N-methyl-D-aspartate receptor functions altered by neuronal PTP1B activation in Alzheimer's disease and schizophrenia models.

Glutamate is the main excitatory neurotransmitter in the brain and binds to two major classes of receptors,theα-amino-3-hydroxy-5-methyl-4-isoxazole propionic acid（AMPA） and the N-methylD-aspartate（NMDA） receptors.Unlike AMPA receptors that are immediately activated by glutamate release,NMDA receptors are blocked by magnesium and can only be activated by glutamate after membrane depolarization.Thus,NMDA receptors are only activated after repeated AMPA receptor activation by glutamate.NMDA receptors are,for the most part,calcium-permeable channels.