Stavudine effects on rat pregnancy outcome

Stavudine exposure results in developmental abnormalities by causing DNA damage, inhibiting cell proliferation and inducing apoptosis in mouse embryos

Stavudine is an anti-AIDS drug widely used to prevent HIV transmission from pregnant mothers to the fetuses in underdeveloped countries for its low price. However, there is still a controversy on whether stavudine affects embryo development. In the current study, embryotoxicity of stavudine was evaluated using cultured mouse embryos with the concentrations: 5, 10, 15 μM and vehicle control. The data indicated that the effect of stavudine was dose-dependent at early neurogenesis. Stavudine exposure reduced somite numbers, yolk sac diameter, crown-rump length, and increased the rate of embryonic degeneration compared with the control. We chose the lowest but clearly toxic concentration: 5 μM to investigate the molecular mechanisms of the damage. At the molecular level, stavudine produced DNA damage, increased the levels of the phospho-CHK1 and cleaved-caspase-3, and decreased the expression level of proliferating cell nuclear antigen. These changes indicated that stavudine caused a coordinated DNA damage response, inhibited cell proliferation, and induced apoptosis in the embryos. Collectively these results suggest that stavudine exposure disturbs the embryonic development, and its use in pregnant mothers should be re-examined.

Neonatal exposure to low doses of endosulfan induces implantation failure and disrupts uterine functional differentiation at the pre-implantation period in rats

We investigated whether neonatal exposure to low doses of endosulfan affects fertility and uterine functional differentiation at pre-implantation in rats. Newborn female rats received the vehicle, 0.2 µg/kg/d of diethylstilbestrol (DES), 6 µg/kg/d of endosulfan (Endo6) or 600 µg/kg/d of endosulfan (Endo600) on postnatal days (PND) 1, 3, 5, and 7. On PND90, the rats were mated to evaluate their reproductive performance on gestational day (GD) 19 and their ovarian steroid serum levels, endometrial proliferation and implantation-associated proteins on GD5. DES and endosulfan decreased the pregnancy rate and the number of implantation sites. On GD5, DES and endosulfan did not change the serum levels of 17β-estradiol (E2) and progesterone (P); the endometrial proliferation decreased, which was associated with silencing of Hoxa10 in the Endo600-treated rats. Both doses of endosulfan increased the progesterone receptor (PR) expression, whereas the higher dose led additionally to an increase in estrogen receptor alpha (ERα). In the Endo600-treated rats, the down-regulation of Hoxa10 was associated with a deregulation of the steroid receptor coregulators. Alterations in endometrial proliferation and the endocrine pathway of Hoxa10/steroid receptors/coregulators might be the mechanism of endosulfan-induced implantation failure.

Neonatal exposure to bisphenol A alters rat uterine implantation-associated gene expression and reduces the number of implantation sites

Endocrine disrupters have been associated with reproductive pathologies such as infertility and gynecological tumors. Using a rat model of early postnatal exposure to bisphenol A (BPA), we evaluated the long-term effects on 1) female reproductive performance, 2) uterine homeobox A10 (Hoxa10) and Hoxa10-target gene expression, and 3) ovarian steroid levels and uterine estrogen receptor α and progesterone (P) receptor expression. Newborn female rats received vehicle, BPA.05 (0.05 mg/kg · d), BPA20 (20 mg/kg · d), diethylstilbestrol.2 (0.2 μg/kg · d), or diethylstilbestrol 20 (20 μg/kg · d) on postnatal d 1, 3, 5, and 7. A significant decrease in the number of implantation sites was assessed in the xenoestrogen-exposed females. To address the molecular effects of postnatal xenoestrogen exposure on the pregnant uterus, we evaluated the expression of implantation-associated genes on d 5 of pregnancy (preimplantation uterus). All xenoestrogen-treated rats showed a lower expression of Hoxa10. In the same animals, two Hoxa10-downstream genes were misregulated in the uterus. β(3) Integrin, which is up-regulated by Hoxa10 in controls, was decreased, whereas empty spiracles homolog 2, which is down-regulated by Hoxa10, was increased. Furthermore a clear down-regulation of estrogen receptor α and P receptor expression was detected without changes in estradiol and P serum levels. The early exposure to BPA produced a lower number of implantation sites in association with a defective uterine environment during the preimplantation period. Alterations in the endocrine-regulated Hoxa10 gene pathways (steroid receptors--Hoxa10--β(3) integrin/empty spiracles homolog 2) could explain, at least in part, the BPA effects on the implantation process.

Effects of chronic stavudine exposure on liver, pancreas and kidneys of pregnant rats and their fetuses: morphological and biochemical aspects

OBJECTIVE

To study the morphological and biochemical effects on liver, pancreas and kidney of pregnant rats and their fetuses subjected to stavudine treatment.

METHODS

Forty animals were distributed in four groups E1, E2, E3, and C (control) and received by gavage once a day 1, 3 or 9 mg/kg of stavudine in 2 mL distilled water, from days 1 to 20 of pregnancy. After this period, the animals were sacrificed; blood samples were collected for further determinations of AST, ALT, creatinine, urea, glucose and amylase. Samples of liver, kidneys and pancreas of every rat and of the corresponding fetuses were taken and examined under light microscopy.

RESULTS

The maternal livers of groups E1, E2 and E3 displayed progressive morphological alterations without corresponding changes in serum AST and ALT activity. Maternal kidney histology and function were similar in all groups. Maternal pancreas of groups E2 and E3 evidenced moderate and progressive signs of tissue damage without functional repercussion. All fetal livers, kidneys and pancreas presented normal morphology.

CONCLUSIONS

High doses of stavudine produced signs of mild to moderate maternal hepatic and pancreatic toxicity at the morphological level. This was not followed by changes in biochemical parameters, most conceivably due to the functional reserve of these organs.