[beta]-Endorphin suppression of acute morphine abstinence in morphine dependent monkeys: Effective given intraventricularly but ineffective given intravenously

Abstract

Six female adult monkeys were made dependent upon morphine sulfate and were implanted with a chronic indwelling needle in the lateral ventricle of the brain for sterile intraventricular injections. Both [beta]-endorphin and morphine, in a dose dependent manner given intraventricularly suppressed the signs of 14 hour acute morphine abstinence. On a molar basis, [beta]-endorphin was more active than morphine in suppressing the signs of morphine abstinence. When given intravenously in much larger doses, [beta]-endorphin was ineffective in contrast to morphine which was effective in suppressing abstinence.