scholarly journals 170 FOLLICULAR FLUID CONCENTRATION AND OOCYTE QUALITY FROM TOGGENBURG GOATS FED WITH UREA

2009 ◽  
Vol 21 (1) ◽  
pp. 184
Author(s):  
E. A. M. Amorim ◽  
L. S. Amorim ◽  
C. A. A. Torres ◽  
J. D. Guimãres ◽  
J. F. Fonseca ◽  
...  
Keyword(s):  
Follicular Fluid ◽  
Follicular Development ◽  
Cumulus Cells ◽  
Oocyte Quality ◽  
Urea Concentration ◽  
Follicular Aspiration ◽  
Randomized Design ◽  
Fluid Concentration

Protein and urea concentrations impair oocyte and embryo development in vivo and in vitro through an unclear mechanism. A possible way to understand this process is to determine the concentration of hormones and metabolites in follicular fluid associated with normal development. The objective of this study was to determine the effect of dietary urea levels on follicular fluid concentration of hormones and metabolites and oocyte quality. A trial was conducted with 9 nonpregnant and nonlactating Saanen goats, which had been distributed in a randomized design and fed with diets with 0 (n = 4) and 2.4% of urea in the total dry matter (DM) of the diet (n = 5). Before follicle aspiration by laparotomy, the goats were synchronized by inserting intravaginal sponges containing 60 mg of acetate medroxyprogesterone (Progespon®, Sintex) for 10 days followed by 125 μg of cloprostenol (Ciosin® Coopers) 48 h before the removal of the sponge. The sponge was removed immediately before the follicular aspiration. The follicular development was stimulated with 70 mg of NIH-FSH-P1 (Folltropin V® Vetrepharm) i.m., and 300 IU of eCG i.m., (Novormon® Sintex) given 36 h before the follicular aspiration. Fluid from the 2 lartest follicles of each ovary were analyzed to determine the concentration of estradiol, progesterone, and testosterone by quimioluminesence, and glucose and urea concentrations were measured by enzymatic kit. The other follicles in each ovary were aspired with new needles and syringes and the oocyte quality was recorded. Oocytes were classified according to cytoplasma aspect and number of granulosa cells: Class A (dark cytoplasm and uniform aspect) with 3 (AMG) and <3 layers of cumulus cells (AmG); class B (cytoplasm with color alterations, desuniform aspect and vacuoles) with 3 (BMG) and <3 layers of cumulus cells (BmG); number of partially denuded oocytes (PD) and number of denuded oocytes (DO). Data were analyzed by ANOVA and treatment difference separated by SNK test. Follicular fluid estradiol concentration was lower in goats fed with urea (4.02 ± 0.16; 4.97 ± 0.18 ng mL–1; P < 0.05), progesterone concentration did not differ between treatments (2.48 ± 0.58; 3.37 ± 0.52 ng mL–1; P > 0.05), testosterone concentration was lower in the control animals (1.17 ± 0.48; 3.20 ± 0.43 ng mL–1; P < 0.05). The glucose (91.44 ± 3.60; 84.78 ± 5.58 mg dL–1) and urea concentration (23.04 ± 1.06; 18.00 ± 2.35) were greater in the animals treated with 2.4% compared with 0% of urea (P < 0.05), respectively. The number of oocytes in the different categories was not affected by treatment (P > 0.05): AMG 1.20 ± 1.09 v. 0.50 ± 0.57, AmG 4.20 ± 2.16 v. 3.50 ± 3.10, BMG 0.40 ± 0.54 v. 0.25 ± 0.50, BmG 1.40 ± 0.54 v. 1.75 ± 1.25, DO 10.20 ± 3.76 v. 11.50 ± 5.44, in the 0 and 2.4% of urea groups respectively. Only the number of PD (1.60 ± 0.54 v. 3.50 ± 1.91) recovered from animals treated with 2.4% was greater than in controls (P < 0.05). The hormone and metabolites concentration in follicular fluid as well as the oocyte quality was affected by the urea concentration of the diet. Supported by grant from: CNPq, FAPEMIG, Shering Plough®, Tecnopec®, Carbogel®.

2 SPECIFIC FATTY ACID FOLLOW-UP REVEALS RUMEN-PROTECTED FAT SUPPLEMENTATION EFFECTS ON BOVINE OOCYTE QUALITY AND EMBRYO DEVELOPMENT

2014 ◽  
Vol 26 (1) ◽  
pp. 115 ◽  
Author(s):  
A. F. González-Serrano ◽  
C. R. Ferreira ◽  
V. Pirro ◽  
J. Heinzmann ◽  
K.-G. Hadeler ◽  
...  
Keyword(s):  
Fatty Acid ◽  
Palmitic Acid ◽  
Embryo Development ◽  
Follicular Fluid ◽  
Oocyte Quality ◽  
Lipid Profiles ◽  
Dependent Manner ◽  
Fat Supplementation

Information on how supplementation of high-yield dairy cows with rumen-protected fat affects fertility in cattle herds is scarce. Here, Holstein-Friesian heifers (n = 84) received a supplement consisting of either rumen-protected conjugated linoleic acid (CLA; cis-9,trans-11-CLA and trans-10,cis-12-CLA) or stearic acid 18 : 0 (SA) on top of an isocaloric grass silage diet. Two supplementation doses were used (100 and 200 g d–1). Blood and follicular fluid were collected at the start and end of the supplementation period for analysis of cholesterol, insulin-like growth factor (IGF), and nonesterified fatty acids (NEFA), and for fatty acid profiling. Although cholesterol, IGF, and NEFA levels did not differ among experimental groups, lipid profiles in blood and follicular fluid were affected in a dose-dependent manner by both supplements. After 45 days of supplementation, oocytes were collected by ovum pick-up (OPU). The mRNA relative abundance of target genes (IGF1r, GJA1, FASN, SREBP1, and SCAP) was analysed in single in vitro- (24 h IVM) and in vivo-matured (collected by OPU 20 h after GnRH injection) oocytes and in vitro-produced blastocysts (Day 8) by qPCR (n = 6/group). Lipid profiling of individual oocytes from the CLA-supplemented (n = 37) and the SA-supplemented (n = 50) was performed by desorption electrospray ionization mass spectrometry (DESI-MS). Oocytes from the CLA-supplemented (n = 413) and the SA-supplemented (n = 350) groups were used for assessing maturation and blastocysts development rates. In immature oocytes, CLA supplementation led to an increase of triacylglycerol 52 : 3 [TAG (52 : 3)] and TAG (52 : 2), squalene, palmitic acid 16 : 0, and oleic acid 18 : 1, and decreased abundance of TAG (56 : 3), TAG (50 : 2) and TAG (48 : 1). In vitro-matured oocytes showed different lipid profiles, with increased abundances of TAG (52 : 3), and TAG (52 : 2) as well as phosphatidylinositol 34 : 1 [Plo (34 : 1)], whereas phosphatidylglycerol (34 : 1) [PG (34 : 1)] and palmitic acid 16 : 0 were less abundant in in vitro-matured oocytes. SCAP was significantly down-regulated in in vitro-matured oocytes from supplemented heifers compared with their in vivo-matured counterparts. Maturation (CLA = 74% v. SA = 67%) and blastocyst rates (CLA = 22.4% v. SA = 12.7%) were different among experimental groups. One-way ANOVA and the Tukey-Kramer test were applied for a multiple comparison of means (P-value ≤ 0.05 was considered as statistically significant). In conclusion, we demonstrate here that fatty acid monitoring along different compartments (i.e. blood system, follicular fluid, and intra-oocyte) after rumen-protected fat supplementation of dairy heifer diet reveals nutritional footprints on oocyte quality and embryo development. These results demonstrate the close relationship between nutrition and cattle herd's fertility and, at the same time, support the role of the bovine model for understanding nutritional-dependent fertility impairments.

188 IMPROVEMENT OF IN VITRO CANINE OOCYTE MATURATION BY OVIDUCTAL SECRETOME

2017 ◽  
Vol 29 (1) ◽  
pp. 202 ◽  
Author(s):  
A. Lange-Consiglio ◽  
C. Perrini ◽  
P. Esposti ◽  
F. Cremonesi
Keyword(s):  
Oocyte Maturation ◽  
In Vitro Maturation ◽  
Cumulus Cell ◽  
Follicular Development ◽  
Cumulus Cells ◽  
Chi Square ◽  
Cell Layers ◽  
Hoechst Staining

The in vitro maturation of canine oocyte is problematic because it is difficult to reproduce the oviducal microenvironment where the in vivo maturation occurs. Because cells are able to communicate with each other by paracrine action, oviducal cells could be in vitro cultivated to obtain the conditioned medium (CM) consisting of soluble factors and microvesicles (MV), which represent a carrier for nonsoluble molecules including microRNA. The aim of the present work was to investigate the effect of the addition of CM or MV, secreted by oviducal cells, to the canine in vitro maturation medium. To generate CM, cells from oviducts of 3 animals in late oestrus were cultured for 5 days at 38.5°C in a humidified atmosphere of 5% CO2. Supernatants were collected, pooled, centrifuged at 2500 × g, and stored at −80°C. Microvesicles were obtained by ultracentrifugation of CM at 100,000 × g for 1 h at 4°C and measured for concentration and size by a Nanosight instrument. Ovaries were obtained from 50 healthy domestic bitches (1–4 years old) of different breeds that underwent ovariectomy regardless of the oestrous cycle. Cumulus-oocyte complexes were released by slicing the ovarian cortex with a scalpel blade, and only Grade 1 cumulus-oocyte complexes (darkly granulated cytoplasm and surrounded by 3 or more compact cumulus cell layers) 110 to 120 µm in diameter were selected for culture. Maturation was performed at 38.5°C in a humidified atmosphere of 5% CO2 and 5% of O2 in bi-phasic systems: 24 h in SOF with 5.0 μg mL−1 of LH followed by 48 h in SOF supplemented with 10% of oestrous bitch serum and 10% CM or 50, 75, 100, or 150 × 106 MV mL−1 labelled with PKH-26. Control was the same medium without CM or MV. Oocytes were observed under a fluorescent microscope to detect metaphase II (MII), by Hoechst staining, and the incorporation of MV. Statistical analysis was performed by chi-square test. Results show that canine oviducal cells secreted MV of 234 ± 23 nm in size, underling that these MV fall within the shedding vesicles category. The incorporation of labelled MV occurred at first in cumulus cells, at 48 h of maturation, and then, at 72 h, in oocyte cytoplasm. These MV had a positive effect on maturation rate (MII) at the concentration of 75 and 100 × 106 MV mL−1 compared with CM and control (20.34 and 21.82 v. 9.09 and 3.95%, respectively). The concentration of 150 × 106 MV mL−1 provided only 9.26% of MII. To understand the role of MV, we assessed the expression of 3 microRNA (miRNA-30b, miR-375, and miR-503) that are involved in some key pathways (WNT, MAPK, ERbB, and TGFβ) regulating follicular development and meiotic resumption. The lower rate of MII with the higher concentration of MV is possibly due to the high level of miR-375, which recent literature shows to suppress the TGFβ pathway, leading to impaired oocyte maturation. In conclusion, the oviducal MV, or specific microRNA, are involved in cellular trafficking during oocyte maturation, and their possible use in vitro could facilitate the exploitation of canine reproductive biotechnologies.

Effect of butafosfan supplementation during oocyte maturation on bovine embryo development

Zygote ◽  
2019 ◽  
Vol 27 (05) ◽  
pp. 321-328
Author(s):  
Lucas Teixeira Hax ◽  
Joao Alveiro Alvarado Rincón ◽  
Augusto Schneider ◽  
Lígia Margareth Cantarelli Pegoraro ◽  
Letícia Franco Collares ◽  
...  
Keyword(s):  
Gene Expression ◽  
Embryo Development ◽  
Oocyte Maturation ◽  
Cumulus Cells ◽  
Oocyte Quality ◽  
Bovine Embryo ◽  
Cleavage Rate ◽  
Nuclear Maturation

SummaryAround 60–80% of oocytes maturated in vivo reached competence, while the proportion of maturation in vitro is rarely higher than 40%. In this sense, butafosfan has been used in vivo to improve metabolic condition of postpartum cows, and can represent an alternative to increase reproductive efficiency in cows. The aim of this study was to evaluate the addition of increasing doses of butafosfan during oocyte maturation in vitro on the initial embryo development in cattle. In total, 1400 cumulus–oocyte complexes (COCs) were distributed in four groups and maturated according to supplementation with increasing concentrations of butafosfan (0 mg/ml, 0.05 mg/ml, 0.1 mg/ml and 0.2 mg/ml). Then, 20 oocytes per group were collected to evaluate nuclear maturation and gene expression on cumulus cells and oocytes and the remaining oocytes were inseminated and cultured until day 7, when blastocysts were collected for gene expression analysis. A dose-dependent effect of butafosfan was observed, with decrease of cleavage rate and embryo development with higher doses. No difference between groups was observed in maturation rate and expression of genes related to oocyte quality. Our results suggest that butafosfan is prejudicial for oocytes, compromising cleavage and embryo development.

Glycosaminoglycan-bound and free inter-α-trypsin inhibitor components of follicular fluid

Zygote ◽  
2001 ◽  
Vol 9 (4) ◽  
pp. 283-288 ◽  
Author(s):  
Lars Ødum ◽  
Torben E. Jessen ◽  
Claus Yding Andersen
Keyword(s):  
Extracellular Matrix ◽  
Trypsin Inhibitor ◽  
Follicular Fluid ◽  
Normal Female ◽  
Heavy Chains ◽  
Rate Limiting Step ◽  
Fluid Concentration ◽  
Rate Limiting

The proteinase inhibitor inter-α trypsin inhibitor (ITI) is a blood-derived protein necessary for normal female fertility. Absence of ITI leads to ovulation of naked oocytes that cannot fertilise. ITI consists of two heavy chains (ITI-HC) and bikunin linked by a chrondroitin sulphate. By binding to hyaluronate, ITI-HC stabilises the extracellular matrix, but ITI-HC also binds to proteoglycans in follicular fluid. In vivo concentrations of ITI components in preovulatory follicular fluid, free as well as bound to hyaluronate or proteoglycan, are unknown. In order to quantify these components, 58 follicular fluids and 13 blood samples were collected in connection with in vitro fertilisation and embryo transfer treatment of 13 women. Quantitation of glycosaminoglycan-bound ITI-HC was performed after separation from free ITI in agarose gel. ITI components were determined by immunoelectrophoresis and hyaluronate by an ELISA method. The follicular fluid concentration of ITI was on average 70% of that in plasma and the concentration of hyaluronate remained low despite follicular production, suggesting that the production of hyaluronate is the rate-limiting step in the formation of the extracellular matrix of the oocyte-cumulus complex. In follicular fluid, the concentration of free ITI-HC was higher than that of glycosaminoglycan-bound ITI-HC. Addition of exogeneous hyaluronate doubled the amount of hyaluronate-bound ITI-HC, further supporting the notion that ITI in follicular fluid is not rate-limiting for cumulus expansion in vivo.

Immunisation against inhibin enhances follicular development, oocyte maturation and superovulatory response in water buffaloes

2011 ◽  
Vol 23 (6) ◽  
pp. 788 ◽  
Author(s):  
D. R. Li ◽  
G. S. Qin ◽  
Y. M. Wei ◽  
F. H. Lu ◽  
Q. S. Huang ◽  
...  
Keyword(s):  
Oocyte Maturation ◽  
Plasma Concentrations ◽  
Follicular Development ◽  
Oocyte Quality ◽  
Control Group ◽  
High Group ◽  
Α Subunit ◽  
And Control

This study was carried out to test the feasibility of enhancing embryo production in vivo and in vitro by immunoneutralisation against inhibin or follistatin. In Experiment 1, multi-parity buffaloes were assigned into three groups: High group (n = 8), which received one primary (2 mg) and two booster (1 mg) vaccinations (28-day intervals) with a recombinant inhibin α subunit in 1 mL of white oil adjuvant; Low group (n = 8), which received half that dose; and Control group (n = 7), which received only adjuvant. Immunisation against inhibin stimulated development of ovarian follicles. Following superovulation and artificial insemination, inhibin-immunised buffaloes had more developing follicles than the Control buffaloes. The average number of embryos and unfertilised ova (4.5 ± 0.6, n = 6) in the High group was higher (P < 0.05) than in the Control group (2.8 ± 0.6, n = 5) and was intermediate (4.1 ± 0.7, n = 7) in the Low group. The pooled number of transferable embryos of the High and Low groups (3.2 ± 0.5, n = 13) was also higher (P < 0.05) than that (1.6 ± 0.7, n = 5) of the controls. The immunised groups also had higher plasma concentrations of activin, oestradiol and progesterone. In Experiment 2, the addition of anti-inhibin or anti-follistatin antibodies into buffalo oocyte IVM maturation medium significantly improved oocyte maturation and cleavage rates following parthenogenic activation. Treatment with anti-follistatin antibody also doubled the blastocyst yield from activated embryos. These results demonstrated that immunisation against inhibin stimulated follicular development, enhanced oocyte quality and maturation competence, yielded more and better embryos both in vivo and in vitro.

176 IN VITRO MATURATION OF DOG OOCYTES IN CANINE FOLLICULAR FLUID

2014 ◽  
Vol 26 (1) ◽  
pp. 202
Author(s):  
K. Reynaud ◽  
S. Canguilhem ◽  
S. Thoumire ◽  
S. Chastant-Maillard
Keyword(s):  
Follicular Fluid ◽  
In Vitro Maturation ◽  
Assisted Reproductive Technologies ◽  
Cumulus Cells ◽  
Reproductive Technologies ◽  
Control Group ◽  
Limiting Factor ◽  
Cytoplasmic Maturation

In the canine species, assisted reproductive technologies, especially in vitro maturation (IVM) and IVF, are still ineffective. The main limiting factor remains the immaturity of the oocytes collected from anestrus ovaries. The ability of an oocyte to reach the MII stage in vitro is linked to the diameter of its follicle and anestrus oocytes, collected from small (<1 mm) follicles, are profoundly immature (De Lesegno et al. 2008). The objective of this study was to improve cytoplasmic quality by mimicking in vivo conditions; that is, to test the effect of pure preovulatory follicular fluid (FF) on survival and IVM rates of anestrus dog oocytes, in order to improve the nuclear and cytoplasmic maturation of these immature oocytes. Follicular fluids samples were collected from 54 Beagle bitches at 2 stages: before the LH peak (n = 23 bitches) and after the LH peak (n = 31 bitches). Only follicular fluid samples from large (>4 mm) follicles were collected and pooled by stage. Control oocytes were matured in 20% FCS/M199 medium. Groups of 5 oocytes were in vitro matured in 30 μL of follicular fluid, in half-area 96-well plates (5% CO2, 38°C). After 72 h of IVM, oocytes were denuded, fixed, and stained for DNA and tubulin before observation by confocal microscopy, and nuclear stages were classified as GV-A to GV-E, MI, and MII (Reynaud et al. 2012). A total of 460 oocytes were collected from 13 anestrus bitches and allocated to either the control medium (n = 155), the Pre-LH FF (n = 145) or the Post-LH FF (n = 160) groups. After 72 h of IVM, the morphology of the cumulus–oocyte complexes (COC) in the post-LH group was different from that of the others: cumulus cells appeared more compact and darker. Analysis of the nuclear stages showed that the degeneration rate was significantly higher (P < 0.05) in the post-LH group (58.7%) than in the pre-LH (40.9%) or in the control group (34.4%). No significant differences (P > 0.05) were observed between the 3 groups in the rate of immature GVA-B oocytes (36.4, 28.5, and 25.3% in the control, Pre-LH, and Post-LH groups, respectively), in the rate of meiotic resumption (GV-C/D/E, MI, MII stages, 44.4, 51.9, and 38.7% in the control, Pre-LH, and Post-LH groups, respectively). Metaphase II rates were not significantly different (12.1, 8.6, and 4.8% in the control, Pre-LH, and Post-LH groups, respectively). In conclusion, canine COC may survive when exposed to IVM in pure follicular fluid, but the degeneration rate was higher in the post-LH group. The presence of follicular fluid did not inhibit meiosis resumption, but did not significantly improve IVM rates. To better mimic in vivo conditions, IVM in a sequence of media, such as IVM in follicular fluid followed by IVM in oviducal fluid remains to be tested.

174 Follicular fluid extracellular vesicles obtained from Holstein cows kept under thermoneutral or heat stress conditions modify gene expression of in vitro-matured oocytes

2019 ◽  
Vol 31 (1) ◽  
pp. 211
Author(s):  
F. M. Dalanezi ◽  
R. A. Ferrazza ◽  
J. C. Ochoa ◽  
H. D. Mogllón ◽  
F. C. Destro ◽  
...  
Keyword(s):  
Gene Expression ◽  
Heat Stress ◽  
Follicular Fluid ◽  
Cumulus Cells ◽  
Oocyte Quality ◽  
Holstein Cows ◽  
Dna Integrity ◽  
Meiotic Progression ◽  
Expression Of Genes

Heat stress (HS) has a massive impact on bovine reproduction. In cows, some of these deleterious effects involve follicular development and oocyte quality. Extracellular vesicles (EV) secreted by granulosa cells play a critical role in the intrafollicular environment by directly influencing cumulus cells and oocyte functions. The objective of this study was to investigate the effect of follicular fluid EV obtained from Holstein cows kept under thermoneutral (TN) or HS conditions, on in vitro bovine oocyte maturation. Non-lactating Holstein cows were synchronized with the Ovsynch protocol and also received an intravaginal progesterone device. From ovulation day (Day 1), cows were randomly assigned to TN (26°C, 73% humidity; n=12) or HS (36°C, 70% humidity; n=12) environments. On Day 9, 2 follicles (F1 and F2) were individually aspirated and all remained follicles were ablated. Then, on Day 14, newly formed F1 and F2 were also aspirated. Follicular fluid from all follicles from each treatment was pooled and EV were obtained according to Silveira et al. (2017 PLoS One 12, 1-25) and diluted in PBS (100μL of PBS per mL of follicular fluid centrifuged). Pools of 20 cumulus-oocyte complexes (COC) grade 1 or 2 (Stojkovic et al. Biol Reprod 200164, 904-992], predominantly from Bos indicus, were submitted to the following treatment groups: Control (n=4): matured in 90μL of TCM-199 with Eagles’ salts, glutamine, NaHCO3, pyruvate, amikacin, and FSH (base medium); TN (n=4): matured in 81μL of base medium+9μL of TN EV suspension; and HS (n=4): matured in 81μL+9μL of HS EV suspension. All treatments were carried out at 38.5°C for 24h in a humid atmosphere with 5% CO2. After 24h of maturation, COC were evaluated for meiotic progression (Hoechst 33342 stain), DNA integrity (TUNEL stain), and expression of genes related to oocyte quality (TaqMan assay, Applied Biosystems/Thermo Fisher Scientific, Waltham, MA, USA). Results were analysed using ANOVA followed by Tukey post hoc test (P&lt;0.05). When the experimental groups were compared with the control group, there was no treatment effect on meiotic progression, DNA integrity, or gene expression of cumulus cells. In the oocytes of the TN group, the genes HSF1, IGFBP2, BMP15, GDF9, CDCA8, HAS2, RPL15, STAT3,and PFKP were less expressed. We concluded that oocytes matured in the presence of EV from follicular fluid of cows kept under TN conditions had lesser expression of genes related to oocyte quality. This study was supported by FAPESP (Grant #2012/18297-7) and CAPES Foundation of Brazil.

Ultrastructure of Baboon Zygotes Produced By Microinjection of Spermatozoa

1985 ◽  
Vol 43 ◽  
pp. 650-651
Author(s):  
T. Caceci ◽  
A.A. Shaikh ◽  
D.C. Kraemer
Keyword(s):  
Polar Body ◽  
Follicular Development ◽  
Male And Female ◽  
Menstrual Cycles ◽  
Follicular Aspiration ◽  
First Polar Body ◽  
Preovulatory Follicles ◽  
Lh Release

Five baboons were treated during seven menstrual cycles with 5.0 mg of FSH-P for five days, starting on either day 3 or day 5 of the cycle. On day 5 of the treatment, the ovaries were examined by laparoscopy to evaluate follicular development. All animals exhibited multiple preovulatory follicles and at that time 100 mg GnRH was administered intramuscularly to induce LH release. Between 24 and 30 hours after injection of GnRH, laparoscopic follicular aspiration was used to collect oocytes. These were matured in vitro (determined by extrusion of the first polar body) and fertilized by microinjection with frozen-thawed baboon spermatozoa. Male and female pronuclei were observed in 32% of the resulting zygotes within 24 hours. These zygotes were compared to a zygote in the same stage that had been fertilized in vivo and obtained by laparoscopy and flushing of the oviduct.

scholarly journals An intercellular pathway for glucose transport into mouse oocytes

2012 ◽  
Vol 302 (12) ◽  
pp. E1511-E1518 ◽  
Author(s):  
Qiang Wang ◽  
Maggie M. Chi ◽  
Tim Schedl ◽  
Kelle H. Moley
Keyword(s):  
Gap Junctions ◽  
Glucose Uptake ◽  
Glucose Transport ◽  
High Glucose ◽  
Mammalian Cells ◽  
Cumulus Cells ◽  
Oocyte Quality ◽  
Intercellular Pathway

Glucose is an essential nutrient for mammalian cells. Emerging evidence suggests that glucose within the oocyte regulates meiotic maturation. However, it remains controversial as to whether, and if so how, glucose enters oocytes within cumulus-oocyte complexes (COCs). We used a fluorescent glucose derivative (6-NBDG) to trace glucose transport within live mouse COCs and employed inhibitors of glucose transporters (GLUTs) and gap junction proteins to examine their distinct roles in glucose uptake by cumulus cells and the oocyte. We showed that fluorescent glucose enters both cumulus-enclosed and denuded oocytes. Treating COCs with GLUT inhibitors leads to simultaneous decreases in glucose uptake in cumulus cells and the surrounded oocyte but no effect on denuded oocytes. Pharmacological blockade of of gap junctions between the oocyte and cumulus cells significantly inhibited fluorescent glucose transport to oocytes. Moreover, we find that both in vivo hyperglycemic environment and in vitro high-glucose culture increase free glucose levels in oocytes via gap junctional channels. These findings reveal an intercellular pathway for glucose transport into oocytes: glucose is taken up by cumulus cells via the GLUT system and then transferred into the oocyte through gap junctions. This intercellular pathway may partly mediate the effects of high-glucose condition on oocyte quality.

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