Browsing by Subject "Chemical and Pharmacologic Phenomena"
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Item [3H] Ethynylbicycloorthobenzoate ([3H] EBOB) Binding in Native and Recombinant GABAA Receptors(2000-05-01) Yagle, Monica A.; Dillon, Glenn; Martin, Michael; de Fiebre, ChristopherYagle, Monica A., [3H] Ethynylbicycloorthobenzoate ([3H] EBOB) Binding in Native and Recombinant GABAA Receptors. Master of Science (Pharmacology), May 2000, 59 pp., 3 tables, 7 illustrations, bibliography, 75 titles. Modulation of the GABAA receptor has been studied with noncompetitive convulsant ligands such as tert-butylbicyclophosphorothionate (TBPS) and picrotoxin (PTX). EBOB is a more recently developed ligand that appears to bind in the same region of the channel at TBPS, but with a higher affinity. While only a few studies have examined the binding of EBOB to vertebrate brain tissue and insect preparations, none have examined potential subunit-dependent binding of EBOB. We have thus examined [3H] EBOB binding in rat cerebellum and HEK293 cells stably expressing human α1β2γ2, human α2β2γ2, and rat α6β2γ2 GABAA receptors. For comparison, [35S] TBPS binding was also examined in α1β2γ2 receptors. Saturation and Scatchard analyses revealed saturable [3H] EBOB binding at one site in all tissue preparations with Kd values ranging from 3 to 9nM. [3H] EBOB binding, like [35S] TBPS binding was inhibited by the CNS convulsants dieldrin, lindane, tert-butylbicyclophosphorothionate (TBOB), PTX, TBPS, and pentylenetetrazole (PTZ) at one site in a concentration dependent fashion. Affinities were in the high nM to low μM range for all compounds except PTZ (low mM range). GABA modulated [3H] EBOB binding in a biphasic manner in α1β2γ2 receptors with a 100-fold difference between stimulatory and inhibitory affinities. Inhibition of GABA-mediated current by TBOB in α1β2γ2 receptors resulted in a functional IC50 of 0.2 μM, in agreement with binding study results. Differences seen in binding between the different receptor subtypes examined suggest that some characteristics of EBOB binding are subunit dependent. In addition, we have shown that [3H] EBOB is a useful ligand in the study of recombinant GABAA receptors and that results obtained with [3H] EBOB are comparable to those obtained with [35S] TBPS.Item A Phase II Clinical Study to Evaluate the Efficacy and Safety of rhThrombin in Subjects Undergoing Arterial Bypass Surgery and AV Graft Formation for Hemodialysis(2004-12-01) Plascencia, Xochitl; Rustin E. Reeves; Della Weis; Don PeskaThe Association of American Medical Colleges Task Force on Clinical Research defines clinical research as a component of medical and health research intended to produce knowledge essential for understanding human disease, preventing and treating illness, and promoting health (Friedman, 1998). A clinical trial is defined as a research study conducted in humans which is designed to answer specific questions using scientifically controlled conditions with specified methodologies and endpoints (Gallin, 2002). Clinical research trials are essential in determining whether or not a drug is safe and effective. There are four phases that investigational drugs go through before they are allowed to be out in the market. Before beginning phase I of a study, there is usually a pre-clinical research and development phase. During this time the initial synthesis of study drug is accomplished and animal testing takes place. Phase I is the initial introduction of an investigational new study drug into humans. Phase I is usually conducted in healthy individuals and the primary goal is to determine the safety profile of the drug. Phase II trials tend to evaluate safety and initial efficacy. Subjects enrolled in this phase tend to have the disease necessary for use of study drug. Phase III studies are conducted to gather additional information about the effectiveness and safety of the drug and to determine the overall benefit-risk relationship of the drug. Finally, phase IV studies are usually referred to as post-marketing studies. During this phase, additional safety information is identified and the drug’s safety during routine use is evaluated. Each phase can range from two to ten years depending on the complexity of the clinical trial (Gallin, 2002). A phase II, randomized, double blind study of the safety and efficacy of topical recombinant human thrombin in patients undergoing peripheral arterial bypass surgery and arterio-venous graft formation for hemodialysis is the focus of the prospective drug study to be carried out in the surgery department at The University of North Texas Health Science Center. The primary objective of this study is to evaluate the safety and efficacy of recombinant human thrombin when used in different types of surgeries. Prior to signing an informed consent, subjects will have to meet inclusion and exclusion criteria set by study protocol. Study specific assessments and procedures will be performed after the informed consent is signed and dated. If bleeding at the anastomosis is found to necessitate intervention, a single application of either rhThrombin or placebo in combination with an absorbable hemostatic sponge to each anastomosis requiring hemostasis will be applied by the surgeon. The safety and efficacy of rhThrombin will be determined by measuring the incidence and severity of adverse events and of laboratory abnormalities. Occurrence of hemostasis within 600 seconds of application of the study drug at the anastomotic surgical site, incidence of anti-rhThrombin product antibodies, and time to hemostasis will also be measured.Item Corticotropin-Releasing Factor and Corticosterone Modulate the Anxiogenic-Like Effects of mCPP(1998-06-01) Jenkins, Jennifer A.; Michael Forster; Robert Luedtke; Patricia GwirtzJenkins, Jennifer A., Corticotropin-Releasing Factor and Corticosterone Modulate the Anxiogenic-Like Effects of mCPP. Doctor of Philosophy (Pharmacology), June 1998, 119 pp., 2 tables, 29 figures, bibliography, 100 titles. The administration of PTZ or mCPP produces anxiety-like behavior as measured by an increase in the percentage of entries into the open arms and the time spent on the open arms of the elevated plus maze (Prunell et al., 1994). Reportedly, PTZ and mCPP substitute for each other in the drug discrimination paradigm (Wallis and Laz, 1998). It is therefore suggested that commonality exists among anxiogenic drugs as perceived by trained animals. Andrews and Stephen (1990) suggested that this overall parallelism is an indication that anxiogenic agents may possess similar properties. Therefore, the question posed is as follows: Is there a common denominator anxiety? The global hypothesis is that the core component of anxiety produced by anxiogenic agents or processes involves stimulation of the HPA axis to release CRF, ACTH and/or CORT. Long Evans rats were trained to discriminate either mCPP (1.4 mg/kg) or PTZ (16mg/kg) from saline in a two-lever choice procedure (FR10) which is food reinforced. Animals were pretreated with CRF, α-helical CRF (a CRF antagonist), two steroid synthesis inhibitors (ketoconazole, KETZ and aminoglutethimide, AMG), CORT or underwent an adrenalectomy prior to behavioral testing in order to test the hypothesis that the release of CRF and/or CORT are components of the discriminate stimulus of the mCPP and/or PTZ. Pretreatment with CRF, KETZ, AMG and an adrenalectomy facilitated mCPP level selection. However in the absence of mCPP neither drug nor adrenalectomy produced drug lever selection. In addition CORT did not alter the mCPP dose response curve. However, CORT replacement therapy returned the does response curve to baseline in adrenalectomized animals. Alpha-helical CRF did not block mCPP discrimination. Unlike mCPP-trained animals, KETZ and AMG decreased PTZ-lever selection in PTZ-trained animals. In addition, CORT enhanced and partially substituted for the discriminative stimulus of PTZ. However, adrenalectomy completely abolished drug lever selection in PTZ animals. To compare the discriminative stimulus effects of mCPP and PTZ, PTZ-trained animals were injected with cumulative doses of mCPP. mCPP-trained animals were injected with cumulative doses of PTZ. mCPP and PTZ minimally substituted for each other. The results suggested that neither CRF nor CORT are components of the discriminative stimulus of mCCP and that the role of the HPA axis in mCPP discrimination maybe be a modulator of the stress response. However, CORT is a component of the discriminative stimulus of PTZ such that CORT is necessary for drug lever selection in PTZ trained animals.Item Cross-Tolerance Between the Discriminative Stimulus Properties of Ethanol, Diazepam and Pentobarbital(1995-12-01) Lytle, Douglas A.; Michael Forster; Glenn Dillon; Thomas YorioLytle, Douglas A., Cross-Tolerance Between the Discriminative Stimulus Properties of Ethanol, Diazepam and Pentobarbital. Doctor of Philosophy (Biomedical Sciences), December, 1995, 132 pp., 8 tables, 19 figures, bibliography, 176 titles. Ethanol, benzodiazepine agonists and barbiturates all facilitate GABA-mediated CT flux. The present experiments tested the hypothesis that, because these agents share this common action, tolerance to discriminative stimulus properties of one of these drugs would result in cross-tolerance to the others. Rats were trained to detect either ethanol (EtOH; 1.0 g/kg), the benzodiazepine diazepam, (DZP; 5.6 mg/kg), or the barbiturate pentobarbital (PB; 10.0 mg/kg) from vehicle using a two-lever choice procedure where food was available under a fixed-ration ten schedule of reinforcement. Subsequently, dose-effect curves for EtOH (0.1-1.78 g/kg), DZP (0.56-17.8 mg/kg), or PB (1.0-17.8 mg/kg) were tested before and after chronic administration of EtOH 96.0 g/kg/12hrs for seven days), DZP (20.0 mg/kg/8hrs for seven days), or PB (32.0 mg/kg/8hrs for seven days). The chronic administration of EtOH conferred tolerance to itself in all cases and cross-tolerance to DZP and PB in subjects trained to detect EtOH, but did not confer cross-tolerance to these agents in their respective discriminations. The chronic administration of DZP conferred tolerance to itself substituting for DZP. Although tolerance developed to DZP substituting for PB after treating animals with chronic DZP, this regimen on DZP did not confer tolerance to itself substituting for EtOH. This regimen of DZP failed to confer significant cross-tolerance to either EtOH or PB under any conditions. The chronic administration of PB conferred tolerance to itself substituting for PB. Although tolerance developed to PB substituting for DZP after treating animals with chronic PB, this regimen of PB did not confer tolerance to itself substituting for EtOH. This regimen of PB failed to confer significant cross-tolerance to either EtOH or DZP under any conditions. In summary, EtOH was found to confer cross-tolerance to DZP and PB only in animals trained to detect EtOH. The chronic administrations of DZP and PB failed to confer tolerance to themselves substituting for EtOH. These results are parsimonious with the heterogeneous nature of the GABA receptor. Finally, tolerance to either DZP or PB does not result in cross-tolerance to the discriminative stimulus properties of the other drug. These results suggest that the mechanisms mediating tolerance to BZs and barbiturates are not linked.Item Delta Opiod Receptor: Parasympathetic Location and Changing Phenotypes in Canine Heart(2007-07-01) Deo, Shekhar H.; James L. Caffrey; H. Fred Downey; Michael SmithDeo, Shekhar H., Delta Opioid Receptor: Parasympathetic Location and Changing Phenotypes in Canine Heart. Doctor of Philosophy (Integrative Physiology), July 23, 112 pp, 4 tables, 24 figures. Delta opioid receptors (DOR) have long been implicated in the complex mechanism of ischemic preconditioning (IPC). Repeated arterial occlusion of the SA node artery in IPC protocol progressively raised the nodal encephalin concentrations and improved vagal transmission during a subsequent extended occlusion. This vagatonic effect was reversed by the DOR-1 antagonist, BNTX. The present thesis tested whether the IPC protocol, the prolonged occlusion or a combination of both was required to demonstrate the vagotonic effect. The study also tested whether the evolution of the vagotonic effect during occlusion might be attributed to erosion of completing vagolytic effects. A progressive improvement in vagal transmission was observed during the IPC protocol. The vagotonic effect was not observed during sham occlusions or during occlusions in animals pretreated with a DOR-1 antagonist. Following the IPC protocol, exogenous MEAP reduced vagal transmission under both normal and occluded conditions. The magnitude of the vagolytic effects was however significantly reduced and eroded further over time compared to time matched shams. The loss of the response was not altered by prior DOR-1. The magnitude of the vagolytic effects was however significantly reduced and eroded further over time compared to time matched shams, however the failure of DOR-1 blockade to slow that process suggests that the PC mediated erosion is independent of receptor activation by DOR-1 agonists. Although DORs are associated with IPC, their precise location remains unconfirmed. DOR and autonomic markers vesicular acetylcholine transporter (VAChT) and tyrosine hydroxylase (TH) were labeled in tissue sections and synaptosomes from canine atrium and SA node. Synapsin I verified the neural character of labeled structures. Acetylcholine and norepinephrine content indicated both cholinergic and adrenergic synaptosomes are present. VAChT and TH signals indicated more than 80% of synapsin positive synaptosomes were cholinergic and less than 8% were adrenergic. Western blots of synaptosomal extracts confirmed by two DOR bands at molecular weights corresponding to reports for DOR monomers and dimmers. The preferential association of DORs with cholinergic nerve terminals supports the hypothesis that post-ganglionic prejunctional DORs regulate local vagal transmission within the heart.Item Intravenous Pyruvate to Prevent Renal Injury Following Cardiac Arrest and Resuscitation(2014-08-01) Hollrah, Roger A.; Robert T. Mallet; Myoung-Gwi Ryou; Rong MaIntroduction: Cardiac arrest followed by resuscitation and recovery of spontaneous circulation (ROSC) produces systemic ischemia reperfusion (I/R), affecting all internal organs, including the kidney. This type of stress generates both a robust increase in reactive oxygen and nitrogen species (RONS) and an intense inflammatory response, which can result in renal cell death. The glycoprotein erythropoietin (EPO) has been shown to combat renal I/R injury by offering cyto-protection against inflammation and oxidative damage, as well as inhibiting apoptosis. The endogenous intermediary metabolite pyruvate has been observed to stabilize specific genetic machinery responsible for the production of EPO. This study was conducted to test the efficacy of intravenous pyruvate in exploiting these endogenous mechanisms of EPO to protect the kidney from cardiac arrest-induced, I/R injury. Hypothesis: Pyruvate administration during cardiopulmonary resuscitation (CPR), defibrillation, and ROSC will protect the kidneys from I/R injury by suppressing oxidative stress and inflammation via increased EPO production at the renal corticomedullary border. Methods: Yorkshire swine underwent 10 minutes of cardiac arrest, CPR effected by precordial compressions, and defibrillation, and were recovered for either 4 hours (acute) or 3 days (chronic). The animals were randomly assigned to 1 of 4 groups. Two groups underwent the cardiac arrest protocol described above: one group received intravenous infusion of 2M sodium pyruvate at a rate of 0.1 mmol∙kg-1∙min-1 during CPR and the first 60 minutes of recovery; the other group received an equimolar infusion of NaCl. The other two groups were surgically prepared and infused with NaCl or sodium pyruvate, but were not subjected to cardiac arrest, CPR, or defibrillation. For the acute protocol (n=28), animals were sacrificed 4hr after cardiac arrest, while in the chronic protocol (n=18), animals recovered for 3d before sacrifice. To evaluate the impact of cardiac arrest and pyruvate treatment on renal metabolism and antioxidant defense, proteins were extracted from snap-frozen renal corticomedullary border tissue for spectrophotometric activity assays of a panel of 10 metabolic and antioxidant enzymes; myeloperoxidase (MPO), an enzyme marker of pro-inflammatory leukocytes, was analyzed to assess inflammation. Plasma was sampled before cardiac arrest and at the time of biopsy to measure creatinine concentration, an indirect measure of glomerular filtration rate (GFR). Enzyme-linked immunosorbent assay (ELISA) kits were used to measure EPO content and Kidney Injury Molecule-1 (KIM-1) content, a receptor expressed on renal tubular cells that plays an important role in apoptosis. Tissue sections were stained with hematoxylin and eosin (H&E) and examined under light microscopy to count neutrophils and monocytes and to compare structure integrity across the different treatment groups and protocols. Results: In this study global I/R stress imposed on the kidneys by reversible cardiac arrest did not appreciably alter the activity of the 10 panel enzymes. Despite having no histological evidence of neutrophil infiltration (H&E stained slides), an increase in renal MPO activity was evident at 4 h recovery in the NaCl group which was prevented by pyruvate treatment (P [less than] 0.05). There was no evidence of ultrastructural damage to renal cortical and outer medullary structures. There was a noticeable increase in renal EPO content at 4 h ROSC vs. the sham group. An apparent, albeit not statistically significant, increase in KIM-1 content was observed in the two CPR groups vs. the NaCl-infused sham group. Plasma creatinine concentrations did not change appreciably between pre-arrest baseline and 3 d recovery. Interpretation and Conclusion: The I/R stress produced by the present cardiac arrest-resuscitation failed to alter appreciably the activities of the 10 panel enzymes, suggesting the oxidative stress was not sufficient to overwhelm the kidney’s endogenous antioxidant defenses. Plasma creatinine concentrations were also stable, implying the GFR was maintained and the glomerular ultrastructures were unaffected by I/R. The increase in MPO activity at 4 h ROSC implied a transient infiltration of inflammatory leukocytes, although none were visible on histological examination. The increase in KIM-1 content, though not statistically significant, suggests modest renal apoptotic activity after cardiac arrest and reperfusion. The transient increase in renal EPO content in the NaCl-infused post-arrest vs. sham pigs supports the possibility that even a brief period of renal ischemia by cardiac arrest can evoke renal EPO production. Collectively, these results indicate the renal I/R imposed by cardiac arrest and resuscitation does not inflict appreciable damage on the kidneys or its enzyme systems, at least within the first 3 d of post-arrest recovery. Abbreviations: AKI: acute kidney injury; ARF: acute renal failure; CK: creatine kinase; CPR: cardiopulmonary resuscitation; CS: citrate synthase; EPO: erythropoietin; GAPDH: glyceraldehyde 3-phosphate dehydrogenase; G6PDH: glucose 6-phosphate dehydrogenase; GFR: glomerular filtration rate; GP: glutathione peroxidase; GR: glutathione reductase; HIF-1: hypoxia-inducible factor 1; I/R: ischemia-reperfusion; KIM-1: kidney injury molecule 1; LDH: lactate dehydrogenase; MPO: myeloperoxidase; PFK: phosphofructokinase; PHD: prolyl hydroxylase; RONS: reactive oxygen and nitrogen species; ROSC: recovery of spontaneous circulation.Item Lal, Harbans, Ph.D.(1994-02-08) Lal, Harbans; Hailey, BlakeDr. Lal, Professor and Chairman of Pharmacology, began his career with TCOM in 1980. He shares his early goals as faculty, his research, and his outlook on the school's future. Interviewed by Blake Hailey, February 8, 1994Item Legal Medicine and Toxicology Volume 2(W.B. Saunders and Company, 1923-01-01) Haines, Walter; Webster, Ralph; Peterson, FredrickItem Psalmotoxin-1 and nonproton ligand interactions with acid-sensing ion channels(2015-05-01) Smith, Rachel N.; Gonzales, Eric B.; Dillon, Glenn H.; Sumien, NathalieAcid-sensing ion channels (ASICs) are trimeric, sodium-selective channels activated by extracellular protons. Although ASICs are intriguing molecular targets for pharmacological agents, there remains a lack of selective compounds that differentiate ASIC subtypes. The peripherally located ASIC3 activates with the simple removal of calcium. Additionally, nonproton ligands, like 2-guanidine-4-methylquinazoline (GMQ), have been identified to selectively activate ASIC3 via the nonproton ligand sensor domain (NPLSD). A pair of glutamates in rat ASIC3 (E79 and E423) responsible for GMQ activation is present in ASIC1, despite having no direct modulation effect on the channel. We proposed that nonproton ligand activation of ASIC1 may be state dependent, and relies on expansion of the NPLSD in order for GMQ to reach the binding site and exert its effects. We utilized two features of ASICs in order to test our hypothesis with whole cell and outside out patch-clamp electrophysiology. First, we induced a persistent current in chicken ASIC1 (cASIC1) via a natural venom toxin, Psalmotoxin-1 (PcTx1). We determined that GMQ acts as a molecular wedge by prying apart the transmembrane domains of the cASIC1-PcTx1 protein complex and potentiating ASIC-current. This led us to better understand that the NPLSD is intact in cASIC1 and is sensitive to GMQ additions, albeit in a state-dependent manner. We then theorized that direct activation of rASIC3 by GMQ is possible due the channel’s interaction with extracellular calcium, and were interested in introducing feature into the cASIC1 channel. We generated a chimeric ASIC combining the extracellular, transmembrane, and intracellular domains of rASIC3 and cASIC1 in order to individually isolate the calcium and nonproton ligand effects on channel activation. This chimera, termed cASIC1 (rASIC3-TM/ITC), is comprised of the extracellular domain of cASIC1 and the transmembrane/intracellular domains of rASIC3, and can be activated by GMQ in the absence of calcium similarly to wild-type rASIC3. Thus, GMQ activation was introduced in cASIC1 by replacing the transmembrane domains with those of ASIC3 suggesting that the ASIC3 TM domains dictate NPLSD influence on channel activity. Taken together, we identified that channel state influences nonproton ligand interaction with ASICs, and the transmembrane domains are critical for this interaction.Item Synergy 2007: Annual Research Report(2007-01-01)Item Synergy 2011: Annual Research Report(2011-01-01)Item The Acute and Chronic Effects of Beta Blockade on Dynamic Exercise Performance and Cardiac Adaptation to Dynamic Exercise Training(1998-06-01) Robbins, H. Bart; Peter B. Raven; Patricia A. Gwirtz; Robert MalletWidespread use of beta-adrenergic blocking agents as treatments for hypertension, ischemic heart disease and postmyocardial infarction has raised many questions concerning the effect of these drugs during exercise. Since exercise is often prescribed as an adjunct treatment in combination with beta blockade, the effect of these drugs on cardiac function during exercise is important to know. It is also important to ascertain if patients taking beta blockers will benefit from chronic dynamic exercise training the same way as normal subjects or if they should be viewed differently. This review of the current biomedical literature is meant to elucidate the cardiac effects, both acute and chronic, of beta-adrenoceptor blockade during dynamic exercise. The acute effects during dynamic exercise and the compensatory mechanisms in the cardiovascular system will be outlined. I will further explore if and how beta blockade significantly affects cardiac adaptation to chronic exercise training. Be reviewing the current literature I will show what is already known and will demonstrate where current knowledge is lacking and where further research is needed. There are two questions which will be addressed by this research. The first question is: “What happens to the cardiovascular system during dynamic exercise when a beta blocker is present in the system?” This question deals with the acute effects of such agents on exercise performance and cardiac function. The second question is: “What effect does beta blockade have on the cardiac adaptations to chronic dynamic exercise training?” This question examines areas of cardiac adaptation that have been postulated to be mediated by beta-adrenergic receptor stimulation (e.g. myocardial hypertrophy). I hypothesize that the acute effects of beta blockade on exercise performance are minimal, while the chronic effects on cardiac adaptation to dynamic exercise training may be significant.Item The Association between Obesity, Cognition, and Visual Function(2011-05-01) Currie-Elolf, Lauren M.; Nathalie SumienPurpose: Obesity is an adverse health condition characterized by excessive weight gain. Aside from the pathological conditions most commonly associated with obesity, recent epidemiological studies have suggested that obesity may be associated with impaired learning and memory. Previous research has linked inflammation and oxidative stress, cellular changes that occur consequent to obesity, to impaired cognitive function. Obese rodent models have been established and are commonly used for obesity-related research; however, with respect to the effect of obesity on cognitive function, the data remain inconclusive. In these studies, two obese mouse models, representing two obesity-inducing causes: genetic vs. environment, were behaviorally characterized in order to determine which model was best suited to study behavioral and cellular changes associated with obesity. Furthermore, a suitable model needed to be identified to carry on studies focusing on the relation between aging and obesity, as one would predict an exacerbation of the impairment in old obese models with age. The current studies were also based on the rationale that a dietary intervention at mid-life would ameliorate behavioral and biochemical changes observed with obesity. Methods: In study I, separate groups of 6-month old male and female C57BL/6 and leptin-deficient (ob/ob) were subjected to a battery of behavioral tests for motor, cognitive and visual function. In study II, separate groups of male C57BL/6 mice aged to 6- or 12-months were fed ad libitum either a control diet or a high-fat diet since 6- weeks of age. In a subset of the aged mice, a dietary intervention was introduced such that these mice were switched from the high-fat diet to the control diet at 6-months of age. Mice were subjected to a battery of behavioral tests at 6- or 12-months that required utilization of various component of memory, learning and visual function. Results: In study I, cognitive impairments were observed in the obese mice, and were exacerbated in female mice. While overall spatial learning was unaffected, male and female ob/ob mice performed worse on an active avoidance paradigm, indicating frontal cortical impairment. The ob/ob mice also performed worse on vision-associated tests. The results from this study suggested that obesity impairs cognitive and visual function in a sex-dependent manner. In study II, increased anxiety was observed in diet-induced obese mice; however, spontaneous activity, spatial capacity and performance on the active avoidance paradigm were unaffected. The dietary intervention reversed the effect of obesity on anxiety-like behaviors, but failed to improve cognitive and motor function. Visual impairments were observed in diet-induced obese mice, and these impairments were exacerbated with age. The results from study II indicated that diet- induced obese mice could be used to study the effects of obesity on visual, but not cognitive function. Conclusions: Overall, the hypothesis that obesity impairs cognitive function and exacerbates age-related impairments was not supported and the dietary intervention had minor effects. However, in both models, obesity impaired visual function and it was exacerbated at older ages. These findings suggest that ob/ob and diet-induced obese mice are valid animal models for investigating obesity-induced visual disorders.