| Resumo: |
Metformin, an oral biguanide approved for the treatment of type II diabetes is widely prescribed for other clinical conditions. Currently, metformin is being investigated as potential anti-tumor agent. However, there have been recent concerns about hepatotoxicity associated with the use of metformin. This study, by means of high resolution transmission electron microscopy (TEM) and morphometry, investigated potential ultrastructural changes induced by metformin treatment on the hepatocytes of spontaneously hypertensive rats (SHR). Morphometric analysis was carried out on images of randomly selected cells from sectioned gluteraldehyde-osmium-fixed, Epon embedded liver tissue. One-way analysis of variance (ANOVA) on morphometric data showed statistically significant differences in the mean volume density (MVD) of lipid bodies (F=136.48, P<0.0001)and mean surface density (MSD) of endoplasmic reticulum (ER) (F=12.45, P<0.003) between hepatocytes of control (n=8) and metformin-treated (MT) (n=8) animals. MVD for control group was 5.42% (±0.36 SEM) but decreased significantly in the MT group (1.13%, ±0.04 SEM). Similarly, MSD of ER for control was 24.7 µm2/µm3 (±1.64 SEM) but decreased for MT animals (18.90 µm2/µm3, ±0.28 SEM). These data are most likely consistent with the effects of metformin on lipid metabolism, and may not reflect on hepatotoxicity induced by the drug, in SHRs.
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