CSF 5-HIAA and aggression in female macaque monkeys: species and interindividual differences.
BACKGROUND
While the relationship among CSF 5-HIAA, impulsivity, and aggression is well characterized in males, its investigation in females is limited, and no studies have assessed its generalizability across primates by making simultaneous comparisons between and within closely-related species.


OBJECTIVE
We tested three hypotheses. First, that female rhesus macaques would have lower CSF 5-HIAA concentrations and be more aggressive than would female pigtailed macaques. Second, that females of both macaque species would exhibit an inverse relationship between interindividual differences in CSF 5-HIAA concentrations and rates of severe aggression. Third, that subjects with high CSF 5-HIAA concentrations would be higher in social dominance within their respective groups than would subjects with low CSF 5-HIAA concentrations.


METHODS
We obtained CSF samples from 61 individually housed female primates of two closely related species: rhesus macaques (Macaca mulatta) and pigtailed macaques (Macaca nemestrina). We later placed subjects in unisex social groups, and correlated interindividual differences in CSF 5-HIAA with aggression, wounding, and acquisition of social dominance rank.


RESULTS
Between-species analyses indicated higher CSF 5-HIAA concentrations in pigtailed macaques, and higher rates of high-intensity aggression, escalated aggression, and wounds requiring medical treatment in rhesus macaques. Within-species analyses indicated that interindividual differences in CSF 5-HIAA concentrations were inversely correlated with escalated aggression and positively correlated with social dominance rank.


CONCLUSIONS
These findings show that agonistic and social differences between closely-related species are correlated with CNS serotonin activity, as species that show relatively high rates of severe aggression also tend to have low concentrations of CSF 5-HIAA. We conclude that serotonergic functioning plays an important role in controlling impulses that regulate severe aggression and social dominance relationships in both male and female primates, and that between-species differences in agonistic temperament can be predicted by species typical CNS serotonin functioning.
Westergaard
G C
GC
Division of Research, LABS of Virginia, Inc., 95 Castle Hall Road, P. O. Box 557, Yemassee, SC 29945, USA. gwprimate@aol.com
Suomi
S J
SJ
Higley
J D
JD
Mehlman
P T
PT
D000374:Aggression / Q000502:physiology*; D000818:Animals; D015415:Biomarkers / Q000134:cerebrospinal fluid; D005260:Female; D006897:Hydroxyindoleacetic Acid / Q000134:cerebrospinal fluid*; D007206:Individuality; D008251:Macaca; D012930:Social Dominance; D013045:Species Specificity
D015415:Biomarkers; D006897:Hydroxyindoleacetic Acid