Origin of taurine in developing rat brain.

The amounts of taurine supplied to the developing rat pup and rat brain by the mother, both in utero throughout gestation, and by the milk throughout weaning, have been determined. Since the total taurine status of the rats is known, the amount biosynthesized at each of these developmental times has been calculated. The surprising result was obtained that 40% of the taurine present in each rat pup, and in brain, at birth has already been obtained through biosynthesis by the fetus during gestation. In comparison, the adult rat derives 80% of its total taurine by biosynthesis, and obtains 20% from its diet. From birth to weaning, the mother contributes a similar amount of taurine to the whole rats as she did during gestation, although a smaller fraction of this taurine is present in brain. Both the rate of disappearance of labelled taurine in brain derived from the mother in utero compared to that derived from the mother in utero compared to that of [3H]taurine in brain derived from a postnatal intraperitoneal injection, suggest the presence of a small pool of taurine in the mitochondria, synaptosomes, and microsomes which is not freely exchangeable.