Moxibustion at Bl-25 Attenuated Stress-Sensitized Colon-Bladder Crosstalk by Thermal Effect Impacting Heat Shock Protein 90-Cochaperone Dynamics of Glucocorticoid Receptor

Besides affective disorders possibly resulting in psychological sequelae, stressful life events also induce gastrointestinal and/or urogenital dysfunctions. Long-lasting stressful events induce the release of glucocorticoid which binds and subsequently activates the glucocorticoid receptors (GRs) to impact nearly every organ and tissue.Not restrictively to its well-established role in somatic pain, our laboratory has demonstrated GR signaling also mediates the spinal plasticity underlying stress-sensitized painful colon-bladder crosstalk (CBC) through impacting NR2B-bearing N-methyl-D-aspartate receptors (NR2B-NMDARs) phosphorylation and trafficking in the dorsal horn neurons. GR activity is regulated by chaperone dynamics, i.e., coupling of heat shock protein 90 (Hsp90) to FK506-binding protein 52 (FKBP52) increases, while to FK506-binding protein 51 (FKBP51) conversely decreases, nuclear translocation and transcription activity of GRs. Moxibustion, a Chinese traditional thermotherapy, is currently used for the management of visceral pain in clinical practice. Notably, moxibustion at BL-25 (Dachangshu) decreases colon pain-associated spinal Hsp protein expression and relieves the bowel hyperalgesia by inactivating spinal NR2B-NMDARs.For heat at 42°C facilitates Hsp90 coupling with FKBP51 and hence impedes GR activity; and the BL-25 locates very close to the entry zone of afferent nerves innervating pelvic organs, we hypothesis moxibustion at BL-25 exhibits therapeutic effect through its heat penetrating through skin to the dorsal horn that prompts Hsp90-FKBP51 coupling and hence damps GRs signaling to ameliorate the stress-sensitize CBC. Using in vivo cystometry as well as western blotting, immunohistochemistry, and immunoprecipitation analyses of spinal cord sample, we first assayed whether stress exposure sensitized CBC activity and enhance spinal Hsp90 expression, Hsp90 acetylation, FKBP51 small ubiquitin-like modification, Hsp90-FKBP51 coupling, nucleus/cytoplasm ratio of GR, serum- and glucocorticoid-induced kinase 1 (SGK1) expression, SGK1 phosphorylation, NR2B expression, NR2B phosphorylation, and membrane/cytoplasm ratio of NR2B in the dorsal horn. Importantly, we next tested if the stress-sensitized CBC and –modified chaperone dynamics in the dorsal horn could be ameliorated by moxibustion at BL-25. We hope, through this project, we can establish a possible rationale for the moxibustion in non-invasive treatment of stressful events-associated visceral pain.