Age-related changes in serotonin 5HT2 receptors on human blood platelets.

Serotonin receptors of the 5HT2 type were labeled on platelet membranes using tritiated ketanserin. Blood was collected from the umbilical cord of newborns and venous samples were collected from 6-year-old children as well as junior-high and high school students (ages 13 through 18) to determine age-related changes in receptor binding. Among the ages sampled, the highest levels of 5HT2 receptor binding were found in 6-year-olds. A sharp decline in receptor binding occurred during adolescence, with levels reduced by half between ages 13 and 17. This pattern is similar to the one we have observed in brain 5HT2 receptors postmortem. There were no significant sex differences in 5HT2 receptors on platelets in newborn and young children. A trend towards higher binding in girls appears around the onset of menstruation in teenage girls (age 14 and up). These results demonstrate that platelet 5HT2 receptors can serve as a model for age dependent changes in 5HT2 receptors in the brain.