TRPA1 and Headache: For example, stimulation of rat TG neurons with parthenolide, a compound extracted from the feverfew herb (Tanacetum parthenium L.), which has been used for centuries to reduce pain, fever, and headaches [148]), induced potent and prolonged desensitization of TRPA1 channels, which rendered peptidergic neurons unresponsive to any stimulus and unable to release CGRP [149].