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Cardiac muscle lesions associated with chronic administration of methamphetamine in rats
1Department of Forensic Medicine, Saga Medical School, Japan.
Abstract:
Cardiovascular complications associated with methamphetamine abuse have increasingly been reported. However, chronic cardiotoxicity of methamphetamine is not experimentally well documented. In this study, methamphetamine (1 mg/kg/day) was subcutaneously injected into 5-week-old male Wistar Kyoto rats (n = 30). Age- and sex-matched Wistar Kyoto rats served as controls (n = 30). After 14 and 56 days, hearts were examined by light and electron microscopy. Foci of myocytic degeneration and necrosis appeared in the sub-endocardial areas on day 14 of methamphetamine exposure. Myocytic degeneration and necrosis became more extensive on day 56. At this stage, myocytolysis, contraction bands, atrophied myocytes, and spotty fibrosis were patchily distributed throughout the myocardium in most of rats treated with methamphetamine. The accompanying ultrastructural features included marked degeneration of cardiac mitochondria with fractured and disrupted cristae, hypercontraction of myofibrils, and loss of myofilament. In contrast, cardiac myocyte lesions were not observed in control rats. These myocardial lesions in rats treated with methamphetamine for 56 days resemble the cardiomyopathy associated with methamphetamine abuse in humans.
Insights
Chronic methamphetamine exposure causes significant heart damage in rats, leading to myocyte degeneration and fibrosis. These findings highlight the cardiotoxic effects of methamphetamine, mirroring human methamphetamine-induced cardiomyopathy.
Area of Science:
- Cardiology
- Toxicology
- Experimental Pathology
Background:
- Cardiovascular complications are frequently reported in individuals abusing methamphetamine.
- The chronic cardiotoxicity of methamphetamine lacks comprehensive experimental documentation.
Purpose of the Study:
- To experimentally investigate the chronic cardiotoxic effects of methamphetamine on the myocardium.
- To document the histological and ultrastructural changes in the heart following prolonged methamphetamine administration in a rat model.
Main Methods:
- Male Wistar Kyoto rats were subcutaneously injected with methamphetamine (1 mg/kg/day) or a placebo for 14 and 56 days.
- Cardiac tissues were analyzed using light and electron microscopy to assess myocardial damage.
Main Results:
- Methamphetamine exposure led to progressive myocytic degeneration and necrosis, particularly in sub-endocardial regions.
- After 56 days, significant lesions including myocytolysis, contraction bands, myocyte atrophy, and fibrosis were observed.
- Ultrastructural analysis revealed mitochondrial damage, myofibril hypercontraction, and myofilament loss in methamphetamine-treated rats.
Conclusions:
- Chronic methamphetamine administration induces significant myocardial lesions in rats.
- The observed cardiac pathology closely resembles human methamphetamine-associated cardiomyopathy, confirming its cardiotoxic potential.