Small-for-pregnancy-age rats submitted to exercise: DNA damage in mothers and newborns, measured by the comet assay.

BACKGROUND: Fetal impairment caused by a deleterious intrauterine environment may have long-term consequences, such as oxidative stress and genetic damage. Rats born as small-for-gestational-age (SPA) were submitted to exercise (swimming) before and during pregnancy. The animals exhibited glucose intolerance, reduced general adiposity, and increased maternal and offspring organ weight, showing the benefit of exercise for these rats. We hypothesised that regular exercise in SPA during gestation could prevent DNA damage in these animals and in their offspring, contributing to altered fetal programming of metabolism in the offspring. Severe diabetes was induced by streptozotocin treatment, to obtain SPA newborns. At adulthood, pregnant SPA rats were randomly distributed into two groups: exercised (SPAex - submitted to swimming program) or not-exercised (SPA - sedentary rats). Post-partum, blood was collected for analysis of DNA damage (comet assay) and oxidative stress. SPAex rats presented lower DNA damage levels, decreased lipid peroxidation, and a lower rate of newborns classified as large-for-pregnancy-age. DNA damage was also lower in SPAex newborns. We conclude that swimming applied to SPA pregnant rats contributes to decreased DNA damage and lipid peroxidation in the dams, and decreased DNA damage and macrosomia in their offspring.

Intrauterine Growth Restricted Rats Exercised at Pregnancy: Maternal-Fetal Repercussions.

To evaluate the effect of swimming in pregnant rats born with intrauterine growth restriction (IUGR) and their offspring, IUGR rats were obtained using the streptozotocin-induced severe diabetic (SD) rats. In this study, the nondiabetic parental generation presented 10 rats and diabetic parental generation presented 116 rats. Of these, the mated nondiabetic female rats were 10 and the number of diabetic rats was 45. In relation to term pregnancy, there were 10 animals in the nondiabetic group and 15 rats in the diabetic group. In the offspring of SD rats (IUGR group), 43 females were classified as small for pregnancy age, 19 rats were classified as appropriate for pregnancy age, and 0 female was classified as large for pregnancy age. The nondiabetic and SD pregnant rats generated offspring with appropriate (control [C]) and small (IUGR) weight for pregnancy age, respectively. At adult life, the C group was maintained as nonexercised C group and IUGR rats were distributed into 2 subgroups, namely, nonexercised (IUGR) and exercised (IUGRex). The rate of mated rats in the IUGR group was reduced compared to the C group. During pregnancy, the IUGR rats presented hyperinsulinemia, impaired reproductive outcomes, decreased body weight, hypertriglyceridemia, and hyperlactacidemia. The IUGRex presented reduced insulin and triglyceride levels. Thus, swimming improved lipid metabolism and increased insulin sensitivity. However, the offspring showed retarded growth, reinforcing the need to stimulate the exercise practice in women under supervision with different professional expertise to promote appropriate gestational conditions and improve perinatal outcomes.

Streptozotocin-induced diabetes models: pathophysiological mechanisms and fetal outcomes.

Glucose homeostasis is controlled by endocrine pancreatic cells, and any pancreatic disturbance can result in diabetes. Because 8% to 12% of diabetic pregnant women present with malformed fetuses, there is great interest in understanding the etiology, pathophysiological mechanisms, and treatment of gestational diabetes. Hyperglycemia enhances the production of reactive oxygen species, leading to oxidative stress, which is involved in diabetic teratogenesis. It has also been suggested that maternal diabetes alters embryonic gene expression, which might cause malformations. Due to ethical issues involving human studies that sometimes have invasive aspects and the multiplicity of uncontrolled variables that can alter the uterine environment during clinical studies, it is necessary to use animal models to better understand diabetic pathophysiology. This review aimed to gather information about pathophysiological mechanisms and fetal outcomes in streptozotocin-induced diabetic rats. To understand the pathophysiological mechanisms and factors involved in diabetes, the use of pancreatic regeneration studies is increasing in an attempt to understand the behavior of pancreatic beta cells. In addition, these studies suggest a new preventive concept as a treatment basis for diabetes, introducing therapeutic efforts to minimize or prevent diabetes-induced oxidative stress, DNA damage, and teratogenesis.

Mild diabetes models and their maternal-fetal repercussions.

The presence of diabetes in pregnancy leads to hormonal and metabolic changes making inappropriate intrauterine environment, favoring the onset of maternal and fetal complications. Human studies that explore mechanisms responsible for changes caused by diabetes are limited not only for ethical reasons but also by the many uncontrollable variables. Thus, there is a need to develop appropriate experimental models. The diabetes induced in laboratory animals can be performed by different methods depending on dose, route of administration, and the strain and age of animal used. Many of these studies are carried out in neonatal period or during pregnancy, but the results presented are controversial. So this paper, addresses the review about the different models of mild diabetes induction using streptozotocin in pregnant rats and their repercussions on the maternal and fetal organisms to propose an adequate model for each approached issue.