Related Experiment Videos
The central hypotensive effect induced by methionin-enkephalin involves a serotonergic pathway
1Catedra de Farmacologia Facultad de Farmacia y Bioquimica, University of Buenos Aires, Argentina.
Summary
Methionine-enkephalin lowers blood pressure via central opioid and serotonin pathways. This hypotensive effect requires specific serotonergic S1 receptors, not S2, indicating a complex interaction in blood pressure regulation.
Area of Science:
- Neuropharmacology
- Cardiovascular Physiology
Background:
- Endogenous opiate peptides and serotonin play roles in regulating blood pressure.
- Understanding the interplay between these systems is crucial for cardiovascular research.
Purpose of the Study:
- To investigate the interaction between central methionine-enkephalin and serotonergic pathways in blood pressure control.
- To elucidate the specific serotonergic receptor subtypes involved in the hypotensive effects of methionine-enkephalin.
Main Methods:
- Experiments conducted on anesthetized normotensive rats.
- Intracerebroventricular administration of methionine-enkephalin.
- Blockade of opioid receptors with naloxone.
- Antagonism of serotonergic receptors with methiothepin and ritanserin.
- Depletion of serotonin using 5,7-dihydroxytryptamine.
Main Results:
- Intracerebroventricular methionine-enkephalin induced a dose-dependent decrease in blood pressure.
- This hypotensive effect was abolished by naloxone, methiothepin, and 5,7-dihydroxytryptamine.
- The S2-selective antagonist ritanserin did not affect the methionine-enkephalin-induced hypotension.
- These findings implicate a serotonergic pathway, specifically involving S1 receptors, in the central hypotensive action of methionine-enkephalin.
Conclusions:
- Central activation of opiate receptors by methionine-enkephalin leads to a hypotensive response.
- This response is dependent on an intact serotonergic pathway.
- The data suggest that the S1 subtype of serotonin receptor is critically involved in mediating this effect.