Cumulus cells protect the oocyte against saturated free fatty acids

In the cow a major characteristic of metabolic stress is an elevated level of plasma free fatty acid, due to increased lipid mobilization from adipose tissue. Elevated levels of free fatty acids in blood (complexed to albumin) are associated with increased lipotoxicity in non-adipose tissue. An overview is provided on the negative impact of free fatty acids and the metabolic stress imposed on the oocyte and early embryo and thus on bovine fertility. There is increasing evidence that in vitro as well as in vivo the elevated levels of free fatty acids in blood during metabolic stress can severely hamper oocyte and embryo development. However, fatty acids do also form an essential nutrient source for the oocyte and embryo, which indicates that these good and bad effects of fatty acids should be in subtle balance to optimize the developmental competence of the oocyte and embryo.

Cumulus cells protect the oocyte against saturated free fatty acids

In the cow a major characteristic of metabolic stress is an elevated level of plasma free fatty acid, due to increased lipid mobilization from adipose tissue. Elevated levels of free fatty acids in blood (complexed to albumin) are associated with increased lipotoxicity in non-adipose tissue. An overview is provided on the negative impact of free fatty acids and the metabolic stress imposed on the oocyte and early embryo and thus on bovine fertility. There is increasing evidence that in vitro as well as in vivo the elevated levels of free fatty acids in blood during metabolic stress can severely hamper oocyte and embryo development. However, fatty acids do also form an essential nutrient source for the oocyte and embryo, which indicates that these good and bad effects of fatty acids should be in subtle balance to optimize the developmental competence of the oocyte and embryo.(AU)

Lipotoxicity: impact on oocyte quality and reproductive efficiency in mammals

Lipotoxicity is characterized by excessive saturated fatty acids in the blood, increasing storage in non-adipose cells, which leads to changes in the expression pattern of genes related to endoplasmic reticulum stress (e.g., ATF4, ATF6, CHOP, And GRP78), pro- and anti-apoptotic pathways (e.g., Baxand Bcl-2, and protein stability, including heat shock proteins, e.g., HSP70). A negative sub-cellular effect is usually an end result, which also occurs in the ovarian follicular population, affecting granulosa cells and cumulus-oocyte complexes (COCs), which leads to adecrease in oocyte quality and mitochondrial activity, and increased apoptosis. The addition of high doses of non-esterified fatty acids to oocyte in vitro maturation medium has been shown to slow the progression of meio sis, hampering oocyte maturation and subsequent in vitro embryo development. Due to its importance in the control of cellular lipid droplets and expression correlation with cytosolic lipid accumulation, the expression of the Plin 2 (Perilipin 2) Protein is also highlighted. The aim of this Review is to discuss some reproductive implications of dietary li pid supplementation in ruminant females, and the potential effects of lipotoxicityon oocyte qualityand reproduction, and the main mechanisms involved in the expression of genes related to endoplasmic reticulum stress and cellular lipid accumulation.

Comparative expression profiles of genes related to cellular stress and development in oocyte of goats fed with distinct concentrations of lipids

Background: Lipotoxicity is characterized by an excess of saturated fatty acids in the blood stream, in which other nonadipose cells begin to store them, thereby altering the expression of genes related to endoplasmic reticulum stress, whoseeffects have been associated with decreased oocyte quality in several species, decreased mitochondrial activity, and increasedapoptosis. The present study was conducted to investigate the lipotoxicity effect of diets with increasing fat levels on geneexpression in goats oocyte and granulosa cells.Materials, Methods & Results: Thirty does were divided into three groups of 10 animals each, which received forage andconcentrate to provide respectively 2.7% of lipids (LL group), 3.9% lipids (LI group) and 5.1% lipids (LH group) for 28days. Three days before oocyte harvest, follicular wave was synchronized by 1 mL PGF2α intramuscularly, followed bythe insertion of an intravaginal progesterone release device. Viable oocytes and granulosa cells were subjected to qRT-PCRto determine the expression of PLIN2, ATF4, CHOP10, BAX, BCL2, HSP70 genes, were checked, evaluated using thedissociation curve analysis, which obtained the following values: 77.8, 80.2, 83.6, 78.0, 81.0 and 82.0ºC, respectively. Thesteps of qPCR thermal cycle was: denaturation and polymerase activation, annealing and final extension.Throughout theexperimental period, blood samples were taken for cholesterol, triglycerides and total lipids measurements. Total plasmalipids determination was calculated with the following equation: 2 x (cholesterol + triglycerides) × 1.1 with sensitivity ofthe assay for cholesterol was 1.472 mg/dL and for triglycerides, 2.845 mg/dL. In LH group, it was recorded a more pronounced increase in total lipids (+ 60.1%) (P < 0.05), cholesterol (+ 18.8%) and triglycerides (+ 8.5%). These increaseswere three times higher than that in LL and LI groups. All genes were expressed in oocytes...(AU)

Lipotoxicity: impact on oocyte quality and reproductive efficiency in mammals

Lipotoxicity is characterized by excessive saturated fatty acids in the blood, increasing storage in non-adipose cells, which leads to changes in the expression pattern of genes related to endoplasmic reticulum stress (e.g., ATF4, ATF6, CHOP, And GRP78), pro- and anti-apoptotic pathways (e.g., Baxand Bcl-2, and protein stability, including heat shock proteins, e.g., HSP70). A negative sub-cellular effect is usually an end result, which also occurs in the ovarian follicular population, affecting granulosa cells and cumulus-oocyte complexes (COCs), which leads to adecrease in oocyte quality and mitochondrial activity, and increased apoptosis. The addition of high doses of non-esterified fatty acids to oocyte in vitro maturation medium has been shown to slow the progression of meio sis, hampering oocyte maturation and subsequent in vitro embryo development. Due to its importance in the control of cellular lipid droplets and expression correlation with cytosolic lipid accumulation, the expression of the Plin 2 (Perilipin 2) Protein is also highlighted. The aim of this Review is to discuss some reproductive implications of dietary li pid supplementation in ruminant females, and the potential effects of lipotoxicityon oocyte qualityand reproduction, and the main mechanisms involved in the expression of genes related to endoplasmic reticulum stress and cellular lipid accumulation.(AU)

Comparative expression profiles of genes related to cellular stress and development in oocyte of goats fed with distinct concentrations of lipids

Background: Lipotoxicity is characterized by an excess of saturated fatty acids in the blood stream, in which other nonadipose cells begin to store them, thereby altering the expression of genes related to endoplasmic reticulum stress, whoseeffects have been associated with decreased oocyte quality in several species, decreased mitochondrial activity, and increasedapoptosis. The present study was conducted to investigate the lipotoxicity effect of diets with increasing fat levels on geneexpression in goat’s oocyte and granulosa cells.Materials, Methods & Results: Thirty does were divided into three groups of 10 animals each, which received forage andconcentrate to provide respectively 2.7% of lipids (LL group), 3.9% lipids (LI group) and 5.1% lipids (LH group) for 28days. Three days before oocyte harvest, follicular wave was synchronized by 1 mL PGF2α intramuscularly, followed bythe insertion of an intravaginal progesterone release device. Viable oocytes and granulosa cells were subjected to qRT-PCRto determine the expression of PLIN2, ATF4, CHOP10, BAX, BCL2, HSP70 genes, were checked, evaluated using thedissociation curve analysis, which obtained the following values: 77.8, 80.2, 83.6, 78.0, 81.0 and 82.0ºC, respectively. Thesteps of qPCR thermal cycle was: denaturation and polymerase activation, annealing and final extension.Throughout theexperimental period, blood samples were taken for cholesterol, triglycerides and total lipids measurements. Total plasmalipids determination was calculated with the following equation: 2 x (cholesterol + triglycerides) × 1.1 with sensitivity ofthe assay for cholesterol was 1.472 mg/dL and for triglycerides, 2.845 mg/dL. In LH group, it was recorded a more pronounced increase in total lipids (+ 60.1%) (P < 0.05), cholesterol (+ 18.8%) and triglycerides (+ 8.5%). These increaseswere three times higher than that in LL and LI groups. All genes were expressed in oocytes...

EXPRESSÃO COMPARATIVA DE GENES RELACIONADOS AO ESTRESSE CELULAR E DESENVOLVIMENTO OOCITÁRIO EM CABRAS ALIMENTADAS COM DIFERENTES CONCENTRAÇÕES DE LIPÍDIOS

O presente estudo foi realizado para investigar o efeito lipotóxico da dieta com níveis crescentes de lipídios na expressão de gênica em células da granulosa e oócitos caprinos. Foram utilizadas trinta cabras, agrupadas em três diferentes dietas (n = 10) recebendo durante 28 dias forragem e concentrado contendo, respectivamente, 2,7% (grupo LL), 3,9% (grupo LI) e 5,1% de lipídios (grupo LH). Três dias antes da colheita de oócitos, a onda folicular foi sincronizada utilizando 1 mL PGF2 intramuscular, seguido de utilização de um dispositivo intravaginal de progesterona. Oócitos viáveis e as células da granulosa foram submetidos à qRT-PCR para determinar a expressão dos genes PLIN2, ATF4, CHOP10, BAX, BCL2, e HSP70. Durante todo o período experimental, amostras de sangue foram coletadas para análise de colesterol, triglicérideos e lipídios totais. No grupo LH obteve-se um aumento mais acentuado do total de lípidos (+ 60,1%) (P <0,05), colesterol (+ 18,8%) e triglicérideos (+ 8,5%). Este aumento foi três vezesmaior que nos grupos LI e LL. Todos os genes foram expressos em oócitos e células da granulosa. Quanto ao efeito da dieta na expressão de PLIN2, esta foi superior no grupo LI para oócito (P <0,05) e células da granulosa. Embora nenhuma diferença (P> 0,05) tenha sido encontrada entre as dietas, o índice apoptótico (BAX \ BCL2), no tratamento LH foi maior e atingiu valores duas vezes superiores nos grupos LI (5,8 vs. 2,3) e LL (5,8 vs. 3,4) respectivamente. Concluímos que o intervalo de lipídios usados nas dietas não foi suficiente para induzir alterações significativas nos genes sinalizadores de estresse da estrutura oocitária e das respectivas células da granulosa.

The present study was conducted to investigate the lipotoxicity effect of diet with increase fat levels on gene expression in goats oocyte and granulosa cells. Thirty doeswere grouped in three diets (n=10) that for 28 days received forage and concentrate toprovide respectively 2.7% (LL group), 3.9% (LI group) and 5.1% lipids(LH group). Three days before the oocyte harvest, follicular wave was synchronized 1mL PGF2 intramuscularly followed by insertion of an intravaginal progesterone drug release. Viable oocytes and granulosa cells were submitted to qRT-PCR for determinethe expression of PLIN2, ATF4, CHOP10, BAX, BCL2, HSP70 genes. Throughout the experimental period, blood samples were taken for cholesterol, triglycerides and totallipids analysis. In LH group was recorded a more pronounced increase of total lipids (+60.1%) (P < 0.05), Cholesterol (+ 18.8%) and triglycerides (+ 8.5%). These augmentwere thrice higher that LL e LI groups. All genes were expressed in oocyte andgranulosa cells. Effect of diet was observed only in PLIN2 gene, when expression was superior in LI group for oocyte (P < 0.05) and granulosa cells. Although no difference (P > 0.05) were recorded in comparison between diets, the apoptotic index(BAX\BCL2), in LH treatment was higher and achieve values twice superior to LI (5.8 vs. 2.3) e LL (5.8 vs. 3.4) groups respectively. We conclude that the lipid interval used in the diets was not enough to induce significant changes of genes stress oocytestructure and its granulosa cells.