Effects Of Pre-puberty DEHP Exposure On Hippocampal Testosterone-metabolizing Enzymes And ERK1/2-CREB Signalingpathway Of Male Rats

As a kind of typical Environmental Endocrine Disruptors(EEDs),DEHP could cause estrogenic,anti-androgenic and even anti-estrogenic effects.A widespread research have indicated that DEHP interferes or stimulates synthesis and metabolism of sex hormones,especially in the critical periods of development and reproductive stages,and thus affects the development and long-term function of hormone-sensitive tissues.Epidemiological datas and animal behavior experiments showed that exposure to DEHP in early life(perinatal or early pubertal)relate to the advanced neural function in rodents and human,such as learning and memory,emotion and social behavior.The present study is to investigat the effects of DEHP on T metabolic enzymes and ERβ/AR mediated ERK-CREB signaling pathways of hippocampus in male rats following pre-pubertal exposure(1,10,50 and 200 mg/kg/d)from postnatal day 24 through postnatal day 31.Part Ⅰ Effects of pre-puberty DEHP exposure on generally toxicity of immature male ratsObjective: To study the generally toxic effects of DEHP pre-pubertal exposure on immature male rats.Methods: Fifty Male SD rats aged 3 weeks were randomly divided into 5 groups by weight(n = 10): solvent control group,1,10,50,200 mg/kg/d DEHP dose group,each was administed introgastrically for 8 days continuously.After sacrificed,heart,liver,spleen,lung,kidney,testis and brain were collected to calculate viscera coefficient,biochemical indexes in serum were also observed.Results:(1)Compared to solvent control group,body weight gain significantly increased of all the treated groups at 8 days(P < 0.01).(2)Kidney viscera coefficients of pups of 10 mg/kg/d DEHP treated group significantly decreased(P < 0.01),and brain viscera coefficients of pups of 50 and 200 mg/kg/d DEHP treated groups obviously increased(P < 0.05).(3)Compared to solvent control group,the level of GLU significantly increased of 1 mg/kg/d DEHP dose groups,GLU and ALB significantly increased of 10 and 50 mg/kg/d DEHP dose groups,Activity of AST obviously increased wheal ALP significantly decreased of 50 mg/kg/d DEHP dose group,Activity of CHE and level of GLU significantly increased of 200 mg/kg DEHP dose group(P < 0.05).Conclusion: Pre-puberty exposure to DEHP of male immature rats has obvious toxicity on liver,kidney and brain.Part Ⅱ Effects of pre-puberty DEHP exposure on hippocampal testosterone-metabolizing enzymes of male ratsObjective: To study the effects of pre-puberty DEHP exposure on the level of hippocampal P450 arom and 5 alpha R2 mRNA of male rats.Methods: Fifty male SD rats aged 3 weeks were randomly divided into 5 groups by weight(n = 10): solvent control group,5,50,200,1000 mg/kg/d DEHP dose group,each was administed introgastrically for 4 weeks continuously.The expression of hippocampal P450 arom and 5 alpha R2 mRNA were detected by RT-PCR.Results: Compared to solvent control group,the relative expression level of hippocampal P450 arom mRNA of 5 mg/kg/d DEHP treated group significantly increased(P = 0.01).No significant difference was found in the relative expression level of hippocampal 5αR2 mRNA(P>0.05).Conclusion: Pre-puberty exposure to DEHP would increase hippocampal P450 arom mRNA expression level in male pup rats.Part Ⅲ Effects of pre-puberty DEHP exposure on hippocampal ERK1/2-CREB signaling pathway of male ratsObjective: To study the effects of DEHP pre-puberty exposure on the expression level of hippocampal AR,ERβ and ERK1/2,p-ERK,CREB,p-CREB of male rats.Methods: Fifty Male SD rats aged 3 weeks were randomly divided into 5 groups by weight(n = 10): solvent control group,1,10,50 and 200 mg/kg/d DEHP dose group,each was administed introgastrically for 8 days continuously.Immune histochemical method was used to detect the expression of AR and ERβ in hippocampus.The expression of hippocampal ERK1/2,p–ERK1/2,CREB,p-CREB were detected by western blot.Results:(1)Compared to solvent control group,the expression level of hippocampal ERβ in CA3 area of 50 mg/kg/d DEHP treated group obviously decreased(P < 0.05);no significant difference was observed of hippocampal AR expression in DG,CA1,CA2 and CA3 areas(P > 0.05);(2)Compared to solvent control group,the level of hippocampal ERK1/2,p–ERK1/2,CREB,p-CREB significantly decreased of all DEHP treated groups(P < 0.05).No significant effect was found in the expression level of hippocampal CREB,P-CREB of 1 mg/kg/d DEHP treated groups(P>0.05).Conclusion: Pre-puberty expose to DEHP could interferes the expression levels of hippocampal ERβ and decreases the level of ERK1/2,p–ERK1/2,CREB,and p-CREB in hippocampous.