Abstract
This study investigated the repercussions of adjuvant-induced arthritis (AIA) on body composition and the structural organization of the soleus and cardiac muscles, including their vascularization, at different times of disease manifestation. Male rats were submitted to AIA induction by intradermal administration of 100 μL of Mycobacterium tuberculosis (50 mg/mL), in the right hind paw. Animals submitted to AIA were studied 4 (AIA4), 15 (AIA15), and 40 (AIA40) days after AIA induction as well as a control group of animals not submitted to AIA. Unlike the control animals, AIA animals did not gain body mass throughout the evolution of the disease. AIA reduced food consumption, but only on the 40th day after induction. In the soleus muscle, AIA reduced the wet mass in a time-dependent manner but increased the capillary density by the 15th day and the fiber density by both 15 and 40 days after induction. The diameter of the soleus fiber decreased from the 4th day after AIA induction as well as the capillary/fiber ratio, which was most evident on the 40th day. Moreover, AIA induced slight histopathological changes in the cardiac muscle that were more evident on the 15th day after induction. In conclusion, AIA-induced changes in body composition as well as in the soleus muscle fibers and vasculature have early onset but are more evident by the 15th day after induction. Moreover, the heart may be a target organ of AIA, although less sensitive than skeletal muscles.
Highlights
Rheumatoid arthritis (RA) is an autoimmune disease affecting about 1% of the world population [1]
In the right hind paw, this diameter increase was statistically significant in relation to the control group from the 4th day, reaching fullness at 15 days after adjuvant-induced arthritis (AIA) induction (Figure 1A)
Body composition Unlike the CTRL animals, the AIA animals showed no gain of body mass throughout the evolution of the disease (Figure 2A)
Summary
Rheumatoid arthritis (RA) is an autoimmune disease affecting about 1% of the world population [1]. Changes in the total body mass, as well as in the masses of both skeletal and adipose tissue, are described in RA patients. These changes may lead to rheumatoid cachexia, characterized by loss of muscle mass, with or without fat mass change [8,9]. Rheumatoid cachexia is a well-studied clinical manifestation in RA patients due to its impact on the health of these patients, many questions remain It is not yet fully established whether the reduction of muscle mass in these patients is consequent to a decrease in the number of muscle fibers or to the loss of proteins that constitute these fibers. Details are not known about the vascular changes that can occur in the muscles affected by arthritis
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Schedule a callMore From: Brazilian journal of medical and biological research = Revista brasileira de pesquisas medicas e biologicas
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