85 The effects of heat exposure on the growth and developmental competence of oocytes derived from early antral follicles in dairy cows

2021 ◽  
Vol 33 (2) ◽  
pp. 150
Author(s):  
K. Kawano ◽  
K. Sakaguchi ◽  
E. Furukawa ◽  
M. Chelenga ◽  
Y. Yanagawa ◽  
...  
Keyword(s):  
Heat Stress ◽  
Heat Shock ◽  
Dairy Cows ◽  
Shock Group ◽  
Developmental Competence ◽  
Control Group ◽  
Oocyte Competence ◽  
Antral Follicles ◽  
Nuclear Maturation ◽  
Summer Heat

Summer heat stress in dairy cows impairs the developmental competence of oocytes from antral follicles (2–8mm) which are used in conventional IVM and IVF systems. Moreover, summer heat stress is considered to impair the oocyte competence derived from smaller follicles; therefore, the impairment of oocyte competence possibly continues into the cooler autumn season. To investigate the thermosensitivity of early antral follicles (<1mm), we evaluated the effects of heat exposure on the growth and developmental competence of oocytes using invitro culture of oocyte–cumulus-granulosa complexes (OCGCs) derived from early antral follicles. OCGCs (n=315) were collected from early antral follicles (0.5–1mm) and cultured for 12 days. OCGCs in the heat shock group were cultured using a temperature cycle of 38.5°C for 5h, 39.5°C for 5h, 40.5°C for 5h, and 39.5°C for 9h, whereas those in the control group were cultured at a constant temperature of 38.5°C for 24h. The diameters of oocytes were measured before culture. Half of the culture medium was replaced every 4 days. Oestradiol-17β (E2) and progesterone (P4) production during the first, second, and third 4-day periods were measured by enzyme immunoassay; the viability of OCGCs was evaluated based on their morphology. Oocytes that survived after 12 days of culture (n=191) were subjected to IVM (38.5°C, 22h); their diameter and nuclear status were evaluated. Some oocytes (n=71) were subjected to IVF (38.5°C, 18h) and embryo culture (39.0°C, 150h). Cleavage and blastocyst rates were evaluated at 48h and 168h after IVF. Effects of treatment groups and culture periods on E2 and P4 production and diameters of oocytes were evaluated by two-way ANOVA followed by Tukey-Kramer or Student’s t-test. The viability of OCGCs, nuclear maturation, cleavage and blastocyst rates between two groups were compared by the chi-squared or Fisher’s exact test. E2 and P4 production and the viability of OCGCs were not different between the 2 groups. Although mean oocyte diameters before culture did not differ between the 2 groups, the mean diameters after IVM were significantly smaller in the heat shock group (108.0µm, n=56) than in the control group (111.7µm, n=61; P<0.05). The nuclear maturation rate in the heat shock group (36.4%, n=55) was significantly lower than in the control group (60.3%, n=58; P<0.05). Cleavage rates were similar between the control (54.5%, n=33) and heat shock groups (45.7%, n=35). However, no oocytes developed to blastocysts in the heat shock group (0%, n=35), whereas 30.3% (n=33) oocytes developed to blastocysts (cell number±s.d.; 92.4±28.4) in the control group (P<0.05). These findings suggest that summer heat stress in dairy cows impairs the growth, nuclear maturation, and developmental competence of oocytes derived from early antral follicles. This experimental model could be used to explore the mechanisms by which heat stress subsequently impairs oocyte competence during the cooler autumn season.

The effects of cysteine addition during in vitro maturation on the developmental competence, ROS, GSH and apoptosis level of bovine oocytes exposed to heat stress

Zygote ◽  
2011 ◽  
Vol 20 (3) ◽  
pp. 249-259 ◽  
Author(s):  
Hisashi Nabenishi ◽  
Hiroshi Ohta ◽  
Toshihumi Nishimoto ◽  
Tetsuo Morita ◽  
Koji Ashizawa ◽  
...  
Keyword(s):  
Heat Stress ◽  
Formation Rate ◽  
Cumulus Cells ◽  
Developmental Competence ◽  
Control Group ◽  
Blastocyst Formation ◽  
Nuclear Maturation ◽  
Maturation Medium ◽  
Bovine Oocytes

SummaryIn the present study, we investigated the effects of various concentrations of cysteine (0.0, 0.6, 1.2 and 1.8 mM) added to the maturation medium on nuclear maturation and subsequent embryonic development of bovine oocytes exposed to heat stress (HS: set at 39.5 °C for 5 h, 40.0 °C for 5 h, 40.5 °C for 6 h, and 40.0 °C for 4 h versus 38.5 °C for 20 h as the control group). This regime mimicked the circadian rhythm of the vaginal temperature of lactating dairy cows during the summer season in southwestern Japan. Moreover, we also evaluated the oocyte's reactive oxygen species (ROS) and glutathione (GSH) levels and the apoptosis levels of the oocytes and cumulus cells in the presence or absence of 1.2 mM cysteine. As a result, HS in the without-cysteine group significantly suppressed (p < 0.05) both the nuclear maturation rate up to the metaphase (M)II stage and the blastocyst formation rate compared with that of the control group. In addition, this group showed significantly higher (p < 0.05) ROS levels and significantly lower (p < 0.05) GSH levels than those of the control group. Moreover, the level of TdT-mediated dUTP nick end labelling (TUNEL)-positive cumulus cells in the HS without-cysteine group was significantly higher (p < 0.05) than that of the control group. However, the addition of 1.2 mM cysteine to the maturation medium restored not only the nuclear maturation, blastocyst formation rates and GSH contents, but also increased the ROS and TUNEL-positive levels of the cumulus cells, but not oocytes, to that of the control group. These results indicate that the addition of 1.2 mM cysteine during in vitro maturation (IVM) may alleviate the influence of heat stress for oocyte developmental competence by increasing GSH content and inhibiting the production of oocyte ROS followed by apoptosis of cumulus cells.

scholarly journals Protective Effects of Inorganic and Organic Selenium on Heat Stress in Bovine Mammary Epithelial Cells

2019 ◽  
Vol 2019 ◽  
pp. 1-10 ◽  
Author(s):  
Yixuan Zou ◽  
Juanjuan Shao ◽  
Yongxin Li ◽  
F.-Q. Zhao ◽  
Jian-Xin Liu ◽  
...  
Keyword(s):  
T Cells ◽  
Heat Stress ◽  
Heat Shock ◽  
Dairy Cows ◽  
T Antigen ◽  
Mammary Epithelial ◽  
Economic Losses ◽  
Control Group ◽  
Protective Effects ◽  
Alveolar Cells

When dairy cows are exposed to high-temperature environment, their antioxidant capacity and productive performance decrease, leading to economic losses. Emerging evidence has shown that selenium (Se) can effectively alleviate heat stress in dairy cows; however, the cellular mechanism underlying this protection is not clear. The purpose of this study was to investigate and compare the protective effects of inorganic Se (sodium selenite, SS) and organic Se (selenite methionine, SM) in MAC-T (mammary alveolar cells-large T antigen, a bovine mammary epithelial cell (BMEC) line) cells during heat stress. MAC-T cells were treated in 4 ways unless otherwise described: (i) cells in the heat treatment (HT) group were cultured at 42.5°C for 1 h and then recovered in 37°C for another 12 h; (ii) the SM group was pretreated with organic Se for 2 h, cultured at 42.5°C for 1 h, and then recovered in 37°C for 12 h; (iii) the SS group was treated similarly to the SM group except that the cells were pretreated with inorganic Se instead of organic Se; and (iv) the control group was continuously cultured in 37°C and received no Se treatment. The results showed that heat shock at 42.5°C for 1 h triggered heat shock response, sabotaged the redox balance, and reduced cell viability in MAC-T cells; and pretreatment of cells with SM or SS effectively alleviated the negative effects of heat shock on the cells. However, the cells were much more sensitive to SS treatment but more tolerant to SM. In addition, two forms of Se appeared to affect the expression of different genes, including nuclear factor erythroid 2-related factor 2 (Nrf2) and inducible nitric oxide synthase (iNOS) in the SM group and thioredoxin reductase 1 (TXNRD1) in the SS group in Nrf2-ARE (antioxidant response element) antioxidant pathway and inflammation response. In summary, results showed the mechanistic differences in the protective effects of organic and inorganic Se on heat stress in BMECs.

scholarly journals Improving oocyte competence in dairy cows exposed to heat stress

2014 ◽  
Author(s):  
Peter J. Hansen ◽  
Zvi Roth ◽  
Jeremy J. Block
Keyword(s):  
Heat Stress ◽  
Elevated Temperature ◽  
Heat Shock ◽  
Dairy Cows ◽  
Genetic Information ◽  
Developmental Competence ◽  
Protective Effects ◽  
Cellular Resistance ◽  
Resistance To Heat

Original Objectives. The overall goal is to develop methods to increase pregnancy rate in lactating dairy cows exposed to heat stress through methods that minimize damage to the oocyte and embryo caused by heat stress. Objectives were as follows: (1) examine the protective effects of melatonin on developmental competence of oocytes exposed to elevated temperature in vitro; (2) test whether melatonin feeding can improve developmental competence of oocytes in vivo and, if so, whether effects are limited to the summer or also occur in the absence of heat stress; and (3) evaluate the effectiveness of improving fertility by facilitating follicular turnover in the summer and winter. Revised Objectives. (1) Examine protective effects of melatonin and follicular fluid on developmental competence of oocytes exposed to elevated temperature in vitro; (2) examine the protective effects of melatonin on developmental competence of embryos exposed to elevated temperature in vitro; (3) evaluate effectiveness of improving fertility by administering human chorionicgonadotropin (hCG) to increase circulating concentrations of progesterone and evaluate whether response to hCG depends upon genotype for four mutations reported to be related to cow fertility; and (4) identify genes with allelic variants that increase resistance of embryos to heat shock. Background. The overall hypothesis is that pregnancy success is reduced by heat stress because of damage to the oocyte and cleavage-stage embryo mediated by reactive oxygen species (ROS), and that fertility can be improved by provision of antioxidants or by removing follicles containing oocytes damaged by heat stress. During the study, additional evidence from the literature indicated the potential importance of treatment with chorionicgonadotropin to increase fertility of heat- stressed cows and results from other studies in our laboratories implicated genotype as an important determinant of cow fertility. Thus, the project was expanded to evaluate hCG treatment and to identify whether fertility response to hCG depended upon single nucleotide polymorphisms (SNP) in genes implicated as important for cow fertility. We also evaluated whether a SNP in a gene important for cellular resistance to heat stress (HSPA1L, a member of the heat shock protein 70 family) is important for embryonic resistance to elevated temperature. Major conclusions, solutions & achievements. Results confirmed that elevated temperature increases ROS production by the oocyte and embryo and that melatonin decreases ROS. Melatonin reduced, but did not completely block, damaging effects of heat shock on the oocyte and had no effect on development of the embryo. Melatonin was protective to the oocyte at 0.1-1 μM, a concentration too high to be achieved in cows. It was concluded that melatonin is unlikely to be a useful molecule for increasing fertility of heat-stressed cows. Treatment with hCG at day 5 after breeding increased first-service pregnancy rate for primiparous cows but not for multiparous cows. Thus, hCG could be useful for increasing fertility in first-parity cows. The effectiveness of hCG depended upon genotype for a SNP in COQ9, a gene encoding for a mitochondrial-function protein. This result points the way to future efforts to use genetic information to identify populations of cows for which hormone treatments will be effective or ineffective. The SNP in HSPA1L was related to embryonic survival after heat shock. Perhaps, genetic selection for mutations that increase cellular resistance to heat shock could be employed to reduce effects of heat stress on fertility. Implications, both scientific and agricultural. This project has resulted in abandonment of one possible approach to improve fertility of the heat-stressed cow (melatonin therapy) while also leading to a method for improving fertility of primiparous cows exposed to heat stress (hCG treatment) that can be implemented on farms today. Genetic studies have pointed the way to using genetic information to 1) tailor hormonal treatments to cow populations likely to respond favorably and 2) select animals whose embryos have superior resistance to elevated body temperatures.   

scholarly journals Oocyte Competence Biomarkers Associated With Oocyte Maturation: A Review

2021 ◽  
Vol 9 ◽  
Author(s):  
Batara Sirait ◽  
Budi Wiweko ◽  
Ahmad Aulia Jusuf ◽  
Dein Iftitah ◽  
R. Muharam
Keyword(s):  
Oocyte Maturation ◽  
Blastocyst Stage ◽  
Current Approach ◽  
Developmental Competence ◽  
Matrix Remodeling ◽  
Oocyte Competence ◽  
Nuclear Maturation ◽  
Oocyte Developmental Competence ◽  
Cumulus Oocyte Complex

Oocyte developmental competence is one of the determining factors that influence the outcomes of an IVF cycle regarding the ability of a female gamete to reach maturation, be fertilized, and uphold an embryonic development up until the blastocyst stage. The current approach of assessing the competency of an oocyte is confined to an ambiguous and subjective oocyte morphological evaluation. Over the years, a myriad of biomarkers in the cumulus-oocyte-complex has been identified that could potentially function as molecular predictors for IVF program prognosis. This review aims to describe the predictive significance of several cumulus-oocyte complex (COC) biomarkers in evaluating oocyte developmental competence. A total of eight acclaimed cumulus biomarkers are examined in the study. RT-PCR and microarray analysis were extensively used to assess the significance of these biomarkers in foreseeing oocyte developmental competence. Notably, these biomarkers regulate vital processes associated with oocyte maturation and were found to be differentially expressed in COC encapsulating oocytes of different maturity. The biomarkers were reviewed according to the respective oocyte maturation events namely: nuclear maturation, apoptosis, and extracellular matrix remodeling, and steroid metabolism. Although substantial in vitro evidence was presented to justify the potential use of cumulus biomarkers in predicting oocyte competency and IVF outcomes, the feasibility of assessing these biomarkers as an add-on prognostic procedure in IVF is still restricted due to study challenges.

scholarly journals 219EFFECTS OF GROWTH HORMONE AND GNRH ANTAGONISTS ON FOLLICULAR AND OOCYTE DEVELOPMENT IN SHEEP

2004 ◽  
Vol 16 (2) ◽  
pp. 231
Author(s):  
P. Gonzalez-Añover ◽  
T. Encinas ◽  
R.M. Garcia-Garcia ◽  
A. Veiga-Lopez ◽  
J. Santiago-Moreno ◽  
...  
Keyword(s):  
Growth Hormone ◽  
Breeding Season ◽  
Developmental Competence ◽  
Control Group ◽  
Gh Treatment ◽  
Gnrh Antagonists ◽  
Nuclear Maturation ◽  
Final Development ◽  
Sigma Chemical ◽  
Experimental Group

Embryo output in sheep is increased when superovulatory FSH treatments are started in the presence of a high number of small follicles (2–3mm in size) and in absence of large follicles (&gt;6mm, Gonzalez-Bulnes et al., 2002. Theriogenology, 57, 1263–1272). Administration of GnRH antagonists (GnRHa) suppresses large follicles (Cognie et al., 2003. Theriogenology, 59, 171–188), whereas the use of growth hormone (GH) would increase the number of small follicles (Campbell et al., 1995. J Reprod Fertil Suppl, 49, 335–350). Our aim was to evaluate the usefulness of pre-treatments with GH or GH plus GnRH antagonists for sheep embryo production. First, we studied the effects on follicular population by serial ultrasonographies. Thereafter, we determined whether such treatments can affect oocyte developmental competence. In a first trial, a total of 18 Manchega ewes were treated with intravaginal FGA sponges (Chronogest®, Intervet Int., H) during breeding season (beginning of April). Six animals received daily i.m. doses of 15mg of ovine GH (Tuenre, GA) for 6 days, while six females received GH plus two s.c. doses of 1.5mg of GnRHa (Antarelix™, Zentaris, G) on Days 0 and 3 of GH treatment, and six ewes acted as controls receiving saline. Number of follicles &gt;2mm, determined by daily transrectal ultrasonography, increased to reach significant differences on Day 4 in sheep treated with GH/GnRHa (22.7±0.8 v. 16.7±0.5, P&lt;0.001) and on Day 5 in ewes injected with GH (20.3±0.4 v. 17.0±0.6, P&lt;0.05). The second trial involved 18 Manchega ewes treated with progestagen sponges on Day 0 and distributed in three groups at the beginning of breeding season (end of July). In the first group (n=7), sheep were treated with two doses of GnRHa on Days 0 and 3 after sponge insertion and with three doses of 15mg of GH on Days 3, 4, and 5. Thereafter, ewes from this group and from a second experimental group (n=7) were treated with 3 doses of 1.5mL of FSH (Ovagen™, ICP, NZ) every 12h, starting on the afternoon of Day 5. A third group of sheep (n=4) did not receive GH/GnRHa or FSH, acting as controls. On Day 7, follicles were aspirated and the cumulus-oocyte complexes (COC) were cultured for 24h at 38.5°C, 5% CO2, in TCM-199 supplemented with ovine FSH (Ovagen), LH, FCS, 17-βoestradiol, cysteamine, and sodium pyruvate (Sigma Chemical Co., MO, USA). Nuclear maturation was measured by Hoechst 33342 fluorescence. Mean number of COC was higher in GH/GnRHa+FSH group (8.7±0.9 v. 6.8±1.3 in FSH group, NS and 4.5±0.8 in control, P&lt;0.05) due to higher number of follicles with similar recovery rates (45.0±4.5, 40.3±1.4, and 39.1±7.1%, respectively). There were no significant differences on the ability of COC to resume meiosis, although this was higher in FSH group (63.1±9.5% for GH/GnRHa+FSH, 79.5±6.3% for FSH and 60.0±8.8% for control group), which can indicate the necessity of a higher FSH supply to induce final development in follicles/oocytes from ewes treated with GH and GnRHa. In conclusion, the use of GH and GnRHa would help to increase the number of gonadotrophin-responsive follicles prior to gonadotrophin injections;; also, adjustment of FSH treatments improved embryo yields in superovulatory protocols.

scholarly journals Improvement of quality of oocytes collected in the autumn by enhanced removal of impaired follicles from previously heat-stressed cows

Reproduction ◽  
2001 ◽  
pp. 737-744 ◽  
Author(s):  
Z Roth ◽  
A Arav ◽  
A Bor ◽  
Y Zeron ◽  
R Braw-Tal ◽  
...  
Keyword(s):  
Heat Stress ◽  
Embryo Development ◽  
Treated Group ◽  
Oocyte Quality ◽  
Control Group ◽  
Delayed Effect ◽  
Cleavage Rate ◽  
Lactating Cows ◽  
Summer Heat

The fertility of dairy cows decreases during the summer and remains low during the cooler autumn although the animals are no longer under heat stress. The aim of this study was to characterize a delayed effect of summer heat stress on oocyte quality in the autumn and to improve oocyte quality by enhanced removal of follicles damaged during the previous summer. Lactating cows (n = 16) were subjected to heat stress during the summer. In autumn, ovarian follicles (3-7 mm in diameter) were aspirated by an ultrasound-guided procedure during four consecutive oestrous cycles. Follicles were aspirated from control cows on day 4 and from treated cows on days 4, 7, 11 and 15 of each oestrous cycle. All cows received PGF(2alpha) and GnRH injections on days 19 and 21, respectively, and maintained cyclicity, as indicated by plasma progesterone concentrations. On day 4 of each cycle, the oocytes recovered were examined morphologically, matured and activated in vitro, and cultured for 8 days. In cycle 1 (early October) both groups showed low percentages of grade 1 oocytes, cleavage, four- and eight-cell embryos, morulae and parthenogenetic blastocysts. Subsequently, the number of grade 1 oocytes increased earlier (cycle 2) in treated than in control cows (cycle 3; P < 0.05). The cleavage rate in the control group remained relatively low throughout (32-58%), whereas in the treated group it increased from 40% (cycle 1) to 75% (cycles 3 and 4; P < 0.05). The number at each stage of embryo development increased slightly but remained low throughout in the control group, whereas in the treated group significant (P < 0.05) increases of all stages were observed in cycles 3 and 4. The results show a delayed effect of summer heat stress on oocyte quality and embryo development in the autumn. Enhanced removal of the impaired cohort of follicles led to earlier emergence of healthy follicles and high quality oocytes in the autumn.

scholarly journals Melatonin protects mouse oocyte from heat stress damage

2020 ◽  
Vol 6 (3) ◽  
pp. 13
Author(s):  
Haiyan Du ◽  
Shouhong Wang ◽  
Weiwei Huang
Keyword(s):  
Heat Shock ◽  
Heat Shock Protein ◽  
Heat Shock Protein 70 ◽  
Spindle Assembly ◽  
Shock Group ◽  
Mouse Oocyte ◽  
Control Group ◽  
Mouse Oocytes ◽  
Early Apoptosis ◽  
Maturation Rate

Objective: To explore the potential effect of melatonin on the in-vitro maturation of mouse oocytes under heat shock condition.Methods: This study used a heat shock model of mouse oocyte maturation. The oocytes were randomly divided into three groups: control group, heat shock group and heat shock + melatonin group, in order to evaluate the effect of 1×10−9 mol/L melatonin on the quality of oocytes after heat shock.Results: In comparison with the control group, the maturation rate of mouse oocytes in heat shock group was significantly decreased [(33.00 ± 0.07)% vs. (85.00 ± 0.03)%, p < .01], with abnormal spindle assembly, and the early apoptosis rate was significantly increased [(59.7 ± 4.5)% vs. (22.0 ± 3.5)%, p < .01]. Compared with heat shock group, the maturation rate ofoocytes was significantly increased in heat shock + melatonin group [(70.00 ± 0.05)% vs. (33.00 ± 0.07)%, p < .01], meanwhile, the spindle abnormality rate and the early apoptosis rate were significantly decreased accordingly [(37.3 ± 6.1)% vs. (59.7 ± 4.5)%, p < .01]. The expression level of heat shock protein 70 was significantly up-regulated in heat shock + melatonin group in comparison with other two groups (p < .01).Conclusions: By regulating the over-expression of heat shock protein 70, melatonin can improve the declined maturation rate of oocytes and the increased rates of spindle assembly abnormality and early apoptosis caused by heat shock.

scholarly journals Chronic heat stress regulates the relation between heat shock protein and immunity in broiler small intestine

2020 ◽  
Vol 10 (1) ◽  
Author(s):  
Sharif Hasan Siddiqui ◽  
Darae Kang ◽  
Jinryong Park ◽  
Mousumee Khan ◽  
Kwanseob Shim
Keyword(s):  
Body Weight ◽  
Small Intestine ◽  
Heat Stress ◽  
Treatment Group ◽  
Heat Shock ◽  
Heat Shock Protein ◽  
Growth Performance ◽  
Control Group ◽  
Immune Functions ◽  
Negative Effect

Abstract Chronic heat stress is considered to decrease the immune functions which makes negative effect on broiler growth performance. Here, we investigated the relationship between chronic heat stress, growth performance, and immunity in the small intestine of broilers. The study included two groups (control and heat stressed group) with eight replications per group. Ten broilers of 20-day aged were allocated in each replication. On day 35, the treatment group was subdivided into two groups based on their body weights (heavy and low body weight). Although, there was only the control and treatment group on day 28. The growth performance decreased and expression of heat shock protein 70 (HSP70), HSP60, and HSP47 increased on days 28 and 35 in the chronic heat stress group as compared with those in the control group. The expression levels of HSPs were significantly higher in the low body weight group than in the control group. The genes HSP70 and HSP60 were significantly associated with pro- and anti-inflammatory cytokines in the small intestine of the broilers of the treatment group. Thus, HSP70 and HSP60 activated the adaptive immunity in the small intestines of the broilers from the treatment group to allow adaptation to chronic heat stress environment.

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