This work concerns the central regulation of dopamine beta-hydroxylase in the adrenal gland of the rat. This enzyme is neurally induced by subjecting rats to stress or to the injection of reserpine. Several neurotransmitter agonists and antagonists were administered in order to clarify the nervous pathways to this organ. The combination of the central or systemic administration of a catecholamine depletor and a serotonin depletor also increases the activity of this enzyme. Serotonin antagonists but not catecholamine antagonists potentiate the action of reserpine. However, the depletion of catecholamines or serotonin alone does not elevate the activity of this adrenal enzyme. Serotonin agonists block the effect of reserpine. Adrenal phenylethanolamine N-methyltransferase exhibits a similar regulation. Electrolytic lesions and administration of a serotonin neurotoxin in the raphe area show that the medial raphe nucleus is the centre of the inhibitory serotonergic pathway regulating adrenal functions. The muscarinic agonist oxotremorine produces a centrally mediated induction of adrenal dopamine beta-hydroxylase. Depletion of central or peripheral catecholamines and serotonin does not modify the elevation of this enzyme activity by oxotremorine. Central and systemic administration of agonists binding to gamma-aminobutyric acid-receptors decreases adrenal dopamine beta-hydroxylase activity and impairs the effect of the cholinergic inducer. These negative effects are blocked by a specific antagonist of gamma-aminobutyric acid type A-receptors. This work suggests a central inhibitory action of the aminoacid and a gamma-aminobutyric-cholinergic interaction in regard to adrenal dopamine beta-hydroxylase. Corticotropin releasing factor, centrally administered at a constant rate, increases adrenal dopamine beta-hydroxylase and phenylethanolamine N-methyltranferase activities without elevating plasma corticosterone. This result supports the role of the peptide as first medi
| Identifer | oai:union.ndltd.org:LACETR/oai:collectionscanada.gc.ca:QMM.72040 |
| Date | January 1985 |
| Creators | Lima, Lucimey. |
| Publisher | McGill University |
| Source Sets | Library and Archives Canada ETDs Repository / Centre d'archives des thèses électroniques de Bibliothèque et Archives Canada |
| Language | English |
| Detected Language | English |
| Type | Electronic Thesis or Dissertation |
| Format | application/pdf |
| Coverage | Doctor of Philosophy (Department of Biochemistry.) |
| Rights | All items in eScholarship@McGill are protected by copyright with all rights reserved unless otherwise indicated. |
| Relation | alephsysno: 000222627, proquestno: AAINL24039, Theses scanned by UMI/ProQuest. |
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