Role for opioid peptides in self-injurious behavior: dissociation from autonomic nervous system functioning.

The effects of acute, orally administered naltrexone (0.5, 1.0, 1.5 and 2.0 mg/kg), a potent opioid receptor antagonist, on self-injurious behavior (SIB), heart rate, and blood pressure in three males (one 10-year-old and two 17-year-olds) were investigated. Subjects were evaluated in a structured test session for SIB. The frequency of the most predominant type of SIB (head and face hitting) was significantly reduced by naltrexone (maximum was 71% at the 1.5 mg/kg dose), while self-biting was not significantly decreased at any dose. In contrast, naltrexone had no significant effect on heart rate or blood pressure. Based upon these and other results it was concluded that naltrexone produced decreases in specific SIBs by blocking opioid receptors in brain, and that such opioid blockade had no effect on two measures of cardiovascular function.