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Articles 1 - 4 of 4
Full-Text Articles in Endocrinology
Neuroendocrine Regulation Of The Luteinizing Hormone Surge And Puberty Onset In Sheep, Max J. Griesgraber
Neuroendocrine Regulation Of The Luteinizing Hormone Surge And Puberty Onset In Sheep, Max J. Griesgraber
Graduate Theses, Dissertations, and Problem Reports (ETD)
Gonadotropin-releasing hormone (GnRH), luteinizing hormone (LH), and follicle stimulating hormone (FSH) are essential for the reproduction of all mammalian species, including both sheep and humans. GnRH is secreted by hypothalamic neurons into the hypophyseal portal vasculature in a pulsatile manner, which then acts within the anterior pituitary to elicit the release of LH and FSH into wider systemic circulation. In females LH and FSH act on the ovaries to promote estradiol (E2) production, follicular development, and under certain conditions in regard to LH, ovulation. Furthermore, while E2 inhibits GnRH and subsequent LH secretion under most conditions, at high concentrations E2 …
Artificial Insemination And Fetal Programming In Beef Production Systems, Dempster M. Christenson
Artificial Insemination And Fetal Programming In Beef Production Systems, Dempster M. Christenson
Department of Animal Science: Dissertations, Theses, and Student Research
Pregnancy to artificial insemination and late gestation fetal programming of the next calf crop are central to genetic development, reproductive longevity, calf crop productivity, and efficiency of cow/calf ranching. The purposes of this research are to find methods to improve pregnancy rate to artificial insemination, the growth and reproductive health of pregnant heifers, and the productivity of their offspring. In the first of four studies we found that extending the period of progesterone administration in an estrus synchronization protocol did not significantly hasten estrus response or increase pregnancy rate to artificial insemination, but timing of estrus within the melengestrol acetate …
Puberty-Associated Changes In Kiss1r, Mc3r, And Mc4r In The Ewe, Ashleigh Caitlyn Thomson
Puberty-Associated Changes In Kiss1r, Mc3r, And Mc4r In The Ewe, Ashleigh Caitlyn Thomson
Graduate Theses, Dissertations, and Problem Reports (ETD)
The neural mechanisms that control the onset of puberty are not completely understood. In livestock, the onset of puberty relies on an increase in gonadotropin releasing hormone (GnRH) and luteinizing hormone (LH). Kisspeptin, neurokinin B, and dynorphin neurons (KNDy) and their receptors, Kiss1r, NK3R, and KOR, respectively, are important regulators of puberty. Previous data from our laboratory has shown that KNDy neurons may be responding to other inputs, including the melanocortin system, that will affect the timing of puberty. Given this, we examined kisspeptin receptor (Kiss1r) mRNA expression in GnRH neurons as well as examining melanocortin 3 and 4 receptor …
Estradiol’S Role In Timely Puberty Onset In The Ewe, Eliana Gerardine Aerts
Estradiol’S Role In Timely Puberty Onset In The Ewe, Eliana Gerardine Aerts
Graduate Theses, Dissertations, and Problem Reports (ETD)
In female sheep, the release of gonadotropin-releasing hormone (GnRH) from the hypothalamus triggers luteinizing hormone (LH) to be released from the pituitary. Luteinizing hormone, in turn, acts on the ovaries to elicit estradiol (E2) release. E2 acts in a negative feedback manner to control the amount of LH released. The increase in LH release that drives puberty onset results from a decrease in sensitivity to E2 as the animal ages. However, the neural mechanisms mediating this change in sensitivity are not known, as is where in the hypothalamus E2-negative feedback occurs. In the arcuate …