Central nervous system serotonin function and cardiovascular responses to stress

Area of Science:

• Neuroscience
• Cardiovascular Physiology
• Genetics

Background:

• Central nervous system (CNS) serotonin plays a role in regulating physiological and behavioral responses.
• The serotonin transporter gene promoter region (5HTTLPR) is a functional polymorphism influencing serotonin transporter expression and CNS serotonin activity.

Purpose of the Study:

• To investigate the relationship between CNS serotonin function markers and cardiovascular reactivity to mental stress.
• To determine if the 5HTTLPR genotype impacts cardiovascular responses during stress.

Main Methods:

• Cerebrospinal fluid (CSF) was collected via lumbar puncture from 54 healthy volunteers to measure 5-hydroxyindoleacetic acid (5HIAA) levels, a marker of serotonin metabolism.
• 5HTTLPR genotypes were determined.
• Participants underwent a mental stress testing protocol to assess cardiovascular reactivity.

Main Results:

• Individuals with one or two long (l) 5HTTLPR alleles exhibited 50% higher CSF 5-HIAA levels compared to those with the s/s genotype.
• Higher CSF 5-HIAA levels and the presence of at least one l allele were associated with greater blood pressure and heart rate increases during mental stress.

Conclusions:

• The 5HTTLPR polymorphism modulates CNS serotonin function, as indicated by 5-HIAA levels.
• Increased CNS serotonin function, influenced by the 5HTTLPR 'l' allele, is linked to heightened cardiovascular reactivity to stress.
• This heightened reactivity may represent a potential mechanism contributing to an increased risk of cardiovascular disease.