Studies on ergothioncine. VI. Distribution and fluctuations of ergothioneine in rats.

(1) Ergothioneine is contained as a component of the organella membranes in the rat liver, and is liberated by heat treatment or dithiothreitol treatment. The amount of bound form increases with aging up to 11 weeks of age, and then decreases. All of the ergothioneine measured by the normal determination procedures can be considered to be free form. (2) Ergothioneine is bound to proteins in the blood plasma, but is present in free form in erythrocytes. (3) Biosynthesis of ergothioneine from amino acids in rats was not detectable. Ergothioneine is ingested from the diet and accumulated in the body. (4) When dietary ergothioneine is restricted for 18 weeks, the amount in the liver falls to a threshold value but apparently does not fall further, and no deficiency symptoms are observed. (5) Experimental ergothioneine-free rats were successfully produced in the second generation (born to parent rats fed on ergothioneine-free diet).