Actions of zinc at mature Golgi cell to granule cell synapses in cerebellum of rats and mice

A recent study has shown that cerebellar GABAergic interneuron (Golgi cell) terminals contain the zinc transporter znt3, raising the possibility that zinc is synaptically released to modulate GABAergic transmission. To test this possibility, the actions of exogenous zinc on Golgi cell to granule cell synaptic transmission were investigated and then the effects of removing endogenous zinc were examined Application of zinc markedly reduced the tonic GABA(A)-receptor-mediated current in granule cells but produced a much smaller heterogeneous inhibitory effect on evoked phasic GABAergic currents. Neither the tonic current, single evoked synaptic currents nor trains of synaptic currents were modulated when endogenous zinc was chelated. Thus, there is no physiological evidence that zinc is released from Golgi GABAergic transmission. (C) 2004 Elsevier Ireland Ltd. All rights reserved