Exposure To Nonylphenol During Gestation And Lactation Induced Neuron Apoptosis In Offspring Hippocampus Through Endoplasmic Reticulum Stress Pathway

Objective: Nonylphenol(NP),one of the most well-known persistent organic pollutants(POPs),is widely used in many industrial and agricultural products.NP is persistent,moderately soluble in water and tends to bioaccumulate in living organism.Human exposure to NP through drinking water and the diet.Previous studies reported that NP may exert negative effects on endocrine system,immune system,reproductive system and nervous system.Gestation and lactation is the critical period of neural development,andis more sensitive to external stimuli.Exposed to NP during Gestation and lactation may induced impair the learning and memory in the offspring.The main function of hippocampus is learning and memory.Hippocampus neurons apoptosis may impaired the function of learning and memory.Previous study found that exposure to NP lead to apoptosis in rats through ER stress apoptotic pathway.ER stress further lead to unfolded protein response(UPR),an adaptive response of ER stress to restore ER homeostasis.UPR alleviated the ER stress in the early time effectively,but it turns to promote the cell apoptosis when ER stress keeps a high level chronically.In our study,we aimed to explore the status of apoptosis in the offspring hippocampal neurons and ER stress,investigated weather the neuronal apoptosis mediated through PERK/ATF4/CHOP and Calpain2/Cleaved Caspase-12 pathway when maternal exposure to NP during pregnancy and lactation.Methods: NP-exposed rat model was established by intragastric administration of nonylphenol during pregnancy and lactation.On pups were analyzed.The Nissl assay,TUNEL assay,Western blot assay and immunofluorescence were performed on hippocampus of offspring.Related proteins of PERK/ATF4/CHOP and Calpain2/Cleaved Caspase-12 pathway were detected by Western blot assay.Results:1.Perinatal exposure to NP induced surviving neurons in the hippocampal tissues of offspring: The average numbers of surviving neurons in NP groups were decreased sharply compared with the control group in the CA1 and CA3(P < 0.05).2.Perinatal exposure to NP induced apoptosis in the hippocampal tissues of offspring: TUNEL-positive cells in hippocampus in NP groups were significantly increased compared with control group in the CA1 of offspring hippocampus(P < 0.05).In the CA3 region of offspring hippocampus,the numbers of TUNEL-positive cells in the NP groups were significantly increased(P < 0.05).3.Perinatal exposure to NP up-regulated the levels of Cleaved Caspase-3 in the hippocampal tissues of offspring: The Western blot revealed that Cleaved Caspase-3 were significantly increased obtain from the hippocampal neurons in the NP groups in the offspring hippocampus(P < 0.05).The immunofluorescence results confirmed that the levels of the Cleaved Caspase-3 were increased.4.Perinatal exposure to NP up-regulated the levels of GRP78 in the hippocampal tissues of offspring: The Western blot assay results showed that GRP78 was significantly upregulated in the NP groups compared with the control group on.It is suggested that the perinatal exposure to NP triggered ER stress in the offspring hippocampus(P < 0.05);The immunofluorescence results showed that the levels of GRP78 were increased in the offspring in hippocampal CA1 and CA3 on.5.Perinatal exposure to NP activated of PERK-ATF4-CHOP pathway in the hippocampal tissues of offspring : The levels of p-PERK were elevated in the groups compared with the control group in the offspring hippocampus(P < 0.05).PERK expression in the NP groups were significantly increased compared with control group on(P < 0.05).Compared with control group,the expressions of ATF4 and CHOP in the NP groups were significantly increased(P < 0.05).6.Perinatal exposure to NP activated Calpain2/Cleaved Caspase-12 pathway in the hippocampal tissues of offspring The: In the NP groups,the expressions of Calpain2 and Cleaved Caspase-12 were increased compared with control group.Conclusion: 1.Perinatal exposure to NP increased apoptosis in the offspring hippocampal neurons.2.Perinatal exposure to NP induced ERS in the offspring hippocampal neurons.3.The mechanism of apoptosis of hippocampal neurons is closely related to ERS pathway.