Extrasynaptic NMDA receptors are glutamate-gated

neurotransmitter receptor A neurotransmitter receptor (also known as a neuroreceptor) is a membrane receptor protein that is activated by a neurotransmitter. Chemicals on the outside of the cell, such as a neurotransmitter, can bump into the cell's membrane, in which the ...

s that are localized to non-synaptic sites on the

neuron A neuron, neurone, or nerve cell is an electrically excitable cell that communicates with other cells via specialized connections called synapses. The neuron is the main component of nervous tissue in all animals except sponges and placozoa. N ...

cell surface The cell membrane (also known as the plasma membrane (PM) or cytoplasmic membrane, and historically referred to as the plasmalemma) is a biological membrane that separates and protects the interior of all cells from the outside environment ( ...

. In contrast to synaptic NMDA receptors that promote acquired neuroprotection and

synaptic plasticity In neuroscience, synaptic plasticity is the ability of synapses to strengthen or weaken over time, in response to increases or decreases in their activity. Since memories are postulated to be represented by vastly interconnected neural circuit ...

, extrasynaptic NMDA receptors are coupled to activation of death-signaling pathways. Extrasynaptic NMDA receptors are responsible for initiating

excitotoxicity In excitotoxicity, nerve cells suffer damage or death when the levels of otherwise necessary and safe neurotransmitters such as glutamate become pathologically high, resulting in excessive stimulation of receptors. For example, when glutamate re ...

and have been implicated in the etiology of

neurodegenerative diseases A neurodegenerative disease is caused by the progressive loss of structure or function of neurons, in the process known as neurodegeneration. Such neuronal damage may ultimately involve cell death. Neurodegenerative diseases include amyotrophic ...

, including

stroke A stroke is a medical condition in which poor blood flow to the brain causes cell death. There are two main types of stroke: ischemic, due to lack of blood flow, and hemorrhagic, due to bleeding. Both cause parts of the brain to stop functionin ...

Huntington’s disease Huntington's disease (HD), also known as Huntington's chorea, is a neurodegenerative disease that is mostly inherited. The earliest symptoms are often subtle problems with mood or mental abilities. A general lack of coordination and an unst ...

Alzheimer’s disease Alzheimer's disease (AD) is a neurodegenerative disease that usually starts slowly and progressively worsens. It is the cause of 60–70% of cases of dementia. The most common early symptom is difficulty in remembering recent events. As t ...

, and

amyotrophic lateral sclerosis Amyotrophic lateral sclerosis (ALS), also known as motor neuron disease (MND) or Lou Gehrig's disease, is a neurodegenerative disease that results in the progressive loss of motor neurons that control voluntary muscles. ALS is the most comm ...

(ALS). Extrasynaptic NMDA receptors form a death signaling complex with the transient receptor potential cation channel subfamily M member 4 (TRPM4). The NMDAR/TRPM4 complex is considered central to glutamate excitotoxicity. NMDAR/TRPM4 interaction interface inhibitors (also known as 'interface inhibitors') disrupt the NMDAR/TRPM4 complex thereby detoxifying extrasynaptic NMDA receptors. In mouse disease models, interface inhibitors protect against stroke induced brain damage and retinal ganglion cell degeneration.

References

{{Reflist Molecular neuroscience