Resistance Training Modulates the Matrix Metalloproteinase-2 Activity in Different Trabecular Bones in Aged Rats

Abstract

Background

Aging decreases osteogenic ability, inducing harmful effects on the bone extracellular matrix (ECM), while exercise training has been indicated as a tool to counteract bone disorders related to advancing age. The modulation of bone ECM is regulated by several types of matrix metalloproteinase (MMP); however, MMP-2 activity in different trabecular bones in response to resistance training (RT) has been neglected. Remodeling differs in different bones under the application of the same mechanical loading. Thus, we investigated the effects of 12 weeks of RT on MMP-2 activity in the lumbar vertebra (L6), tibia, and femur of young (3 months) and older rats (21 months).

Methods

Twenty Wistar rats were divided into four groups (five animals per group): young sedentary or trained and older sedentary or trained. The 12-week RT consisted of climbing a 1.1-m vertical ladder three times per week with progressive weights secured to the animals’ tails. The animals were killed 48 h after the end of the experimental period. The MMP-2 activity was assessed by the zymography method.

Results

The aging process induced lower MMP-2 activity in the lumbar vertebrae and tibia (p=0.01). RT upregulated pro, intermediate, and active MMP-2 activity in the tibia of young rats (p=0.001). RT also upregulated pro and active MMP-2 activity in the lumbar vertebrae and tibia with advancing age (p=0.01). There was no significant difference (p>0.05) between groups for MMP-2 of the femur, regardless of age and RT.

Conclusion

The aging process impairs MMP-2 activity, but RT is a potential therapeutic approach to minimize the deleterious effects of ECM degeneration in different aged bones. Distinct MMP-2 responses to exercise training may result in specific remodeling processes.

Keywords:

• senescent
• skeletal system
• remodeling
• matrix metalloproteinase
• exercise

Acknowledgments

The authors are grateful for the financial support provided by Fundação de Apoio a Pesquisa do Distrito Federal (FAPDF) (grant numbers 193.001.452/2016; 193.000.653/ 2015, 00193.00000641/2018-45 and 00193.0000168/2019-87) and FAPESP (2013/00798-2 and 2011/11229-3), the Decanato de Pesquisa e Inovação e de Pós-Graduação (grant number DPI/DPG N.º 02/2020), the Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES Finance Code 001) and Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq) (grant numbers 445069/2014-7 and 312136/2018-8) from Brazil. We also thank Robin Hambly for reviewing the English.

Data Sharing Statement

The de-identified data sets generated during the study are available from the corresponding author.

Ethics Approval

The present study was approved by the Animal Research Ethics Committee of the Federal University of Sao Carlos, SP, Brazil (protocol number: 044/2011). The research has been carried out in accordance with the Guide for the Care and Use of Laboratory Animals (US National Research Council, Washington DC, USA).

Author Contributions

All authors made a significant contribution to the work reported, whether that is in the conception, study design, execution, acquisition of data, analysis and interpretation, or in all these areas; took part in drafting, revising or critically reviewing the article; gave final approval of the version to be published; have agreed on the journal to which the article has been submitted; and agree to be accountable for all aspects of the work.

Disclosure

The authors declare that they have no competing interests.