The Studying Of Effects Of DEHP On Male Reproductive System

In April 2011,Taiwan health administration found that one kind of food that named "Jingyuan Probiotics" contained the plasticizer di(2-ethylhexyl)-phthalate(DEHP),which concentration is up to 600 ppm. Then the following-up study found that DEHP comes from Yu Shen spice company.On June 13, the enterprises that have been contaminated increased to 294, and related products rose to 973.This incident caused a huge sensation in the Taiwan island food administration, the China mainland food administration and even in the entire Asian food industry, then at the same time, this incident also brought“plasticizer” into human sight.Plasticizer is widely used in industrial production, among all of the plasticizers, di(2-ethylhexyl)-phthalate(DEHP) is the most widely used phthalate and now has became a global environmental pollutant.In 2012,our country produced 4 million tons DEHP one year,then one kilo underground water contains 100μg DEHP,one kilogram despoised litter contains 200 mg DEHP, many literatures reported that DEHP can cause some aspects toxicity, among all of these, their reproductive toxicity is the most notably.In order to investigate the toxicity mechanism of DEHP, we have carried out experiments on animals. A total of 40 healthy 5-week-old SPF male Sprague-Dawley rats were randomly divided into four groups with 10 rats in each group. The DEHP doses were 0 mg/kg in control group(corn oil), 100 mg/kg in low dose group, 500 mg/kg in medium dose group and 1500 mg/kg in high dose group. Rats were exposed to DEHP via gavage administration for continuous six weeks, DEHP administration was once a day and five times a week. After the exposure, rats were anesthetized through ether, then sacrificed for the further study.After the rats were exposed to DEHP,we found that there were no changes in the general health or behavior of the rats following 6 weeks of treatment,and the total body weight was also not changed in each group, but the weight of testis and ratio of testis/body weight were decreased in the group treated with 1500mg/kg DEHP group(p<0.01).Histological obversation showed that there was relatively slight damage to the testicular tissue in the group treated with 100mg/kg/day. Slight loss of spermatogenesis and Sertoli cell was shown in the group treated with 500mg/kg/day. Obviously injury of the testicular tissue, characterized by severe atrophy and vacuoles of the seminiferous tubulesand sertoli cell, loss of spermatogenesisand Leydig cell hyperplasia were observed in the group treated with 1500mg/kg/day.Electronic microscope observation showed in the low dose DEHP treated rats, intra-nuclear inclusions were observed and vacuoles appeared in the cytoplasm. Mitochondria showed mild swelling, broken and de-granulation on mitochondrial cristae could be easily observed.Inclusions in sperm head and abnormality in mitochondrial sheath were also noteworthy. Moreover, in the medium dose DEHP treated rats, numerous vacuoles in the nucleus, fragmented cell membranesreduced mitochondria and cavitation in the cytoplasm of spermatogenic cells were observed. Development of secondary spermatocytes and sperm cells also showed abnormality, which followed with reduced density of electrons. Abnormal ultrastructure, reduced mitochondria, cavitation and aberrant of mitochondrial cristae were observed in cervical and middle sperm tail(mitochondrial cristae), and no microtubule structure could be found in the sperm tail. More damage appeared in the high dose DEHP treated rats, disorder of cell structure, and no sperm cells could be observed. Larger and dented nucleus indicated massive malformation. Increased nucleus/cytoplasm ratio, and attachment of heterochromatin to the crude nuclear membrane with notch were obvious. However the number of mitochondria was increased and with various shapes.Reduced cell organelles and mitochondrial cristae, cell necrosis, serious nuclear deformation, karyopyknosis, appearance of inclusions and increased heterochromatin in leydig cells were also observed.After evaluating the expression of genes, we found that compared to the control group, the expression of St AR、3β-HSD were up-regulated in all treated group(p<0.01 or p<0.05).17β-HSD and ERα were up-regulated in the group treated with 1500mg/kg/day(p<0.01), Gn RH was down-regulated in the group treated with 500mg/kg/day and 1500mg/kg/day(p<0.01 or p<0.05), while the expression of ERβwas decreased in the group treated with 100mg/kg/day and 500mg/kg/day, but increased in the group treated with 1500mg/kg/day.Then we focused on three proteins: Gonadotropin-Releasing Hormone Receptor(Gn RHR)、3β-hydroxysteroid dehydrogenase(3β-HSD) and Follicle stimulating hormone Receptor(FSHR). Compared to the control group, the expression of Gn RHR and FSHR were decreased(p<0.01 or p<0.05) in the group treated with 1500mg/kg/day,while the expression of 3β-HSD was increased(p<0.05) in the group treated with 1500mg/kg/day. Thus, through the aminal experiment,we focused on the male reproductivetoxicity of DEHP,then we found that DEHP can effect the expression of some genes and proteins that have something to do with the synthesis of hormone,these findings indicated some scientific basis for revealing the mechanism of male reproductive toxicity of DEHP,these also provide mportant theoretical significance and practical application value for the future research of plasticizer harm to the health of populations.