Nicotine facilitates noradrenaline release in the rat supraoptic nucleus

Nicotine injected in the supraoptic nucleus facilitates vasopressin release from the neurohypophysis. Nicotinic acetylcholine receptors have been found not only on vasopressin-producing cell bodies but also on presynaptic nerve terminals in the nucleus. Vasopressin cells receive excitatory synaptic inputs from noradrenergic neurones. To test whether nicotine facilitates noradrenaline release in the supraoptic nucleus, we perfused the supraoptic nucleus with nicotine through a microdialysis probe. Nicotine increased the extracellular noradrenaline concentrations in the nucleus. A noradrenaline uptake inhibitor, desipramine, increased the extracellular noradrenaline concentrations in the nucleus and did not block the noradrenaline increase after nicotine. The results suggest that nicotine acts within the supraoptic nucleus to facilitate noradrenaline release pre-synaptically. This presynaptic action may contribute, in part, to vasopressin release after nicotine.