Mixed inhibitory synaptic balance correlates with glutamatergic synaptic phenotype in cerebellar unipolar brush cells.
نویسندگان
چکیده
Inhibitory synapses display a great diversity through varying combinations of presynaptic GABA and glycine release and postsynaptic expression of GABA and glycine receptor subtypes. We hypothesized that increased flexibility offered by this dual transmitter system might serve to tune the inhibitory phenotype to the properties of afferent excitatory synaptic inputs in individual cells. Vestibulocerebellar unipolar brush cells (UBC) receive a single glutamatergic synapse from a mossy fiber (MF), which makes them an ideal model to study excitatory-inhibitory interactions. We examined the functional phenotypes of mixed inhibitory synapses formed by Golgi interneurons onto UBCs in rat slices. We show that glycinergic IPSCs are present in all cells. An additional GABAergic component of large amplitude is only detected in a subpopulation of UBCs. This GABAergic phenotype is strictly anti-correlated with the expression of type II, but not type I, metabotropic glutamate receptors (mGluRs) at the MF synapse. Immunohistochemical stainings and agonist applications show that global UBC expression of glycine and GABA(A) receptors matches the pharmacological profile of IPSCs. Paired recordings of Golgi cells and UBCs confirm the postsynaptic origin of the inhibitory phenotype, including the slow kinetics of glycinergic components. These results strongly suggest the presence of a functional coregulation of excitatory and inhibitory phenotypes at the single-cell level. We propose that slow glycinergic IPSCs may provide an inhibitory tone, setting the gain of the MF to UBC relay, whereas large and fast GABAergic IPSCs may in addition control spike timing in mGluRII-negative UBCs.
منابع مشابه
Pii: S0306-4522(00)00123-8
Unipolar brush cells are a class of interneurons in the granular layer of the mammalian cerebellum that receives excitatory mossy fiber synaptic input in the form of a giant glutamatergic synapse. Previously, it was shown that the unipolar brush cell axon branches within the granular layer, giving rise to large terminals. Single mossy fiber stimuli evoke a prolonged burst of firing in unipolar ...
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عنوان ژورنال:
- The Journal of neuroscience : the official journal of the Society for Neuroscience
دوره 32 13 شماره
صفحات -
تاریخ انتشار 2012