ROLE OF TAURINE IN NEONATES
INTRODUCTION : Recent advances in the knowledge of the composition of human milk indicate that several substances like cholesterol, taurine and carnitine are also present in human milk. Recent papers indicate that none of the proprietary preparations are incorporating these amino acids.

CHEMISTRY : Taurine is the major free intracellular Amino acid found in mammalian tissues. The Amino group (-NH2 resides on B - Carbon ring. It is a sulphonic acid rather than carboxylic acid.

NH2 - CH2 - CH2 - SO3

It is not a constituent of any protein, thus remains free in intracellular fluid. This is based on several theories about its role as a regulator of all volume and osmolarity.
Taurine is derived from the metabolism of Sulphur containing Amino acids metheonine and cysteine.

BIOSYNTHESIS AT FETAL LIVER / BRAIN : the biosynthesis is taking place through a series of steps from Metheonine and Cysteine. Struman and Hayes found that all of the enzymes required for conversion of Metheonine are present in the liver but not in the brain.

The level of the enzymes in developing brain are so limited that Taurine in the Central Nervous System must come from breast mild.

Two path ways are explained in the process of metabolism from Cysteine to Taurine.

CSA PATHWAY :
1. Cysteine -> Cysteine sulphonic acid -> Cysteic acid -> TAURINE
CYSTEAMINE PATHWAY :
2. Cysteine -> Cysteamine -> Hypotaurine -> Taurine

As Gaull points out, the highest concentration of Taurine in the brain occurs in infancy, when the activity of the CSA pathway is lowest. Thus dependence on a dietary source of taurine is certain, since hepatic CSA decarboxylase activity is limited in man, as compared to rats. Gaull further speculates that man may always require an exogenous source of Taurine. The main biochemical reaction involving Taurine is the conjugation of bile acids to form bile salts. Providing extra Taurine or Taurine-ureodeoxycholic acid (UDCA) in the diet will increase the proportion of Taurine - conjugates to 40 percent. Hepatic bile acid synthesis is altered with a greater proportion of Taurine - conjugated bile acids and a change in the Glycine - to Taurine ratio. The preferential conjugation of bile acids to Taurine after Taurine supplementation and Taurine reduction, will lower the proportion of Taurine - conjugated bile acids in man.

TAURINE IN THE NERVOUS SYSTEM : The major role of Taurine is that of neuro inhibitor, similar to GABA (aminobutyric acid). Another role of taurine in the brain CNS tissue as well as in other excitable membranes, is its influence on Calcium fluxes. Taurine enhances the flow of Calcium through membranes and permits calcium re-entry into synaptosomes. Loss of the phospholipid as Taurine leaves the CNS intracellular compartment destabilises the neural membranes. The role of Taurine in containing certain forms of epilepsy is notable.

TAURINE IN OCULAR CAPACITY : This is the most abundant Amino acid in the retina. It is localised to photoreceptor cells. It is most important in neurotransmission within the retina. Taurine deficiency results in retinitis pigmentosa. This was found out after a study in INDIA. Most of these patients were children suffering from chronic short-gut syndrome or other neonatal gut disorder.

TAURINE IN NUTRITION : Taurine influences plasma, urinary and bile acid conjugation but not body size, growth, or bile acid kinetics. Cows milk has lowest Taurine in late gestation. Thus the infants fed on cow's milk based formulas are low in Taurine compared to breast milk fed babies.

TAURINE : The Taurine level of Lactonil is based on the standard of Taurine present in the breast milk. This is a Sulpha Based Free intracellular Amino Acid which is conditionally essential for conditions like cystic fibrosis and Retinitis pigmentosa. This Amino Acid conjugates with bile acids to form water soluble bile salts. Taurine seems to contain certain forms of epilepsy in Neo-nates and develops A.B.E.R. in pre-term babies.