Following a traumatic brain injury (TBI), patients are predisposed to develop post-traumatic cortical network dysfunction and epilepsy. Chronic seizures can be a significant cause of disability for TBI patients, especially when the seizures do not respond to the currently available anticonvulsant therapies. We utilize a mouse model of TBI to study how the cortical network becomes prone to seizure activity, and we have shown cortical hyperexcitability and a loss of inhibitory interneurons following injury in this model. This suggests that there is an excitatory/inhibitory imbalance of the network, and that preserving the inhibitory cells may be able to prevent network dysfunction and seizure activity. Based on the knowledge that glycolytic activity is increased following injury, and that metabolism is a known anticonvulsive target, we are examining glycolysis as a potential therapeutic target to preserve interneurons following TBI. We propose a model of post-traumatic epileptogenesis in which glycolysis-dependent increases in excitation lead to excitotoxic cell death of interneurons and permanent losses in cortical inhibition. We hypothesize that 2-deoxyglucose (2DG), a competitive glycolytic inhibitor, is neuroprotective after TBI by attenuating the acute increases in glycolytic activity and excitatory neuronal activity that occur after injury. My preliminary data shows that in vivo 2DG treatment prevents the development of epileptiform activity following injury and attenuates the loss of parvalbumin-expressing interneurons. In this proposal, I seek to examine the changes in synaptic activity (using electrophysiology) and interneuron survival (using immunohistochemistry and genetic labeling) that occur at early time points after TBI and may predispose the network to hyperexcitability. Additionally, I will examine whether glycolytic inhibition with 2DG can attenuate these pathophysiological changes. I have also used electrophysiological techniques to explore the effects of glycolytic inhibition with 2DG on neuronal excitability, and have collected preliminary results suggesting that 2DG decreases the excitability of excitatory pyramidal neurons, but not inhibitory interneurons. In the outlined experiments, I will further examine this idea as a potential mechanism for 2DG after TBI. Finally, I will use single-cell qPCR and immunohistochemistry to compare the mRNA levels and expression of metabolic proteins in excitatory versus inhibitory neurons after CCI. This research may provide evidence for a role for glycolytic inhibition in the preservation of interneurons following TBI and may reveal a novel cell type-specific coupling of metabolism to neuronal excitability. Importantly, the proposed experiments will provide excellent training opportunities to deepen my understanding of neural networks, improve my capabilities as an experimentalist, and support my development as a future neuroscientist under the mentorship of an experienced team of individuals.
Traumatic brain injury (TBI) is a significant cause of death and disability that results in over 2.5 million emergency room visits per year and predisposes individuals to developing cortical network dysfunction and epilepsy. The experiments outlined in this proposal seek to better understand the pathophysiology of epileptogenesis following TBI and will potentially identify a neuroprotective target (hyperglycolysis after injury) to preserve inhibitory network function after TBI. By exploring the effects of glycolytic inhibition on neuronal excitability, these experiments may also reveal a novel cell type-specific coupling of metabolism to excitability that has relevance to multiple neurological disorders.