ABSTRACT
Mitochondrial reactive oxygen species (mROS) that are overproduced by mitochondrial dysfunction are linked to pathological conditions including sensory abnormalities. Here, we explored whether mROS overproduction induces itch through transient receptor potential canonical 3 (TRPC3), which is sensitive to ROS. Intradermal injection of antimycin A (AA), a selective inhibitor of mitochondrial electron transport chain complex III for mROS overproduction, produced robust scratching behavior in naïve mice, which was suppressed by MitoTEMPO, a mitochondria-selective ROS scavenger, and Pyr10, a TRPC3-specific blocker, but not by blockers of TRPA1 or TRPV1. AA activated subsets of trigeminal ganglion neurons and also induced inward currents, which were blocked by MitoTEMPO and Pyr10. Besides, dry skin-induced chronic scratching was relieved by MitoTEMPO and Pyr10, and also by resveratrol, an antioxidant. Taken together, our results suggest that mROS elicit itch through TRPC3, which may underlie chronic itch, representing a potential therapeutic target for chronic itch.
Subject(s)
Animals , Mice , Antioxidants/pharmacology , Mitochondria , Pruritus/chemically induced , Reactive Oxygen Species/metabolism , TRPA1 Cation ChannelABSTRACT
Objective To observe the expression change of TRPC3 in cortex of rats with Kainic acid(KA)-induced sei-zures,and to explore the role of TRPC3 in epileptogenesis.Methods Fifty-four adult Sprague Dawley(SD)rats were randomly divided into two groups(18 for control group,36 for epilepsy group).The behavior of rats was observed and recorded.The epi-lepsy group was treated with KA(2 μg/kg,about 7 μL,lateral intracerebroventricular injection),and control group was treated with isotonic Nachloride(equivalent volume with KA,lateral intracerebroventricular injection).For epilepsy group,samples were taken 48 and 72 h after seizure burst.For control group,samples were taken 48 h after isotonic Nachloride injection.The mRNA level of TRPC3 in cortex was detected and recorded by RT-PCR,and the protein level of TRPC3 in cortex was measured by Western blotting,and immunohistochemistry was also used to display the TRPC3 expression in cortex.Results The control group showed no seizure activity,and the epilepsy group showed classical seizure activity(Ⅳ-Ⅴ level)about 5 min after injection and last for several hours.The mRNA and protein levels of TRPC3 in epilepsy group were both higher than those in control group with obvious distinction(P< 0.05).Conclusion The TRPC3 level increases in cortex of rats with KA-induced sei-zures.These results point out that TRPC3 is possibly involved in epilepsy etiopathogenesis and development.
ABSTRACT
During membrane depolarization associated with skeletal excitation-contraction (EC) coupling, dihydropyridine receptor [DHPR, a L-type Ca2+ channel in the transverse (t)-tubule membrane] undergoes conformational changes that are transmitted to ryanodine receptor 1 [RyR1, an internal Ca2+-release channel in the sarcoplasmic reticulum (SR) membrane] causing Ca2+ release from the SR. Canonical-type transient receptor potential cation channel 3 (TRPC3), an extracellular Ca2+-entry channel in the t-tubule and plasma membrane, is required for full-gain of skeletal EC coupling. To examine additional role(s) for TRPC3 in skeletal muscle other than mediation of EC coupling, in the present study, we created a stable myoblast line with reduced TRPC3 expression and without alpha1SDHPR (MDG/TRPC3 KD myoblast) by knock-down of TRPC3 in alpha1SDHPR-null muscular dysgenic (MDG) myoblasts using retrovirus-delivered small interference RNAs in order to eliminate any DHPR-associated EC coupling-related events. Unlike wild-type or alpha1SDHPR-null MDG myoblasts, MDG/TRPC3 KD myoblasts exhibited dramatic changes in cellular morphology (e.g., unusual expansion of both cell volume and the plasma membrane, and multi-nuclei) and failed to differentiate into myotubes possibly due to increased Ca2+ content in the SR. These results suggest that TRPC3 plays an important role in the maintenance of skeletal muscle myoblasts and myotubes.