Nicotinamide Supplementation during the In Vitro Maturation of Oocytes Improves the Developmental Competence of Preimplantation Embryos: Potential Link to SIRT1/AKT Signaling

Abstract

Nicotinamide (NAM), the amide form of vitamin B3, plays pivotal roles in regulating various cellular processes including energy production and maintenance of genomic stability. The current study aimed at deciphering the effect of NAM, when administered during in vitro maturation (IVM), on the developmental competence of bovine preimplantation embryos. Our results showed that low NAM concentrations reduced the oxidative stress and improved mitochondrial profile, total cleavage and 8–16 cell stage embryo development whereas the opposite profile was observed upon exposure to high NAM concentrations (10 mM onward). Remarkably, the hatching rates of day-7 and day-8 blastocysts were significantly improved under 0.1 mM NAM treatment. Using RT-qPCR and immunofluorescence, the autophagy-related (Beclin-1 (BECN1), LC3B, and ATG5) and the apoptotic (Caspases; CASP3 and 9) markers were upregulated in oocytes exposed to high NAM concentration (40 mM), whereas only CASP3 was affected, downregulated, following 0.1 mM treatment. Additionally, the number of cells per blastocyst and the levels of SIRT1, PI3K, AKT, and mTOR were higher, while the inner cell mass-specific transcription factors GATA6, SOX2, and OCT4 were more abundant, in day-8 embryos of NAM-treated group. Taken together, to our knowledge, this is the first study reporting that administration of low NAM concentrations during IVM can ameliorate the developmental competence of embryos through the potential regulation of oxidative stress, apoptosis, and SIRT1/AKT signaling.

Melatonin Alleviates the Toxicity of High Nicotinamide Concentrations in Oocytes: Potential Interaction with Nicotinamide Methylation Signaling

“…The antioxidant activity of melatonin during the process of embryonic development has been comprehensively studied, whereas the impact of high NAM concentrations on such developmental process has been fewly reported [6,7,13,18,38]. To date, the potential linkage between melatonin and NAM in the context of embryo development has not yet been clarified.…”

“…Oocyte Maturation and Actin Stabilization. We have previously reported that high NAM concentrations can negatively affect the process of embryo development [13]. To investigate whether melatonin can alleviate this effect, bovine oocytes were treated with 20 mM NAM for 22 h in the presence and absence of 10 −7 M melatonin.…”

“…On the other hand, nicotinamide (NAM), a water soluble form of niacin (vitamin B3), is a dietary supplement that controls several conditions and diseases including cell survival, inflammations, cancer, and metabolic disorders [12]. Supplementation of NAM at low concentrations during in vitro maturation (IVM) significantly improved the developmental competence of oocytes and embryos [13]. However, exposure to high NAM concentrations has shown many adverse effects comprising obesity, liver toxicity, growth inhibition, DNA damage, risk of thrombocytopenia, epigenetic modifications, and cancer progression [14][15][16][17].…”

“…However, exposure to high NAM concentrations has shown many adverse effects comprising obesity, liver toxicity, growth inhibition, DNA damage, risk of thrombocytopenia, epigenetic modifications, and cancer progression [14][15][16][17]. Moreover, it induced apoptosis, spindle defects, and mitochondrial dysfunction that significantly interfered with the developmental competence of oocytes and embryos, albeit the cellular signaling pathways regulating these adverse effects have not been entirely elucidated [13,18,19]. According to the global NAM market report in 2017, the consumption rate of NAM has increased by 30% [17].…”

Induction of Oxidative Stress and Mitochondrial Dysfunction by Juglone Affects the Development of Bovine Oocytes

“…The COCs were collected and cultured, as previously mentioned [ 50 ]. Briefly, COCs, aspirated from ovarian follicles using 18-gauge needles connected to 50 mL tubes containing TL-HEPES, were washed, and those comprising more than three cumulus layers were collected under a stereomicroscope (Olympus SZ51, Tokyo, Japan), washed three times in TL-HEPES, and cultured (around 50 COCs per well) in four-well plates containing 700 μL IVM medium (TCM-199 supplemented with 10% ( v/v ) fetal bovine serum (FBS), 10 μg/mL follicle-stimulating hormone (FSH), 1 μg/mL estradiol-17β, 0.2 mM sodium pyruvate, 10 ng/mL epidermal growth factor (EGF), 0.6 mM cysteine, 0.1 mg/mL streptomycin, and 100 IU/mL penicillin), in the absence or the presence of juglone (12.5, 25.0, and 50.0 μM) at 38.5 °C and 5% CO 2 for 22 h. Checking the literature for juglone in vitro studies revealed that it could be used at concentrations in the range of 1.0–100.0 µM [ 25 , 30 ].…”