ABSTRACT
Objective To observe the influence of circadian rhythm disruptions on exercise capability in rats. Methods A total of 30 spontaneously hypertensive rats (SHR) and age and weight matched homologous normal blood pressure WKY rats were randomly divided into normal circadian rhythm group (control group), twelve hours cir-cadian rhythm disruption group (observation group 1), six hours circadian rhythm disruption group (observation group 2). Each group included ten SHR rats and WKY rats, changing the light/dark time to construct circadian rhythm disruption model. Exercise endurance, blood pressure and heart rate after exhaustion were measured be-fore and one, two and three months after modeling. Results The interaction of time and circadian rhythm was significant on the exhaustion time of SHR rats (F=2.409, P=0.047). After three months of modeling, the exhaustion time of the control group was more than that of the obser-vation groups 1 and 2 (F=4.290, P=0.032). The interaction of time and circadian rhythm was not significant on the exhaustion time of WKY rats (F=0.717, P=0.638), there was no significant difference in the exhaustion time among groups (P>0.05). For SHR rats, after three months of modeling, the systolic pressure, diastolic pressure and mean arterial pressure after exhaustion of the observation group 1 were higher than those of the control group and the observation group 2 (P<0.05), the heart rate of the observation groups 1 and 2 was higher than that of the control group (P<0.05). But there was no significant difference in the systolic pressure, diastolic pressure, average arterial pressure and heart rate of WKY rats among groups (P>0.05). Conclusion Circadian rhythm disruptions can reduce the exercise endurance of SHR rats, which may be related to the cardiovascular function impairment.
ABSTRACT
Osteoclasts are multinucleated giant cell, which derived from mononuclear myeloid hematopoietic stem cells with the function of bone absorption. Osteoclasts plays a key role in bone metabolism, therefore the body is very strict to regulation of osteoclastogenesis. Mobilization and differentiation of osteoclast maturation is a complex and sophisticated multi-level regulatory processes. In the relevant regulatory mechanisms, OPG/RANKL/RANK system plays a pivotal role in the process of osteoclast differentiation and maturation. Recent studies revealed that immune cells and osteoclasts were closely connect with each other in the field of bone metabolism, also provide a new therapeutic target for the treatment of bone diseases. The apoptosis of osteoclasts in bone metabolism have been payed more attention,while its mechanism is still not clear, which need further research.