DISSOCIATION OF POMC PEPTIDES AFTER SELF-INJURY PREDICTS RESPONSES TOCENTRALLY ACTING OPIATE BLOCKERS

Apparent insensitivity to pain, ritualistic patterns of behavior, and improvement in symptoms after administration of opiate receptor blocke rs implicated the endogenous opioid system in the initiation and maint enance of SIE. This study was designed to determine whether plasma lev els of proopiomelanocortin (POMC)-derived peptides, beta-endorphin-lik e activity (PE), ACTH, and adrenal cortisol immediately after an episo de of SIE predicted subsequent response to an opiate blocker. Blood sa mples were collected from 10 patients with mental retardation within m inutes of a self-injuring act and during an SIE-free control period. O n another day, morning and afternoon samples were collected at least o ne week apart from the other samples. Effects on SIE of-naltrexone hyd rochloride (NTX) were examined in a double-blind, placebo-controlled c rossover study. After an SIE episode, beta E, but not ACTH, was elevat ed compared with morning levels, p < .003. Patients with increased pla sma levels of beta E after SIE had the most positive response to 2 mg/ kg NTX, p < .03. Results suggest that changes in the hypothalamic-pitu itary-adrenal axis after SIE may predict differences in individual pat ient response to opiate blockers.