Effects of hypervitaminosis A on rat fetus esophagus smooth muscle cells

RESUMO

Excessive ingestion of vitamin A during pregnancy causes teratogenic effects on the offspring. Houever, many of these modifications have not been described at the cellular level. the objective of the present study was to characterize alterations of the smooth muscle cells of the esophagus of rat fetuses. On thetenth day after conception, 42 pregnant rats (5 months of age) subdivided into 6 groups received a single intraperitoneal injection of vitamin A at doses of 30,000, 40,000, 50,000, 70,000, 100,000 or 150,000 IU. Seven pregnant control rats received saline solution. After the twentieth day of pregnancy, the fetuses were delivered by cesarian section and weighed and the length of their umbilical cords was measured. Histologic sections were obtained from the esophagus and characterized with the light microscope under oil immersion. There was a significant increase in the nuclear volume of the cells of esophageal smooth muscle from treated animals compared to the control group. The median for the group treated with 100,000 IU of vitamin A(23.8 µm3) was significantly greater than that for the control group (12.3 µm3). The body weight (reported as mean ñ SEM) of fetuses treated with the various doses of vitamin A was lower (1.78 ñ 0.18, 1.77 ñ 0.08, 1.48 ñ 0.20, 1.72 ñ 0.11, 1.70 ñ 0.09 and 1.54 ñ 0.13 g, respectively) than that of the control group (2.14 ñ 0.13g). The mean lenght of the umbilical cord of fetuses treated with 30,000 (1.66 ñ 0.15 cm), 40,000 (1.78 ñ 0.18 cm), 50,000 (1.58 ñ 0.15 cm), 70,000 (1.90 ñ 0.19 cm), 100,000 (1.58 ñ 0.24 cm) and 150,000 IU (1.48 ñ 0.11 cm) vitamin A was significantly shorter when compared with the mean lenght of the umbilical cords of control fetuses (c.1 ñ 0.46 cm). Malformations in treated animals such as agnathia, palpebral aplasia, hepatomegaly, exophthalmos, fochomelia and spina bifida were observed macroscopically