| Dissertation |
Thesis (M.D.) --NUI, 2014 at Department of Anatomy & Neuroscience, UCC. |
| Summary |
The microbiota-gut-brain axis has been proven to be involved in the regulation of physiological functions and maintenance of homeostasis. This includes maintenance of neurotransmitters such as serotonin (5-HT), neurotrophic factors such as brain-derived neurotrophic factor (BDNF), and corticosterone, factors that influence adult hippocampal neurogenesis in the hippocampus. This study has shown that the gut microbiota influenced the survival of newly-born cells in the dentate gyrus of the hippocampus. We also found that there seems to be a critical window in early life during which the gut microbiota influences the nervous system given that colonization of germ-free mice in adolescence did not reverse this effect of the gut microbiota on the hippocampus. Similarly, ingested probiotics have been shown to influence the central nervous system, and this effect is thought to be linked to the ability of certain probiotics to regulate BDNF. However, in this study Lactobacillus rhamnosus (JB-1) did not affect the expression of BDNF mRNA in the hippocampus. However, we have shown that vagotomy decreased the expression of BDNF mRNA in broth-fed mice, and there was a trend for JB-1 to reverse this effect of vagotomy. This suggests the existence of vagus-dependent and independent mechanisms through which the gut microbiota alters brain function. In the same vein, using Ki-67 and BrdU immunohistochemistry, it was demonstrated that vagotomy decreased the proliferation and survival of newly-born cells in the ventral and dorsal hippocampus respectively. This, for what is to our knowledge the first time that the vagus nerve tonically regulates adult hippocampal cell proliferation. Overall, we showed that the gut microbiota and the signalling from the gut to the brain can affect hippocampus function, and this connection may serve as potential therapeutic targets in the future for the management of neuropsychiatric and neurodegenerative disorders linked to adult hippocampal neurogenesis plays a role. |
| Subject |
Neurosciences.
|
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Anatomy.
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| Collection |
Theses Masters
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Theses Anatomy and Neuroscience Department
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| Description |
151 pages ; 30 cm. |
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