Endocrine Abstracts

Decamethylcyclopentasiloxane (D5) is one of the most common chemical ingredients for daily necessities that can be absorbed through the skin, aerosol, or even orally. People are exposed to D5 daily, but the risk of prenatal exposure to D5 is not completely understood. In this study, the effects of prenatal exposure to D5 on neural development were assessed through behavioral tests on offspring mice. First, the developmental neurotoxicity test (DNT) was performed to determine if D5 is a neurotoxicant. From the DNT, D5 was classified as a developmental neurotoxicant because their score of the discriminant function (SDF) was -1.55603, which is less than the standard score 0 of DNT. The estimated daily exposure of D5 to humans has been reported to be around 0.6 mg/kg. In this study, the pregnant mice were treated with 3, 6, and 12 mg/kg of D5 with corn oil per day from embryonic day 10 (E10) through postnatal day 7 through oral administration. All behavior tests were performed after the pups reached six weeks of age. As a result, the administration of 12 mg/kg of D5 (high dose group) increased the repetitive activity in both the grooming and marble burying tests and even a depression in tail suspension and forced swimming test compared to the vehicle group. In addition, high dose group showed a decrease in social behavior and cognitive ability in the three-chamber test. In the novel object recognition test, impairment of memory and exploring ability was found on the high dose group. The expression level of the four genes, brain-derived neurotrophic factor (BDNF), tyrosine hydroxylase (TH), acetylcholinesterase (AChE), and GABA type A receptor associated protein like 1 (GABARAPL1) related to neural development, were measured in the whole brain. The administration of high dose of D5 decreased the transcription level of BDNF and increased AChE and TH compared to the vehicle. On the other hand, there is no meaningful difference in GABARAPL1. These results show that the maternal exposure to D5 impairs the social and memory ability of mouse offspring and alters gene expression in the brain. In conclusion, maternal exposure to D5 can cause behavioral disorders in their offspring. Therefore, it is necessary to discuss the excessive usage of D5.