TRPA-1 in Planaria: Exploring Regeneration and Avoidance in the Presence of Irritants

Abstract

Planaria are a genus of freshwater flatworms widely studied for their regenerative properties. Regeneration is possible because planarians have large populations of stem cells, called neoblasts, distributed throughout their bodies. Planaria and humans share a gene that encodes for the transient receptor potential ankyrin 1 (TRPA-1), which is an ion channel that, in humans, activates pain, cold, and itch reception. In planarian cells, TRPA-1 is a receptor for heat and chemical irritation, and it is activated by reactive oxygen species produced in response to subsequent tissue damage. In this study, we investigate TRPA-1 activation in amputated Dugesia dorotocephala. In the first experiment, we aim to explore TRPA-1 activation during the planarian regeneration process. We exposed amputated worms to three known activators of TRPA-1 during regeneration and observed regeneration over 7 days. In the second experiment, we explored the relationship between TRPA-1 distribution and irritant avoidance. We placed amputated worms onto plates with irritants and tested the amputated worm pieces’ individual avoidance. We observed that while TRPA-1 may not be directly involved in regeneration, activation in response to irritants can slow secondary tissue regeneration. Additionally, we observed that irritant avoidance is stronger in worm heads, where TRPA-1 is primarily localized.