Matching Items (75)
Description
Abstract: The RAS/RAF/MEK/ERK (RAS signaling cascade) pathway is a highly conserved biochemical signaling cascade that exists in every mammalian cell. The pathway is highly versatile in functionality due to hundreds of substrates that regulate metabolism, apoptosis, and proliferation in both adult and developing tissues. The RAS signaling cascade has been examined in the context of cancers since mutations can lead to the disruption of the cell cycle and unregulated cellular proliferation. In addition, germline mutations in the pathway have been shown to cause a group of syndromes known as RASopathies. RASopathies are marked by facial defects, seizures, developmental delays, and cognitive dysfunction often due to enhanced activation of the RAS signaling cascade. Although there are noted factors that play roles in neurological disease, such as a hyperactivated RAS signaling cascade, the pathogenesis of neurological defects is not fully understood. The Newbern lab uses conditional mutagenesis to examine how hyperactivating the RAS/MAPK pathway affects GABAergic neurons in a cortical microcircuit, especially during development. Inhibitory neurons are implicated in seizures and epilepsy is common in RASopathies, thus GABAergic neurons are of particular interest (Rauen, 2013). Gain-of-function ERK was not found to significantly alter global locomotion or anxiety-like behaviors. Interestingly, the mutant mice exhibited freezing behavior in the first twenty-two seconds of the open field assay that appeared to be consistent with absence seizures. Direct EEG recordings confirmed spontaneous seizure activity and mutants had a reduced seizure threshold. We hypothesized that these deficits were due to altered GABAergic neuron number. Indeed, mutant mice exhibited a 30% reduction in total cortical GABAergic neuron number. This effect appeared to be cell subtype specific, where neurons expressing somatostatin (SST) existed in similar numbers among controls and mutants but a significant decrease in the number of those expressing parvalbumin (PV) was observed. I hypothesized that a recently identified GABAergic neuron expressing vasoactive intestinal polypeptide (VIP) would also be affected in such a manner that fewer VIP neurons exist in the mutants than the wildtype. Subsequent histological studies in these mice found there to be no significant difference in VIP populations. Selective affects seem to only have an effect on the development of PV neurons in the cortex. Further studies are underway to define the mechanism responsible for aberrant GABAergic neuron development.
ContributorsGonzalez, Javier (Author) / Newbern, Jason (Thesis director) / Neisewander, Janet (Committee member) / Barrett, The Honors College (Contributor)
Created2016-05
Description
Modeling sporadic amyotrophic lateral sclerosis (sALS) has been a challenge since there is no known single gene mutation that triggers disease pathogenesis. Although human induced pluripotent stem cells (hiPSCs) have created new opportunities in studying sALS, they do not retain important age associated phenotypic markers due to the rejuvenation stage that takes place during the reprogramming of somatic cells into hiPSCs. To overcome this obstacle, we performed an alternative method of direct neuronal conversion from patient fibroblasts that utilizes two transcription factors, Ngn2 and Ascl1. These transcription factors were sufficient to initiate direct neuronal conversion and produce induced neurons (iNeurons). Through the positive staining of neuronal markers Map2, Synapsin-1, and Human Nuclear Marker we found that induced neurons do display neuronal features that are seen in mature neurons.
ContributorsSwinford, Sarah Joan (Author) / Neisewander, Janet (Thesis director) / Sattler, Rita (Committee member) / Nelson, Andrew (Committee member) / College of Integrative Sciences and Arts (Contributor) / Barrett, The Honors College (Contributor)
Created2017-05
Description
Abstract Cocaine is highly addictive because it exacerbates the action responsible for creating the feeling of "reward," which is controlled by the neurotransmitter dopamine. Dopamine receptors can be divided into five subtypes: D1, D2, D3, D4, and D5. The localization of D3 receptors is restricted to the mesolimbic pathway, which is often called the "reward pathway." This pathway is associated with emotions, motivation, and behavior. There is evidence that these receptors are upregulated in response to the repeated use of psychostimulants, such as cocaine, making these receptors a potential target for pharmaceutical therapeutics for drug addiction. In the present study, two compounds selective for D3 receptors, MC-250041 and LS-3-134, were examined for their effects on spontaneous and cocaine-primed locomotor activity. The present study also aimed to examine the effects of MC-250041 and LS-3-134 on the number of lever presses and infusions under a progressive ratio (PR) schedule when subjects are trained to self-administer cocaine within an operant conditioning chamber. Based on the present research on D3 receptor compounds and D3Rs, I hypothesized that pretreatment with MC-250041 or LS-3-134 decreases cocaine self-administration under a progressive ratio (PR) schedule of cocaine reinforcement at doses that would have no effect on locomotor activity. The results showed no significant effects on spontaneous or cocaine-primed locomotor activity following an injection of MC-250041 (1, 3, 5.6 mg/kg IP). Similarly, there was no change in the amount of lever presses or drug infusions within an operant conditioning chamber at any of the examined doses of MC-250041 (3, 5.6, 10 mg/kg IP) during self-administration. LS-3-134 decreased cocaine-primed locomotor activity, as well as lever presses and infusions during self-administration at the 5.6 mg/kg dose; however, there was no effect on spontaneous locomotor activity at any of the examined doses (1, 3.2, 5.6 mg/kg IP). In conclusion, the results of the study suggest that LS-3-134 effectively reduced motivation for cocaine at the 5.6 mg/kg dose; whereas, MC-250041 was unsuccessful at warranting any significant effect on motivation for cocaine at any of the examined doses.
ContributorsMendoza, Rachel Ann (Author) / Neisewander, Janet (Thesis director) / Olive, Foster (Committee member) / Powell, Greg (Committee member) / School of Social Transformation (Contributor) / School of Life Sciences (Contributor) / Barrett, The Honors College (Contributor)
Created2017-05
Description
Previously we found that the serotonin 1B receptor (5-HT1BR) agonist CP 94,253 (CP) enhances the reinforcing properties of cocaine when given to male rats self-administering the drug daily, however, CP had the opposite effect following a 21-day period of abstinence. Methamphetamine, like cocaine, has similar mechanisms of action on the monoamine neurotransmitter systems. Therefore, we predicted that CP would have effects on the reinforcing properties of methamphetamine similar to cocaine. Additionally, we examined effects of the FDA-approved 5-HT1B/DR agonist, zolmitriptan, on psychostimulant self-administration. We first tested the effects of CP on methamphetamine self-administration utilizing a fixed ratio or progressive ratio schedule of reinforcement and found that regardless of whether or not rats experienced abstinence, CP decreased methamphetamine intake. We next verified that the effects of CP were mediated by 5-HT1BRs by demonstrating they were reversed when paired with a 5-HT1BR antagonist. We then tested the effects of zolmitriptan on methamphetamine responding and found the same results as found with CP. Finally, we tested whether the effects of zolmitriptan generalize to female rats. Both male and female rats were given access to various doses of cocaine after treatment with zolmitriptan. We also ruled out 5-HT1BR ligands has having an effect on locomotion, to rule out motor impairment as the reason behind the decreases in drug intake. Unlike our previous findings with CP effects on cocaine self-administration, zolmitriptan attenuated cocaine intake both before and after abstinence in both male and female rats. The pre-abstinence effects of zolmitriptan in attenuating intake of different psychostimulants suggest its potential as a pharmacological treatment for psychostimulant use disorders.
ContributorsCotter, Austin Richard (Author) / Neisewander, Janet (Thesis director) / Newbern, Jason (Committee member) / Garcia, Raul (Committee member) / School of International Letters and Cultures (Contributor) / School of Life Sciences (Contributor) / Department of Psychology (Contributor) / Barrett, The Honors College (Contributor)
Created2018-05
Description
Free coenzyme A (CoASH) carries acyl groups for the tricarboxylic acid (TCA) cycle and fatty acid metabolism, and donates acyl groups for protein posttranslational modifications. Cellular de novo CoASH synthesis starts with a pantothenate kinase (PANK1-3) phosphorylating pantothenate (vitamin B5). Mutations in PANK2 cause a subtype of neurodegeneration with brain iron accumulation (NBIA). The PANKs have differential subcellular distribution and regulatory properties. However, the purpose of each PANK has remained obscure, with knockout mouse models presenting with mild phenotypes unless challenged with a high-fat diet. Based on PANK2’s known activation by palmitoylcarnitine, the PANK2-deficient cells were challenged with palmitic acid (PAL) added to glucose-containing media. The high nutrient mixture generated a surprising “starvation” profile of reduced proliferation, low ATP, AMPK activation, and autophagy upregulation in PANK2-deficient PAL-challenged cells. Further experiments showed that fatty acids accumulated and that PANK2-deficient cells had reduced respiration when provided with palmitoylcarnitine as a substrate, seemingly due to an impaired ability to oxidize fatty acids during PAL-induced Randle Cycle activation. Intriguingly, whole-cell CoASH levels remained stable despite the PAL-induced starvation phenotype, and increasing CoASH via PANK1β overexpression did not rescue the phenotype, demonstrating a unique role for PANK2 in fatty acid metabolism. Even though a direct CoASH deficiency was not detected, there were changes in short chain CoA-derivatives, including acetyl-CoA, succinyl-CoA, and butyryl-CoA, as well as evidence of impaired TCA cycle function. These impairments in both the TCA cycle and fatty acid oxidation implicate a role for PANK2 in regulating mitochondria CoA dynamics.
ContributorsNordlie, Sandra Maria (Author) / Kruer, Michael C (Thesis advisor) / Neisewander, Janet (Thesis advisor) / Padilla Lopez, Sergio (Committee member) / Katsanos, Christos (Committee member) / Arizona State University (Publisher)
Created2022
Description
This dissertation research project developed as an urgent response to physical inactivity, which has resulted in increased rates of obesity, diabetes, and metabolic disease worldwide. Incorporating enough daily physical activity (PA) is challenging for most people. This research aims to modulate the brain's reward systems to increase motivation for PA and, thus, slow the rapid increase in sedentary lifestyles. Transcranial direct current stimulation (tDCS) involves brain neuromodulation by facilitating or inhibiting spontaneous neural activity. tDCS applied to the dorsolateral prefrontal cortex (DLPFC) increases dopamine release in the striatum, an area of the brain involved in the reward–motivation pathways. I propose that a repeated intervention, consisting of tDCS applied to the DLPFC followed by a short walking exercise stimulus, enhances motivation for PA and daily PA levels in healthy adults. Results showed that using tDCS followed by short-duration walking exercise may enhance daily PA levels in low-physically active participants but may not have similar effects on those with higher levels of daily PA. Moreover, there was a significant effect on increasing intrinsic motivation for PA in males, but there were no sex-related differences in PA. These effects were not observed during a 2-week follow-up period of the study after the intervention was discontinued. Further research is needed to confirm and continue exploring the effects of tDCS on motivation for PA in larger cohorts of sedentary populations. This novel research will lead to a cascade of new evidence-based technological applications that increase PA by employing approaches rooted in biology.
ContributorsRuiz Tejada, Anaissa (Author) / Katsanos, Christos (Thesis advisor) / Neisewander, Janet (Committee member) / Sadleir, Rosalind (Committee member) / Buman, Matthew (Committee member) / Arizona State University (Publisher)
Created2023
Description
The presence of pesticide contaminants in cannabis, such as organophosphate and pyrethroid pesticides, has resulted in multiple recalls by manufacturers in the U.S. There are no national guidelines to mitigate the health risk of pesticide exposure in cannabis because it is an illicit Schedule I substance under federal law. Here, we reviewed the state-level regulations of organophosphate and pyrethroid pesticides in cannabis between 2019 and 2023 and found that 14 more jurisdictions (for a total of 29) are regulating organophosphate or pyrethroid pesticides in the U.S. We evaluated the potential connections between pyrethroids, organophosphates, cannabinoids, and Parkinson’s disease using the Comparative Toxicogenomics Database (CTD). 10 pyrethroids, 27 organophosphates, and 15 cannabinoids were associated with 68 genes to form 2,320 inferred and curated Chemical-Gene-Phenotype-Disease tetramers. Exposure to chlorpyrifos and permethrin, but not Δ9-tetrahydrocannabinol (THC) and cannabidiol (CBD), results in dose-dependent effects on 1-nonanol repulsive behaviors in Caenorhabditis elegans, indicating dopaminergic neurotoxicity (p < 0.01). Dose-dependent effects of chlorpyrifos, but not permethrin, are different in the presence of Δ9-THC and CBD (p < 0.001). Our findings show that (1) U.S. states are reaching a consensus on pesticide regulation in cannabis and (2) regulators need to consider the mechanistic interaction of pesticides and cannabinoids. Further research should apply new approach methodologies such as C. elegans and CTD can help inform pesticide regulation in cannabis by chemical class.
ContributorsRivera, Albert (Author) / Leung, Maxwell (Thesis director) / Neisewander, Janet (Committee member) / Barrett, The Honors College (Contributor) / Department of Psychology (Contributor)
Created2023-12
Description
I examined the slogan, “Mental illnesses are illnesses like any other,” widespread in psychiatry and medicine, and in society more generally, to determine if it accurately and usefully characterizes mental illnesses, given current neurological and neurophysiological knowledge. Rather than focus on disease entities for comparison, I scrutinized the symptoms of somatic illnesses and mental illnesses and compared them in three areas: their production, their relationship to social and cultural context, and their potential use as indicators of underlying disease or dysfunction. In all three areas, I found that, contrary to the claim of the slogan, the symptoms of mental illness are not like the symptoms of somatic illness and therefore, by extension, mental illness is not “illness like any other.” I briefly surveyed the implications of this difference between mental illnesses and somatic illnesses, and provided some broad suggestions regarding how this finding might help to inform the characterization of mental illnesses, as well as help direct research and treatment of these conditions.
ContributorsDennert, James (Author) / Robert, Jason (Thesis advisor) / Creath, Richard (Thesis advisor) / Phillips, Ben (Committee member) / Neisewander, Janet (Committee member) / Maienschein, Jane (Committee member) / Arizona State University (Publisher)
Created2024
Description
The RASopathies are a collection of developmental diseases caused by germline mutations in components of the RAS/MAPK signaling pathway and is one of the world’s most common set of genetic diseases. A majority of these mutations result in an upregulation of RAS/MAPK signaling and cause a variety of both physical and neurological symptoms. Neurodevelopmental symptoms of the RASopathies include cognitive and motor delays, learning and intellectual disabilities, and various behavioral problems. Recent noninvasive imaging studies have detected widespread abnormalities within white matter tracts in the brains of RASopathy patients. These abnormalities are believed to be indicative of underlying connectivity deficits and a possible source of the behavioral and cognitive deficits. To evaluate these long-range connectivity and behavioral issues in a cell-autonomous manner, MEK1 loss- and gain-of-function (LoF and GoF) mutations were induced solely in the cortical glutamatergic neurons using a Nex:Cre mouse model. Layer autonomous effects of the cortex were also tested in the GoF mouse using a layer 5 specific Rbp4:Cre mouse. Immunohistochemical analysis showed that activated ERK1/2 (P-ERK1/2) was expressed in high levels in the axonal compartments and reduced levels in the soma when compared to control mice. Axonal tract tracing using a lipophilic dye and an adeno-associated viral (AAV) tract tracing vector, identified significant corticospinal tract (CST) elongation deficits in the LoF and GoF Nex:Cre mouse and in the GoF Rbp4:Cre mouse. AAV tract tracing was further used to identify significant deficits in axonal innervation of the contralateral cortex, the dorsal striatum, and the hind brain of the Nex:Cre GoF mouse and the contralateral cortex and dorsal striatum of the Rbp4:Cre mouse. Behavioral testing of the Nex:Cre GoF mouse indicated deficits in motor learning acquisition while the Rbp4:Cre GoF mouse showed no failure to acquire motor skills as tested. Analysis of the expression levels of the immediate early gene ARC in Nex:Cre and Rbp4:Cre mice showed a specific reduction in a cell- and layer-autonomous manner. These findings suggest that hyperactivation of the RAS/MAPK pathway in cortical glutamatergic neurons, induces changes to the expression patterns of P-ERK1/2, disrupts axonal elongation and innervation patterns, and disrupts motor learning abilities.
ContributorsBjorklund, George Reed (Author) / Newbern, Jason M (Thesis advisor) / Neisewander, Janet (Committee member) / Smith, Brian (Committee member) / Orchinik, Miles (Committee member) / Mangone, Marco (Committee member) / Arizona State University (Publisher)
Created2018
Description
Evidence from the 20th century demonstrated that early life stress (ELS) produces long lasting neuroendocrine and behavioral effects related to an increased vulnerability towards psychiatric illnesses such as major depressive disorder, post-traumatic stress disorder, schizophrenia, and substance use disorder. Substance use disorders (SUDs) are complex neurological and behavioral psychiatric illnesses. The development, maintenance, and relapse of SUDs involve multiple brain systems and are affected by many variables, including socio-economic and genetic factors. Pre-clinical studies demonstrate that ELS affects many of the same systems, such as the reward circuitry and executive function involved with addiction-like behaviors. Previous research has focused on cocaine, ethanol, opiates, and amphetamine, while few studies have investigated ELS and methamphetamine (METH) vulnerability. METH is a highly addictive psychostimulant that when abused, has deleterious effects on the user and society. However, a critical unanswered question remains; how do early life experiences modulate both neural systems and behavior in adulthood? The emerging field of neuroepigenetics provides a potential answer to this question. Methyl CpG binding protein 2 (MeCP2), an epigenetic tag, has emerged as one possible mediator between initial drug use and the transition to addiction. Additionally, there are various neural systems that undergo long lasting epigenetics changes after ELS, such as the response of the hypothalamo-pituitary-adrenal (HPA) axis to stressors. Despite this, little attention has been given to the interactions between ELS, epigenetics, and addiction vulnerability. The studies described herein investigated the effects of ELS on METH self-administration (SA) in adult male rats. Next, we investigated the effects of ELS and METH SA on MeCP2 expression in the nucleus accumbens and dorsal striatum. Additionally, we investigated the effects of virally-mediated knockdown of MeCP2 expression in the nucleus accumbens core on METH SA, motivation to obtain METH under conditions of increasing behavioral demand, and reinstatement of METH-seeking in rats with and without a history of ELS. The results of these studies provide insights into potential epigenetic mechanisms by which ELS can produce an increased vulnerability to addiction in adulthood. Moreover, these studies shed light on possible novel molecular targets for treating addiction in individuals with a history of ELS.
ContributorsLewis, Candace (Author) / Olive, M. Foster (Thesis advisor) / Hammer, Ronald (Committee member) / Neisewander, Janet (Committee member) / Sanabria, Federico (Committee member) / Arizona State University (Publisher)
Created2015