Grape Residue Extract Improves Mitochondrial Function and Promotes Sheep Oocyte Meiotic Resumption from In vitro-Grown Secondary Follicles

Oxidative stress resulting from the inherent conditions of in vitro culture can compromise oocyte quality. In this regard, there is a growing interest in the use of natural products to prevent oxidative damage and to promote in vitro follicular development. This study was conducted to evaluate the effects of the addition of acidified extract of grape industrial residue (Vitis vinifera cv. Syrah) as a supplement to the base medium for in vitro culture of isolated sheep secondary follicles. Secondary follicles were isolated and cultured for 12 days in α-MEM⁺ (control medium) or in α-MEM⁺ supplemented with different grape residue extract concentrations (0.1, 0.2, or 0.4 mg/ml). Follicular morphology, antrum formation, follicular and oocyte diameter, glutathione (GSH) levels, mitochondrial activity, DNA fragmentation and meiotic resumption were evaluated. After 12 days of culture, there was no difference (P >0.05) among the treatments in relation to morphology, antral cavity formation, follicular diameter, DNA fragmentation and the percentage of fully grown oocytes (≥ 110 µm). Furthermore, the GSH levels were similar (P >0.05) among the α-MEM⁺, 0.2, and 0.4 mg/ml grape residue extract groups at the end of culture. Nevertheless, oocytes from secondary follicles cultured in 0.4 mg/ml grape residue extract showed higher (P <0.05) mitochondrial activity and greater meiotic resumption than oocytes cultured in the control medium. In conclusion, supplementation with 0.4 mg/ml grape residue extract maintained survival, improved mitochondrial activity, and promoted the meiotic resumption of oocytes from sheep secondary follicles cultured in vitro.

Keywords:
Antioxidant; In vitro culture; Ovine; Preantral follicle; Oxidative stress.

Grape residue extract maintains survival, follicular development and GSH levels.

Grape residue extract (0.4 mg/mL) improves mitochondrial activity.

Grape residue extract (0.4 mg/mL) promotes meiotic resumption.

Grape extract can be an alternative supplement for the in vitro oocyte development.