Effects of intrauterine exposure to nicotine on cellular and epigenetic events in ovaries, ovarian follicular reserve and sex hormones in adult female rats

• Grant number: 24/01377-5
• Support Opportunities: Regular Research Grants
• Start date: October 01, 2024
• End date: September 30, 2026
• Field of knowledge: Health Sciences - Medicine - Maternal and Child Health
• Principal Investigator: Camila Cicconi Paccola
• Grantee: Camila Cicconi Paccola
• Host Institution: Escola Paulista de Medicina (EPM). Universidade Federal de São Paulo (UNIFESP). Campus São Paulo. São Paulo , SP, Brazil
• Associated researchers: Cristiane Damas Gil

Abstract

Some reports indicate damages on fertility of offspring exposed to nicotine, the main component of cigarettes. The effects can occur during pre- and post-natal development, such as changes in the onset of puberty and variations in the sex hormones, both in males and females, inaddition to irregular reproductive cycles and anticipation of menopause. However, the data in the literature are conflicting regarding the type of change and the phase in which they occur; thusthere is a need for research to clarify these points. Therefore, this work aims to verify the effects of exposure to nicotine, during the intrauterine phase and breastfeeding, on the regularity of the estrous cycle, the hormonal profile and the ovarian follicular reserve of adult female rats. For this, ten pregnant rats will receive an osmotic pump containing 2mg/kg/day of nicotine from the first day of pregnancy, in order to expose the offspring throughout pregnancy and breastfeeding. Other ten pregnant rats will receive the osmotic pump without nicotine (sham control group). Two females from each offspring (20/group) will be euthanized on the 90th postnatal day, when blood and ovaries will be collected. Hormones (GnRH, FSH, LH, estradiol, progesterone and AMH) will be measured in the blood to check the ovarian follicular reserve. Part of these rats (5/group) will have the ovary collected and frozen to western-blotting analysis of hormone receptors (GnRH, FSH and LH), cellular proliferation (PCNA) and death (Caspase-3), andepigenetic markers (Dnmt-1, HDAC-4 and histone acetylation or methylation). The other part ofthese rats (5/group) will have the ovary collected, fixed and processed in order to count healthy or unhealthy oocytes immunolabeled with a specific marker to oocyte and cell death (TUNEL). (AU)