Which of the following neurotransmitters has been implicated as a cause of cell death following stroke? A 79-year-old woman complained of sharp headache in the temporal area. Fifteen minutes later she lost consciousness and was brought to the Emergency Room. A CT scan showed a diffuse brain hemorrhage and the diagnosis of a left middle cerebral artery stroke was made.
A. Acetylcholine B. Norepinephrine C. GABA D. Serotonin E. Glutamate
(katzung, pp 347, brunton, pp 332)
although glutamate is essential for brain function, too much glutamate can be toxic to neurons.
when blood flow to the brain tissue is impaired, mechanism of normal glutamate reuptake
stops and glutamate accumulates into the synaptic cleft. this high concentration of glutamate
can activate a large amount of glutamate ionotropic receptors, so triggering a huge influx of
ca++ into postsynaptic cells. this intracellular high ca++ level can cause neuronal death. this
property of glutamate is called excitotoxicity and can play an important role in a number of
brain disorders including stroke and epilepsy.
a, b, c, d) these neurotransmitters do not cause excitotoxicity.