Perineuronal net

A. Perineuronal nets are made of chondroitin sulfate proteoglycans (CSPGs). Here, the CSPGs neurocan, versican, brevican, and aggrecan are noncovalently bonded to hyaluronan. Associations occur between other CSPGs through tenascin (T, triangles). Tenascin, in turn, binds to CS glycosaminoglycans (red lines) as well as cell surface CSPGs. Phosphacan can also bind to cell surface receptors such as NCAM. B. Application of chondroitinase ABC (ChABC) degrades all the CS glycosaminoglycans (red lines) as well as hyaluronan (pink line), causing major disruptions in the structure of the perineuronal net. These disruptions may allow axons to penetrate the vacated space and permit restoration of neural plasticity.

Perineuronal nets (PNNs) are specialized extracellular matrix structures responsible for synaptic stabilization in the adult brain.[1] PNNs are found around certain neuron cell bodies and proximal neurites in the central nervous system. PNNs play a critical role in the closure of the childhood critical period, and their digestion can cause restored critical period-like synaptic plasticity in the adult brain. They are largely negatively charged and composed of chondroitin sulfate proteoglycans, molecules that play a key role in development and plasticity during postnatal development and in the adult.

PNNs appear to be mainly present in the cortex, hippocampus, thalamus, brainstem, and the spinal cord. Studies of the rat brain have shown that the cortex contains high numbers of PNNs in the motor and primary sensory areas and relatively fewer in the association and limbic cortices.[2] In the cortex, PNNs are associated mostly with inhibitory interneurons and are thought to be responsible for maintaining the excitatory/inhibitory balance in the adult brain.[3]

  1. ^ Flores, CE; Méndez, P (2014). "Shaping inhibition: activity dependent structural plasticity of GABAergic synapses". Frontiers in Cellular Neuroscience. 8: 327. doi:10.3389/fncel.2014.00327. PMC 4209871. PMID 25386117.
  2. ^ Galtrey, C. M.; Fawcett, J. W. (2007). "The role of chondroitin sulfate proteoglycans in regeneration and plasticity in the central nervous system". Brain Research Reviews. 54 (1): 1–18. doi:10.1016/j.brainresrev.2006.09.006. PMID 17222456. S2CID 13913614.
  3. ^ Cite error: The named reference Hensch was invoked but never defined (see the help page).