Serotonin and the blood vessel wall

Area of Science:

• Cardiovascular Pharmacology
• Neuropharmacology

Background:

• Serotonin (5-hydroxytryptamine) exerts diverse cardiovascular effects, including blood pressure modulation and vascular tone changes.
• These effects are receptor-dependent, mediated by various serotonin receptor subtypes (e.g., S2 and S1) located on vascular smooth muscle, endothelium, and nerve terminals.

Purpose of the Study:

• To elucidate the complex role of serotonin in cardiovascular regulation.
• To investigate the alterations in serotonin's cardiovascular effects in the context of hypertension.

Main Methods:

• Review of existing literature on serotonin's cardiovascular actions.
• Analysis of receptor-mediated mechanisms (S2, S1) for vasoconstriction and vasodilation.
• Examination of serotonin's indirect actions, including potentiation of other agonists and release of vasoactive substances.

Main Results:

• Serotonin's effects vary based on species, vascular bed, dosage, and administration route.
• Vasoconstriction is primarily mediated by S2-serotonergic receptors, while vasodilation involves S1-serotonergic receptors.
• In hypertension, constrictor responses to serotonin are augmented, and vasodilator effects are diminished, suggesting functional vascular adaptations.

Conclusions:

• Hypertensive blood vessels exhibit enhanced constrictor sensitivity to serotonin, exceeding responses to other agonists.
• Accelerated platelet turnover and impaired serotonin removal contribute to elevated peripheral vascular resistance in hypertension.
• Serotonin's altered vascular and platelet function may play a role in hypertension pathogenesis and complications, supported by the antihypertensive effects of ketanserin (an S2-serotonergic antagonist).