Serotonin concentrations in plasma and variations during the menstrual cycle

Area of Science:

• Biochemistry
• Neuroscience
• Clinical Chemistry

Background:

• Serotonin (5-HT) is a crucial neurotransmitter affecting mood and physiological functions.
• Establishing accurate reference intervals for plasma serotonin is essential for clinical diagnostics.
• Variations in serotonin levels may occur with age and hormonal fluctuations.

Purpose of the Study:

• To determine the reference interval for serotonin concentration in platelet-poor plasma in healthy adults.
• To investigate potential differences in plasma serotonin levels based on sex and age.
• To explore fluctuations in plasma serotonin throughout the menstrual cycle.

Main Methods:

• A specific and sensitive radioenzymatic assay was employed.
• Plasma serotonin concentrations were measured in 98 healthy volunteers (49 males, 49 females).
• Serial measurements were conducted in 20 women across two menstrual cycles.

Main Results:

• The reference interval for plasma serotonin was established as 0-11 nmol/L, with a median of 2.8 nmol/L.
• No significant differences in serotonin levels were observed between sexes or across different age groups, except for the elderly.
• Significantly elevated serotonin concentrations were noted in very elderly volunteers (86-92 years).
• Plasma serotonin levels were higher during the periovulatory and premenstrual phases compared to the start of menstruation.

Conclusions:

• The established reference interval provides a benchmark for plasma serotonin levels in healthy adults.
• Plasma serotonin concentrations may increase in very elderly individuals.
• Hormonal changes during the menstrual cycle influence serotonin levels in women.