Abstract
In this thesis, the HT-22 mouse hippocampal cell line model, which is characterised by lack of glutamate receptors, was used to elucidate the mechanism of the glutamate- induced cell death mechanism through the glutamate receptor-independent pathway. It is shown that the HT-22 cells die through a form of programmed cell death that shares features of both classical apoptosis and necrosis. Inhibition of the kinase activity of receptor interacting protein 1 (RIP-1) by Necrostatin-1 inhibited glutamate-induced cell death, suggesting that glutamate-induced HT-22 cell death occurred through necroptosis. Glutamate induced an increase in reactive oxygen species (ROS) levels in HT-22 cells which originated primarily from the mitochondria. Glutamate also caused a dose-dependent decrease in mitochondrial membrane potential which was correlated ROS levels in the cells. Under these conditions of oxidative stress induced by glutamate, mitochondrial permeability transition (MPT) occurred through opening of the MPT pores, which in turn lead to collapse and ultimately contributed to glutamate- induced cell death. Cell cycle analysis revealed that cell division in HT-22 cells was intimately linked to the process of cell death. L-glutamate treatment of HT-22 cells did not affect the cell cycle. However, the role of cell cycle in glutamate-induced HT-22 cell death pathway was shown through arresting the cell cycle at specific points. Cell cycle arrest protected the cells from glutamate-induced cell death. Further confirmation that re-entry to the cell cycle is involved in glutamate-induced cell death came from the observation that glutamate only caused cell death once the cycle was allowed to progress by removal of the inhibitory conditions. In conclusion, the work presented in this thesis shows that glutamate-induced oxidative cell injury involves the formation of ROS and mitochondrial damage. However, cell death depends on the ability of the cells to progress through the cell cycle past mitosis.