Low Mercury Levels Leads to Abnormal Reproductive and Metabolic Features in Female Rats

Presentation Number: SAT 259
Date of Presentation: April 1st, 2017

Eduardo Merlo*1, Julia F P Araújo1, Priscila Lang Podratz1, Leandro C Freitas-Lima1, Leandro Miranda-Alves2, Maylla Ronacher Simões3, Dalton Valentim Vassalo3, Ian Victor Silva1 and Jones B Graceli4
1Federal University of Espirito Santo, Vitoria, Brazil, 2Federal University of Rio de Janeiro, Rio de Janeiro, BRAZIL, 3Universidade Federal do Espírito Santo, Vitoria, Brazil, 4Federal University of Espirito Santo, Vitoria, BRAZIL

Abstract

Mercury (Hg) is a heavy metal environmental pollutant that exposure was associated with high toxicity, leading to endocrine-disrupting effects, such as reproductive and metabolic abnormalities. Metabolic disorders, like obesity, are associated with abnormal adiposity and inflammation, affecting the reproductive function, that may occur due exposure to heavy metal. However, studies that have investigated the toxic Hg effects at low levels in the reproductive and metabolic functions are especially rare. Here, we describe the reproductive and metabolic characterization as result of low levels of Hg exposure in female rats. To study whether Hg disrupted reproductive and metabolic function, we administered vehicle (CON, saline solution) and Hg (Hg, first dose 4.6µgkg-1, subsequent doses 0.07µgkg-1day-1) in the Wistar female rats for 30 days via i.m. Hg rats displayed a no significant changes in body weight (p≥0.05; n=8-10). Hg rats exhibited abnormal estrous cyclicity, showing more days in the metestrus-diestrus phase (CON:2.01±0.18 vs Hg:2.83±0.15 d; p≤0.05; n=8-10). A reduction in pituitary, uterus and ovaries weights were observed in Hg rats (p≤0.05; n=8-10). Hg rats had higher serum testosterone (CON:0.13±0.01 vs TBT:0.21±0.04 ng/mL; p≤0.05; n=5-6) and lower serum estrogen levels (CON: 28.33±1.02 vs Hg:22.42±1.69 pg/mL; p≤0.01; n=5-6). Irregular ovarian follicular development, raised atretic and cystic follicles and reduced corpora lutea number was noted in Hg ovaries (p≤0.05; n=5). Further, ovary and uterus atrophy, as well uterine inflammation (p≤0.05; n=4-6), apoptosis and fibrosis were observed in Hg rats. High glucose levels were observed in Hg-fasted rats. (CON: 92.10±4.51 vs Hg:115.26±5.52 mg/dL, p≤0.05; n=6-8). Increased values for the glucose tolerance test at 15 and 30 min (p ≤ 0.05; n=6-8) and the insulin sensitivity test at 30 and 60 min (p ≤ 0.05; n=6-8) were identified in the Hg rats. Thus, Hg disrupted proper functioning of the reproductive and metabolic function. This work supports the hypothesis that low levels of Hg impair the normal reproductive and metabolic control in female rats.

 

Nothing to Disclose: EM, JFPA, PLP, LCF, LM, MRS, DVV, IVS, JBG