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Naturally Produced Defensive Alkenal Compounds Activate TRPA1
Nathaniel T Blair1, Benjamin I Philipson2, Paige M Richards3
1Howard Hughes Medical Institute (HHMI), Boston, MA, USA, Department of Cardiology, Boston Children's Hospital, Boston, MA 02115, USA, Department of Neurobiology, Harvard Medical School, Boston, MA 02115, USA.
Chemical Senses
|February 5, 2016
Summary
Defensive (E)-2-alkenals deter predators by activating the TRPA1 channel in sensory neurons. This research identifies TRPA1 as a key target for these naturally occurring deterrent compounds.
Area of Science:
- Chemical Ecology
- Neuroscience
- Molecular Biology
Background:
- Organisms utilize (E)-2-alkenals for defense, deterring predators through secretions.
- The precise mechanism by which these alkenals function as deterrents is not fully understood.
Purpose of the Study:
- To investigate the effects of (E)-2-alkenals on transient receptor potential (TRP) channels.
- To identify the specific TRP channel(s) involved in the defensive action of alkenals.
Main Methods:
- Tested (E)-2-alkenals (C6-C12) on various TRP channels.
- Utilized electrophysiology to measure channel activation (EC50 values).
- Performed site-directed mutagenesis on TRPA1.
- Conducted rat trigeminal nerve recordings and behavioral assays.
Main Results:
- (E)-2-alkenals potently activated TRPA1 channels (EC50s 10-100 µM).
- TRPV1 and TRPV3 showed weak activation; TRPV2, TRPV4, and TRPM8 were insensitive.
- Mutagenesis studies suggested complex cysteine involvement in TRPA1 activation.
- (E)-2-hexenal demonstrated aversive properties in behavioral tests.
Conclusions:
- Transient receptor potential ankyrin subtype 1 (TRPA1) is a primary target for (E)-2-alkenals.
- TRPA1 activation by these compounds likely mediates their defensive and aversive effects.
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