Effects Of Prenatal Dehp Exposure On Apoptosis Of Nerve Cells In The Hypothalamus And Gonad Cells In Offspring Rats

Objective:To investigate the potential mechanisms of neurotoxicity and reproductive toxicity in rats of prenatal di-(2-ethylhexyl) phthalate(DEHP) exposure by the detection of the expression of apoptosis-related genes in hypothalamus and reproductive glands of offspring rats.Methods:32 healthy SPF pregnant SD rats were randomly divided into corn oil, 2, 10, 50 mg/kg DEHP treated groups, 8 rats each group. The pregnant rats were given by gavage with different doses of DEHP from gestation day 14(G14) to G19 once a day. One female and male pup on postnatal day 1(PND1) were euthanized. The other offspring rats were breast feeding to 3 weeks old and then normally fed to 10 weeks. Then two female and male offspring rats 10 weeks old per litter were randomly selected, one female and one male rats per litter were decapitated, others were killed after perfusion fixation with paraformaldehyde. The real-time quantitative PCR was used to detect the expression levels of apoptosis-related genes Caspase-3, B-cell lymp Homa-2(Bcl-2)and Bcl-2 associated X protein(Bax) of the hypothalamus in Postnatal day(PND1), the expression levels of Bcl-2 and Bax in adult rat preoptic area(POA) tissue, ovarian /testicular tissue. TUNEL method was used to detect apoptosis of the POA in adult rats.Results:1. There were no significant difference in the expression levels of Bcl-2,Bax and the ratio of Bcl-2/Bax of hypothalamus nerve tissue in female offsprings at PND1 among the groups(P>0.05)2. There were no significant difference in the expression levels of Bcl-2,Bax and the ratio of Bcl-2/Bax of hypothalamus nerve tissue in male offsprings at PND1 among the groups(P>0.05)3. There were no significant difference in the expression levels of Bcl-2 of POA in adult female offsprings(P> 0.05).The expression levels of Bax among treatment and control groups was statistically different(P<0.05). Compared with the control group, the expression levels of Bax in 2 mg/kg, 10 mg/kg groups were lower significantly(P<0.05).The ratio of Bcl-2/Bax among treatment and control groups was statistically different(P<0.05). Compared with the control group, the ratio of Bcl-2/Bax of 10 mg/kg group was higher significantly(P<0.05).4. The expression levels of Bcl-2 among treatment and control groups was statistically different(P<0.05). Compared with the control group, the expression levels of Bcl-2 in all DEHP treated groups were lower significantly(P<0.05). The expression levels of Bax among treatment and control groups was statistically different(P<0.05). Compared with the control group, the expression levels of Bax in all DEHP treated groups were lower significantly(P<0.05). The ratio of Bcl-2/Bax among treatment and control groups was statistically different(P<0.05). Compared with the control group, the ratio of Bcl-2/Bax of 2 mg/kg and 10 mg/kg group was higher significantly(P<0.05).5. There was no apoptotic cells were detected in the POA in all groups.6. There was no significant difference in the expression levels of Bcl-2, Bax and the ratio of Bcl-2/Bax of ovarian in adult female offsprings among the groups(P>0.05).7. There was no significant difference in the expression levels of Bcl-2 and Bax among treatment and control groups of testis in adult male offsprings(P>0.05).The ratio of Bcl-2/Bax in 10 and 50 mg/kg DEHP treated groups decreased significantly compared with the control group in testes(P<0.05).Conclusion:1. Prenatal DEHP exposure may not disturb the gene expression levels of apoptosis-associated gene of hypothalamus innewborns.2. Prenatal DEHP exposure may not disturb the gene expression levels of apoptosis-associated gene of POA in adult rats.3. Prenatal exposure to DEHP could induced the decrease of the ratio of Bcl-2/Bax of testis in sex matured offspring rats,which may be one of the underlying mechanisms of reproductive toxicity in males.