Morfologia dos cardiomiócitos e quantificação do colágeno no miocárdio de ratas tratadas com isoflavonas ou estrogênios / Cardiomyocytes morphology and collagen quantification in the myocardium of female rats treated with isoflavones or estrogens

RESUMO

OBJETIVOS: Avaliar a morfologia dos cardiomiócitos e quantificar o colágeno presente no miocárdio de ratas tratadas com extrato concentrado de soja ou 17β-estradiol (E2). MÉTODOS: Vinte e oito ratas foram divididas em quatro grupos GCtrl - fase de estro; GOvx - ovariectomizadas (Ovx); GIso - Ovx tratadas com extrato de soja (150 mg/kg, por dia); GE2 - Ovx tratadas com E2 (10 µg/kg, por dia). As drogas e o veículo (0,2 mL de propilenoglicol) foram administrados após 30 dias da realização da ovariectomia, por 30 dias consecutivos. No último dia os animais foram anestesiados, o coração retirado, mergulhado em formaldeído a 10%, e fragmentos dos ventrículos submetidos a processamento histológico, sendo os cortes corados pela hematoxilina e eosina ou pelo picrosirius-red. As análises histomorfométricas (contagem, volume nuclear e quantificação do colágeno) foram realizadas em microscópio de luz e software AxioVision Rel. 4.2, sendo o colágeno determinado pelo programa Imagelab 2000. Os dados foram submetidos ao teste de ANOVA complementado pelo teste de Tukey (p<0,05). RESULTADOS: Notamos maior quantidade de núcleos de cardiomiócitos nos animais dos grupos Ovx e Iso do que no GE2 e GCtrl (GOvx=121,7±20,2=GIso=92,8±15,4>GE2=70,5±14,8=GCtrl=66,3±9,6; p<0,05), sendo o volume nuclear maior nos animais do grupo Ctrl e E2 (GE2=35,7±4,8=GCtrl=29,9±3,6>GIso=26,5±4,5=GOvx=22,4±2,9; p<0,05). Com relação ao colágeno notamos maior concentração no grupo Ovx (GOvx=5,4±0,1>GCtrl=4,0±0,1=GIso=4,4±0,08=GE2=4,3±0,5; p<0,05). CONCLUSÕES: Os estrogênios previnem a diminuição do volume nuclear dos cardiomiócitos e a deposição de colágeno entre as fibras musculares cardíacas. Já a administração de isoflavonas previne somente a deposição de colágeno, o que pode preservar as propriedades mecânicas das fibras cardíacas.

ABSTRACT

PURPOSES: To evaluate the histomorphometry of cardiomyocytes and collagen present in the myocardium of rats treated with a concentrated extract of soy or 17β-estradiol (E2). METHODS: Twenty-eight rats were divided into four groups GCtrl - estrus phase; GOvx - ovariectomized (Ovx) and receiving vehicle; GIso - Ovx and treated with soy extract (150 mg/kg per day); GE2 - Ovx and treated with E2 (10 µg/kg per day). The drugs and vehicle (0.2 mL propylene glycol) were administered for 30 consecutive days after ovariectomy. On the last day the animals were anesthetized, the hearts removed, submerged in 10% formaldehyde and fragments of the ventricles underwent histological procedures, and the sections were stained with hematoxylin and eosin or picrosirius-red. Histomorphometric analysis (number and volume of nuclei and quantification of collagen) was performed under a light microscope with AxioVision Rel. 4.2 software, and collagen fibers were quantified using IMAGELAB-2000 software. Data were submitted to ANOVA followed by the Tukey test (p<0.05). RESULTS: We observed a higher number of cardiomyocyte nuclei in animals of the Ovx and Iso groups than in GE2 and GCtrl animals (GOvx=121.7±20.2=GIso=92.8±15.4>GE2=70.5±14,8=GCtrl=66.3±9.6; p <0.05), while the nuclear volume was greater in the Ctrl and E2 groups (GE2=35.7±4.8 GCtrl=29.9±3.6=>GIso=26.5±4.5=GOvx=22.4±2.9; p <0.05). Collagen concentration was higher in the Ovx group (GOvx=5.4±0.1>GCtrl=4.0±0.1=GIso=4.4±0.08=GE2=4.3±0.5; p <0.05). CONCLUSIONS: Estrogen may prevent the reduction of the nuclear volume of cardiomyocytes and collagen deposition between heart muscle fibers, while the administration of isoflavones only prevents the deposition of collagen, which can preserve the mechanical properties of cardiac fibers.