Progestin-Induced Puberty and Secretion of Luteinizing Hormone in Heifers1

Anderson, Lloyd L.; McDowell, Colleen M; Day, M. L.

doi:10.1095/biolreprod54.5.1025

Cited by 98 publications

(67 citation statements)

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“…Concentrations of progesterone in plasma were determined in duplicate using a double-antibody RIA (Anderson et al 1996). The intra-assay CV was 3.4% and the inter-assay CV (three assays) was 14.9% for standard pools containing 1.4 and 6.9 ng ml 21 progesterone.…”

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confidence: 99%

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Histological and steroidogenic changes in dominant ovarian follicles during oestradiol-induced atresia in heifers

et al. 2005

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Histological and steroidogenic changes within dominant ovarian follicles (DFs) undergoing atresia following systemic administration of oestradiol benzoate (ODB) were characterized in beef heifers. At 5.6 6 0.1 days after the onset of oestrus, heifers received 1 mg ODB i.m./500 kg body weight (ODB; n 5 15) or served as controls (n 5 15). Timing of treatment initiation was designated as hour (h) 0 on day (d) 0, and coincided with the presence of the DF of the first follicular wave (DF1). Within treatments, the DF1 was collected following ovariectomy in four animals at h 12, h 36 or after ultrasonic detection of a new wave (NW) of ovarian follicular development. In heifers of the NW groups (n 5 7 per treatment), blood samples were collected at intervals of 20 min for 12 h beginning at h 2 12, 0, 24 and 48 to characterize circulating LH patterns. Administration of ODB suppressed (P < 0.01) mean concentrations of LH at h 24 and h 48 by preventing (P < 0.05) the increase in LH pulse amplitude observed in controls, but had no effect on FSH. Follicular fluid (FF) concentrations of androgens and oestradiol were reduced at h 36 in the ODB-treated group. The diameter of the DF1 and the number of granulosa cell layers were also reduced in ODB-treated as compared with control heifers. Treatment differences were not observed in the proportion of apoptotic granulosa cells as assessed using the TUNEL assay method, and timing of a new wave of follicular development (d 4.6 6 0.2) was similar (P > 0.1) among treatments. A prominent characteristic of oestradiol-induced atresia of the DF1 of the oestrous cycle in heifers was a loss in oestrogenic function associated with reduced LH support. However, the timing of new follicular development may be influenced by a factor(s) other than the status of the DF undergoing oestradiol-induced atresia.Reproduction (2005) 129 611-620

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“…Concentrations of oestradiol in plasma were determined in duplicate using a double-extraction single-antibody RIA (Anderson et al 1996). The antibody used (Dr N R Mason, Lilly Research Laboratories, Indianapolis, IN, USA) has a 71% cross-reactivity with ODB (Kesler et al 1977).…”

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confidence: 99%

Histological and steroidogenic changes in dominant ovarian follicles during oestradiol-induced atresia in heifers

et al. 2005

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“…Concentrations of E 2 in follicular fluid were measured using a single-antibody RIA procedure routinely employed in our laboratory for measuring E 2 in serum or plasma (Anderson et al 1996). This assay was modified by increasing the range of standard concentrations (2-2000 pg/ml) and using samples directly (without extraction of lipids).…”

Section: Ria Of Ementioning

confidence: 99%

Dihydrotestosterone influenced numbers of healthy follicles and follicular amounts of LH receptor mRNA during the follicular phase of the estrous cycle in gilts

Cárdenas

Jimenez²,

Pope³

2008

Reproduction

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The present experiments were conducted to determine androgenic effects on numbers, health, and amounts of gonadotropin receptor mRNA in late developing follicles of gilts. Gilts (nZ5 per group) received daily injections of one of the following treatments on days 13-16 or days 13-18 of the estrous cycle: corn oil, 5a-dihydrotestosterone (DHT, 10 mg), flutamide (1.5 g, an androgen receptor inhibitor), DHT (10 mg) plus flutamide (1.5 g), testosterone (10 mg), and testosterone (10 mg) plus flutamide (1.5 g). Ovarian follicles R5 mm in diameter were evaluated on day 17 or 19, 24 h after receiving the last treatment dose. Follicles were classified as healthy (H), moderately atretic (MA), or very atretic (VA). Treatment with DHT increased (P!0.05) the numbers of H follicles relative to control gilts on days 17 and 19. DHT administration from days 13 to 16 diminished (P!0.05) the amounts of LH receptor (LHR) mRNA in H follicles from day 17 (relative amounts: 1.45G0.33 and 2.72G0.33 for DHT-and vehicle-treated gilts respectively). The effects of DHT on numbers of H follicles and LHR mRNA were not observed in gilts receiving DHT plus flutamide. Androgens did not influence numbers of MA, VA, and total follicles, or follicular estradiol-17b concentrations and amounts of FSHR mRNA. Treating gilts with DHT during follicular recruitment and selection did not induce changes in the numbers of total follicles R5 mm, but rather increased the numbers of healthy follicles in this follicular population in association with decreased amounts of LHR mRNA.

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“…Anderson et al (1996) supposes that exogenous progesterone reduces the number of hypothalamic estradiol receptors, resulting in increased frequency of LH pulses after the end of treatment with P4. Day et al (1987) observed that the cytosolic concentration of estradiol receptors on the anterior and medial basal hypothalamus and anterior pituitary reduced linearly as puberty approached.…”

Section: Peripheral Concentration and The Pulses Frequency Of Luteinimentioning

confidence: 99%

“…Several studies demonstrated that the use of progesterone may advance puberty in heifers (GONZALEZ-PADILLA, 1975;ANDERSON, et al 1996;CLARO JR, et al 2010). …”

Section: Introductionmentioning

confidence: 99%

Estudo do mecanismo molecular da progesterona e do estradiol sobre o início da puberdade em novilhas Nelore

Magalhães¹

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AGRADECIMENTOSAgradeço a Deus e a Nossa Senhora por me fazerem forte, me manterem firme, segura dos meus objetivos, e persistente. Agradeço toda a proteção e às bênçãos recebidas.À minha família, meu maior tesouro, meu chão, meu mundo. Em especial à minha mãe, Leila, meu porto seguro e meu maior apoio, a quem tanto amo. Ao meu pai que me apresentou outro mundo e a quem tenho aprendido a compreender. Aos meus avós, Maria e Afonso, fontes de inspiração, alicerces da nossa família, exemplos de união e amores da minha vida. À minha avó Estelita, muitas saudades e ao avô Ernesto que não tive oportunidade de conhecer. Aos meus tios e padrinhos, Keila (amiga inseparável e verdadeira), Marciano (incentivador das minhas idéias mais malucas), tio Júnior (pai dos meus amores), Marlon, Sônia, Netinho, Smênia, Valmira, Xandy, Néia, Vanusa, Alípio, Toninho, Mara, eternos cúmplices, amigos, apoios, pessoas que ajudaram a formar minha personalidade e me ajudaram a ser uma pessoa melhor, obrigada por confiarem em mim. Aos meus irmãos Newton, Daniel, Grégory, parceiros eternos de vida, farras, bons momentos e dificuldades e às minhas irmãs Isabela e Lívia, minhas lindas! Amo a todos vocês! Aos meus primos lindos, Neto, Gu, Bia, Arthur, Lorrane, Igor, Fred, Breno, Grazian, Dani (e família), amo vocês demais apesar da distância. Aos meus dois afilhados Arthurzinho e Gu, que me desmontam a cada passagem por Brasília. E o agradecimento mais especial aos novos presentes de Deus que trouxeram vida nova e alegria à família meus sobrinhos Esther, Enzo e Anna.A todos os meus amigos de Brasília, que entendem o motivo da minha distância, mas não menor consideração.À FAPESP pela concessão da bolsa de doutorado e pelo auxílio financeiro à pesquisa, que me possibilitaram ter tranquilidade no desenvolvimento de minhas atividades. À Prefeitura do Campus da USP de Pirassununga por disponibilizar as instalações do abatedouro escola e parte dos animais.Ao professor Luis Felipe Prada e Silva, por todo o apoio, confiança, amizade e estrutura, sem os quais não seria possível o desenvolvimento do trabalho. E por todo o aprendizado e vivência fora do projeto de pesquisa, mas dentro do contexto do LPGC, que só me auxiliam a crescer e me fazem uma melhor profissional a cada dia. The understanding of the molecular mechanisms by which nutrition, genetics and hormonal treatments affect the beginning of puberty is of great importance for developing strategies aiming to reduce the age at first calving, and therefore increase the slaughter rate in Nellore cattle. The effects of progesterone device and of endogenous estradiol on the molecular mechanisms controlling the attainment of puberty in Nellore heifers were investigated.Specifically, the molecular pathways of progesterone and estradiol were studied in the hypothalamus. Thirty five non-pubertal heifers, between 13 and 14 months of age, were divided into four treatment (nine or eight per treatment): P4 device without estradiol (SP), P4 device with estradiol (PE), without P4 device and without estradiol (SS...

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Progestin-Induced Puberty and Secretion of Luteinizing Hormone in Heifers1

Cited by 98 publications

References 21 publications

Histological and steroidogenic changes in dominant ovarian follicles during oestradiol-induced atresia in heifers

Histological and steroidogenic changes in dominant ovarian follicles during oestradiol-induced atresia in heifers

Dihydrotestosterone influenced numbers of healthy follicles and follicular amounts of LH receptor mRNA during the follicular phase of the estrous cycle in gilts

Estudo do mecanismo molecular da progesterona e do estradiol sobre o início da puberdade em novilhas Nelore

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