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Presynaptic Noradrenergic Regulation of Glutamate Inputs to Hypothalamic Magnocellular Neurones
Author(s) -
Boudaba C.,
Di S.,
Tasker J. G.
Publication year - 2003
Publication title -
journal of neuroendocrinology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.062
H-Index - 116
eISSN - 1365-2826
pISSN - 0953-8194
DOI - 10.1046/j.1365-2826.2003.01063.x
Subject(s) - excitatory postsynaptic potential , glutamate receptor , norepinephrine , supraoptic nucleus , glutamatergic , postsynaptic potential , magnocellular cell , inhibitory postsynaptic potential , neuroscience , medicine , endocrinology , neurotransmitter , biology , chemistry , oxytocin , dopamine , receptor , central nervous system
Glutamate and norepinephrine transmitter systems play critical roles in the synaptic control of hypothalamic magnocellular neurones. We recently reported on a norepinephrine‐sensitive glutamate circuit within the paraventricular nucleus (PVN) that projects to magnocellular neurones. Here, we present evidence for norepinephrine regulation of glutamate release in the PVN and supraoptic nucleus (SON) via actions on presynaptic terminals. Whole‐cell synaptic currents were recorded in magnocellular neurones of the SON and PVN in an acute slice preparation. Bath application of norepinephrine (100 µ m ) caused a robust, reversible increase in the frequency of spontaneous glutamatergic excitatory postsynaptic currents in 100% of SON neurones (246%) and in 88% of PVN magnocellular neurones (259%). The norepinephrine‐induced increase in glutamate release was mediated by activation of both presynaptic α 1 receptors and α 2 receptors, but the α 1 ‐receptor component was the predominant component of the response. The presynaptic actions of norepinephrine were predominantly, although not completely, resistant to blockade of Na‐dependent spikes, implicating a presynaptic terminal locus of action. Interestingly, the spike‐dependent component of the response was greater in PVN than in SON magnocellular neurones. This robust presynaptic facilitation of glutamate release by norepinephrine, combined with the known excitatory postsynaptic actions of norepinephrine, activational effects on local glutamate circuits, and inhibitory effects on γ‐aminobutyric acid release, indicate a strong excitatory role of norepinephrine in the regulation of oxytocin and vasopressin release during physiological stimulation.