Final answer:
Excessive stimulation of glutamate triggers neurodegeneration in Huntington's disease, leading to cell death through excitotoxic mechanisms involving increased calcium influx via extrasynaptic NMDA receptors.
Step-by-step explanation:
Excessive stimulation of glutamate results in neurodegeneration, which is a hallmark of Huntington's disease. This overactivation of glutamate receptors, particularly at extrasynaptic locations, is implicated in the pathophysiology of Huntington's disease. Glutamate excitotoxicity involves increased intracellular calcium concentrations due to extrasynaptic NMDA receptor activity, which can disrupt mitochondrial membrane potential and lead to cell death. Hence, the correct option related to the question would be (c) Glutamate.