Follicle-stimulating hormone mediates the consumption of serum-derived glycogen by bovine cumulus-oocyte complexes during in vitro maturation

Abstract

Background and Aim: Oocyte in vitro maturation (IVM) is an appealing approach for several assisted reproductive technologies and dissecting oocyte maturation. Nonetheless, IVM leads to lower developmental competence and usually relies on undefined, serum-containing media. Therefore, biochemical profiling aimed to explore fluctuations in IVM media content during the acquisition of oocyte developmental competence. Materials and Methods: Bovine cumulus-oocyte complexes (COCs) underwent IVM in TCM199 medium with Earle's salts, supplemented with 2.0 mM L-glutamine, 10% fetal bovine serum, antibiotics, and 0.05 IU/mL porcine follicle-stimulating hormone (FSH+) or vehicle control (CTL) medium for 22 h. Results: FSH withdrawal (CTL) diminished several processes associated with the acquisition of oocyte developmental competence, such as reduced cumulus cell expansion, diminished estradiol synthesis (FSH+: 116.0±0.0 pg/mL vs. CTL: 97.6±18.0 pg/mL), and lower oocyte nuclear maturation rate (FSH+: 96.47% vs. CTL: 88.76%). Fresh media formulations (i.e., TCM199 with FSH or vehicle) were indistinguishable under biochemical profiling threshold conditions. Biochemical profiling showed similar total protein and lipid concentrations between groups. Further, total sugar concentrations diminished from fresh media to their post-IVM counterparts, albeit in an FSH-independent manner. Glycogen concentrations remained unaltered after IVM within CTL media, albeit were substantially lower after IVM under FSH+ conditions. Conclusion: FSH mediates the consumption of serum-derived glycogen by bovine COCs during IVM and implies that serum-free media should contain increased glucose concentrations to facilitate the acquisition of oocyte developmental competence.

MYC integrates FSH signalling networks in cumulus cells during bovine oocyte maturation

“…1). Hallmarks of FSH-mediated effects were absent under CTL conditions (e.g., lower nuclear maturation efficiency, diminished expansion of CCs), which were described elsewhere (Cantanhêde et al, 2021). Therefore, these results validated the experimental design at the cellular level in this previous study.…”

“…These procedures were carried out as described by Cantanhêde et al (2021). Ovaries were collected at a local slaughterhouse (Caruaru, Pernambuco, Brazil) and transported in saline solution (0.9% NaCl) containing 10 mg mL À1 penicillin and streptomycin (Gibco) at 35 8C.…”

The follicle-stimulating hormone triggers rapid changes in mitochondrial structure and function in porcine cumulus cells

“…FSH is required for oocyte maturation and developmental competence within the ovarian follicule 14 . The supplementation of FSH in the IVM medium induces important metabolic changes in cumulus cells, including steroid synthesis, glucose uptake, and glycogen consumption 29 , 30 . To determine how FSH affects mitochondrial response, we first determined mitochondrial structure in COCs (10 COCs by replicate for each culture condition, n = 3) incubated for different times in the absence or presence of FSH (at 0.01 µg/ml which has been optimized for cumulus cells expansion and the percentage of meiotic resumption measured as germinal vesicle breakdown (GVBD)) 31 .…”

“…FSH is already known as a cumulus cell metabolic regulator 23 , 47 , 50 . It has been observed that FSH stimulates serum-derived glycogen consumption in bovine COCs during IVM 30 . In mouse and cow COCs, FSH induces high glucose consumption as well as elevated lactate production 51 , 52 .…”