Histological study of sodium fluoride effect on cardiac muscle of male adult albino rat

ABSTRACT

Fluoride exists in varying concentrations in the environment either naturally or as a consequence of human activities such as agricultural and industrial processes. Humans are in great risk of exposure to fluoride through different ways either in water, foods or in drugs. Fluoride is toxic by all routes especially when consumed in excessive amounts. Several clinical studies recorded that intake of fluoride at high concentration for prolonged periods was associated with cardiovascular failure and impairment in myocardial function. Accordingly, this work was performed to evaluate the effect of sodium fluoride on the cardiac muscle of male adult albino rats and to study the possibility of recovery or regression of this effect after its withdrawal. For this purpose, 30 adult male albino rats were used and divided into two main groups; the control group [10 rats] and the experimental group [20 rats] that were divided into four subgroups [A, B, C and D] five rats each. The first three subgroups received sodium fluoride in a dose of 5, 20 and 50mg /kg b.wt. respectively orally once daily for three months. The subgroup D [recovery group] received sodium fluoride in a dose of 50 mg/kg b.wt. for three months and then left without treatment for another two months. Light microscopic examination of sodium fluoride treated subgroups [A, B and C] revealed loss of the normal architecture with wide separation and fibrillolysis of the cardiac muscle fibers. All these changes were associated with cytoplasmic vacuolation and nuclear pyknosis in association with vascular congestion and cellular infiltration. Transmission electron microscopic examination confirmed the previous findings in association with myofibrillar degeneration, shortening of the sarcomeres, disruption of the sarcolemma, mitochondrial changes and deposition of collagen fibrils. The recovery group [subgroup D] displayed regression of dilation and congestion of myocardial blood vessels together with resolving of cellular infiltration. However, the cardiac muscle fibers showed no evidence of regression of most of the histological alterations. Could be concluded according to this research that, sodium fluoride has a dose dependant cardiotoxic effect which was shown to be irreversible two months after withdrawal of the highest dose