Effect of tolbutamide on TEA-induced postsynaptic zinc signals at hippocampal mossy fiber-CA3 synapses.

Effect of tolbutamide on TEA-induced postsynaptic zinc signals at hippocampal mossy fiber-CA3 synapses. Can J Physiol Pharmacol. 2017 Jun 27;: Authors: Bastos FM, Corceiro VN, Lopes SA, Almeida JG, Matias CMM, Dionisio JC, Mendes PJ, Sampaio Dos Aidos FD, Quinta-Ferreira RM, Quinta-Ferreira ME Abstract The application of tetraethylammonium (TEA), a blocker of voltage-dependent potassium channels, can induce long-term potentiation in the synaptic systems CA3 - CA1 and mossy fibers - CA3 pyramidal cells of the hippocampus. In the mossy fibers the depolarization evoked by extracellular TEA induces a large amount of glutamate and also of zinc release. It is considered that zinc has a neuromodulatory role at the mossy fiber synapses, which can, at least in part, be due to the activation of presynaptic ATP-dependent potassium (KATP) channels. The aim of this work was to study properties of TEA-induced zinc signals, detected at the mossy fibers region, using the permeant form of the zinc indicator Newport Green. The application of TEA caused a depression of those signals that was partially blocked by the KATP channels inhibitor tolbutamide. After the removal of TEA, the signals usually increased to a level above baseline. These results are in agreement with the idea that intense zinc release during strong synaptic events triggers a negative feedback action. The zinc depression, caused by the LTP-evoking chemical stimulation, turns into pote...
Source: Canadian Journal of Physiology and Pharmacology - Category: Drugs & Pharmacology Authors: Tags: Can J Physiol Pharmacol Source Type: research