Avaliação dos efeitos do óleo essencial de lippia sidoides na criopreservação de folículos pré-antrais inclusos em córtex ovariano bovino

Abstract

Cryopreservation of ovarian tissue is an important strategy for preserving fertility in mammals; however, its efficiency can be compromised by structural, cellular, and biochemical damage resulting from oxidative stress generated during the freezing and thawing processes. In this context, the present study aimed to evaluate the effects of different concentrations of Lippia sidoides essential oil on the viability of bovine cumulus cells, as well as during the vitrification of bovine ovarian tissue. Bovine cumulus cells were cultured in vitro with different concentrations of Lippia sidoides essential oil (4, 40, and 400 µg/mL), and cell viability was evaluated using the calcein-AM and ethidium homodimer-1 fluorescence assay. Bovine ovaries were collected at a local slaughterhouse, and fragments of the ovarian cortex were subjected to vitrification in the absence (vitrified control) or in the presence of L. sidoides essential oil at concentrations of 4, 40, and 400 µg/mL. After warming, the fragments were cultured in vitro for 24 hours at 38.5°C with 5% CO₂. Subsequently, ovarian tissue cell viability, morphological integrity and follicular activation, stromal cell density, extracellular matrix collagen content, and oxidative profile were evaluated through the activities of the antioxidant enzymes superoxide dismutase (SOD), catalase (CAT), glutathione peroxidase (GPX), and reduced thiol levels. The results demonstrated that the effects of L. sidoides essential oil were concentration-dependent. Concentrations of 4 and 40 µg/mL, especially 40 µg/mL, favoured the preservation of cumulus cell and ovarian tissue viability, follicular morphology and activation, ovarian stromal organisation, and redox balance after vitrification and in vitro culture. On the other hand, the concentration of 400 µg/mL did not promote additional benefits and was associated with a lower proportion of morphologically normal follicles and the absence of stimulation of follicular activation when compared to lower concentrations. It is concluded that L. sidoides essential oil, at a concentration of 40 µg/mL, has potential as an adjuvant agent in bovine ovarian tissue vitrification protocols, contributing to the structural and functional preservation of the tissue after warming.