Publicação
Hilar hippocampal cytogenesis: a new source of neural plasticity in the adult mammalian brain?
| Resumo: | The continuous capacity to generate new neuronal and glial cells, a process known as adult brain cytogenesis, persists in restricted niches of the adult mammalian brain. This phenomenon occurs traditionally in two regions: the subgranular zone (SGZ) of the hippocampal dentate gyrus (DG) and the periventricular subependymal zone. The dentate gyrus has been classically involved in important brain functions such as learning and memory. Beyond the participation in cognitive processing, the newborn neurons have been also shown to be important for several emotion domains. Despite the fact that brain cytogenesis in rodents is well accepted, the functional importance of adult neurogenesis in mammals has been a matter of much debate. Just recently, discussion around this fundamental subject of neurosciences was stirred up. The dentate hilus is one of the most complex and cellular diverse sub-regions of the hippocampal formation with a central role in key cognitive hippocampal functions. Few descriptions exist of cytogenesis in the adult hilus. Moreover, the field lacks a morphological and functional characterization of hilar newborn cells. Hence this work provides an unprecedented neuroanatomical description of hilar cytogenesis complemented with insights on its extrinsic modulation, in the adult rat brain. Results show that newborn hilar cells acquire neuroblasts’ cell markers, although they present more incipient cytomorphological traits, when compared to their subgranular counterparts. Contrarily to SGZ neurogenesis, newborn hilar neurons do not express the final maturation marker, NeuN. A significantly small fraction of new hilar cells within the hilus reflect the astrogliogenic process, described to be ubiquitous in the adult brain. Even though the number of newborn cells in the hilus is lower than in the SGZ, that region emerges as an important niche of neural plasticity. Indeed, stress exposure, physical activity and treatment with psychotropic drugs differentially modulate hilar cytogenesis. Work on this thesis improves current knowledge on structural plasticity of the adult mammalian brain, and revisits pre-established notions on the regional distribution and functional importance of post-natal neuro- and gliogenic niches. |
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| Autores principais: | Araújo, Bruna Alexandra Vale |
| Assunto: | Hilar cytogenesis Hippocampus Neural plasticity Citogénese hilar Hipocampo Plasticidade neuronal Ciências Médicas |
| Ano: | 2019 |
| País: | Portugal |
| Tipo de documento: | dissertação de mestrado |
| Tipo de acesso: | acesso aberto |
| Instituição associada: | Universidade do Minho |
| Idioma: | inglês |
| Origem: | RepositóriUM - Universidade do Minho |
| Resumo: | The continuous capacity to generate new neuronal and glial cells, a process known as adult brain cytogenesis, persists in restricted niches of the adult mammalian brain. This phenomenon occurs traditionally in two regions: the subgranular zone (SGZ) of the hippocampal dentate gyrus (DG) and the periventricular subependymal zone. The dentate gyrus has been classically involved in important brain functions such as learning and memory. Beyond the participation in cognitive processing, the newborn neurons have been also shown to be important for several emotion domains. Despite the fact that brain cytogenesis in rodents is well accepted, the functional importance of adult neurogenesis in mammals has been a matter of much debate. Just recently, discussion around this fundamental subject of neurosciences was stirred up. The dentate hilus is one of the most complex and cellular diverse sub-regions of the hippocampal formation with a central role in key cognitive hippocampal functions. Few descriptions exist of cytogenesis in the adult hilus. Moreover, the field lacks a morphological and functional characterization of hilar newborn cells. Hence this work provides an unprecedented neuroanatomical description of hilar cytogenesis complemented with insights on its extrinsic modulation, in the adult rat brain. Results show that newborn hilar cells acquire neuroblasts’ cell markers, although they present more incipient cytomorphological traits, when compared to their subgranular counterparts. Contrarily to SGZ neurogenesis, newborn hilar neurons do not express the final maturation marker, NeuN. A significantly small fraction of new hilar cells within the hilus reflect the astrogliogenic process, described to be ubiquitous in the adult brain. Even though the number of newborn cells in the hilus is lower than in the SGZ, that region emerges as an important niche of neural plasticity. Indeed, stress exposure, physical activity and treatment with psychotropic drugs differentially modulate hilar cytogenesis. Work on this thesis improves current knowledge on structural plasticity of the adult mammalian brain, and revisits pre-established notions on the regional distribution and functional importance of post-natal neuro- and gliogenic niches. |
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