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Altered hypothalamic-pituitary-adrenocortical function in rhesus monkeys (Macaca mulatta) with self-injurious
Stefan Tiefenbacher1, Melinda A Novak, Lucinda M Marinus
1Harvard Medical School, New England Regional Primate Research Center, Division of Behavioral Biology, One Pine Hill Drive, Southborough, MA 01772, USA. stefan_tiefenbacher@hms.harvard.du
Psychoneuroendocrinology
|January 30, 2004
Summary
Self-injurious behavior (SIB) in rhesus monkeys is linked to altered hypothalamic-pituitary-adrenocortical (HPA) axis function. Lower cortisol responsivity is associated with recent self-wounding and biting, suggesting complex HPA changes in SIB.
Area of Science:
- Neuroscience
- Primatology
- Endocrinology
Background:
- Self-injurious behavior (SIB), such as self-biting, is observed in individually housed rhesus monkeys, sometimes causing severe tissue damage.
- Previous research indicated lower plasma cortisol levels in monkeys with a history of self-wounding (SW) compared to non-wounders (NW).
- Cortisol levels were found to be negatively correlated with the rate of self-directed biting.
Purpose of the Study:
- To further investigate the relationship between hypothalamic-pituitary-adrenocortical (HPA) axis activity, self-wounding (SW), and self-directed biting in rhesus monkeys.
- To characterize HPA function in relation to wounding history and biting frequency.
Main Methods:
- Examined basal 24-h urinary free cortisol excretion in 24 rhesus monkeys.
- Assessed the urinary free cortisol response to a low-dose dexamethasone suppression test.
- Measured the plasma cortisol response to ACTH stimulation in relation to wounding history and biting frequency.
Main Results:
- No significant group differences in physiological measures were found when analyzed by wounding history alone.
- Plasma cortisol response 30 min post-ACTH stimulation correlated with wounding recency; lower responsivity was linked to more recent wounding.
- High frequency biters (HFB) exhibited decreased HPA negative feedback sensitivity to dexamethasone and a trend towards attenuated cortisol response to ACTH compared to low frequency biters (LFB).
Conclusions:
- Self-injurious behavior (SIB) in socially reared monkeys is associated with complex alterations in HPA axis function.
- These HPA changes are related to the expression of self-directed biting and the recency of self-wounding episodes.
- Further research is needed to determine if similar HPA alterations are present in humans exhibiting SIB.