Postnatal morphology and functional capacity of the kidney following prenatal treatment with dinoseb in rats

Postnatal fate of prenatal-induced fetal alterations in laboratory animals

Currently it is common practice to evaluate the developmental toxicity hazard of chemicals or pharmaceuticals by evaluation of fetuses after administration of the compound to pregnant animals. These studies are designed to provide possible compound-related fetal changes near term, which are usually classified into malformations or variations. Malformations, but not variations are expected to adversely affect the survival or health. Therefore, classification has striking different regulatory consequences. For categorization as variation reversibility is an important criterion, but it is usually not examined in a standard guideline study. Although this issue has already been recognized long time ago, data dealing with the postnatal reversibility of fetal alterations are still rare. In the current review, literature data, regulatory documents as well as in-house data were compiled. Beside skeletal alterations of skull, vertebral column, ribs, shoulder and pelvic girdle, and extremities, kidney and heart defects are discussed and assessed.

Combined repeated dose and reproductive/developmental toxicity screening test of the nitrophenolic herbicide dinoseb, 2-sec-butyl-4,6-dinitrophenol, in rats

In a combined repeated dose toxicity study with reproduction/developmental toxicity screening test, Crj:CD(SD)IGS rats were dosed with dinoseb, 2-sec-butyl-4,6-dinitrophenol, by gavage at 0 (vehicle), 0.78, 2.33, or 7.0 mg/kg bw/day. Six males per group were dosed for a total of 42 days beginning 14 days before mating. Twelve females per group were dosed for a total of 44-48 days beginning 14 days before mating to day 6 of lactation throughout the mating and gestation period. Recovery groups of six males per group and nonpregnant six females per group were dosed for 42 days followed by a 14-day recovery period. No deaths were observed in males of any dose group or in females of the recovery groups. At 7.0 mg/kg bw/day, eight females died and two animals were moribund during late pregnancy, and a significant decrease in body weight gain was found in both sexes. Hematocrit was significantly higher at 0.78 mg/kg bw/day and above in the main group males at the end of administration period. Reduction in extramedullary hematopoiesis in the spleen was significant at 2.33 mg/kg bw/day in the main group females. Sperm analysis revealed a decrease in sperm motility and an increase in the rates of abnormal sperm, abnormal tail, and abnormal head at 7.0 mg/kg bw/day. A number of dams delivered their pups and of dams with live pups at delivery was significantly lowered in the 7.0 mg/kg bw/day group. Based on these findings, the LOAEL for males and NOAEL for females were 0.78 mg/kg bw/day, and the NOAEL for reproductive/developmental toxicity was considered to be 2.33 mg/kg bw/day.

In utero aminoglycosides-induced nephrotoxicity in rat neonates

Pregnant Wistar females were treated with gentamicin (G), netilmicin (N) or amikacin (A) during two periods of pregnancy covering organogenesis and the beginning of nephrogenesis. Deliveries occurred normally. We studied functional effects--influence of sex, litter size, diuresis, creatinine clearance, G-kidney concentration, and kidney morphological alterations--in rat neonates on day 1 of life. After G and N, the creatinine clearance of the neonates was decreased according to the dosage given to the mother. Whatever the aminoglycoside, kidneys presented proximal tubular alterations (close to those observed in adults) at protonic microscopy and, with electron microscopy, some modifications of distal tubules and of mature and immature glomeruli. It is concluded that the developing kidney can be altered after treating pregnant mothers with aminoglycosides. This model of in utero-induced nephrotoxicity is dose-dependent. Mature and/or immature structures could be affected. The toxicity of the investigated antibiotics could be asserted as G greater than or equal to N greater than A.

The heart and diaphragm: target organs in the neonatal death induced by nitrofen (2,4-dichlorophenyl-p-nitrophenyl ether)

This paper examines the effects of in utero exposure to 2,4-dichlorophenyl-p-nitrophenyl ether (nitrofen) on the viability of neonatal Long-Evans rats. Oral administration of this herbicide on days 8-18 of gestation reduced neonatal survival and birth weight. Day 11 of gestation was the most sensitive day for induction of neonatal mortality; 116 mg/kg to the dam on this day was the LD50 for the neonate. An increased incidence of hydronephrosis was observed in 35-day survivors. This increase was dose-related in animals exposed on day 11 of gestation. Fetuses exposed on day 11 and examined at term had reduced weights, delayed skeletal ossification, and an increased frequency of hydronephrosis and diaphragmatic hernias. While nitrofen did cause a high incidence of hydronephrosis, BUN or creatinine levels in 4-h neonates were not elevated. Detailed examination of the hearts of term fetuses revealed cardiac malformations classified as ventricular septal defect, double outlet right ventricle, and transposition of the great vessels. We conclude from these studies that the heart and the diaphragm are the target organs in nitrofen-induced neonatal death.