High +Gz Loadings Stimulate Mechanical Behavior and Microstructure of Bone Tissue in Rats

Abstract

The bone tissue is susceptible to the high positive acceleration (+Gz) environment. How much +Gz value is beneficial to the growth of bone tissue, and how much +Gz value has a negative impact on bone tissue? These critical values need to be discussed and studied in detail. The objective of this study is to characterize the effect of different high +Gz values (+1Gz, +4Gz, +8Gz, +10Gz, +12Gz and +20Gz) on the mechanical properties, microstructure, and cellular metabolism of bone tissue in rats. When the high positive acceleration is between +1Gz and +8Gz, the mechanical properties of bone are not inhibited, and the bone microstructure is improved at +4Gz. When the high positive acceleration exceeds +8Gz, the ultimate load and deflection of tibia decrease, the degree of separation of trabeculae is significantly increased, and OPG mRNA expression is promoted while RANKL mRNA expression is inhibited.Our results show that the +8Gz acceleration may be the threshold of high +Gz mechanical regulation for bone tissue. Positive acceleration over +8Gz can cause serious negative effect on bone tissue, but moderate mechanical stimulation can help bone tissue growth. This study provides a theoretical basis for the optimization of anti-Gz training and the treatment of bone tissue damage caused by high +Gz environment.

Note:
Funding Information: The project was supported by the National Natural Science Foundation of China (Nos.11972198, 12072235 and 12002388) and Open Fund of Tianjin Enterprise Key Laboratory on Hyaluronic Acid Application Research (No. KTRDHA-Y201905)

Declaration of Interests: There are no conflicts of interest for either author.

Ethics Approval Statement: Approval for the animal experiments conducted in this study was obtained from the Institutional Animal Care and Use Committee at Academy of Military Medical Science. All experimental protocols were made to minimize suffering of animals.

Keywords: High +Gz, Tibia, Mechanical property, Microstructure, Cellular metabolism