| Phthalate acid esters(PAEs), a group of chemicals which have similar structures,are widely used to increase the flexibility of plastic consumer products . Unlike other PAEs, dibutyl phthalate( DBP) is not currently used as a plasticizer in PVC. Typically, DBP is now used as a component of latex adhesives.lt is also used in cosmetics and other care products, as a plasticizer in cellulose plastics, and as a solvent for dyes. Because DBP is not bound to the final product, it can be released during the use or disposal of the product. There are several ways that people may be exposed to DBP at home or at work. Human exposure to DBP can occur during the manufacture of DBP-containing products such as latex adhesives, during the use of such products, or through the presence of DBP in the environment. It is generally accepted that orally ingested DBP is quantitatively hydrolyzed by gut lipases and absorbed almost entirely as the corresponding monoester. There is little or no bioaccumulation observed in rodents. Greater than 90% of oral administration of DBP in rats is recovered in the urine within 2 days.Although there is no direct evidence that exposure of people to DBP adversely affects reproduction or development, studies with laboratory rodents show that exposure to DBP can cause adverse effects if the levels of exposure are sufficiently high. DBP canreduce the testosterone biosynthesis and sperm production, and in some instances, exposure of pregnant dams to relatively high doses of DBP was associated with skeletal malformations and abnormalities of the reproductive system in both male and female offspring. But the toxic mechanisms of DBP remain unclear. To gain possible insight into the effect of DBP on the reproductive system, we developed this study , which would provide some reference indices for human early biologic monitoring.Part I Changes in Spermatogenic Impairment and Sperm Motility of rats Induced by Dibutyl Phthalate in RatsThis study was performed to evaluate the effects of di-butyl phthalate(DBP) on spermatogenic impairment and sperm motility of rats induced by dibutyl phthalate. Healthy 6-week-old male Sprague Dawlay rats were randomly divided into 4 groups with 16 animals in each group. DBP dissolved in peanut oil was administered by gavage at doses of 0,250,500 and 1000mgkg.After 2-week DBP exposure, half of the rats were kindly killed, the rest were killed following 4-week DBP exposure. The related organs were selected and weighed to assess the organ body ratios. The activities of testicular enzymes , glutathione peroxidase (GSHPx) and superoxide dismutase (SOD) in serum and in testis homogenate were determined respectively by spectrophotography. The levels of glutathione (GSH) and malondialdehyde (MDA) in serum and in testis homogenate were measured by spectrophotography too. Lastly, the sperm motility in the cauda epididymis was assessed by computer assisted sperm analysis (CASA). The results showed that the body weight gain of DBP treated groups was lower than those of control, especially in 1000mgkgd. A significant decrease in organ to body weight ratios was seen in both 2- and 4-week DBP exposure. Sperm head count(SPC) and daily sperm product(SPR) deceased rapidly in middle and in high dose-group. After 2-week DBP exposure, GSHPx activities in serum and GSH levels in testis homogenate showed a decreasing tendency, however, GSHPxactivities increased markedly in testis homogenate (p<0.05). After 4-week DBP exposure, while alkaline phosphatase (ALP) activities in serum revealed an increasing tendency, sorbitol dehydrogenase (SDH) activities were observed to be inhibited significantly in both serum and testis homogenate at dose of 1000 mgkgd compared with control group (p<0.01). Furthermore, GSH contents in serum were also affected at this group of treatment(p<0.05). In addition, DBP had shown the inhibitive effect on SOD activities in the testis, with a statistical significance at 1000 mgkgcompared with the control (p<0.05). However, there were no differences in serum SOD activ... |
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