Neuron
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Six members of the mammalian transient receptor potential (TRP) ion channels respond to varied temperature thresholds. The natural compounds capsaicin and menthol activate noxious heat-sensitive TRPV1 and cold-sensitive TRPM8, respectively. The burning and cooling perception of capsaicin and menthol demonstrate that these ion channels mediate thermosensation. ⋯ We further show that phospholipase C is an important signaling component for TRPA1 activation. Cinnamaldehyde, the most specific TRPA1 activator, excites a subset of sensory neurons highly enriched in cold-sensitive neurons and elicits nociceptive behavior in mice. Collectively, these data demonstrate that TRPA1 activation elicits a painful sensation and provide a potential molecular model for why noxious cold can paradoxically be perceived as burning pain.
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Comparative Study
A Cacna1a knockin migraine mouse model with increased susceptibility to cortical spreading depression.
Migraine is a common, disabling, multifactorial, episodic neurovascular disorder of unknown etiology. Familial hemiplegic migraine type 1 (FHM-1) is a Mendelian subtype of migraine with aura that is caused by missense mutations in the CACNA1A gene that encodes the alpha(1) subunit of neuronal Ca(v)2.1 Ca(2+) channels. ⋯ Our data show that the increased susceptibility for CSD and aura in migraine may be due to cortical hyperexcitability. The R192Q FHM-1 mouse is a promising animal model to study migraine mechanisms and treatments.