The research was designed to investigate the effects of AIT-082, a derivative of the purine hypoxanthine containing a para-amino benzoic acid moiety, on neural cells. AIT-082 has been shown to possess a number of neurotrophic and neuroprotective properties and to enhance memory. Furthermore, AIT-082 is undergoing clinical trials as a potential treatment for Alzheimers disease.<p>The first part of the study investigated the ability of AIT-082 to influence cellular ATP levels in cortical neurons. Decreased energy metabolism is a key point in Yings (Ying, 1996a) theory of the development of Alzheimers disease. Previous work with AIT-082 had shown that it could protect hippocampal neurons from cellular damage caused by sublethal doses of glutamate. Specifically, AIT-082 prevented neurite degeneration. Also, AIT-082 was shown to increase mitochondrial membrane potential, especially at the distal tips of the neurites, in hippocampal neurons. I hypothesized that AIT-082 was protecting the neurons by increasing the ability of the mitochondria to generate ATP and thereby increasing the amount of ATP available to the cell. ATP was collected and measured from cortical neuron cultures that were exposed to glutamate, AIT-082, glutamate and AIT-082. The ATP levels were compared to the ATP levels from cortical neuron cultures that were exposed to vehicle for glutamate and AIT-082. The results did not significantly increase ATP levels in cortical neurons following glutamate exposure. <p>The next set of experiments involved investigations into the ability of AIT-082 to influence phosphorylation events in neural cells. AIT-082 shares some neurotrophic and neuroprotective properties with a group of drugs called the immunophilin ligands. The neuroprotective properties of the immunophilin ligands are mainly due to their ability to influence protein phosphorylation by inhibiting the activity of calcineurin a protein phosphatase. The first set of experiments used western blot techniques to measure serine peptide and threonine peptide phosphorylation levels in proteins from whole brain homogenates that were incubated with vehicle, AIT-082, and GMP. Both AIT-082 and GMP caused an increase in the level of serine peptide phosphorylation compared to vehicle but only the increase caused by GMP treatment proved to be significant. Further, threonine phosphorylation levels were significantly increased by GMP but not AIT-082.
Phosphorylation levels of short peptide sequences containing either a phosphorylated serine or threonine residue were also measured in neuronal and astrocytic cultures. The neuronal cultures were exposed to 4 h of hypoxia to mimic the conditions of reduced energy availability observed in Alzheimers disease brains. Astrocyte cultures were exposed to 4 h of hypoxia/ischemia for the same reason. Both cell types were allowed to recover for 0, 1, 4, 12 and 24 hours with or without AIT-082 following the insult. AIT-082 treatment did not significantly affect phosphorylation levels of proteins harvested from either neuron or astrocyte cultures at any time period. I conclude therefore, that AIT-082 is not able to influence phosphorylation of the short amino acid sequences containing phosphorylated serine or threonine residues that could be detected by the primary antibodies used in my experiments.
| Identifer | oai:union.ndltd.org:LACETR/oai:collectionscanada.gc.ca:SSU.etd-09082003-100608 |
| Date | 11 September 2003 |
| Creators | Bintner, Jasper Santos |
| Contributors | Ovsenek, Nicholas (Nick), Juurlink, Bernhard H. J., Desautels, Michel, Pato, Mary D. |
| Publisher | University of Saskatchewan |
| Source Sets | Library and Archives Canada ETDs Repository / Centre d'archives des thèses électroniques de Bibliothèque et Archives Canada |
| Language | English |
| Detected Language | English |
| Type | text |
| Format | application/pdf |
| Source | http://library.usask.ca/theses/available/etd-09082003-100608/ |
| Rights | unrestricted, I hereby certify that, if appropriate, I have obtained and attached hereto a written permission statement from the owner(s) of each third party copyrighted matter to be included in my thesis, dissertation, or project report, allowing distribution as specified below. I certify that the version I submitted is the same as that approved by my advisory committee. I hereby grant to University of Saskatchewan or its agents the non-exclusive license to archive and make accessible, under the conditions specified below, my thesis, dissertation, or project report in whole or in part in all forms of media, now or hereafter known. I retain all other ownership rights to the copyright of the thesis, dissertation or project report. I also retain the right to use in future works (such as articles or books) all or part of this thesis, dissertation, or project report. |
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