Dissertation (Ph.D.)--Auburn University, 2007. / Abstract. Vita. Includes bibliographic references.

Thesis (M.S.)--Virginia Polytechnic Institute and State University, 1991. / Vita. Abstract. Includes bibliographical references (leaves 109-118). Also available via the Internet.

Thesis (m.s.)--University of Kentucky, 2004. / Title from document title page (viewed Jan. 7, 2005). Document formatted into pages; contains 70 p. : ill. Includes abstract and vita. Includes bibliographical references (p. 58-68).

Thesis (M.S.)--University of North Carolina at Greensboro, 2007. / Title from PDF title page screen. Advisor: Dennis LaJeunesse; submitted to the Dept. of Biology. Includes bibliographical references (p. 23-26).

CURRENTLY UNDER EMBARGO UNTIL THE 26/4/2019: Type 2 diabetes is a metabolic disorder characterised by inflammation, insulin resistance and the inability of pancreatic β-cells to secrete enough insulin to produce a physiological effect. Obesity and high levels of triacylglycerol’s are associated with the development of Type 2 diabetes. Adipose tissue is an active endocrine organ that secretes various protein and peptide hormones, known as adipokines, which mediate important metabolic functions. In an insulin resistant and hyperglycaemic state, levels of anti-inflammatory adipokines, adiponectin, are reduced, whereas levels of pro-inflammatory cytokines, interleukin-6 and interleukin-1β, are elevated; this results in a shift from an anti- to a pro-inflammatory state that is accompanied by dysfunction and apoptosis of the pancreatic β-cells. Cannabis sativa L. has been traditionally used as an anti-inflammatory agent in Southern Africa, specifically treating snakebites, fever and malaria. Δ9-tetrahydrocannabinol is the main psychoactive compound derived from C. sativa, whereas the other major cannabinoids, cannabinol and cannabidiol, have shown anti-inflammatory and sedative properties respectively. Marrubiin is a compound derived from the plant Leonotis leonurus L. and has been traditionally used as an anti-inflammatory and anti-diabetic agent. To determine the effects of these compounds in a hyperglycaemic state, pre- and differentiated mouse adipocytes (3T3-L1 cells) were exposed for seven and fourteen days to the following treatments: Δ9-tetrahydrocannabinol, cannabidiol, cannabinol, marrubiin, anandamide (an endogenous endocannabinoid) and cannabis extract, individually and in combination, under normal glucose and hyperglycaemic conditions. Levels of adiponectin, interleukin-6, leptin, tumour-necrosis factor-α and interleukin-1β were quantified using mouse enzyme-linked immunosorbent assay kits and Oil Red O staining was carried out to determine lipid distribution and lipid droplet characteristics. Results indicate that various cannabinoids, in combination, mediate an anti-inflammatory effect by decreasing the expression of various pro-inflammatory cytokines, which may have allowed for a shift from a pro- to an anti-inflammatory state by these compounds, and may also contribute to the reduction of lipid, which may be used as a supplementary option to current diabetic treatment regimes.

Graduation date: 1996

The accumulation of excessive fat is a serious concern in both the livestock production and human health fields. Obesity is a condition of excessive energy storage in the form of body fat ( triacylglycerols ). The cellular basis for obesity is not yet understood but numerous factors have been suggested. Genetic factors and altered metabolism may be two cellular parameters that contribute to the excessive accumulation of fat. Adipocytes are responsive to extracellular signals, which have a dramatic effect on their metabolism implying that these metabolic responses may be the result of differences in the composition or responsiveness of adipocyte receptors. The purpose of this research was to identify adipocyte specific marker proteins and to determine if there are any differences in the expression of these proteins that may be associated with the conditions of genetic obesity or leanness. Identification of adipocyte-specific markers should allow for a better understanding of adipocyte growth and development and determination of the adipocytes role in energy metabolism. A hybridoma line was produced which secreted a monoclonal antibody (LA-1) directed against a novel 64-kD protein unique to porcine adipocyte plasma membranes, having an undetermined function in the unique physiology of the adipocyte. This protein was found to be expressed in genetically lean adipocytes but not adipocytes derived from genetically obese sources. In order to elucidate the role of this unique adipocyte-specific plasma membrane protein, a porcine adipocyte eDNA library was produced. This library was screened with LA-1 and a eDNA clone isolated. This eDNA clone was used to study the expression of the gene responsible for this unique protein at the nucleic acid level. Northern blot analysis revealed a 5000- and a 7000-base pair species of poly (A+) RNA present in total RNA isolated from contemporary porcine adipose tissue. Determination of the nucleic acid sequence of the eDNA clone should allow for the determination of the actual identity and possible function of this adipocyte-specific protein and the possible role it may serve in regulating adipocyte growth and development. / Graduation date: 1991

Radioreceptor binding studies were carried out in broiler chickens in order to characterize adrenergic receptors on their abdominal fat adipocytes. The radioligands ($ sp3$H) DHA and ($ sp3$H) YOH were used to identify $ beta$- and $ alpha sb2$-adrenoceptors respectively. The determination of receptor criteria indicated that the optimal protein concentration for the simultaneous binding of both receptor types was between 0.35 and 1.0 mg/ml. Pharmacological specificity for both $ beta$- and $ alpha sb2$-adrenoceptors was demonstrated using receptor specific antagonists and an agonist. Saturation isotherms indicated that ($ sp3$H) DHA and ($ sp3$H) YOH labelled with high affinity, a homogenous population of non interacting $ beta$- and $ alpha sb2$-binding sites respectively. Scatchard analysis of the saturation data for ($ sp3$H) DHA revealed a Kd value of 8.1 nM and a Bmax value of 420 fmol/mg protein, while ($ sp3$H) YOH binding had a Kd value of 7.0 nM and a Bmax value of 68 fmol/mg protein. The variation in $ beta$- and $ alpha sb2$-adrenoceptor binding parameters was then investigated on the abdominal fat pad adipocytes of male and female broiler chickens at 4, 6 and 9 weeks of age. Scatchard analysis of the binding data for $ beta$-adrenoceptors indicated that Bmax values were greater in male and female broilers at 9 weeks of age (p $<$ 0.05) and that overall Bmax values were greater in females than in males (p $<$ 0.05). Scatchard analysis of $ alpha sb2$-adrenoceptor binding revealed that in females Bmax values remained constant but differed at all ages in males. The $ beta$-adrenoceptor Bmax values were always significantly greater (p $<$ 0.05) than the corresponding $ alpha sb2$-adrenoceptor Bmax values. / These results established for the first time the existence of adrenergic receptors on broiler chicken adipocytes using a radioreceptor binding assay. Although the physiological implication of these receptors is not known, it is a critical step toward the understanding of the influence of the adrenergic system on adipose tissue metabolism in avian species.

Currently more than 300 million adults are obese and 1 billion are overweight throughout the world. Obesity is frequently accompanied by an array of health conditions such as hyperglycemia, hyperlipidemia, hypertension, cardiovascular diseases, and diabetes which are all considered to be part of what is now known as the metabolic syndrome. The role of adipose tissue as an endocrine organ has been emphasized by the characterization of its hormones: leptin, adiponectin and resistin. All three proteins regulate energy utilization. Over the past decade, leptin and resistin have also been shown to affect the reproductive system. This suggests that other adipocytokines, such as adiponectin, may also affect reproduction. This relationship was investigated using a porcine in vitro maturation system. When porcine cumulus oocyte complexes were matured in the presence of 30mug/mL of recombinant adiponectin an improvement in the meiotic maturation was observed. Moreover, maturation of denuded oocytes revealed that adiponectin acts through the cumulus cells to improve meiotic maturation of porcine oocytes. Finally, maturation of cumulus-oocyte complexes in the presence of MAPK pathway inhibitors suggested that adiponectin acts at or downstream of MEK1/2 and 38MAPK. This study shows, for the first time, an effect of adiponectin on porcine oogenesis. Further investigation will determine whether adiponectin also affects embryo development.

Male Sprague-Dawley rats were used to determine whether insulin resistance develops between 1.5-4.0 months of age and whether it is related to aging or the development of obesity. Animals were randomly placed into a single 1.5 months old group (1.5 CN) or raised in one of three 4.0 month old groups; exercise trained (ET), pairfed (PF), or sedentary control (4.0 CN). The ET group was fed ad Iibitum and had free access to a spontaneous exercise wheel, while the PF group was fed to maintain equal body weight with the ET group. The young group was sacrificed with nembutal injection (45 mg/kg body weight) at 1.5 months while the other three groups were sacrificed at 4.0 months of age. Epididymal fat pads were removed, digested with collagenase (5 mg/ml) and the isolated cells sized and assayed for 2-deoxyglucose transport over a range of insulin concentrations (0-1000 µU/ml). Body composition (percent fat, bone and muscle) was performed on the carcasses of these animals at a later date. The 2-deoxyglucose transport of the 1.5 CN group was significantly greater than the 4.0 CN group at insulin concentrations of 50, 250 and 1000 uU/ml and significantly greater than all 4.0 months groups at 1000 11U/ml- The adipocyte size was significantly smaller in the 1.5 CN group followed in ascending order by the ET, PF and 4.0 CN group. The body compositions demonstrated the expected trends as the 1.5 CN group had the highest percent bone and muscle while demonstrating the lowest percent fat. The ET group was most able to maintain the body composition of the 1.5 CN group, while the PF and 4.0 CN groups were least able to maintain this composition respectively.The results indicate that: 1) Adipocyte insulin resistance develops in the rat between 1.5 and 4.0 months of age. 2) This development of insulin resistance is related to obesity and not to aging. 3) Exercise may prevent the development of insulin resistance by preventing adipocyte hypertrophy. 4) Exercise helps maintain optimal body composition. These results should be of interest to type II diabetics as an exercise program may decrease their adipocyte size, enhance body composition and decrease insulin resistance.