ALARM PHEROMONE INDUCES STRESS ANALGESIA VIA AN OPIOID SYSTEM IN THE HONEYBEE

Changes of the stinging response threshold of Apis mellifera scutellat a were measured on foragers fixed on a holder and stimulated with an e lectric shock as a noxious stimulus. The threshold of responsiveness t o the noxious stimulus increased when bees were previously stimulated with isopentyl acetate, which is a main component of the alarm pheromo ne of the sting chamber. This effect is antagonised by previous inject ion of naloxone-hydrochloride (Endo Laboratories Inc.). Results sugges t that in the honeybee an endogenous opioid system activated by isopen tyl acetate is responsible for modulation of perception for nociceptiv e stimuli. The resulting stress-induced analgesia in the defender bee would reduce its probability of withdrawal thus increasing its efficie ncy against enemies. (C) 1998 Elsevier Science Inc.