Short-term facilitation and depression in the cerebellum: some observations on wild-type and mutant rodents deficient in the extracellular matrix molecule tenascin C
Date
2005-09-12Abstract
Short-term plasticity was studied on synapses to Purkinje cells (PC):
paired-pulse facilitation in parallel fibers (PF) and paired-pulse depression in
climbing fibers (CF). Both phenomena relate to synaptic strength. These forms of
short-term plasticity were tested on cerebellar slices in rat by early postnatal
synchronous stimulation of olivary neurons (i.e., CFs) with harmaline and by
inhibition of a metabotropic glutamate receptor (mGluR) as well as in mice that
were deficient in the extracellular matrix glycoprotein tenascin-C. Harmaline
stimulation delayed the developmental competition between CF inputs and
maintained multiple innervation. Paired-pulse depression of the CF-PC synapse
after harmaline treatment was more expressed. However, paired-pulse facilitation
in PF-PC synapses remained unchanged. Electrophysiological responses of
postsynaptic mGluR1 in CF-PC synapses could be obtained only with AMPA receptors
blocked and glutamate uptake impaired. The mGluR1-specific antagonist CPCCOEt
suppressed the CF-mGluR EPSC in some PCs and potentiated it in other PCs. CF
paired-pulse depression was not changed with CPCCOEt, thus excluding a
presynaptic effect. The postsynaptic effect was underlined by CPCCOEt-induced
rise in amplitude of EPSC and by a prolongation of its decay time. Tenascins are
extracellular matrix glycoproteins that may restrict the regenerative capacity of
the nervous tissue. Testing short-term presynaptic plasticity in
tenascin-C-deficient mice showed that CF paired-pulse depression was less
expressed while PF paired-pulse facilitation was augmented except in a group of
cells where there was even depression. The results underline differences in forms
of short-term plasticity with regard to susceptibility to diverse modulatory
factors.
Description
Citation : Andjus, P.R. et al. (2005) Short-term facilitation and depression in the cerebellum: some observations on wild-type and mutant rodents deficient in the extracellular matrix molecule tenascin C. Annals of the New York Academy of Sciences, 1048, pp. 185-197.
ISSN : 0077-8923
Research Institute : Leicester Institute for Pharmaceutical Innovation - From Molecules to Practice (LIPI)
Peer Reviewed : Yes