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Delayed dispersal and elevated monoaminergic activity in free-ranging rhesus monkeys
Jay R Kaplan1, M Babette Fontenot1, John Berard2
1Department of Comparative Medicine, Bowman Gray School of Medicine of Wake Forest University, Winston-Salem, North Carolina.
American Journal of Primatology
|January 12, 2020
Summary
Delayed dispersal in male rhesus monkeys is linked to higher serotonin and dopamine activity. This suggests altered neurotransmitter levels may influence social behavior and group emigration in primates.
Area of Science:
- Primate behavior
- Neuroendocrinology
- Animal behavior
Background:
- Male rhesus monkeys typically disperse from natal groups between 3-5 years of age.
- Some males exhibit delayed dispersal beyond 5 years of age.
- Understanding factors influencing dispersal timing is crucial for social behavior studies.
Purpose of the Study:
- To investigate central monoaminergic neurotransmitter activity as a correlate of delayed dispersal in male rhesus monkeys.
- To compare cerebrospinal fluid (CSF) metabolite levels between dispersing and non-dispersing males.
Main Methods:
- Collected CSF from 54 male rhesus monkeys (Macaca mulatta) of varying ages.
- Measured CSF concentrations of 5-hydroxyindoleacetic acid (5-HIAA), 3-methoxy-4-hydroxyphenylglycol (MHPG), and homovanillic acid (HVA).
- Compared metabolite levels between males who had dispersed and those who delayed dispersal.
Main Results:
- Males with delayed dispersal showed higher CSF 5-HIAA (serotonin metabolite) and HVA (dopamine metabolite) than dispersing males.
- 5-HIAA independently differentiated between dispersing and delayed-dispersing males.
- Younger males (<60 months) showed no significant differences in metabolite levels, regardless of dispersal status.
Conclusions:
- Elevated CSF 5-HIAA and HVA may be associated with delayed dispersal in male rhesus monkeys.
- Delayed dispersers may not experience the typical adolescent decline in serotonergic activity.
- Neurotransmitter activity, particularly serotonin, plays a role in regulating dispersal timing in primates.
