당뇨병 치료제 metformin의 수생태 독성평가 및 내분비계 교란영향

학위논문 (석사)-- 서울대학교 대학원 : 환경보건학과, 2017. 2. 최경호.Metformin, one of the most prescribed anti-diabetic pharmaceuticals, has been frequently detected in ambient water. However, knowledge of its effects on aquatic organisms is very limited. In this study, acute and chronic toxicity of metformin was evaluated using two freshwater organisms, a crustacean (Daphnia magna) and Japanese medaka fish (Oryzias latipes) following Organization for Economic Co-operation and Development (OECD) test guidelines. Endocrine disruption potential of metformin and its underlying mechanisms were also investigated using adult Japanese medaka. In 21 d chronic D. magna test, no observed effect concentration (NOEC) for survival was determined at 40 mg/L of metformin, but significant changes in reproduction were not observed at this concentration. In early life stage toxicity test with medaka, NOEC for survival was determined at 100 mg/L of metformin. Predicted no effect concentration (PNEC) value of metformin was determined at 4 mg/L, based on D. magna 21 d NOEC. Hazard quotient (HQ) was estimated less than 1 suggesting negligible risk. In adult male Japanese medaka, plasma 17β-estradiol (E2) level and E2 to testosterone (T) ratio were significantly increased following 21 d exposure to metformin. In addition, transcription of steroidogenic genes such as star, cyp11a, hsd3b, cyp19a, hsd11b2, and cyp11b was significantly up-regulated. In female Japanese medaka, 11-ketotestosterone (11-KT) level as well as cyp11b gene transcription level was increased following 21 d exposure to metformin. Our observation suggests that current level of metformin in ambient water is not likely to be of concern among freshwater organisms. However, its endocrine disruption potential through alteration of steroidogenic pathway warrants long-term exposure studies.1. Introduction 1 2. Materials and Methods 4 2.1. Test Chemical 4 2.2. Test organisms and maintenance 4 2.3. Acute and chronic toxicity test 5 2.3.1. D. magna toxicity test 5 2.3.2. O. latipes toxicity test 6 2.3.3. Ecological risk assessment 7 2.4. Endocrine disrupting effects in O. latipes 8 2.4.1. Early-life stage (ELS) exposure 8 2.4.2. 21 d adult fish exposure 8 2.5. Measurement of sex hormones 9 2.6. Quantitative analysis of the genes related to HPG axis 9 2.7. Statistical analysis 10 3. Results 12 3.1. Measurement of exposure media 12 3.2. Acute and chronic toxicity 14 3.2.1. D. manga acute and chronic exposures 14 3.2.2 O. latipes acute and chronic exposures 16 3.2.3. Ecological risk assessment of metformin 18 3.3. Sex endocrine related effects of metformin on O. latipes 22 3.3.1. Transcriptional changes of sex hormone related genes in fish early life stage 22 3.3.2. Effects on plasma sex steroid hormones in adult fish after 21 d exposure 24 3.3.3. Transcriptional changes of genes related to HPG-axis in adult fish 27 4. Discussion 32 5. Reference 37 Supporting information 46 Abstract in Korean 50Maste