Glucose entry into the brain and its subsequent metabolism to L-lactate, regulated by
astrocytes, plays a major role in synaptic plasticity and memory formation. A recent
study has shown that L-lactate produced by the brain upon stimulation of glycolysis, and
glycogen-derived L-lactate from astrocytes and its transport into neurons, is crucial for
memory formation.
A recent study revealed the molecular mechanisms that underlie the role of L-lactate in
neuronal plasticity and long-term memory formation. L-lactate was shown to induce a
cascade of molecular events via modulation of redox-sensitive N-Methyl-D-aspartate
(NMDA) receptor activity that was mimicked by nicotinamide adenine dinucleotide
hydride (NADH) co-enzyme. This indicated that changes in cellular redox state,
following L-lactate transport inside the cells and its subsequent metabolism, production
of NADH, and favouring a reduced state are the key effects of L-lactate. Therefore, we
are investigating the role of L-lactate in modulating NMDA receptor function via redox
modulatory sites. Accordingly, crucial redox-sensitive cysteine residues, Cys320 and
Cys87, of the NR2A NMDA receptor subunit are mutated using site-directed mutation,
transfected, and expressed in HEK293 cells. This cellular system will then be used to characterise and monitor its activity upon Llactate
stimulation, compared to the wild type. This will be achieved by calcium imaging,
using fluorescent microscopy.
Our data shows that L-lactate potentiated NMDA receptor activity and increased
intracellular calcium influx in NR1/NR2A wild type compared to the control condition
(WT NR1/NR2A perfused with (1μM) glutamate and (1μM) glycine agonist only),
showing faster response initiation and slower decay rate of the calcium signal to the
baseline. Additionally, stimulating with L-lactate associated with greater numbers of cells
having high fluorescent intensity (peak amplitude) compared to the control. Furthermore,
L-lactate rescued the mutated NMDA NR1/NR2A C320A C87A receptor response that
showed altered activity upon mutation up to the control level. Future experiments need to
be carried out on different redox-sensitive residues of various NMDA receptor subunits
to reveal the exact molecular mechanisms of L-lactate.
| Identifer | oai:union.ndltd.org:kaust.edu.sa/oai:repository.kaust.edu.sa:10754/609187 |
| Date | 05 1900 |
| Creators | Alzahrani, Ohood |
| Contributors | Magistretti, Pierre J., Biological and Environmental Sciences and Engineering (BESE) Division, Fiumelli, Hubert, Arold, Stefan T. |
| Source Sets | King Abdullah University of Science and Technology |
| Language | English |
| Detected Language | English |
| Type | Thesis |
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