Investigations into the cellular and molecular changes in the amygdala in models of temporal lobe epilepsy and maternal immune activation

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dc.contributor.advisor McDermott, Kieran en O'Loughlin, Elaine K. 2015-11-20T12:50:27Z 2015 2015
dc.identifier.citation O'Loughlin, E. K. 2015. Investigations into the cellular and molecular changes in the amygdala in models of temporal lobe epilepsy and maternal immune activation. PhD Thesis, University College Cork. en
dc.description.abstract The amygdala is a limbic structure that is involved in many of our emotions and processing of these emotions such as fear, anger and pleasure. Conditions such as anxiety, autism, and also epilepsy, have been linked to abnormal functioning of the amygdala, owing to improper neurodevelopment or damage. This thesis investigated the cellular and molecular changes in the amygdala in models of temporal lobe epilepsy (TLE) and maternal immune activation (MIA). The kainic acid (KA) model of temporal lobe epilepsy (TLE) was used to induce Ammon’s-horn sclerosis (AHS) and to investigate behavioural and cytoarchitectural changes that occur in the amygdala related to Neuropeptide Y1 receptor expression. Results showed that KA-injected animals showed increased anxiety-like behaviours and displayed histopathological hallmarks of AHS including CA1 ablation, granule cell dispersion, volume reduction and astrogliosis. Amygdalar volume and neuronal loss was observed in the ipsilateral nuclei which was accompanied by astrogliosis. In addition, a decrease in Y1 receptor expressing cells in the ipsilateral CA1 and CA3 sectors of the hippocampus, ipsi- and contralateral granule cell layer of the dentate gyrus and ipsilateral central nucleus of the amygdala was found, consistent with a reduction in Y1 receptor protein levels. The results suggest that plastic changes in hippocampal and/or amygdalar Y1 receptor expression may negatively impact anxiety levels. Gamma-aminobutyric acid (GABA) is the main inhibitory neurotransmitter in the brain and tight regulation and appropriate control of GABA is vital for neurochemical homeostasis. GABA transporter-1 (GAT-1) is abundantly expressed by neurones and astrocytes and plays a key role in GABA reuptake and regulation. Imbalance in GABA homeostasis has been implicated in epilepsy with GAT-1 being an attractive pharmacological target. Electron microscopy was used to examine the distribution, expression and morphology of GAT-1 expressing structures in the amygdala of the TLE model. Results suggest that GAT-1 was preferentially expressed on putative axon terminals over astrocytic processes in this TLE model. Myelin integrity was examined and results suggested that in the TLE model myelinated fibres were damaged in comparison to controls. Synaptic morphology was studied and results suggested that asymmetric (excitatory) synapses occurred more frequently than symmetric (inhibitory) synapses in the TLE model in comparison to controls. This study illustrated that the amygdala undergoes ultrastructural alterations in this TLE model. Maternal immune activation (MIA) is a risk factor for neurodevelopmental disorders such as autism, schizophrenia and also epilepsy. MIA was induced at a critical window of amygdalar development at E12 using bacterial mimetic lipopolysaccharide (LPS). Results showed that MIA activates cytokine, toll-like receptor and chemokine expression in the fetal brain that is prolonged in the postnatal amygdala. Inflammation elicited by MIA may prime the fetal brain for alterations seen in the glial environment and this in turn have deleterious effects on neuronal populations as seen in the amygdala at P14. These findings may suggest that MIA induced during amygdalar development may predispose offspring to amygdalar related disorders such as heightened anxiety, fear impairment and also neurodevelopmental disorders. en
dc.description.sponsorship Health Research Board (Grant Code HRA_POR/2010/159) en
dc.format.mimetype application/pdf en
dc.language.iso en en
dc.publisher University College Cork en
dc.rights © 2015, Elaine K. O'Loughlin. en
dc.rights.uri en
dc.subject Amygdala en
dc.subject Epilepsy en
dc.subject Neurodevelopment en
dc.subject Glia en
dc.subject Neuroinflammation en
dc.title Investigations into the cellular and molecular changes in the amygdala in models of temporal lobe epilepsy and maternal immune activation en
dc.type Doctoral thesis en
dc.type.qualificationlevel Doctoral en
dc.type.qualificationname PhD (Medicine and Health) en
dc.internal.availability Full text not available en Indefinite en 10000-01-01
dc.description.version Accepted Version
dc.contributor.funder Health Research Board en
dc.description.status Not peer reviewed en Anatomy en Biosciences Institute en Medicine en
dc.check.reason This thesis is due for publication or the author is actively seeking to publish this material en
dc.check.opt-out Yes en
dc.thesis.opt-out true
dc.check.entireThesis Entire Thesis Restricted
dc.check.embargoformat E-thesis on CORA only en
dc.internal.conferring Summer Conferring 2015

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© 2015, Elaine K. O'Loughlin. Except where otherwise noted, this item's license is described as © 2015, Elaine K. O'Loughlin.
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