PATHOLOGY

Detailed explanation-1: -The amino acid tryptophan is the precursor of several important products including serotonin or melatonin (Fig. 2). These molecules are biogenic amines of low molecular weight that belong to the indole group. It has been observed that the synthesis of melatonin in the pineal gland diminishes with aging.

Detailed explanation-2: -Niacin, also known as vitamin B3, is synthesized from tryptophan via kynurenine and quinolinic acids.

Detailed explanation-3: -The melatonin derivative 2-iodomelatonin179 has higher affinity for these receptors than melatonin and is used widely to histologically localize melatonin receptors, to characterize their binding feature, and to measure melatonin levels by radioimmunoassays.

Detailed explanation-4: -Melatonin, a derivative of an essential amino acid, tryptophan, was first identified in bovine pineal tissue and subsequently it has been portrayed exclusively as a hormone.

Detailed explanation-5: -The precursor to melatonin is serotonin, a neurotransmitter that itself is derived from the amino acid tryptophan. Within the pineal gland, serotonin is acetylated and then methylated to yield melatonin. Synthesis and secretion of melatonin is dramatically affected by light exposure to the eyes.