Modification of extracellular matrix by enzymatic removal of chondroitin sulfate and by lack of Tenascin-R differentially affects several forms of synaptic plasticity in the hippocampus
O. Bukalo et al., Modification of extracellular matrix by enzymatic removal of chondroitin sulfate and by lack of Tenascin-R differentially affects several forms of synaptic plasticity in the hippocampus, NEUROSCIENC, 104(2), 2001, pp. 359-369
The extracellular matrix is a complex network of macromolecules including g
lycoproteins, polysaccharides and proteoglycans. Tenascin-R and chondroitin
sulfate proteoglycans are essential components of hippocampal extracellula
r matrix co-localised in perineuronal nets on interneurons. Mutant mice def
icient in expression of tenascin-R showed a two-fold reduction of long-term
potentiation induced by theta-burst stimulation of Schaffer collaterals in
the stratum radiatum of the CA1 region of the hippocampus, as compared to
wild-type mice. The same reduction in potentiation was observed in slices f
rom wild-type mice pretreated for 2 h with chondroitinase ABC that complete
ly removed chondroitin sulfates from the extracellular matrix. Treatment of
slices from tenascin-a deficient animals with the enzyme did not further r
educe potentiation in comparison with untreated slices from these mice, sho
wing an occlusion of effects produced by removal of tenascin-R and chondroi
tin sulfates. However, the level of potentiation recorded immediately after
theta-burst stimulation was significantly higher in wild-type than in tena
scin-R deficient mice, whereas cbondroitinase ABC had no significant effect
on this short-term form of plasticity. Enzymatic treatment also did not af
fect short-term depression evoked by low-frequency stimulation, whereas thi
s farm of synaptic plasticity was reduced in tenascin-R deficient mice. In
contrast, long-term depression in CA1 was impaired by digestion of chondroi
tin sulfates but appeared normal in tenascin-R mutants.
Our data demonstrate that tenascin-R and chondroitin sulfate proteoglycans
differentially modulate several forms of synaptic plasticity, suggesting th
at different mechanisms are involved. (C) 2001 IBRO. Published by Elsevier
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