Role Of Brain-derived DHT/AR Pathway In PFOS-induced Learning And Memory Disability In Adult Male Rats

Background: Perfluorooctane sulfonate(PFOS)is one of the final degradation products of perfluorinated compounds(PFCs).PFOS was widely used in industry,agriculture and daily life due to its hydrophobic and hydrophobic properties,good surface activity and stability.PFOS,which is difficult to be degraded in the environment,had a long half-life(about 5 years).It is recognized as an environmental persistent organic pollutant.The accumulation of PFOS in the body is very high,which has potential damage to animal and human health.Toxicological studies showed that PFOS could affect weight,hepatomegaly,lipid and energy metabolism in experimental animals,and has multiple toxic effects such as embryotoxicity and neurotoxicity.However,the neurotoxic mechanism of PFOS is not very clear.The brain hippocampus can synthesize androgen testosterone at 5α-reductase from androgen testosterone.DHT could bind with androgen receptor(AR),lead to phosphorylation of serine and threonine in AR,thus regulating synapse and maintaining memory process.In addition,testosterone and related androgens also play a key role in regulating disease-related neuronal damage.At present,it is unclear whether DHT/AR pathway is involved in PFOS neurotoxicity.Therefore,this study focuses on the role of DHT/AR pathway in the impairment of learning and memory ability of adult male rats by PFOS and its possible molecular mechanism.Objective: Based on the brain-derived DHT/AR pathway,the effects of PFOS on learning and memory in vivo and molecule mechanism in vitro were studied.The results would provide basic research data for PFOS neurotoxicity interfence,and PFOS alternatives.Methods:(1)Establish a PFOS exposure model for adult Wistar male rats: After PFOS exposure,brain tissue and organs were collected,and the organ coefficient was calculated.Morris water maze(MWM)was employed to investigate the learning and memory ability of rats.Enzyme-linked immunosorbent assay(ELISA)was used to detect the content of androgen dihydrotestosterone(DHT)in rat hippocampus and testicular tissue.Western Blot and real-time time quantitative(RT-q PCR)were used to detect 5α-reductase,androgen receptor(AR),calcineurin(PP2B),protein phosphatase 1(PP1),α-amino-3-hydroxy-5-methyl-4-isoxazolpropionic acid receptors(AMPAR),synaptophysin(SYP),postsynaptic density 95(PSD95)protein expression and gene expression.(2)Model in vitro: The PFOS exposure model of rat PC12 cells was established,and androgen receptor antagonist(MDV3100)and DHT were used for intervention.The survival rate of PC12 cells was detected by thiazole blue(3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide(MTT);Western Blot and RT-q PCR were used to detect 5α-reductase,AR,PP2 B,PP1,SYP,PSD95,AMPAR protein and gene expression.Results:(1)Effects of PFOS exposure on neurotoxicity and expression of related biochemical molecules in adult male Wistar rats:(1)Compared with the control group,weight increased could be found with PFOS exposure concentration increased(P<0.05);(2)There was no significant difference in organ coefficient of rats(P>0.05);(3)Compared with the control group,the results in MWM showed that the escape latency of rats in the high-dose exposure group was significantly prolonged,the time percentage of the third quadrant of rats in the high-dose exposure group was decreased(P<0.05,P<0.05);(4)Compared with the control group,the results of ELISA showed that the content of DHT in the hippocampus of rats in the low-dose exposure group increased(P<0.05);the content of DHT in testicular tissue of rats increased slightly(P>0.05);(5)Compared with the control group,5α-reductase protein and gene were significantly increased(P<0.05,P<0.001);the expression of AR protein and gene were decreased(P<0.01,P>0.05);the expression of PP2 B protein and gene were increased significantly(P<0.05,P>0.05);the content of PP1 protein and gene expression were significantly increased(P<0.05,P>0.05);the AMPAR protein and gene expression were significantly increased(P<0.05,P>0.05);the content of SYP protein and gene expression of rats were decreased significantly(P<0.05,P<0.05);the expression of PSD95 protein and gene were decreased(P<0.05,P>0.05).(2)The role of DHT/AR pathway in PFOS exposed PC12 cells:(1)Compared with the control group,the survival rate of PC12 cells could be significantly decreased in the50 μmol/L,100 μmol/L and 200 μmol/L groups exposed to PFOS(P<0.01,P<0.001,P<0.001);MDV3100 reduced the survival rate of PC12 cells(P<0.05),and DHT reduced the survival rate of PC12 cells(P>0.05);(2)Compared with the control group,the number of cells in the MDV3100 group and DHT group decreased slightly,the number of cells in the PFOS group,MDV3100+PFOS group and DHT+PFOS group decreased,the number of dead cells increased,the cell antenna shortened and gradually rounded;(3)Compared with the control group,5α-reductase protein and gene were increased(P<0.05,P<0.01);the expression of AR protein and gene were decreased(P<0.05,P>0.05).PP2B、PP1and AMPAR protein and gene expression were increased,the expression of SYP and PSD95 protein and gene were decreased,the expression of AR protein and gene in the PFOS group decreased compared to the MDV3100 group in PC12 cells,the expression of AR protein in the PFOS group decreased compared to the DHT group in PC12 cells.Conclusion:(1)PFOS exposure could cause learning and memory impairment in adult male rats.(2)DHT/AR-PP2B-PP1 pathway was involved in PFOS-induced abnormal synapse protein expression in rats.(3)Brain-derived DHT/AR pathway is one of the molecular mechanisms of PFOS-induced learning and memory impairment in adult male rats.