Effect of taurine in rat milk on the growth of offspring

The physiological significance of taurine in milk in the growth of rat pups was investigated. Our results confirmed that taurine was at an exceptional ly high concentration in rat milk during the lactational period, especially for the first few days after birth. Pups taking no milk from natural dams but from foster mothers at an advanced lactational period showed a slower g rowth rate. Intraperitoneal administration of taurine to the foster mothers in the first five days restored this growth retardation. On the other hand , intraperitoneal administration of beta-alanine, a transport antagonist of taurine, to the natural darns through the lactational period induced a slo wer growth rate of pups. This beta-alanine treatment to dams increased beta -alanine concentration, but did not decrease taurine concentrations in milk , and serum taurine concentration in the pups receiving this milk was eleva ted. Direct administration of beta-alanine to pups also increased the serum taurine concentrations dose-dependently, beta-Alanine administration to pu ps significantly decreased [H-3]taurine incorporation into all the organs e xamined, and in contrast, [H-3]taurine concentrations in serum and urine we re elevated. Thus, beta-alanine inhibited taurine incorporation into cells and accelerated taurine excretion into either urine or milk. Serum IGF-I le vels in pups receiving beta-alanine either directly or via their mothers wa s significantly lower than those in control pups. Cumulatively, taurine ing estion from milk at an early lactational period seems critical for normal g rowth of rat neonates due to its role in maintaining normal serum IGF-I lev els.