Simonetti, M., Giniatullin, R., and Fabbretti, E.
Notes: These authors investigated the mechanism of action of the migraine mediator calcitonin gene-related peptide (CGRP), which is known to sensitize the P2X3 pain receptors to increase impulse flow to brain stem trigeminal nuclei. They showed that CAM KII inhibitors prevented CGRP-induced upregulation of P2X3 mRNA using real-time RT-PCR, and then confirmed that active CAM KII was involved in the signaling mechanism by staining with Anti-ACTIVE® CAM KII Antibodies. The immunoreactivity was upregulated by CGRP treatment of trigeminal neurons, and the distribution of the active CAM KII was localized to the membrane region. They then examined the mechanism of transcriptional activation of the P2X3 pain receptor genes and showed that the transcription factor CREB, which is known to be dependent on CAM KII for activation and nuclear localization, was involved. The authors also investigated the role of BDNF in the process, because CGRP is known to promote BDNF expression by trigeminal neurons, and because BDNF is thought to be involved in pain processing. They used the BDNF Emax Immunoassay System to measure BDNF levels in culture media after application of CGRP to neuronal cell cultures, and demonstrated that there was a fourfold increase in BDNF after CGRP exposure. They also showed that BDNF promoted CAMKII and CREB activation. (3873)