Interleukin-1 beta induces cyclic AMP formation in isolated human osteoblasts: a signalling mechanism that is not related to enhanced prostaglandin formation

Dose-Response Relationship between Reach Repetition and Indicators of Inflammation and Movement Dysfunction in a Rat Model of Work-Related Musculoskeletal Disorder

The purpose of this study was to compare the effects of a high or low repetition reaching and grasping task on serum levels of interleukin-1α (IL-1α) and IL-1β and on reach performance in a rat model of work-related musculoskeletal disorder (MSD). Forty-seven rats reached repetitively for 2 hours/day, 3 days/week for 6–8 weeks at a high or low rate. Reach rate and abnormal movement patterns were recorded. Serum was collected at 6 and 8 weeks for ELISA assay of IL-1α and IL-1β. High repetition animals experienced a 2-fold decline in reach rate, strong emergence of a raking movement, and increased IL-1α. IL-1α decreased in the low repetition group. IL-1β decreased in both groups. This model provides evidence that inflammation increases with repetition. At the higher reach rate, persistent IL-1α serum levels indicate chronic inflammation that is attenuated at the lower reach rate. These findings support the use of risk reduction in MSD prevention.

Direct action of nitric oxide on osteoblastic differentiation

The effect of nitric oxide (NO) on osteoblastic differentiation was examined in cultured mouse osteoblasts. Interleukin-1beta and tumor necrosis factor-alpha expressed inducible NO synthase gene with little effect on constitutive NO synthase gene. These cytokines increased NO production, which was inhibited by L-NMMA pretreatment, and decreased alkaline phosphatase (AIPase) activity, which was not restored by L-NMMA. Furthermore, NO donors, sodium nitroprusside and NONOate dose-dependently elevated AIPase activity and expression of osteocalcin gene. These results suggest that NO directly facilitates osteoblastic differentiation and the cytokine-induced inhibition of AIPase activity is mediated via mechanism other than NO.