RESUMO

In this study, endometrial samples were collected in 14 Nelore cows on days zero (ovulation), five, nine, thirteen and nineteen of the estrous cycle (biopsy group), and in 15 females these collections weren't performed (control group). Biopsies were done on the uterine horn endometrium contralateral to the ovary with corpus luteum. Blood samples were taken at -24, -16, -8, 0 +8, +16 and +24 hours in relation to progesterone drop (<1ng/mL, zero moment) and evaluated for 13, 14-dihydro-15-keto prostaglandin F2-alpha (PGFM) by radioimmunoassay (RIA). Plasma progesterone concentration was determined by RIA every 24 hours. Data were analyzed by ANOVA using the PROC GLM and MIXED of the SAS. The mean value for PGFM during the entire period evaluated was greater in the biopsy group. The mean concentration of PGFM at moment zero was not different between the groups; the mean concentration of PGFM was higher in the biopsy group before and after the drop in progesterone level. The maximum mean concentration observed was not different between the groups; however, the mean minimum concentration was different with high values in the biopsy group. Although the PGFM concentrations were higher in the biopsy group, the biopsy and control groups had similar length of estrous cycle showing that repeated endometrial biopsy on the side contralateral to the ovary with corpus luteum does not affect luteolysis and the length of the estrous cycle.

No presente estudo, foram coletadas amostras endometriais de 14 vacas Nelore nos dias zero (dia da ovulação), cinco, nove, 13 e 19 do ciclo estral (grupo controle), e em 15 fêmeas essas coletas não foram realizadas (grupo controle). As biópsias foram realizadas no corno uterino contralateral ao ovário contendo o corpo lúteo. Amostras plasmáticas foram coletadas nos momentos -24, -16, -8, 0 +8, +16 e +24 horas em relação à queda de progesterona (<1ng/mL, momento zero) e avaliadas quanto à concentração de 13, 14-di-hidro-15-ceto prostaglandina F2-alpha (PGFM) por radioimunoensaio (RIA). As concentrações plasmáticas de progesterona foram avaliadas a cada 24 horas também por RIA. Os dados foram analisados por ANOVA empregando-se PROC GLM e MIXED do SAS. O valor médio de PGFM durante todo o período avaliado foi maior no grupo biópsia. A concentração média de PGFM no momento zero não diferiu entre os grupos, e foi maior no grupo biópsia antes e após a queda de progesterona. A concentração máxima observada não foi diferente entre os grupos, porém a concentração mínima diferiu com maiores valores observados no grupo biópsia. Embora as concentrações de PGFM fossem maior no grupo biópsia, ambos os grupos apresentaram o mesmo comprimento do ciclo estral, demonstrando que a coleta repetitiva de biópsias endometriais no corno uterino contraletral ao ovário contendo o corpo lúteo não afeta a luteólise e o comprimento do ciclo estral.

Assuntos

RESUMO

In this study, endometrial samples were collected in 14 Nelore cows on days zero (ovulation), five, nine, thirteen and nineteen of the estrous cycle (biopsy group), and in 15 females these collections weren't performed (control group). Biopsies were done on the uterine horn endometrium contralateral to the ovary with corpus luteum. Blood samples were taken at -24, -16, -8, 0 +8, +16 and +24 hours in relation to progesterone drop (<1ng/mL, zero moment) and evaluated for 13, 14-dihydro-15-keto prostaglandin F2-alpha (PGFM) by radioimmunoassay (RIA). Plasma progesterone concentration was determined by RIA every 24 hours. Data were analyzed by ANOVA using the PROC GLM and MIXED of the SAS. The mean value for PGFM during the entire period evaluated was greater in the biopsy group. The mean concentration of PGFM at moment zero was not different between the groups; the mean concentration of PGFM was higher in the biopsy group before and after the drop in progesterone level. The maximum mean concentration observed was not different between the groups; however, the mean minimum concentration was different with high values in the biopsy group. Although the PGFM concentrations were higher in the biopsy group, the biopsy and control groups had similar length of estrous cycle showing that repeated endometrial biopsy on the side contralateral to the ovary with corpus luteum does not affect luteolysis and the length of the estrous cycle.(AU)

No presente estudo, foram coletadas amostras endometriais de 14 vacas Nelore nos dias zero (dia da ovulação), cinco, nove, 13 e 19 do ciclo estral (grupo controle), e em 15 fêmeas essas coletas não foram realizadas (grupo controle). As biópsias foram realizadas no corno uterino contralateral ao ovário contendo o corpo lúteo. Amostras plasmáticas foram coletadas nos momentos -24, -16, -8, 0 +8, +16 e +24 horas em relação à queda de progesterona (<1ng/mL, momento zero) e avaliadas quanto à concentração de 13, 14-di-hidro-15-ceto prostaglandina F2-alpha (PGFM) por radioimunoensaio (RIA). As concentrações plasmáticas de progesterona foram avaliadas a cada 24 horas também por RIA. Os dados foram analisados por ANOVA empregando-se PROC GLM e MIXED do SAS. O valor médio de PGFM durante todo o período avaliado foi maior no grupo biópsia. A concentração média de PGFM no momento zero não diferiu entre os grupos, e foi maior no grupo biópsia antes e após a queda de progesterona. A concentração máxima observada não foi diferente entre os grupos, porém a concentração mínima diferiu com maiores valores observados no grupo biópsia. Embora as concentrações de PGFM fossem maior no grupo biópsia, ambos os grupos apresentaram o mesmo comprimento do ciclo estral, demonstrando que a coleta repetitiva de biópsias endometriais no corno uterino contraletral ao ovário contendo o corpo lúteo não afeta a luteólise e o comprimento do ciclo estral.(AU)

Assuntos

RESUMO

The corpus luteum (CL) releases progesterone, which acts on the endometrium to induce release of histotroph that supports the free-floating conceptus and prepares for epithelial-chorial placentation. Two steroidogenic cell types, which are classified based on size, contribute to serum progesterone concentrations. Large luteal cells produce the bulk of progesterone because of constitutively active protein kinase A. Small luteal cells also contribute to serum progesterone concentrations through release of progesterone in response to luteotrophic stimuli. The CL is maintained in ruminants until endometrial-derived prostaglandin F2 alpha (PGF) initiates functional and structural regression. The decline in serum progesterone and loss of negative feedback on the hypothalamus and anterior pituitary sets up hormonal responses resulting in a new estrous cycle that is characterized by estrus, ovulation and formation of a new CL. If a conceptus is present, interferon tau (IFNT) is released from the conceptus, which binds receptors in the endometrium and prevents up-regulation of estrogen receptor (ESR1) and consequently oxytocin (OXT) receptor (OXTR). As a consequence, pulses of PGF are disrupted which results in rescue of the CL from lu teolysis. In addition to these paracrine actions, early pregnancy also has direct endocrine action on the CL through inducing IFN- stimulated genes (ISGs) in the CL and resistance of the CL to PGF. Endocrine actions of IFNT have been described through detection of IFNT in uterine vein blood, induction of several ISGs in the CL during pregnancy, and following both in vivo (via miniosmotic pumps) and in vitro (in cultured small, large, and mixed luteal cells) delivery of recombinant ovine (ro) IFNT. These endocrine actions of IFNT might be applied to reducing embryo mortality and associated economic consequences in ruminants.

Assuntos

RESUMO

The corpus luteum (CL) releases progesterone, which acts on the endometrium to induce release of histotroph that supports the free-floating conceptus and prepares for epithelial-chorial placentation. Two steroidogenic cell types, which are classified based on size, contribute to serum progesterone concentrations. Large luteal cells produce the bulk of progesterone because of constitutively active protein kinase A. Small luteal cells also contribute to serum progesterone concentrations through release of progesterone in response to luteotrophic stimuli. The CL is maintained in ruminants until endometrial-derived prostaglandin F2 alpha (PGF) initiates functional and structural regression. The decline in serum progesterone and loss of negative feedback on the hypothalamus and anterior pituitary sets up hormonal responses resulting in a new estrous cycle that is characterized by estrus, ovulation and formation of a new CL. If a conceptus is present, interferon tau (IFNT) is released from the conceptus, which binds receptors in the endometrium and prevents up-regulation of estrogen receptor (ESR1) and consequently oxytocin (OXT) receptor (OXTR). As a consequence, pulses of PGF are disrupted which results in rescue of the CL from lu teolysis. In addition to these paracrine actions, early pregnancy also has direct endocrine action on the CL through inducing IFN- stimulated genes (ISGs) in the CL and resistance of the CL to PGF. Endocrine actions of IFNT have been described through detection of IFNT in uterine vein blood, induction of several ISGs in the CL during pregnancy, and following both in vivo (via miniosmotic pumps) and in vitro (in cultured small, large, and mixed luteal cells) delivery of recombinant ovine (ro) IFNT. These endocrine actions of IFNT might be applied to reducing embryo mortality and associated economic consequences in ruminants.(AU)

Assuntos

RESUMO

The aim of this experiment was to determine the interval between the beginning of the spontaneous or induced oestrus and the ovulation in females buffaloes using ultrasonography. This will be useful in the determination of the most proper moment for the pre-fixed artificial insemination. In the reproductive season, autumn in the South of Brazil (march-june), 132 clicling females were divided in 3 groups: Group A: 53 females were treated with auricular subcutaneous implant of norgestomet or intravaginal device of progesterone. In the moment that the devices were removed, 250mg of cloprostenol were applied for intravulvar submucosis (ivsm). Group B: 48 buffaloes females were treated twice with 250mg of cloprostenol for ivsm with interval of 11 days. Group C: 31 buffaloes females remained without any treatment (control group). All of them were inseminated in the moment that was observed the biggest diameter of pre-ovulatory follicle determinated by ultrasonography. In the 3 groups, there was significative difference between pregnant and non-pregnant females in the oestrus-ovulation interval and in the A.I.-ovulation interval. The pregnancy rates were 41.5%, 52.1% and 54.8% in the groups A, B amd C, respectively. The variation in the oestrus-ovulation in buffaloes is the major obstacle to achieve high pregnancy rates using pre-fixed artificial insemination in spontaneous and induced oestrus.

O objetivo deste experimento foi determinar o intervalo entre o início do estro induzido ou espontâneo e a ovulação em fêmeas bubalinas (Bubalus bubalis) com o auxílio da ultra-sonografia, o que permitirá a determinação de um horário mais apropriado para a I.A. pré-fixada. Nos meses de março a junho, outono no sul do Brasil (época reprodutiva dos bubalinos), 132 fêmeas adultas ciclando foram divididas em 3 grupos experimentais: Grupo A - 53 fêmeas foram tratadas com implante subcutâneo de Norgestomet ou espiral intravaginal contendo progesterona. Na retirada dos dispositivos, foi aplicado 250mg de cloprostenol pela via intra-submucosa vulvar (i.s.m.v.), Grupo B - 48 búfalas foram tratadas com dupla aplicação de 250mg de cloprostenol pela via i.s.m.v. com intervalo de 11 dias e Grupo C - 31 búfalas foram consideradas testemunhas, sem tratamento. Todas as búfalas foram inseminadas no momento da observação do maior diâmetro do folículo pré-ovulatório, detectado por ultra-sonografia, durante o estro. Após o diagnóstico de prenhez, constatou-se, nos três tratamentos, que houve diferença significativa entre as búfalas prenhes e vazias no período compreendido entre o início do estro até o momento da ovulação e no período entre a I.A.e a ovulação. Os índices de prenhez foram de 41,5%, 52,1% e 54,8% nos grupos A, B e C, respectivamente. A variação no intervalo estro-ovulação nas búfalas é uma barreira para a obtenção de taxas de prenhez por I.A. pré-fixada comparáveis à monta natural, tanto no estro induzido através de progesterona e prostaglandina F2 alfa como no estro espontâneo.

RESUMO

The aim of this experiment was to determine the interval between the beginning of the spontaneous or induced oestrus and the ovulation in females buffaloes using ultrasonography. This will be useful in the determination of the most proper moment for the pre-fixed artificial insemination. In the reproductive season, autumn in the South of Brazil (march-june), 132 clicling females were divided in 3 groups: Group A: 53 females were treated with auricular subcutaneous implant of norgestomet or intravaginal device of progesterone. In the moment that the devices were removed, 250mg of cloprostenol were applied for intravulvar submucosis (ivsm). Group B: 48 buffaloes females were treated twice with 250mg of cloprostenol for ivsm with interval of 11 days. Group C: 31 buffaloes females remained without any treatment (control group). All of them were inseminated in the moment that was observed the biggest diameter of pre-ovulatory follicle determinated by ultrasonography. In the 3 groups, there was significative difference between pregnant and non-pregnant females in the oestrus-ovulation interval and in the A.I.-ovulation interval. The pregnancy rates were 41.5%, 52.1% and 54.8% in the groups A, B amd C, respectively. The variation in the oestrus-ovulation in buffaloes is the major obstacle to achieve high pregnancy rates using pre-fixed artificial insemination in spontaneous and induced oestrus.

O objetivo deste experimento foi determinar o intervalo entre o início do estro induzido ou espontâneo e a ovulação em fêmeas bubalinas (Bubalus bubalis) com o auxílio da ultra-sonografia, o que permitirá a determinação de um horário mais apropriado para a I.A. pré-fixada. Nos meses de março a junho, outono no sul do Brasil (época reprodutiva dos bubalinos), 132 fêmeas adultas ciclando foram divididas em 3 grupos experimentais: Grupo A - 53 fêmeas foram tratadas com implante subcutâneo de Norgestomet ou espiral intravaginal contendo progesterona. Na retirada dos dispositivos, foi aplicado 250mg de cloprostenol pela via intra-submucosa vulvar (i.s.m.v.), Grupo B - 48 búfalas foram tratadas com dupla aplicação de 250mg de cloprostenol pela via i.s.m.v. com intervalo de 11 dias e Grupo C - 31 búfalas foram consideradas testemunhas, sem tratamento. Todas as búfalas foram inseminadas no momento da observação do maior diâmetro do folículo pré-ovulatório, detectado por ultra-sonografia, durante o estro. Após o diagnóstico de prenhez, constatou-se, nos três tratamentos, que houve diferença significativa entre as búfalas prenhes e vazias no período compreendido entre o início do estro até o momento da ovulação e no período entre a I.A.e a ovulação. Os índices de prenhez foram de 41,5%, 52,1% e 54,8% nos grupos A, B e C, respectivamente. A variação no intervalo estro-ovulação nas búfalas é uma barreira para a obtenção de taxas de prenhez por I.A. pré-fixada comparáveis à monta natural, tanto no estro induzido através de progesterona e prostaglandina F2 alfa como no estro espontâneo.