Journal of Neuroscience, Vol 9, 3929-3936, Copyright © 1989 by Society for Neuroscience
Vasopressin receptors of the vasopressor (V1) type in the nucleus of the solitary tract of the rat mediate direct neuronal excitation
M Raggenbass, E Tribollet, M Dubois-Dauphin and JJ Dreifuss
Department of Physiology, University Medical Center, Geneva, Switzerland.
The existence of vasopressin-sensitive neurons in the nucleus of the
solitary tract of the rat and the presence in this brain area of
vasopressin binding sites were investigated using extracellular single-
unit recordings from brain-stem slices and light microscopic
autoradiography. About 45% of the recorded neurons responded to vasopressin
at 5-2000 nM by a reversible, concentration-dependent increase in firing
rate. The action of vasopressin was direct, was suppressed by a vasopressor
antagonist, and was mimicked by a vasopressor agonist. Oxytocin was 10-100
times less efficient than vasopressin and a specific antidiuretic agonist
was without effect. Using light microscopic autoradiography and 3H-arginine
vasopressin as a ligand, high-affinity vasopressin binding sites were found
distributed over the whole rostrocaudal extent of the nucleus of the
solitary tract. Binding was displaced by unlabeled vasopressor agonist but
not by unlabeled antidiuretic agonist. Thus, the nucleus of the solitary
tract contains V1-type vasopressin receptors which are, at least in part,
located on neuronal membranes and whose activation generates bioelectrical
signals. Solitary tract vasopressin-sensitive neurons may be the target of
a vasopressinergic innervation originating in the hypothalamic
paraventricular nucleus and could be involved in the central regulation of
cardiovascular functions.
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