Summary
The current paper summarizes the fi ndings on endogenous morphine isolated by HPLC and characterized by mass spectroscopy in Schistosoma mansoni, Dracunculus medinensis and Ascaris suum. Morphine-6-glucuronide (M6G) has also been found by HPLC and confi rmed by mass spectroscopy
in Dracunculus medinensis and Ascaris suum. In addition, a morphine like substance has been isolated from Trichinella spiralis by HPLC and mice infected with Trichinella spiralis show a naloxone reversible analgesia. We discuss in greater detail the tissue distribution, course of secretion, and
sex differences of morphine in Ascaris suum. Finally, we explore the function of morphine as both an internal signaling molecule and its use in immune evasion in Ascaris suum.

Keywords: Ascaris suum - chemistry, Helminths - chemistry, Helminths - parasitology, Schistosoma mansoni - chemistry, Trichinella - chemistry, Trichinosis - metabolism, Ascaris suum - chemistry, Chromatography, High Pressure Liquid, Helminths - parasitology, Mass Spectrometry, Morphine - isolation & purification, Schistosoma mansoni - chemistry, Trichinella - chemistry, Trichinellosis - metabolism