Developmental Toxicity Of Perfluorooctane Sulfonate On Glucose And Lipid Metabolism And Central Nervous System Of Adult Offspring Rats

PFOS, which is a kind of fluorine-saturated eight-carbon compounds possessing multiple unique physical and chemical properties, has been widely used in a variety of industry applications and daily commodities since the middle of last century. Results from multiple scientific researches have proven that PFOS are widely distributed in the nature environment (such as water and soil), and as a result of its bioaccumulation character, the chemical compounds can be detected in both of wild animals and human beings. After recognition of the tremendous detrimental effects of PFOS, the Environmental protection agency of the United States has banned the usage of PFOS in the 2000. However, the chemical compounds are still produced elsewhere in many developing countries, the environmental hazards result from PFOS should not be underestimated.Scientific evidences have proven that PFOS could penetrate the placental barrier and secreted from milk, as a result of this, the developmental toxicity of PFOS has attracted increasingly more attentions from both the public and the scientific community. PFOS exposure during the developmental periods can lead to low birth weight of laboratory animals, what's more, it could also trigger toxic effects on the liver, heart, lung, metabolic system, immune system and nervous system. In the recent years, many human epidemiological studies have revealed the possibility that developmental PFOS exposure might be correlated with disturbed glucose and lipid homeostasis. However, so far there is no information from animal studies investigating this very topic. In addition, although PFOS has been proven to be a developmental neurotoxicity substance, but the interaction of PFOS and other environmental neurotoxic factors (such as high fat diet) on the neurotoxicity of laboratory animals are largely unknown. The goal of this study is to explore the possible effect of gestational and lactation PFOS exposure on the homeostasis of glucose and lipid metabolism, and to investigate the synergy effect of developmental PFOS exposure and high fat diet ingestion during adulthood on the neurotoxicity of the rat pups, so as to evaluate the potential health effects and provide experimental and theoretical foundation for the chemical compounds.Objective:To observe the effects of developmental PFOS exposure on the glucose homeostasis of adult rat offspring. Method:30 pregnant wistar rats were randomly distributed into control,0.5mg/kg bw/day,1.5mg/kg bw/day PFOS treating group, PFOS were given by gavage once daily from gestation day (GD) 0 to PND 21. Control received 0.5% Tween-20 vehicle (4mg/kg bw/day). PFOS concentrations in the serum and liver of offspring were determined on postnatal day (PND) 0 and PND21 by High Performance Liquid Chromatography (HPLC)-tandem mass spectrometry. Fasting blood glucose (FBG) values were measured on 5,9,13,17 weeks after weaning. Oral glucose tolerance test (OGTT) was performed on 10 and 15 weeks after weaning, and the area under curve were calculated. Fasting serum insulin levels were detected by radioimmunoassay on 10 and 18 weeks after weaning. Serum adiponectin levels were measured by ELISA. All the rats were sacrificed on 22 weeks after birth, weights of internal organs were weighed. Liver were removed and frozen at -80℃until use for Real-time PCR. Pancreas were removed and fixed in 4% paraformaldehyde and embedded in paraffin for immunofluorescence assay. Results:Body weights of rat pups from PFOS exposure groups were significantly lower than control group, the trend last until 8 weeks after weaning. PFOS concentration in the serum and liver were elevated in a dose-dependent manner, PFOS concentration on PND 21 were higher than that of PND 0. Though the fasting blood glucose levels were not affected by developmental PFOS exposure, it could impair the glucose tolerance of rat pups. Serum insulin levels were elevated and adiponectin levels were reduced by developmental high dose PFOS exposure, the degree of insulin resistance was elevated either. Results form QPCR revealed that PFOS down-regulate the expression level of hypoglycemic gene G6P, however, the expression level of glycemic gene PEPCK was not affected. Conclusion: Developmental exposure to PFOS disturbed the glucose homeostasis of rat pups in the adulthood, lead to insulin resistance and increased the risk of diabetes and metabolic disorder.Objective:To observe the effects of developmental PFOS exposure on lipid metabolism of rat pups in the adulthood. Method:30 pregnant wistar rats were randomly distributed into control,0.5mg/kg bw/day,1.5mg/kg bw/day PFOS treating group, PFOS were given by gavage once daily from gestation day (GD) 0 to PND 21. Control received 0.5% Tween-20 vehicle (4mg/kg bw/day). Concentration of serum fasting triglyceride and total cholesterol were measured on 10 and 18 weeks after weaning. Serum leptin levels were measured by radioimmunoassay on 10 and 18 weeks after weaning. All the rats were sacrificed on 22 weeks after birth. Liver, heart, muscle and fat were fixed in 4% paraformaldehyde and embedded in paraffin for morphological detection. Oil red O staining was performed for liver, muscle, heart. HE staining was performed for adipose tissue, the areas for adipocytes were caculated. Expression levels of genes related to lipid metabolism were detected by real-time quantification PCR. Results:Serum triglyceride and total cholesterol were not affected by developmental PFOS exposure, however, serum leptin levels were elevated at both 10 and 18 weeks. Lipid storage in the liver was elevated in PFOS treated rat pups. Gonadal fat weights were also elevated by PFOS exposure. The expression level for ACC1, SCD1 and FAS and transcription factors LXR, ChREP,SREBP-1C were all elevated. Conclusion:Developmental PFOS exposure could disturb the lipid metabolism homeostasis of rat pups in the adulthood, and increase the risk for liver steatosis.Objective:To observe co-exposure of developmental PFOS and high fat diet (HFD) ingestion after weaning for the rat pups in the adulthood. Method:60 pregnant wistar rats were randomly distributed into control,0.5mg/kg bw/day,1.5mg/kg bw/day PFOS treating group, PFOS were given by gavage once daily from gestation day (GD) 0 to PND 21. Control received 0.5% Tween-20 vehicle (4mg/kg bw/day). Pups were randomly distributed into normal diet group (ND) and high fat diet (HFD) group immediately after weaning. All the rats were sacrificed on 22 weeks after weaning, brain was removed immediately after sacrifice, hippocampus and cortex were separated. The expression levels of mRNA and Proteins related to neurotrophic factor, inflammation and apoptotic response were detected by QPCR and Western Blot respectively. Bain embedded in the paraffin were cut into slices to perform Nissle, TUNEL staining and BDNF, GFAP, Caspase-3 immunohistochemical staining. Results:BDNF protein and mRNA levels were decreased in PFOS and HFD co-exposure groups, accompanied by down-regulation of Gap-43,Syn,Syp; Developmental PFOS exposure can aggravate the inflammatory reaction induced by HFD ingestion, including activation of hippocampal astrocytes and elevated expression of Pro-inflammatory cytokines; PFOS also aggravate the apoptic response of neuronal cells induced by HFD ingestion. Conclusion:Developmental PFOS could result in a synergetic effect on the neurotoxicity induced by HFD ingestion, the possible mechanism of which might be the aggravation of inflammatory reaction, and reduce support from BDNF neurotrophic effects and elevated apoptotic response.