Abstract
Abstract Background Skeletal muscle injuries are frequently encountered in athletes and military personnel. Incomplete functional recovery of these injuries usually occurs due to fibrosis of the skeletal muscle. Recently, oral administration of losartan antihypertensive drug was claimed to have a role in improving skeletal muscle healing, but still to be furtherly investigated. Aim of the work This work aimed to assess the healing effect of losartan on the histological structure of induced lacerated skeletal muscle fibers of adult male albino rats. Material and Methods Forty male albino rats were used in this study. They were divided into three groups: Group I: served as a control group and included 15 adult rats. Group II (muscle laceration group): consisted of 15 rats that were subjected to muscle laceration injury. They were subdivided into subgroup IIa: consisted of five rats that were sacrificed one day after injury, subgroup IIb: it included 10 rats that were left for spontaneous recovery for two weeks after injury. Group III (losartan-treated group): it consisted of 10 rats that were subjected to muscle laceration injury then they received oral losartan from day three till end of experiment. All rats, except rats of subgroup IIa, were sacrificed two weeks after injury. Right gastrocnemius muscle specimens were taken and processed for light microscopic examination by H & E and Masson's trichome stains as well as morphometric and statistical analysis. Results In group II, there was almost complete affection of myofibers at site of injury after 1 day of induced laceration in the form of myofibers fragmentation, disorganization and distortion with apparent mononuclear cellular infiltration mainly neutrophils and macrophages. After 2 weeks some myofibers were seen distorted and ended abruptly into connective tissue, others were branched with unclear striations. Mononuclear cellular infiltration between myofibers and apparent dilated blood vessels at laceration site were also noticed. A significant increase in collagen fibers deposition between regenerating muscle fibers (p<0.05) was also demonstrated. Treatment of the muscle laceration by losartan in group III showed apparent partial improvement in the form of significant decrease in collagen fibers deposition (p<0.05) and apparent decrease in mononuclear cellular infiltration as compared to that of group II. Also, some of the regenerated myotubes were noticed with chains of central nuclei. Conclusion Excess collagen fibers deposition between myofibers hinders regular arrangement of generating myotubes. Losartan might enhance muscle regeneration through decreasing collagen fibers deposition. However, it needs longer duration to assure complete muscle healing.
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