Inhibiting the rabbit caudal ventrolateral medulla prevents baroreceptor-initiated secretion of vasopressin.
The A 1 noradrenergic neurones are known to project from the caudal ventrolateral medulla to the vasopressin-secreting neuroendocrine cells in the hypothalamus. They therefore represent a possible central pathway from the medulla to the hypothalamus for baroreceptor-initiated secretion of vasopressin. We tested this hypothesis in the anaesthetized rabbit. Muscimol, a gamma-aminobutyric-acid-receptor agonist, was injected into the caudal ventrolateral medulla to inhibit the A 1 noradrenergic neurones. Secretion of vasopressin, measured by radioimmunoassay, was initiated either by arterial haemorrhage or by constriction of the inferior vena cava. After injection of vehicle into the caudal ventrolateral medulla, or after injection of muscimol into nearby control areas, both haemorrhage and constriction of the inferior vena cava produced the expected elevation in plasma vasopressin. After injection of muscimol into the caudal ventrolateral medulla, secretion of vasopressin in response to haemorrhage and to constriction of the inferior vena cava, was completely abolished. The A 1 noradrenergic neurones may be the sole pathway transmitting the reflex for baroreceptor-initiated secretion of vasopressin from the medulla to the hypothalamus.[1]References
- Inhibiting the rabbit caudal ventrolateral medulla prevents baroreceptor-initiated secretion of vasopressin. Blessing, W.W., Willoughby, J.O. J. Physiol. (Lond.) (1985) [Pubmed]
Annotations and hyperlinks in this abstract are from individual authors of WikiGenes or automatically generated by the WikiGenes Data Mining Engine. The abstract is from MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine.About WikiGenesOpen Access LicencePrivacy PolicyTerms of Useapsburg