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Leptin’S Role In The Obesity Epidemic, Alyssa C. Washeleski

Honors College Theses

Weight loss methods have been around for decades, but yet, individuals still can’t lose weight or keep it off. Researchers have pondered if there is more to being incapable of losing body fat than individuals having a lack of willpower. While the environment plays a critical role in weight regulation, genetics may be just as important.

Research has discovered a hormone called leptin that controls energy expenditure and satiety. Leptin plays a part in many physiological roles, including appetite control, sexual function, immunity, insulin sensitivity, and the metabolism of lipid and bone. Studies done with mice and humans have concluded …

Leptin Effects On Bone Metabolism, Elizabeth Bark

Williams Honors College, Honors Research Projects

Scales from adult zebrafish, Danio rerio, are an established model for studying osteoblast and osteoclast activity. In this study, scales in a cell culture were used to determine if the hormone leptin has an effect on activity of these bone remodeling scales. Alkaline phosphatase (ALP) and tartrate-resistant acid phosphatase (TRAP) activities of zebrafish scales were measured and compared with and without leptin treatment. There was no statistically significant difference between leptin treatments in terms of ALP and TRAP activity. Differences between TRAP values between days 1 and 2 did look promising although they were not statistically significant. This study …

Non-Invasive Method For Leptin Supplementation In Zebrafish (Danio Rerio), Regan Mcnamara

Williams Honors College, Honors Research Projects

I tested the hypothesis that recombinant leptin protein can be introduced to zebrafish in vivo through non-invasive soaking in a solution containing the protein. One way to study various molecules’ effects in vivo is through intraperitoneal or intracerebroventricular injections during the embryonic or larval stage, which is invasive, difficult to administer, and can have a high mortality rate. 48 hours post fertilization (hpf) zebrafish were soaked in a His-tagged recombinant leptin protein solution at 10 nM and 100 nM concentrations (produced by Genscript). After soaking, zebrafish larvae were washed extensively to remove all recombinant protein on their exterior before homogenization. …

The Effect Of Maternal Dietary Habits During Pregnancy On Neonate Leptin Methylation Patterns And Gestational Age, Sean Fitzpatrick

Legacy Theses & Dissertations (2009 - 2024)

The health of a newborn baby is inextricably linked to the health status of its mother and in turn the mother’s diet during pregnancy. Leptin (LEP) is an adipokine hormone involved in metabolism regulation and has been linked fetal development through the hypothalamic-pituitary-adrenal axis (HPA). Prior work suggests that gestational epigenetic alterations the LEP gene may be sensitive to adverse exposures during pregnancy, which in turn could explain variation in neonate outcomes. However, no prior work has examined this possibility explicitly. The objective of this study was to investigate the association between dietary patterns of mothers during pregnancy and their …

Regulations Of Pathogenic Cd4+ T Helper Lymphocytes In Inflammatory Diseases, Handong Zheng

Biomedical Sciences ETDs

In this comprehensive project, three interrelated studies with distinct foci were employed to understand the regulations of specific CD4⁺ T helper cell population in inflammatory diseases.

Pathogenic TH17 cells play an essential role in the initiation and development of both human multiple sclerosis (MS) and animal experimental autoimmune encephalomyelitis (EAE). Nevertheless, the underlying mechanism by which the pathogenicity of TH17 cells is controlled in the autoimmune neuro-inflammation remains unclear. In aim 1, we revealed that lumican (Lum), an extracellular matrix (ECM) protein, negatively regulates encephalitic TH17 cell responses. Our findings highlighted a TH17 cell-intrinsic effect of Lum in suppressing …

Preliminary Investigations Into Endospanin Expression In Zebrafish, Brittany Gray

Williams Honors College, Honors Research Projects

This study investigated endospanin expression in zebrafish by performing western blots to identify which tissues expressed endospanin. A feeding study was also conducted to see if endospanin expression varied in fed versus unfed fish. After tissues were dissected, protein assays were performed on homogenized tissues and then gels were run using gel electrophoresis. The primary antibody rabbit anti-endospanin peptide was used on the finished blots. Chemiluminescence was then used to visualize the blots using GeneSnap software. Endospanin expression was evident in heart, liver, and ovary tissues. The feeding study showed that endospanin expression in liver tissue was not significantly different …

Measuring The Effects Of High-Fat Diet On Breathing And Oxygen-Sensitivity Of The Carotid Body Type I Cell, Ryan J. Rakoczy

Browse all Theses and Dissertations

The carotid bodies (CB), the primary peripheral chemoreceptors, respond to changes in blood gases with neurotransmitter release, thereby increasing carotid sinus nerve firing frequency and ultimately correcting the pattern of breathing. It has previously been demonstrated that acute application of the adipokine leptin caused perturbations of intracellular calcium and membrane ion movement in isolated CB Type I cells (Pye et al, 2015) and augmented the response of the intact CB to hypoxia (Pye et al, 2016). This study's aim was to examine, in-vivo, if elevated leptin modulated CB function and breathing. Rats were fed high-fat chow or control chow for …

Effect Of Reproductive Efficiency In Regards To Workload On Peripheral Circulations Of Blood Cortisol And Leptin In The Open Mare, Michaelle K. Coker

Electronic Theses and Dissertations

ABSTRACT

Effect of Reproductive Efficiency in Regards to Workload on Peripheral Circulations of Blood Cortisol and Leptin in the Open Mare

(December, 2016)

Michaelle Kathleen Coker, B.S., Texas A&M University

Thesis Director: Dr. John Michael Mehaffey

Quarter and Paint horse mares (n= 9) were randomly assigned to 1 of 3 groups after being blocked based by expected conception date. Groups consist of mares on no work (NW), light work (LW), and moderate work (MW). Blood was taken weekly via jugular venipuncture prior to first heat cycle from each mare. Additionally, blood was taken at time of ovulation and then weekly …

Hunger Games: The Effects Of Alternate Day Fasting On Food Intake, Body Weight, And Leptin And Ghrelin In Rats, Debra Kirsty Mortel Tacad

UNLV Theses, Dissertations, Professional Papers, and Capstones

PURPOSE: To determine whether a compensatory increase in food intake occurs following a day of fasting, and to determine whether leptin and/or ghrelin levels change in response to ADF compared with ad libitum feeding.

INTRODUCTION: Recently, alternate-day fasting (ADF) has grown in popularity as an alternative to continuous energy restriction (CER) diets as a method for improving health and controlling food intake. Leptin and ghrelin are two hormones implicated in the regulation of food intake and body weight, however their response to ADF is unclear.

METHODS: Male Wistar rats of the same age and weight were randomly assigned to the …

Leptin Regulates The Expression Of Autophagy-Related Genes In Chickens, Peter Olawale Ishola

Graduate Theses and Dissertations

Autophagy or cellular self-digestion, a lysosomal degradation pathway that is conserved from yeast to human, plays a key role in recycling cellular constituents, including damaged organelles. It also plays a pivotal role in the adaptation of cells to a plethora of distinct stressors including starvation. Autophagy has been extensively studied in mammals and yeast, but little is known in avian species. Thus, the major objective of the present study was to determine the effects of leptin on autophagy-related genes in chicken hypothalamus, muscle and liver. Leptin is an adipocytokine that is mostly produced by white adipose cells in mammals (as …

Effect Of Progesterone, Terbutaline And Leptin On The Function Of Alveolar Type Ii Cells, Shamili Sammohi

Browse all Theses and Dissertations

The "surfactant" produced by type II pneumonocytes is deficient in term and preterm infants born and diagnosed with Respiratory Distress Syndrome (RDS). Corticosteroids such as dexamethasone or betamethasone are clinically used as the primary line of treatment to stimulate the production of surfactant. The steroidal hormone, progesterone appears to play a role in the fetal lung development and also appears to increase the expression of inflammatory markers in both term and preterm infants. However, the impact of progesterone on surfactant production remains unknown. Like progesterone, the tocolytic drug terbutaline has also been implicated in phosphatidylcholine production in the pneumonocytes of …

Effects Of Leptin On Established Glioblastoma Cell Lines, Nicholas J. Cook

All NMU Master's Theses

Glioblastoma is one of the most difficult cancers to treat because it is aggressive and resistant to therapy. The discovery of new therapeutic targets is drastically needed as zero improved treatment options have been added to the standard of care over the past 15 years. New and promising therapeutic targets are arising from psychosocial and environmental enrichment studies examining the role of stress in cancer progression. In animal models, eustress appears to slow tumor growth and recurrence resulting in increased overall survival and progression free survival while distress is associated with decreased overall survival. The cellular pathways activated by eustress …

Leptin Resistance Induced Obesity And Diabetes Promote Neuropathological Changes In The Aging Brain, Thomas Platt

Theses and Dissertations--Molecular and Cellular Biochemistry

The aging brain is prone to the development of pathology and dementia. With a rapidly growing elderly population diagnoses of neurodegenerative diseases, such as Alzheimer’s disease (AD), frontotemporal dementia (FTD), and Parkinson’s disease are on the rise. Additionally, diabetes and obesity are linked to an increased risk of dementia. The convergence of this increasingly aged population with the obesity and diabetes epidemic give rise to new concerns regarding the future of prevention and treatment of neurodegenerative diseases. Our lab has previously shown that leptin, an adipokine involved in signaling satiety to the hypothalamus, can modulate the generation of the amyloid …

Identification Of Kinase Signaling Pathways Inducing Morphological Changes In Dendritic Cells Upon Leptin Treatment, Marisol Ann O'Neill

Open Access Theses & Dissertations

Leptin is a pleiotropic hormone secreted by white adipose tissue. Obesity leads to overexpression of leptin as a result of leptin receptor desensitization. Obese leptin serum levels (160ng/ml) have been found to enhance immune functions in macrophages, natural killer cells, B cells, T cells, and dendritic cells. Previous data from our lab suggests that obese concentrations of leptin cause morphological changes in DCs, although further studies are required to verify these results. We hypothesized that leptin promotes DC cytoskeletal changes though activation of PI3K signaling. Morphological and functional changes were evaluated in JAWS II immortalized DCs though microscopy, transwell migration, …

The Effect Of Exogenous Leptin On Dendritic Cell Migration And Interactions With T Cells, Amanda L. Gonzales

Open Access Theses & Dissertations

Obesity is a complex, chronic disease that has reached epidemic proportions in the United States and shows no indication of receding. It is a state of chronic low-grade inflammation that is initiated by morphological changes in large accumulations of adipose tissue. Leptin is a pleiotropic hormone secreted by adipose tissue, presenting a possible link between obesity and inflammation. In this study, we assessed the effect of leptin on bone marrow-derived (BM) dendritic cells (DC) (BM-DC) function, antigen presenting cells vital for the activation of naí¯ve T cells. Previous data produced in our laboratory established that the addition of leptin to …

The Effects Of Intracerebroventricular Leptin On Milk Availability In Lactating Rats, Brittany Lynita Moore

Electronic Theses and Dissertations

Reports have linked energy balance along with adipocyte derived leptin action to improved fertility. Recent evidence indicates that leptin hormone is present in breast milk and leptin receptors are well expressed in mammary epithelial cells. The hypothesis that insufficiency of leptin restraint in the hypothalamus may underlie infertility in rodents and the failure of lactating breast to express adequate amount of milk was tested. Female Sprague-Dawley rats were injected leptin through intracerebroventricular cannulation (ICVC) of the third ventricle. Female rats were mated with stud males and observed throughout gestation. Compared to the control groups, leptin treatment increased prolactin levels in …

Altered Leptin Signaling On Dendritic Cells As A Potential Mechanism For Cancer Immunotherapy, Lorena Y. De Los Santos

Open Access Theses & Dissertations

Leptin is a pleiotropic hormone synthesized primarily by white adipocytes and its receptors are expressed in a variety of tissues and cells such as in the hypothalamus and cells of the immune system. Multiple cell types can produce a considerable amount of leptin such as skeletal muscle, placenta, and osteoblasts to name a few and its synthesis has been shown to be regulated by sex hormones and a broad range of inflammatory mediators. Although leptin has been shown to directly affect immune response, we are interested in how leptin affects dendritic cell function and their ability to induce a proper …

Effect Of Exogenous Leptin On Thrombotic And Metabolic Profiles Of Fvb/B6 Lipodystrophic Mice, Hoda Chaouki Kadouh

Wayne State University Theses

Lipodystrophy caused by fat deficiency contributes to metabolic disease for which several treatment modalities have been implemented, with leptin therapy being the most effective to date. In addition to playing a role in energy homeostasis and metabolism, leptin was also shown to play a pro-thrombotic role in mice. This role was not examined in fatless mice, neither was thrombosis measured. The AZIP/F-1 (FVB) lipodystrophic mouse appeared to have a prolonged arterial occlusion time (p〈0.05) in a trial done in our lab, with clotting factors being normal. The present study was designed to observe the thrombotic and metabolic characteristics of fatless …

Transcriptional Regulation Of Adipocyte Function, Kivanc Birsoy

Student Theses and Dissertations

The increased white adipose tissue mass associated with obesity is the result of both hyperplasia and hypertrophy of adipocytes. While adipocyte development and transcriptional processes are well studied in vitro, regulation of in vivo genes (such as leptin), the identity of the adipocyte progenitor cells and the development of the adipose organ have not been defined invivo. In this thesis, firstly KLF4 was discovered to be an essential early regulator of adipogenesis. KLF4 together with Krox20 cooperatively transactivates C/EBPβ, suggesting that KLF4 and Krox20 are part of an immediate early transcriptional network. This network is upregulated in a lipodystrophic animal …

Implication For The Role Of Leptin-Induced Signaling As A Negative Regulator Of Dendritic Cell Function, Oscar Ramirez

Open Access Theses & Dissertations

The incidence of obesity among the distinct world populations has become an ever growing concern. Central to the regulation of obesity is the adipocyte-derived hormone, and in more recent years cytokine, leptin. Leptin plays a central role in the maintenance of food consumption as well as the efficient use of peripheral energy stores. Leptin exerts its physiological role in energy homeostasis by regulating the expression of orexigenic peptides in the central nervous system. However, recent research has implicated leptin in other physiological roles including those of the immune system. As a pleiotropic cytokine, the absence of leptin has been shown …

The Effects Of Leptin And Thyroid Hormone On Metabolism And Lipid Trafficking In The Liver And Adipose Tissue Of Ob/Ob Mice, Candace Michelle Reno

Theses Digitization Project

The purpose of this project was to study how the key metabolic hormones, insulin, leptin, and thyroid hormone alter metabolic pathways and lipid and glucose trafficking in order to find possible therapies for treatment for obesity and its complications.

Distributions And Associations Of Single Nucleotide Polymorphisms In The Leptin Gene Of Bos Taurus And Bos Indicus Cattle, Douglas Henry Fischer, Jr

LSU Master's Theses

In recent years, the use of genetic markers has become more and more prevalent in beef breeding programs. This research focused on four previously identified single nucleotide polymorphisms in a leptin gene on chromosome 4 of beef cows. The SNP were E2FB, T945M, UA1, and UA2. Beef cows used in this research were maintained at the Louisiana State University AgCenter Central Research Station. Cows consisted of purebred Bos tauras and Bos indicus cattle as well as crossbreds. The objectives were to estimate genotypic and allelic frequencies for each SNP and to determine the influence of cow breed type, cow age, …

Equine Obesity-Related Hyperleptinemia, Nan Killen Huff

LSU Doctoral Dissertations

Plasma leptin concentrations in obese adult horses have been shown to vary widely, and horses tend to fit into two groups: low leptin (<10 ng/mL) and hyperleptinemic (10 to 50 ng/mL). Observations over time revealed that the hyperleptinemic condition was consistent, possibly indicating a relatively permanent underlying cause. Based on these observations, three experimental approaches were used to further study equine obesity-related hyperleptinemia. The first experiment determined the prevalence of hyperleptinemia among postpartum, lactating mares, evaluated its consequence on their re-breeding success, and investigated correlations between leptin levels in lactating and non-lactating mares. Postpartum mares (n = 198) and non-foaling mares (n = 31) were categorized based on their leptin status: normoleptinemic or hyperleptinemic. Leptin in the lactating mares averaged 4.8 ng/mL, and 11 of the 198 (13%) displayed hyperleptinemia. Leptin in the non-lactating mares averaged 7.5 ng/mL, with 9 mares (29%) displaying hyperleptinemia. Of the 198 lactating mares bred, 81% became pregnant; there was no effect of leptin status on re-breeding success. To study one possible cause for hyperleptinemia in well-fed horses, a second experiment explored polymorphism(s) within exon 2 of the equine leptin gene. The DNA from five hyperleptinemic and five normal mares of high body condition was used to analyze exon 2 of the leptin gene for polymorphisms. Based on the 10 mares tested, there was no polymorphism in exon 2 of the equine leptin gene; therefore, polymorphism is not a likely explanation for the high vs. low leptin difference. The third experiment explored the possible effects of hyperleptinemia on the endocrine and immune systems. Endotoxin was given to mares and geldings to investigate the role and/or regulation of leptin in the pro-inflammatory cytokine response. Of the endpoints measured, only platelet count differed between normal and hyperleptinemic horses. Endotoxin infusion caused the expected pro-inflammatory cytokine and endocrine responses, but leptin status was not a significant factor for any endpoint. It is concluded that hyperleptinemia in mares is not associated with polymorphism in exon 2 of the leptin gene, does not affect re-breeding rates of foaling mares, and does not alter the endotoxin-induced responses of the endocrine and immune systems.

Effect Of Age, Body Condition, Pregnancy And Lactation On Circulating Leptin Concentrations In Beef Cattle, Glen Talmage Gentry, Jr.

LSU Doctoral Dissertations

A series of experiments were conducted to evaluate the potential role of leptin in bovine reproduction. In Experiment 1, mean circulating leptin concentrations of postpartum cows were not affected by exogenous dexamethasone treatments. In Experiment 2, mean leptin concentrations were not correlated with female age or body weight but were positively correlated with body condition scores of beef cattle. Leptin concentrations were higher in 1 year old heifers (8.9 ng/ml) compared with 2 year old cows (6.0 ng/ml), but heifer leptin concentrations were not different than 4 to 6 year old cows (8.0 ng/ml) and cows ≥7 years of age …

Reproductive And Metabolic Effects Of Recombinant Equine Leptin On Seasonally Anovulatory Mares, Pamela Boliew Mitcham

LSU Master's Theses

Mares of poor body condition have low plasma leptin concentrations, while obese mares have the highest concentrations. Leptin is a primary signal of body condition to the brain in other species; therefore, low leptin concentrations in thin mares could contribute to their extended anovulatory period in winter compared to obese mares. The current experiment was designed to determine whether recombinant equine leptin, administered to seasonally anovulatory mares, would induce ovarian activity and ovulation in the winter. Leptin effects on metabolism were also studied. Beginning January 7, leptin-treated mares (n = 9) received daily i.m. injections of 10 mg recombinant equine …

Reproductive Characteristics Of High Body Condition Mares With High Versus Low Leptin Concentrations, Cara A. Waller

LSU Master's Theses

Two experiments were performed to discover what, if any, reproductive differences exist in high body condition (BCS) mares with varying concentrations of leptin. Previous research showed that mares with high body condition scores can have a range of leptin levels, from very low (<5 ng/mL) to very high (>10 ng/mL). Earlier results indicated that most mares with high body condition scores maintain estrous cycles or show significant follicular activity during the winter. Among these high BCS mares, about 30% of them exhibit hyperleptinemia and hyperinsulinemia. The first experiment was designed to compare the reproductive characteristics of high BCS mares with high versus low leptin …

Site And Mechanism Of Leptin's Antisteatotic And Insulin Sensitizing Actions In Lipodystrophic Liver, Esra Asilmaz

Student Theses and Dissertations

An adipocyte hormone which functions as the afferent signal in a negative feedback loop regulating energy balance, has profound effects on glucose and lipid metabolisms. Lipodystrophic humans and mice have a complete or partial absence of adipose tissue and a secondary reduction of leptin. This is associated with insulin resistance and hepatic steatosis, which are corrected by leptin administration. This thesis aimed to define the site of leptin action and understand the molecular basis of leptin's insulin sensitizing and antisteatotic effects in lipodystrophy. To determine the site of leptin action, we treated lipodystrophic aP2-nSREBP-lc mice with a low dose of …

Life Without Gpr7, The Neuropeptide W1 Receptor: Regulation Of Energy Homeostasis By Gpr7 And Its Endogenous Neuropeptide Ligands, Makoto Ishii

Student Theses and Dissertations

Classic lesion experiments from the 1940s have established the hypothalamus as playing an essential role in controlling energy homeostasis. Gold-thioglucose (GTG) induces lesions in the ventromedial nucleus of the hypothalamus (VMH) resulting in hyperphagia and obesity. To identify genes involved in the hypothalamic regulation of energy homeostasis, we employed a screen to search for genes that were dysregulated in GTG induced obese mice. In this screen, GPR7, the endogenous G protein-coupled receptor (GPCR) for the recently identified ligands neuropeptide B (NPB) and neuropeptide W (NPW), was found to be specifically down-regulated after GTG treatment. The physiological role of GPR7 was …

Leptin In Horses: Influences Of Body Condition, Gender, Insulin Insensitivity, Feeding, And Dexamethasone, Joshua Allen Cartmill

LSU Doctoral Dissertations

The experiments described herein were designed to answer questions that arose from initially attempting to determine whether treatment with dexamethasone increased concentrations of leptin in geldings. Dexamethasone treatment did in fact increase leptin concentrations in mares, geldings, and stallions. Additional experiments were designed to determine leptin's interaction, not only with the adrenal axis, but with the thyroid axis, the growth hormone/insulin-like growth factor-1 axis, as well as glucose and insulin metabolism in geldings, mares, and stallions. During the course of these experiments, differences in leptin concentrations in the horse were attributed to degree of body condition, gender, and feeding time. …