Expression of P2X3 and TRPV1 receptors in primary sensory neurons from estrogen receptors-α and estrogen receptor-β knockout mice.

In women, pain symptoms and nociceptive thresholds vary with the reproductive cycle, suggesting the role of estrogen receptors (ERs) in modulating nociception. Our previous data strongly suggest an interaction between ERs and ATP-induced purinergic (P2X3) as well as ERs and capsaicin-induced vanilloid (TRPV1) receptors at the level of dorsal root ganglion (DRG) neurons. In this study, we investigated the expression of P2X3 and TRPV1 receptors by western blotting and immunohistochemistry in lumbosacral DRGs from wild type, ERα, and ERβ knockout mice. We found a significant decrease for both P2X3 and TRPV1 in ERαKO and ERβKO. This phenomenon was visualized in L1, L2, L4, and L6 levels for P2X3 receptors and in L1, L2, and S2 levels for TRPV1 receptors. This tan interaction between P2X3/TRPV1 and ERs expression in sensory neurons may represent a novel mechanism that can explain the sex differences in nociception observed in clinical practice. The DRG is an important site of visceral afferent convergence and cross-sensitization and a potential target for designing new anti-nociceptive therapies.