betadex and alpha-beta-methyleneadenosine-5--triphosphate

We examined the importance of membrane cholesterol for the function and expression of TRPV1 (vanilloid receptor subtype 1) and P2X(3) in adult rat dorsal root ganglion (DRG) neurons. Cholesterol, an essential component of lipid rafts, was depleted using methyl beta-cyclodextrin (MCD). We found that MCD significantly reduced TRPV1-mediated capsaicin- and proton-activated currents. By contrast, inward currents activated by alpha,beta-methylene ATP (alpha,beta-meATP), a non-hydrolysable ATP analogue, were not altered. Immunoreactivity for TRPV1, but not P2X(3), in the plasma membrane was markedly reduced by MCD. A reduction of TRPV1 protein in membrane fractions was found following cholesterol depletion. Our data show that the level of cholesterol determines the activity and the amount of membrane TRPV1, suggesting that TRPV1 might be localized in cholesterol-rich microdomains in nociceptors. The differential dependence on the membrane cholesterol of TRPV1 and P2X(3) may have physiological significance in nociception during inflammation.

Topics: Adenosine Triphosphate; Animals; beta-Cyclodextrins; Capsaicin; Cell Membrane; Cells, Cultured; Cholesterol; Ganglia, Spinal; Immunohistochemistry; Male; Membrane Microdomains; Neurons; Nociceptors; Patch-Clamp Techniques; Protons; Rats; Rats, Sprague-Dawley; Receptors, Purinergic P2; Receptors, Purinergic P2X3; TRPV Cation Channels