Evolution of Serotonin: Sunlight to Suicide
Evolution of Serotonin: Sunlight to Suicide
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DOI：
10.1016/s1569-7339(10)70069-2
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发表时间：
2010-01-01
期刊：
影响因子：
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通讯作者：
Azmitia, Efrain C.
中科院分区：
文献类型：
--
作者：
Azmitia, Efrain C.
Serotonin is involved in many of the behaviors and biological systems that are central to human life, extending from early developmental events related to neurogenesis and maturation, to apoptosis and neurodegeneration that underlie dementia and death. How can a single chemical be so powerful in determining the quality and quantity of human life? In this chapter, the evolution of serotonin and its biosynthetic pathways from tryptophan are examined. The essential components of the serotonin biosynthetic pathway are highly conserved. Tryptophan-based chemicals, including serotonin, melatonin and auxin, have important action in the differentiation, mitosis and survival of single cell organisms. As the complexity of life evolved into multicellular organisms, especially plants, serotonin levels rose dramatically. The importance of tryptophan, serotonin and auxin is evident in photosynthesis and plant growth. When the animal kingdom began, the ability to synthesize tryptophan was lost, and serotonin levels dropped accordingly. Animals had to develop many special mechanisms to secure tryptophan from their diets, and to carefully conserve its integrity during circulation throughout the body. There was the emergence of multiple receptors and reuptake proteins that permit serotonin actions without utilization of serotonin itself. Serotonin receptors appear as early as the blastula and gastrula stages of embryonic development, and continually monitor and regulate ontogenic changes as it serves phylogenic evolution.The most amazing concept to emerge from an analysis of serotonin evolution is its relation to light. Beginning with the light-absorption properties of the indole ring of tryptophan, a direct path can be drawn to the effects of sunlight on photosynthesis and serotonin levels in plants. Progressing further in phylogeny, the effects of sunlight are seen on serotonin levels and on mood, sleep and suicide ideation in humans. The focus on the evolution of serotonin leads from an awareness of the beginning of life to the current human struggle to enjoy our dominant position on earth.
