Normal CSF levels of met-enkephalin-like material in a case of naloxone—Reversible congenital insensitivity to pain

Abstract In a case of naloxone-reversible congenital insensitivity to pain, met-enkephalin-like immunoreactivity in the CSF was in the normal range and not affected by the administration of naloxone. Chromatographic analysis of the met-enkephalin-like material revealed that it corresponded to at least two classes of molecules. A clear difference in the relative proportions of these two classes was detected in the CSF of the patient insensitive to pain when compared to controls. The possible functional significance of this alteration is discussed in relation to the well known antinociceptive action of enkephalins.