Final answer:
Glutamate is the neurotransmitter that has neurotoxic effects at high levels, causing excitotoxicity and contributing to brain damage and various neurological disorders such as TBI, stroke, and neurodegenerative diseases.
Step-by-step explanation:
The neurotransmitter that is known to have major neurotoxic effects at high levels and is implicated in brain damage is glutamate. Excessive activation of glutamate receptors, specifically N-methyl-D-aspartate (NMDA) receptors, leads to a harmful process known as excitotoxicity. This occurs when excessive calcium influx into neurons triggers a cascade of events resulting in cell damage and death. Excitotoxicity is associated with various neurological conditions such as traumatic brain injury (TBI), stroke, and neurodegenerative diseases like Alzheimer's and Parkinson's disease.
In cases of TBI, there is an acute initial damage followed by secondary injury, which can be attributed to glutamate dysregulation leading to excitotoxic necrosis of neurons. Despite extensive research, effective pharmacological interventions to prevent or reverse the excitotoxic cascade have been elusive. Understanding the implications of excitotoxicity and its contribution to neural damage is critical for developing therapeutic strategies to combat these devastating conditions.