Suspended moxibustion relieves chronic visceral hyperalgesia and decreases hypothalamic corticotropin-releasing hormone levels

AIM:To evaluate the effect of suspended moxibustion(SM) on rectal sensory thresholds and to analyze the possible mechanisms involved in SM treatment of chronic visceral hypersensitivity(CVH) in rats.METHODS:SM was administered once daily to 37-dold CVH rats for 7 d.The two pairs of acupoints(ST25 and ST37,bilateral) were simultaneously treated with SM.Each treatment lasted for 30 min.Rats undergoing treatment with SM were not anesthetized.Untreated CVH rats and normal rats were used as controls.The abdominal withdrawal reflex was determined 30-90 min after the seven treatments.The hypothalamic corticotropin-releasing hormone(CRH) mRNA level was measured using real-time quantitative reverse transcriptionpolymerase chain reaction.RESULTS:We found that SM treatment significantly decreased visceral sensitivity to colorectal distention in this rat model.In treated animals,SM also decreased the relative hypothalamic CRH mRNA expression level to control levels.CONCLUSION:Lower hypothalamic CRH levels may mediate the beneficial effects of SM in this rat irritable bowel syndrome model.

Studies on sensitivity to tension and gating pathway of MscL by molecular dynamic simulation

Mechanosensitive（MS） ion channels play an important role in various physiological processes.Although the determination of the structure of mechanosensitive channel of large conductance（MscL） makes the simulation study possible,it has not so far been possible to directly simulate the gating mechanism of MscL in atomic detail.In this article,MscL has been studied via molecular dynamic（MD） simulations to gain a detailed description of the sensitivity to lateral tension and the gating pathway.MscL undergoes conformational rearrangement in sustaining lateral tension,and the open state is obtained when 2.0 MPa lateral tension is directly applied on the pure protein.During the opening process,Loop region responds to tension first,and the mechanical sensitivity is followed by S1 domain.Transmembrane（TM） bundle is the key position for channel opening,and the motion of TM1 helices finally realizes the significant expansion of the constricted gating pore.C-terminus domain presents expansion later during the TM opening.In our study,return of the whole protein to the initial closed state is achieved only in the early opening stage.During the relaxation from the open state,the TM helices are the most mobile domain,which is different from the opening process.