Relations among whole blood serotonin and sex, age, diet, and social status in Macaca nemestrina.

Whole blood serotonin (WBS) determinations were made in 56 pigtailed macaques (Macaca nemestrina) with approximately equal numbers in three age groups: young-adult (4-5 years), middle-aged (13-14 years), and old (over 18 years). The animals were housed in ten living groups with one female and male of each age group in each living group. Half of the groups were fed a diet high in lipid, cholesterol, simple sugars, and sodium; the other half received a restricted diet.