Biological effects of melatonin on osteoblast/osteoclast cocultures, bone, and quality of life: Implications of a role for MT2 melatonin receptors, MEK1/2, and MEK5 in melatonin-mediated osteoblastogenesis.

The Melatonin Osteoporosis Prevention Study (MOPS) demonstrated that nightly melatonin resulted in a time-dependent decrease in equilibrium ratios of serum osteoclasts and osteoblasts in perimenopausal women. This study examines mechanisms related to the ratios of osteoblasts and osteoclasts using coculture models (transwell or layered) of human mesenchymal stem cell (MSC) and human peripheral blood monocytes (PBMCs). Human MSC/PBMC cocultures exposed to melatonin in osteogenic (OS+) medium for 21 days induced osteoblast differentiation and mineralization; however, only in layered cocultures did melatonin inhibit osteoclastogenesis. Melatonin effects were mediated through MT2 melatonin receptors, MEK1/2, and MEK5. In layered but not transwell cocultures, melatonin increased OPG:RANKL ratios by inhibiting RANKL, suggesting that contact with osteoclasts during osteoblastogenesis inhibits RANKL secretion. Melatonin modulated expression of ERK1/2, ERK5, ß1 integrin, GLUT4, and IRß that was dependent upon the type of coculture; however, in both cultures, melatonin increased RUNX2 and decreased PPARγ expression, indicating a role for metabolic processes that control osteogenic vs adipogenic cell fates of MSCs. Furthermore, melatonin also has osteoblast-inducing effects on human adipose-derived MSCs. In vivo, one-year nightly melatonin (15 mg/L) given to neu female mice in their drinking water increased pErk1/2, pErk5, Runx2, and Opg and Rankl levels in bone consistent with melatonin's already reported bone-enhancing effects. Finally, analysis of daily logs from the MOPS demonstrated a significant improvement in mood and perhaps sleep quality in women receiving melatonin vs placebo. The osteoblast-inducing, bone-enhancing effects of melatonin and improvement in quality of life suggest that melatonin is a safe and effective bone loss therapy.

Utilization of 3-month yoga program for adults at high risk for type 2 diabetes: a pilot study.

Various modes of physical activity, combined with dieting, have been widely recommended to prevent or delay type 2 diabetes. Among these, yoga holds promise for reducing risk factors for type 2 diabetes by promoting weight loss, improving glucose levels and reducing blood pressure and lipid levels. This pilot study aimed to assess the feasibility of implementing a 12-week yoga program among adults at high risk for type 2 diabetes. Twenty-three adults (19 Whites and 4 non-Whites) were randomly assigned to the yoga intervention group or the educational group. The yoga group participated in a 3-month yoga intervention with sessions twice per week and the educational group received general health educational materials every 2 weeks. All participants completed questionnaires and had blood tests at baseline and at the end of 3 months. Effect sizes were reported to summarize the efficacy of the intervention. All participants assigned to the yoga intervention completed the yoga program without complication and expressed high satisfaction with the program (99.2%). Their yoga session attendance ranged from 58.3 to 100%. Compared with the education group, the yoga group experienced improvements in weight, blood pressure, insulin, triglycerides and exercise self-efficacy indicated by small to large effect sizes. This preliminary study indicates that a yoga program would be a possible risk reduction option for adults at high risk for type 2 diabetes. In addition, yoga holds promise as an approach to reducing cardiometabolic risk factors and increasing exercise self-efficacy for this group.