Introduction to Neural Plasticity Mechanism

In researches that examine neuroplasticity, many studies that are performed directly on isolated neurons in the pyramidal cells of CA1 area (CA1) and slices of the hippocampus indicate that changes occur at the molecular and cellular levels during long-term synaptic potentiation (LTP), and these changes are dependent on N-methyl-D-aspartate (NMDA) acid receptors and/or purinergic receptors. Electrophysiological studies and the chemical induction of LTP of synaptic neurotransmissions provide key evidence that LTP is dependent on the volume of Ca2+ influx through postsynaptic NMDA receptors, in addition to the subsequent activation and autophosphorylation of Ca2+/calmodulin-dependent protein kinase II (CaMKII) and the increase in the density of α-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid (AMPA) receptors on postsynaptic neuronal membranes. The primary peculiarity of LTP in the central nervous system (CNS) excitatory synapses is the synthesis of additional AMPA receptors in the postsynaptic elements. Furthermore, the proteolysis of the extracellular matrix (ECM) has an important role in the synaptic neuroplasticity of the CNS. Proteases from the serine family and metalloproteinases of the extracellular matrix are localized within the synapses and are released into the extracellular space in proportion to the degree of neuronal excitation. These enzymes cause changes in the morphology, shape and size, as well as the overall number of synapses and synthesize new synaptic connections. The proteinases also change the function of receptors, and consequently, the secretions of neurotransmitters from the presynaptic elements are strengthened or weakened.