ß-Endorphin as a potent analgesic by intravenous injection

AN untriakontapeptide¹ with significant opiate activity from camel pituitary glands was shown to have an amino acid sequence identical to the carboxyl-terminal 31 amino acids of β-lipotropins^2,3. The peptide, designated as β-endorphin, has recently been synthesised ⁴, and when administered directly into the brain, it was found ⁵ to be considerably more potent than morphine in molar basis, and its actions were blocked by naloxone. Other peptides related to β-lipotropins have also been shown to possess in vitro opiate-like activity^6-9. We report here the analgesic effects of β-endorphin when it is injected intravenously.