University of North Dakota, USA
Scientific Tracks Abstracts: Neurochem Neuropharm
Whereas the entorhinal cortex (EC) receives profuse dopaminergic innervations from the midbrain, the effects of dopamine (DA) on GABAergic interneurons in this brain region have not been determined. We probed the actions of DA on GABAA receptor-mediated synaptic transmission in the EC. Application of DA increased the frequencies not the amplitudes of sIPSCs and mIPSCs recorded from entorhinal principal neurons but slightly reduced the amplitude of the evoked IPSCs. The effects of DA were unexpectedly found to be mediated by Ã?Â±1 adrenoreceptors not by DA receptors. DA endogenously released by application of amphetamine also increased sIPSC frequency. Ca2+ influx via T-type Ca2+ channels was required for DA-induced facilitation of sIPSCs and mIPSCs. DA depolarized and enhanced the firing frequency of action potentials of interneurons. DA-induced depolarization was independent of extracellular Na+ and Ca2+ and did not require the functions of Ih channels and T-type Ca2+ channels. DA-generated currents showed a reversal potential close to the K+ reversal potential and inward rectification suggesting that DA inhibits the inward rectifier K+ channels (Kirs). Our results demonstrate that DA facilitates GABA release by activating Ã?Â±1 adrenoreceptors to inhibit Kirs which further depolarize interneurons resulting in secondary Ca2+ influx via T-type Ca2+ channels.
Saobo Lei has completed his PhD from the University of Alberta and Post-doctoral studies from the National Institutes of Health. He is a Professor in the Department of Biomedical Sciences in University of North Dakota. His research includes modulation of hippocampal and entorhinal functions by neuromodulators including neurotransmitters and neuropeptides. He has published more than 50 papers in excellent journals and has been serving as an Editorial Board Member of more than 10 reputed journals.