Alterações anatomopatológicas em corações de camundongos submetidos à inalação crônica de cocaína crack / Anatomopathological alterations in hearts of mice submitted to chronic inhalation of crack cocaine

AUTOR(ES)
DATA DE PUBLICAÇÃO

2009

RESUMO

Crack cocaine is the currently popular form of cocaine, due to its low cost and rapid effects on the central nervous system. Alterations caused by cocaine on the hearts of humans and animals are well known and severe disorders in the cardiovascular system, which are sometimes fatal, are frequent. Considering the growing concern regarding the increase in the use of this smoked form of cocaine, especially by young individuals, it becomes necessary to carry out experimental studies using the drug in its natural form, which is not usually available for experiments due to legal difficulties. The present study aimed at assessing the effects of the chronic inhalation of crack cocaine on the hearts of mice. A total of 24 BALB/c male animals were used in the experiment, both young and old, with 6 animals in each group (n=6), which were exposed to crack cocaine smoke that resulted from the burning of 5 g of cocaine, for 5 minutes, 5 days a week, for 39 days, except on weekends and holidays, during a two-month period. An inhalation chamber was used to keep the animals during the sessions, whereas the same number of animals from the control group (n=6) were kept at the animal facility of the institution under favorable conditions. The drug had been originally apprehended by the police in the course of criminal investigations and its use in research was previously authorized by the Department of Justice. The pharmacological analysis of the drug verified the presence of 57.66% of cocaine in the crack rocks, which satisfied the criterion used for the experience. The quantification of cocaine at 212.5 ng/mL in the blood of the animals was also considered representative for our objectives of assessing morphological alterations in the hearts of mice. The results were analyzed by One-Way-ANOVA and Generalized Linear Model, and the differences were considered significant when p<0.05. The studies showed a significant difference in the mean (±SD) weight of the hearts of the animals exposed to the crack cocaine smoke, both young and adult ones, when compared to the corresponding control groups. In the young group, the increased number of nuclei per ventricular area might be related to the myocardial atrophy of the right and left ventricles (p<0.001), demonstrated by the morphometry of the striated heart muscle fibers, using the system of point reticulum. In the exposed adult animals, in spite of the decreased heart weight, the morphometry did not show myocardial atrophy in neither side (p>0.05). The microscopic assessment of the ventricular walls, carried out with hematoxylin and eosin (H&E) staining, showed a small number of heart muscle fibers with loss of striations and hyalinization of the cytoplasm, which favored apoptosis. The morphometry of the intramural coronary vessels, with lumen, medial and adventitial layer measurement, showed a significant decrease in the lumen/wall ratio in exposed animals, regardless of age, when compared to the control group (p=0.001). These data characterize vasoconstriction, due to the probable sympatheticomimetic action of the drug, which justifies a relative ischemia of the heart and a consequent increase in apoptosis, well documented by immunohistochemistry through TUNEL staining. This immunostaining extensively identified the nuclei of apoptotic cells in the right and left ventricles of the exposed animals, when compared to the non-exposed animals (p<0.001). Optical microcopy with H&E and Picrosirius suggested periadventitial fibrosis in the adult exposed animals. Collagen quantification after polarization showed a non-significant increase in the coronary branches of the adult exposed animals and in the right ventricular interstitium in the two exposed groups (p>0.05). The present study, carried out using a novel experimental model, confirmed the presence of anatomopathological alterations that had been previously described in the literature, such as vasoconstriction with acute ischemia and increased apoptosis and showed alterations that had not been previously reported as being chronic effects of cocaine, such as decreased heart weight and myocardial atrophy. Although there were limitations, considering that other substances eventually present in the test sample were not identified, the present study demonstrated important morphological findings for public health, which must be studied in autopsies. Further studies are recommended, using other exposure durations and environments, with and without the association of drugs, as well as different percentages of cocaine in crack rocks and isolating the substances present in the drug in its natural form.

ASSUNTO(S)

apoptose apoptosis cocaína crack/toxicidade atrofia coronary vasospasm coração/anatomia &histologia heart/anatomy &histology mice camundongos vasoespasmo coronário crack cocaine/toxicity atrophy

ACESSO AO ARTIGO

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