Green Tea Polyphenol Epigallocatechin Gallate Activates TRPA1 in an Intestinal Enteroendocrine Cell Line, STC-1

The 5 senses—sight, taste, touch, smell and hearing—are of vital importance to life and its survival. By providing information about the surrounding environment, the senses allow all living things to learn about what is around them and to develop behaviors that will best position them for survival. When looking specifically at one sense, in this case taste, it becomes clear that there are specific biological mechanisms occurring in order for a person to experience a certain taste sensation. There are receptors on the tongue that are activated when they come across certain substances, which send signals to the brain that are translated into taste. For exampleamiloride-sensitive Na+ channels play a role in producing the familiar salty taste. These interactions exist across all taste receptors. However, what is curious is that recent findings have indicated that the tongue is not the only place where taste sensing takes place. There is significant evidence to suggest that this type of information is also absorbed by the gastro intestinal system to help regulate certain functions such as the secretory activity of GI glands, the resorptive activity, motility and blood supply of the intestinal tract and satiation. This largely comes from STC-1 cells, which have been established as enteroendocrine cells and have also been shown to posses certain taste receptors and respond to certain taste substances.

Kurogi et al. from the Nagahama Institute of Bio-Science and Technology in Nagahama, Japan set out to deepen this understanding by taking a look at how STC-1 cells respond to astringent taste that is generally associated with foods such as green tea and red wine. However, little is known about what causes this taste and how it is perceived in the gastrointestinal system. Through calcium imaging and a series of channel blocking experiments , Kurogi and his team were able to determine that the transient receptor potential A1 (TRPA1) is activated by a typical green tea polyphenol epigallocatechin gallate (ECGC). To do this calcium imaging, the researchers made use of the Fluo-8 AM fluorescent indicator. The advantage of such a tool is that it has significantly more intense signals and is more robust than previous indicators. By being several times brighter than these indicators, results are much more easily obtained and interpreted, which allows for more valid studies.

This study is useful as it allows for a further understanding as to how the different senses work. Understanding the causal mechanisms behind such vital processes is essential for further advancement in the field; by using Fluo-8 AM, the researchers in this study were doing just that. Improved loading and a resistance to temperature changes makes this indicator superior in terms of the quality of results. Images obtained can be trusted as being accurate, which allows researchers to focus instead on teasing out the implications of their work. These types of advancements have helped make science more exact and are proving to be invaluable as the field expands and deeper understanding of biological mechanisms are obtained.

References

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1. Kurogi, Mako, et al. "Green tea polyphenol epigallocatechin gallate activates TRPA1 in an intestinal enteroendocrine cell line, STC-1." Chemical senses (2011): bgr087.