Name: CIDÁLIA DE FÁTIMA JANUÁRIO
Publication date: 21/10/2025
Examining board:
Name |
Role |
|---|---|
| ALESSANDRA SIMAO PADILHA | Examinador Interno |
| GLAECIR ROSENI MUNDSTOCK DIAS | Examinador Externo |
| JHON LENNON DE PAIVA COIMBRA | Examinador Externo |
| JONES BERNARDES GRACELI | Presidente |
| LIVIA CARLA DE MELO RODRIGUES | Examinador Interno |
Summary: Tributyltin (TBT) and mercury (Hg) are endocrine-disrupting chemicals that individually
cause reproductive complications. However, the reproductive consequences of
coexposure to a mixture of TBT plus Hg are not well known. We hypothesized that
coexposure to a mixture of TBT plus Hg would alter hypothalamic-pituitary-gonadal
(HPG) axis function. Female rats were exposed to daily doses of TBT (100 ng/kg/day
by gavage), plus doses of Hg (1st dose 4.6 g/kg IM, subsequent doses of 0.07
g/kg/day IM), for 15 days, after which chemical accumulation in the tissues,
morphology, hormone levels, inflammation, fibrosis, and protein expression in the
reproductive organs were assessed. Increases in tin (Sn) and Hg levels were detected
in the serum, HPG axis, and uterus of TBT-Hg rats. TBT-Hg rats exhibited irregular
estrous cycles. TBT-Hg rats showed an increase in gonadotropin releasing hormone
(GnRH) protein expression and follicle-stimulating hormone (FSH) levels and a
reduction in luteinizing hormone (LH) levels. Reduced ovarian reserve, antral follicles,
corpora lutea (CL) number, and estrogen levels and increased atretic and cystic
follicles were found, suggesting that TBT-Hg exposure exacerbated premature ovarian
insufficiency (POI) features. Furthermore, TBT-Hg rats exhibited increased ovarian
mast cell numbers, expression of the inflammatory markers IL-6 and collagen
deposition. Apoptosis and reduced gland number were observed in the uteri of TBT
Hg rats. A reduction in the number of pups/litters for 90 days was found in TBT-Hg rats,
suggesting impaired fertility. Strong negative correlations were found between serum
and ovarian Sn levels and ovarian Hg levels and ovarian reserve and CL number.
Collectively, these data suggest that TBT plus Hg exposure leads to abnormalities in
the HPG axis, exacerbating POI features and reducing fertility in female rats.
