For example, electron microscopic studies have demonstrated a positive correlation between the volume of a spine and postsynaptic density (PSD).n) The PSD is a large protein complex that anchors a diverse variety of neurotransmitter receptors, channels, adhesion molecules, and scaffold proteins.
The authors attributed the 48 h rise in GluN1 mainly to an increase in NMDARs at the cell surface, though not at the synaptic membrane, as GluN1 was not significantly higher in the postsynaptic density fraction .
Glutamate then activates NMDA receptors [~50 NMDA receptors dispersed over a 400-nm-diameter postsynaptic density (1) at postsynaptic membrane which further propagates excitatory impulse to cell body and also it activates calcium and calmodulin to bind with each other (2) and causes release of nitric oxide (NO) from nitric oxide synthetase (NOS) (One NOS molecule generates 20 NO molecules per second).
So to look into these issues with more details, the current experimental study employed transmission electron microscopy to compare the effects of morphine consumption on synaptic plasticity, postsynaptic density thickness, and synaptic curvatures in CA1 area of hippocampus formations.
The postsynaptic terminals were seen to contain subsynaptic cisterns formed by membranes of smooth endoplasmic reticulum beneath the postsynaptic density, whereas the presynaptic terminal showed numerous electron transparent synaptic vesicles.