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Hypothalamic opioid peptide regulation of catecholamine secretion
Neuropeptides
|December 1, 1984
Summary
Endogenous opioid peptides stimulate catecholamine secretion by activating mu receptors in the hypothalamic paraventricular nucleus (PVN). This pathway increases central sympathetic outflow, as demonstrated by [D-Ala2, MePhe4, Gly5-ol]enkephalin (DAGO) infusion effects.
Area of Science:
- Neuroscience
- Endocrinology
- Pharmacology
Background:
- The hypothalamic paraventricular nucleus (PVN) plays a crucial role in sympathoadrenal regulation.
- Opioid binding sites are abundant in the PVN, suggesting a role for endogenous opioids in this region.
Purpose of the Study:
- To investigate the role of mu opioid receptors in the PVN in regulating plasma catecholamine responses.
- To compare the potency of beta-endorphin, morphine, and [D-Ala2, MePhe4, Gly5-ol]enkephalin (DAGO) in stimulating catecholamine secretion.
Main Methods:
- Intracisternal administration of beta-endorphin and mu receptor agonists.
- Direct infusion of DAGO into the PVN and frontoparietal cortex.
- Systemic administration of naloxone to block opioid receptors.
Main Results:
- DAGO was more potent than morphine in stimulating catecholamine secretion.
- DAGO infusion into the PVN dose-dependently increased plasma catecholamine levels, with effects observed at 10 pmol.
- Naloxone blocked the DAGO-induced catecholamine release, while DAGO was ineffective in the frontoparietal cortex.
Conclusions:
- Endogenous opioid peptides stimulate central sympathetic outflow and catecholamine secretion via mu receptors in the PVN.
- The PVN is a key site for opioid-mediated regulation of the sympathoadrenal system.