Chronic pain states are characterized by long-term sensitization of spinal cord neurons that relay nociceptive information to the brain. Among the mechanisms involved, up-regulation of Cav1.2-comprising
L-type calcium channel (Cav1.2-LTC) in spinal dorsal horn have a crucial role in chronic
neuropathic pain. Here, we address a mechanism of translational regulation of this
calcium channel. Translational regulation by
microRNAs is a key factor in the expression and function of eukaryotic genomes. Because perfect matching to target sequence is not required for inhibition, theoretically,
microRNAs could regulate simultaneously multiple mRNAs. We show here that a single
microRNA, miR-103, simultaneously regulates the expression of the three subunits forming Cav1.2-LTC in a novel integrative regulation. This regulation is bidirectional since knocking-down or over-expressing miR-103, respectively, up- or down-regulate the level of Cav1.2-LTC translation. Functionally, we show that miR-103 knockdown in naive rats results in
hypersensitivity to
pain. Moreover, we demonstrate that miR-103 is down-regulated in neuropathic animals and that miR-103 intrathecal applications successfully relieve
pain, identifying miR-103 as a novel possible therapeutic target in neuropathic
chronic pain.