The anxiogenic drug FG7142 increases self-injurious behavior in male rhesus monkeys (Macaca mulatta).
OBJECTIVE
Self-injurious behavior (SIB), which is deliberate infliction of self-injury without suicidal intent, is a significant human health problem. SIB is not unique to humans but is also manifested in a small percentage of captive macaques, typically as self-directed biting. Although the onset and maintenance of SIB have been linked to increased anxiety in both humans and nonhuman primates, no previous studies have directly tested the anxiety-SIB hypothesis. Here, we determined whether rhesus monkeys increase their self-directed biting following a challenge with the anxiogenic compound N-methyl-beta-carboline-3-carboxamide (FG7142).


METHODS
Ten rhesus monkeys (Macaca mulatta) with a veterinary record of self-wounding (SIB) as well as six age- and weight-matched non-wounding control monkeys were given intramuscular injections of 0.1, 0.3, or 1.0mg/kg FG7142. Behavior was observed following drug administration with special attention to displacement behaviors (scratching, self-grooming, and yawning), locomotor stereotypy, and self-directed biting. Plasma cortisol and ACTH were also measured as physiological indices of stress.


RESULTS
Self-directed biting rates dose-dependently increased in a subset of SIB monkeys, but did not change in control animals. Furthermore, administration of FG7142 led to an increase in scratching, yawning, and locomotor stereotypy in all monkeys, but did not affect the frequency self-grooming. Additionally, there was a dose-dependent increase in plasma cortisol concentrations, but not ACTH, in all animals.


CONCLUSIONS
The present findings indicate that self-biting is anxiety-related in some but not all SIB monkeys, suggesting that this behavioral pathology is heterogeneous as has previously been suggested for SIB in humans.
Major
Christine A
CA
New England Primate Research Center, Harvard Medical School, Southborough, MA, United States.
Kelly
Brian J
BJ
Novak
Melinda A
MA
Davenport
Matthew D
MD
Stonemetz
Karen M
KM
Meyer
Jerrold S
JS
D000324:Adrenocorticotropic Hormone / Q000097:blood; D000818:Animals; D001007:Anxiety / Q000139:chemically induced*; D002243:Carbolines / Q000494:pharmacology*; D004305:Dose-Response Relationship, Drug; D006854:Hydrocortisone / Q000097:blood; D008253:Macaca mulatta; D008297:Male; D016728:Self-Injurious Behavior / Q000139:chemically induced*
D002243:Carbolines; C035874:FG 7142; D000324:Adrenocorticotropic Hormone; D006854:Hydrocortisone