Statins are important class of cholesterol lowering drugs that provide cardio-protective effect. They act by inhibiting 3-hydroxy-3-methyl glutaryl coenzyme A reductase (HMG Co reductase), the rate limiting enzyme involved in cholesterol biosynthesis pathway. A lot of researches are in progress to reveal the other effects of statins including anti-inflammatory activity and antioxidant activity properties. However, statin-induced myopathy, which is considered a side effect of statins' use, limits their utilize. Statins induced myopathy may result from reduced muscular coenzyme Q10 levels.
This study was carried to evaluate the effects of ingestion of two different doses of atorvastatin for six weeks on the masseter muscle of rats. Eighteen males Sprague Dawley albino rats weighted 200-250 grams at the age of 6-8 weeks were used in this study. They were divided into 3 groups, group I (control group), group II (20 mg/kg b.w atorvastatin received rats) and group III (40 mg/kg atorvastatin received rats). Masseter muscle specimens were fixed in formal saline solution, dehydrated using ascending grades of alcohol, cleared using xylene then infiltrated with paraffin and finally embedded in it. Histological results revealed fragmented and disorganized muscle fibers, centrally located nuclei and clear external rims around some fibers. Immunohistochemical results using Bax showed increased in the cytoplasmic immunopositivity in the muscle fibers of both experimental groups. These results suggested that atorvastatin exhibits significant myotoxicity on rats' masseter muscle. Atorvastatin side effects were found to be dose dependent.