KENOTOXIN

KENOTOXIN (from Greek kenoo- I devastate, deprive and toxikon- poison), a name given by Weichardt in 1912 to a hypothetical substance, supposedly isolated by him in crystalline form from the muscles and other tissues of fatigued animals, and also found in their urine and exhaled air. This substance, when injected into normal animals, causes signs of fatigue (drop in temperature, slowing of respiration), and in small doses leads to the formation of antibodies-"anti-kenotoxin." Weichardt's discovery was once very popular; it was proposed to use anti-kenotoxin for immunization against fatigue (spraying in school rooms, etc.). However, upon verification of Weichardt's experiments, it turned out that K. could also be obtained from non-fatigued muscles, that the product isolated by Weichardt was not crystalline and dialyzes, and that Weichardt's kenoprecipitin reaction is not specific; at present, the theory of K. can be considered refuted. Recently, Economo (C. v. Economo; 1929) applies the term K. to all metabolic products formed in the body during fatigue and possessing toxic and hypnotic effects. In addition to lactic acid and carbon dioxide, this includes the substance discovered by Legendre and Piéron simultaneously with Weichardt's work, called by them "hypnotoxin" and contained in the blood serum of strongly fatigued animals, which is proven by the fact that injection of such serum gives normal rested animals a deep sleep. Hypnotoxin is apparently a specific nerve poison, since when introduced in large doses into the body it causes toxic changes in the large cells of the frontal lobe cortex; Piéron (1913) believes that under normal conditions hypnotoxin causes sleep not by direct toxic action on the cortex, but by exciting central inhibition reflexively.