The current study aimed to investigate the effects of perinatal exposure to
nonylphenol (NP) on delivery outcome of pregnant rats and subsequent inflammatory
hepatic injury in newborn rats. The pregnant rats were divided into 2 groups: control
group (corn oil) and NP exposure group. Thirty-four pregnant rats were administered
NP or corn oil by gavage from the sixth day of pregnancy to 21 days postpartum, with
blood samples collected at 12 and 21 days of pregnancy and 60 days after delivery.
The NP concentration was measured by HPLC, with chemiluminescence used for detection
of estrogen and progesterone levels. Maternal delivery parameters were also observed.
Liver and blood of the newborn rats were collected and subjected to automatic
biochemical detection of liver function and blood lipid analyzer
(immunoturbidimetry), and ultrastructural observation of the hepatic microstructure,
with the TNF-α and IL-1β hepatic tissue levels evaluated by immunohistochemistry.
Compared with the control group, the pregnant and postpartum serum NP and estradiol
levels of the mother rats in the NP group were significantly increased, together with
lowered progesterone level, increased number of threatened abortion and dystocia, and
fewer newborn rats and lower litter weight. Serum and hepatic NP levels of the
newborn rats measured 60 days after birth were significantly higher than those of the
control group, as well as lower testosterone levels and increased estradiol levels.
When observed under electron microscope, the hepatocyte nuclei of the control group
were large and round, with evenly distributed chromatin. The chromatin of hepatocytes
in the NP group presented deep staining of the nuclei, significant lipid decrease in
the cytoplasm, and the majority of cells bonded with lysate. The results of
immunohistochemistry showed that there was almost no TNF-α or IL-1β expression in the
hepatocytes of the control group, while the number of TNF-α-, PCNA-, and
IL-1β-positive cells in the NP group was increased, with higher integral optical
density than the control group. Compared to the control group, the serum levels of
alanine aminotransferase, aspartate aminotransferase, triglyceride and low-density
lipoprotein in the newborn rats of the NP group were significantly increased. There
was no significant difference in the serum level of high-density lipoprotein or
cholesterol between the groups. Perinatal exposure to NP can interfere with the
in vivo estrogen and progesterone levels of pregnant rats,
resulting in threatened abortion, dystocia and other adverse delivery outcomes. High
liver and serum NP levels of the newborn rats led to alteration of liver tissue
structure and function. The NP-induced hepatotoxicity is probably mediated by
inflammatory cytokines TNF-α and IL-1α.