Transient receptor potential channel A1 involved in calcitonin gene-related peptide release in neurons

Transient receptor potential channel A1 is one of the important transducers of noxious stimuli in the primary afferents, which may contribute to generation of neurogenic inflammation and hyperalgesia. The present study was designed to investigate if activation of transient receptor potential channel A1 may induce calcitonin gene-related peptide release from the primary afferent neurons. We found that application of allyl isothiocyanate, a transient receptor potential channel A1 activator, caused calcitonin gene-related peptide release from the cultured rat dorsal root ganglion neurons. Knock- down of transient receptor potential channel A1 with an antisense oligodeoxynucleotide prevented calcitonin gene-related peptide release by allyl isothiocyanate application in cultured dorsal root ganglion neurons. Thus, we concluded that transient receptor potential channel A1 activation caused calcitonin gene-related peptide release in sensory neurons.

In vivo neuronal and astrocytic activation in somatosensory cortex by acupuncture stimuli

Acupuncture is a medical treatment that has been widely pra cticed in China for over 3000 years,yet the neural mechanisms of acupuncture are not fully understood.We hypothesized that neurons and astrocytes act independently and synergistically under acupuncture stimulation.To investigate this,we used two-photon in vivo calcium reco rding to observe the effects of acupuncture stimulation at ST36(Zusanli)in mice.Acupuncture stimulation in peripheral acupoints potentiated calcium signals of pyramidal neurons and astrocytes in the somatosensory cortex and resulted in late-onset calcium transients in astrocytes.Chemogenetic inhibition of neurons augmented the astrocytic activity.These findings suggest that acupuncture activates neuronal and astrocytic activity in the somatosensory co rtex and provide evidence for the involvement of both neurons and astrocytes in acupuncture treatment.

Connexin 36 Mediates Orofacial Pain Hypersensitivity Through GluK2 and TRPA1

Trigeminal neuralgia is a debilitating condition,and the pain easily spreads to other parts of the face.Here,we established a mouse model of partial transection of the infraorbital nerve(pT-ION)and found that the Connexin 36(Cx36)inhibitor mefloquine caused greater alleviation of pT-ION-induced cold allodynia compared to the reduction of mechanical allodynia.Mefloquine reversed the pT-IONinduced upregulation of Cx36,glutamate receptor ionotropic kainate 2(GluK2),transient receptor potential ankyrin 1(TRPA1),and phosphorylated extracellular signal regulated kinase(p-ERK)in the trigeminal ganglion.Cold allodynia but not mechanic al allodynia induced by pT-ION or by virusmediated overexpression of Cx36 in the trigeminal ganglion was reversed by the GluK2 antagonist NS 102,and knocking down Cx36 expression in Nav1.8-expressing nociceptors by injecting virus into the orofacial skin area of Nav1.8-Cre mice attenuated cold allodynia but not mechanic al allodynia.In conclusion,we show that Cx36 contributes greatly to the development of orofacial pain hypersensitivity through GluK2,TRPA1,and p-ERK signaling.