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Title

Electrophysiology of oxytocin actions on central neurons

Authors
Dreifuss, Jean-Jacques
Widmer, H.
Published in Annals of the New York Academy of Sciences. 1992, vol. 652, p. 46-57
Abstract The action of oxytocin on neurons located in the dorsal motor nucleus of the vagus nerve was studied in brain slices in vitro. It acted postsynaptically and caused a reversible, concentration-dependent excitation of vagal motoneurons in rats. This effect is specific, since it could be mimicked by a selective agonist and suppressed by an oxytocin antagonist. Single-electrode voltage-clamp recordings from rat vagal motoneurons indicated that oxytocin generates a noninactivating inward current, whose amplitude increased as the membrane was depolarized. This current was insensitive to TTX, to a reduction of membrane calcium currents, and to a reversal in the transmembrane chloride gradient; and it was unaffected by several potassium channel blockers. By contrast, it was reversibly reduced by partially substituting extracellular sodium with equimolar N-methyl-D-glucamine. These results suggest that oxytocin exerts its neuronal action in the rat brainstem by generating a sustained voltage-dependent sodium current. Vasopressin activates a similar current when acting on motoneurons located in the facial nucleus of newborn rats. These fast, neurotransmitter-like actions of oxytocin and of vasopressin may provide an explanation--though not necessarily the sole explanation--for their central effects on maternal, sexual, and social behaviors.
Keywords AnimalsElectrophysiologyMaleOxytocin/ physiologyRatsSynaptic Transmission/ physiologyVagus Nerve/ physiologyVasopressins/ physiology
Stable URL http://archive-ouverte.unige.ch/unige:10232
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PMID: 1320838
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