Bei S&auml;ugetieren werden neue Neuronen Riechkolben (OB) zeitlebens hinzugef&uuml;gt. Die meisten dieser neuen Neuronen, Granulat- und Periglomerular Zellen stammen aus der subventrikul&auml;re Zone (SVZ) Futter der Seitenventrikel und migrieren &uuml;ber den K&ouml;rperabschnitt wandernden Stream in Richtung der FAG-Tausende neuer Nervenzellen erscheinen jeden Tag, aber die Funktion dieser laufenden Neurogenese bleibt unklar.

Zellul&auml;re und Verhaltenseigenschaften Auswirkungen der kraniale Bestrahlung der subventrikul&auml;re Zone im Erwachsenen M&auml;usen.

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En los mam&#xED;feros, se a&#xF1;aden nuevas neuronas al bulbo olfatorio (OB) durante toda la vida. La mayor&#xED;a de estas nuevas neuronas, las c&#xE9;lulas granulosas y periglomerular proceden de la zona subventricular (SVZ) que recubre los ventr&#xED;culos laterales y migrar a trav&#xE9;s de la corriente migratoria rostral hacia el OB. Miles de nuevas neuronas aparecen cada d&#xED;a, pero la funci&#xF3;n de esta neurog&#xE9;nesis en curso a&#xFA;n no est&#xE1; claro.

Djoher Nora Abrous

Physiopathologie de la plasticité neuronale,
Neurocentre Magendie,
Physiopathologie de la plasticité neuronale, Neurocentre Magendie

Université de Bordeaux

Visualization and Genetic Manipulation of Dendrites and Spines in the Mouse Cerebral Cortex and Hippocampus using In utero Electroporation

Djoher Nora Abrous

.css-o250i3{font-size:18px;font-family:Open Sans,sans-serif;line-height:21.6px;}Physiopathologie de la plasticité neuronale,Neurocentre Magendie,Physiopathologie de la plasticité neuronale, Neurocentre Magendie

Université de Bordeaux

Visualization and Genetic Manipulation of Dendrites and Spines in the Mouse Cerebral Cortex and Hippocampus using In utero Electroporation

Physiopathologie de la plasticité neuronale,
Neurocentre Magendie,
Physiopathologie de la plasticité neuronale, Neurocentre Magendie