Endocrinology Commons^™

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 …

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

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 …

The Exposome, Metabolic Dysfunction And Silicosis: A Pulmonary And Pathophysiology Study, Janet A. Thompson

Graduate Theses, Dissertations, and Problem Reports (ETD)

The exposome encompasses the concept that an individual’s health is a combination of genetic, environmental, and occupational exposures. A worker’s exposomal profile could potentially influence their susceptibility to hazardous occupational exposures. Over 35% of adults in the United States have metabolic dysfunction (MetDys), yet interactions between MetDys and hazardous occupational exposures are generally unknown. MetDys is associated with HFWD-consumption and obesity and induces a chronic low grade systemic inflammation and alters serum adipokine profiles. Silicosis, a progressive inflammatory lung disease, results from occupational inhalation exposure to respirable crystalline silica particles. This research tests the hypothesis “Inflammation resulting from HFWD-induced …

Morphological And Functional Evidence Of Sexual Dimorphism In The Retrochiasmatic Area Population Of Nk3r-Containing Neurons In Sheep, Justin A. Lopez

Graduate Theses, Dissertations, and Problem Reports (ETD)

Neurokinin B (NKB) and kisspeptin are critical for fertility and potent stimulators of gonadotropin-releasing hormone (GnRH) and luteinizing hormone (LH) secretion in sheep. We previously demonstrated that administration of NKB receptor (NK3R) agonist, senktide, within the retrochiasmatic area (RCh) resulted in surge-like release of LH and increased expression of kisspeptin neurons in the arcuate nucleus (ARC) of female lambs. We concluded that NKB-responsive neurons in the RCh stimulate GnRH secretion by inducing kisspeptin release from neurons in the ARC.

We have demonstrated morphological and functional evidence of sexual dimorphism in NKB-NK3R signaling in ovine RCh. RCh senktide administration resulted in …

The Acute Effect Of Propanil On Reproductive Hormones, Ovarian Gene Expression And Splenic Cells In C57bl/6 Female Mice, Malia Danielle Berg

Graduate Theses, Dissertations, and Problem Reports (ETD)

Earlier evidence indicates exposure to propanil, a post-emergent herbicide used on rice and wheat fields, increases the number of antibody-secreting cells (ASC) in the spleen of mice after immunization with heat-killed Streptococcus pneumoniae (HKSP, 2x10⁸ CFU). Interestingly, an intact hypothalamic-pituitary-gonadal (HPG) axis is required for this immune response assessed on day 7-10 after immunization in female mice. Hence, an overarching premise is that propanil arbitrates the connection between the reproductive and immune system by altering the concentration of hormones involved in the HPG axis, which may then affect the populations of splenic cells. Hypotheses were tested with C57Bl/6 female …

Population Health Of Spotted Salamanders (Ambystoma Maculatum) In Created Vernal Pools: An Integrative Approach, Alice R. Millikin

Graduate Theses, Dissertations, and Problem Reports (ETD)

Habitat creation is an important tool for conservation to counteract habitat loss and degradation. Vernal pools are susceptible to destruction due to limited detection, protection, and regulation. These wetlands provide fishless breeding habitat for many amphibian species including spotted salamanders (Ambystoma maculatum) in eastern North America. Determining whether created vernal pool habitat is successful is often determined by demographic data of colonizing populations. I suggest that hormone levels, population genetics, and disease prevalence can improve our understanding of population health in created habitat. The goal of this dissertation was to assess the health of spotted salamander larvae in …