Neurotransmitters, Neuroregulators and Neurotoxins in Plants.

The transmission of signals between living cells is essential for the life of an organism as it provides the mechanism by which cells respond to external stimuli. Plants produce a wide range of phytochemicals that mediate cell function and translate environmental cues for survival and many of these are human neuroregulatory molecules. For example, the human neurotransmitter melatonin (N-acetyl-5-methoxytryptamine) is a ubiquitous, highly conserved molecule associated with timing of circadian rhythms in many organisms, including higher plants. Other compounds such as hyperforin, now isolated from several plant species, may function as serotonin transport or nonspecific cation channel activators in human brains and potentially in higher plants. A different group of neuroregulatory molecules produced by plants overstimulate human neurons, resulting in neuronal cell damage and death. Excitotoxins such as β-methylamino-L-alanine not only affect human health but are also regulatory molecules redirecting plant growth. Many fascinating questions in future research will be defining the role of neurotransmitters, neuroregulators and neurotoxins in the growth and development of plants. As newer technologies emerge, it will become possible to understand more about the role of neurological compounds in the inner workings of plant metabolism, plant environment interactions and the impact of plant neurosystems on human neurology. [ABSTRACT FROM AUTHOR]