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Monoamine neurotransmitters (e.g., serotonin, norepinephrine, and dopamine) are powerful modulators of mood and cognitive function in health and disease. We have been investigating the modulation of monoamine clearance in select brain regions via organic cation transporters (OCTs), a family of nonselective monoamine transporters. OCTs are thought to complement the actions

Monoamine neurotransmitters (e.g., serotonin, norepinephrine, and dopamine) are powerful modulators of mood and cognitive function in health and disease. We have been investigating the modulation of monoamine clearance in select brain regions via organic cation transporters (OCTs), a family of nonselective monoamine transporters. OCTs are thought to complement the actions of selective monoamine transporters in the brain by helping to clear monoamines from the extracellular space; thus, assisting to terminate the monoamine signal. Of particular interest, stress hormones (corticosterone; CORT) inhibit OCT3-mediated transport of monoamine, to putatively lead to prolonged monoamine signaling. It has been demonstrated that stress levels of CORT block OCT3 transport in the rat hypothalamus, an effect that likely underlies the rapid, stress-induced increase in local monoamines. We examined the effect of chronic variable stress (CVS) on the development of mood disorders and OCT3 expression in limbic and hypothalamic regions of the rat brain. Animals subjected to CVS (14-days with random stressor exposure two times/day) showed reduced body weight gain, indicating that CVS was perceived as stressful. However, behavioral tests of anxiety and depressive-like behaviors in rats showed no group differences. Although there were no behavioral effects of stress, molecular analysis revealed that there were stress-related changes in OCT3 protein expression. In situ hybridization data confirmed that OCT3 mRNA is expressed in the hippocampus, amygdala, and hypothalamus. Analysis of Western blot data by two-way ANOVA revealed a significant treatment effect on OCT3 protein levels, with a significant decrease in OCT3 protein in the amygdala and hippocampus in CVS rats, compared to controls. These data suggest an important role for CORT sensitive OCT3 in the reduction of monoamine clearance during stress.
ContributorsBoyll, Piper Savannah (Author) / Orchinik, Miles (Thesis director) / Conrad, Cheryl (Committee member) / Talboom, Joshua (Committee member) / School of Life Sciences (Contributor) / Barrett, The Honors College (Contributor)
Created2016-05
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Description
Rasopathies are a family of developmental syndromes that exhibit craniofacial abnormalities, cognitive disabilities, developmental delay and increased risk of cancer. However, little is known about the pathogenesis of developmental defects in the nervous system. Frequently, gain-of-function mutations in the Ras/Raf/MEK/ERK cascade (aka ERK/MAPK) are associated with the observed pathogenesis. My

Rasopathies are a family of developmental syndromes that exhibit craniofacial abnormalities, cognitive disabilities, developmental delay and increased risk of cancer. However, little is known about the pathogenesis of developmental defects in the nervous system. Frequently, gain-of-function mutations in the Ras/Raf/MEK/ERK cascade (aka ERK/MAPK) are associated with the observed pathogenesis. My research focuses on defining the relationship between increased ERK/MAPK signaling and its effects on the nervous system, specifically in the context of motor learning. Motor function depends on several neuroanatomically distinct regions, especially the spinal cord, cerebellum, striatum, and cerebral cortex. We tested whether hyperactivation of ERK/MAPK specifically in the cortex was sufficient to drive changes in motor function. We used a series of genetically modified mouse models and cre-lox technology to hyperactivate ERK/MAPK in the cerebral cortex. Nex:Cre/NeuroD6:Cre was employed to express a constitutively active MEK mutation throughout all layers of the cerebral cortex from an early stage of development. RBP4:Cre, caMEK only exhibited hyper activation in cortical glutamatergic neurons responsible for cortical output (neurons in layer V of the cerebral cortex). First, the two mouse strains were tested in an open field paradigm to assess global locomotor abilities and overall fitness for fine motor tasks. Next, a skilled motor reaching task was used to evaluate motor learning capabilities. The results show that Nex:Cre/NeuroD6:Cre, caMEK mutants do not learn the motor reaching task, although they performed normally on the open field task. Preliminary results suggest RBP4:Cre, caMEK mutants exhibit normal locomotor capabilities and a partial lack of learning. The difference in motor learning capabilities might be explained by the extent of altered connectivity in different regions of the corticospinal tract. Once we have identified the neuropathological effects of various layers in the cortex we will be able to determine whether therapeutic interventions are sufficient to reverse these learning defects.
ContributorsRoose, Cassandra Ann (Author) / Newbern, Jason M. (Thesis director) / Olive, Foster (Committee member) / Bjorklund, Reed (Committee member) / School of Life Sciences (Contributor) / Barrett, The Honors College (Contributor)
Created2016-12
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The aim of this study was to determine whether IUD administration, with and without the presence of Levo, and with and without the presence of the ovaries, impacts cognition in a rat model. Rats received either Sham or Ovariectomy (Ovx) surgery (removal of the ovaries), plus either no IUD, a

The aim of this study was to determine whether IUD administration, with and without the presence of Levo, and with and without the presence of the ovaries, impacts cognition in a rat model. Rats received either Sham or Ovariectomy (Ovx) surgery (removal of the ovaries), plus either no IUD, a Blank IUD (without Levo), or a Levo-releasing IUD (Levo IUD), enabling us to evaluate the effects of Ovx and the effects of IUD administration on cognition. Two weeks after surgery, all treatment groups were tested on the water radial arm maze, Morris water maze, and visible platform task to evaluate cognition. At sacrifice, upon investigation of the uteri, it was determined that some of the IUDs were no longer present in animals from these groups: Sham\u2014Blank IUD, Ovx\u2014Blank IUD, and Sham\u2014Levo IUD. Results from the remaining three groups showed that compared to Sham animals with no IUDs, Ovx animals with no IUDs had marginally impaired working memory performance, and that Ovx animals with Levo IUDs as compared to Ovx animals with no IUDs had marginally enhanced memory performance, not specific to a particular memory type. Results also showed that Ovx animals with Levo IUDs had qualitatively more cells in their vaginal smears and increased uterine horn weight compared to Ovx animals with no IUDs, suggesting local stimulation of the Levo IUDs to the uterine horns. Overall, these results provide alternative evidence to the hypothesis that the Levo IUD administers Levo in solely a localized manner, and suggests that the possibility for the Levo IUD to affect reproductive cyclicity in ovary-intact animals is not rejected. The potential for the Levo IUD to exert effects on cognition suggests that either the hormone does in fact systemically circulate, or that the Levo IUD administration affects cognition by altering an as yet undetermined hormonal or other feedback between the uterus and the brain.
ContributorsStrouse, Isabel Martha (Author) / Bimonte-Nelson, Heather (Thesis director) / Glenberg, Arthur (Committee member) / Sirianni, Rachael (Committee member) / Conrad, Cheryl (Committee member) / School of Life Sciences (Contributor) / Department of Psychology (Contributor) / Barrett, The Honors College (Contributor)
Created2018-12
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Description
The RAS/MAPK (RAS/Mitogen Activated Protein Kinase) pathway is a highly conserved, canonical signaling cascade that is highly involved in cellular growth and proliferation as well as cell migration. As such, it plays an important role in development, specifically in development of the nervous system. Activation of ERK is indispensable for

The RAS/MAPK (RAS/Mitogen Activated Protein Kinase) pathway is a highly conserved, canonical signaling cascade that is highly involved in cellular growth and proliferation as well as cell migration. As such, it plays an important role in development, specifically in development of the nervous system. Activation of ERK is indispensable for the differentiation of Embryonic Stem Cells (ESC) into neuronal precursors (Li z et al, 2006). ERK signaling has also shown to mediate Schwann cell myelination of the peripheral nervous system (PNS) as well as oligodendrocyte proliferation (Newbern et al, 2011). The class of developmental disorders that result in the dysregulation of RAS signaling are known as RASopathies. The molecular and cell-specific consequences of these various pathway mutations remain to be elucidated. While there is evidence for altered DNA transcription in RASopathies, there is little work examining the effects of the RASopathy-linked mutations on protein translation and post-translational modifications in vivo. RASopathies have phenotypic and molecular similarities to other disorders such as Fragile X Syndrome (FXS) and Tuberous Sclerosis (TSC) that show evidence of aberrant protein synthesis and affect related pathways. There are also well-defined downstream RAS pathway elements involved in translation. Additionally, aberrant corticospinal axon outgrowth has been observed in disease models of RASopathies (Xing et al, 2016). For these reasons, this present study examines a subset of proteins involved in translation and translational regulation in the context of RASopathy disease states. Results indicate that in both of the tested RASopathy model systems, there is altered mTOR expression. Additionally the loss of function model showed a decrease in rps6 activation. This data supports a role for the selective dysregulation of translational control elements in RASopathy models. This data also indicates that the primary candidate mechanism for control of altered translation in these modes is through the altered expression of mTOR.
ContributorsHilbert, Alexander Robert (Author) / Newbern, Jason (Thesis director) / Olive, M. Foster (Committee member) / Bjorklund, Reed (Committee member) / School of Life Sciences (Contributor) / Barrett, The Honors College (Contributor)
Created2017-05
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Description
Chronic restraint stress leads to apical dendritic retraction in CA3 pyramidal neurons and often no quantifiable changes in CA1 dendritic complexity. When chronic stress ends, a post-stress recovery period results in an enhancement in CA3 dendritic complexity. We investigated the relationship between CA3 and CA1 pyramidal neurons to determine whether

Chronic restraint stress leads to apical dendritic retraction in CA3 pyramidal neurons and often no quantifiable changes in CA1 dendritic complexity. When chronic stress ends, a post-stress recovery period results in an enhancement in CA3 dendritic complexity. We investigated the relationship between CA3 and CA1 pyramidal neurons to determine whether dendritic restructuring in CA3 neurons leads to region-specific changes in the dendritic complexity of CA1 neurons. Adult male Sprague-Dawley rats were restrained (wire mesh, 6h/d/21d) and brains were removed soon after restraint ended (Str-Imm) or after a 21d post-stress recovery period (Str-Rec). In addition, BDNF downregulation targeting the CA3 region prevents enhancement in dendritic complexity following recovery in chronically stressed rats, providing robust conditions to investigate the CA3-CA1 relationship. Consequently, rats were infused into the CA3 area with either an AAV vector with a coding sequence against BDNF (shRNA) or a sequence with no known mRNA complements (Scr). Apical and basal dendritic complexity of CA3 and CA1 was quantified by counting total dendritic bifurcations and dendritic intersections using the Sholl analysis (20 µm distances from soma). Please note that the quantification of the CA3 dendritic arbors was not part of this thesis project. The outcome of that investigation revealed that apical CA3 dendritic retraction was found in Str-Imm-Scr and Str-Rec-shRNA. For the CA1 apical area, gross dendritic bifurcation differences were not detected, but the Sholl quantification revealed regionally-enhanced dendritic complexity that varied by distance from the soma at the distal apical dendrites (Str-Imm-Scr) and proximal basal dendrites (Str-Rec-shRNA). For the latter, significant increases in basal branch points were detected with total branch point quantification method. Moreover, a correlation using all groups revealed a significant inverse relationship between CA3 apical dendritic complexity and CA1 basal dendritic complexity. The results demonstrate that chronic stress-induced CA3 apical dendritic retraction may relate to region-specific changes in CA1 dendritic complexity. The inability of past studies to detect changes in CA1 dendritic complexity may be due to the shortcoming of gross dendritic arbor measures in accounting for subtle region-specific alterations. To address this, the current study included a cohort with BDNF downregulated in the CA3 region. Overall, this suggests that decreased levels of BDNF in the hippocampus provide robust conditions in which changes to CA1 dendritic complexity can be detected.
ContributorsDaas, Eshaan Jatin (Author) / Conrad, Cheryl (Thesis director) / Orchinik, Miles (Committee member) / Ortiz, J. Bryce (Committee member) / School of Life Sciences (Contributor) / Barrett, The Honors College (Contributor)
Created2016-12
Description

This paper provides a multidisciplinary analysis of the relationship between beauty and addiction, with a focus on the emerging field of neuroaesthetics. Neuroaesthetics investigates the neural mechanisms that underlie aesthetic experiences and how the brain cognitively processes beauty. Since there is a biological foundation of this report, I will predominantly

This paper provides a multidisciplinary analysis of the relationship between beauty and addiction, with a focus on the emerging field of neuroaesthetics. Neuroaesthetics investigates the neural mechanisms that underlie aesthetic experiences and how the brain cognitively processes beauty. Since there is a biological foundation of this report, I will predominantly discuss neuroanatomy, neurological studies, and the overlap in neural circuitry between beauty and addiction. In addition, I will discuss the philosophical roots of beauty, as well as the environmental elements involved. Chapter 1 begins by explaining the history of beauty and its importance. I discuss the main constituents of beauty and differentiate between key terms involved in the beauty experience. In order to understand the link between beauty and addiction, it is essential to have a knowledgeable background on what beauty is. Next, I discuss the neurobiology of addiction. The main component of this chapter involves the mesolimbic and mesocortical reward pathways. I also describe neuroanatomical terms involved in addiction. The last chapter considers the implications of neuroaesthetics in various studies, which primarily involve the use of fMRIs. I discuss the sensory evaluations of beauty and the brain regions involved in the beauty experience. From this, I found that the experience of beauty activates these main brain regions: PFC, amygdala, striatum, NAcc, cingulate, VTA, and most remarkably, field A1 of the mOFC. By combining the neurological studies with studies of aesthetics, I reached the conclusion that there is an overlap in the neural pathways during the experience of beauty and during addiction. Although it is necessary for further research to be conducted to properly declare this, I discovered that the pursuit of beauty can lead to addictive behaviors, as the reward centers of the brain are activated by aesthetic experiences.

ContributorsFarrell, Natalie (Author) / de Alcantara, Christiane Fontinha (Thesis director) / Conrad, Cheryl (Committee member) / Barrett, The Honors College (Contributor) / School of Life Sciences (Contributor) / Department of Marketing (Contributor)
Created2023-05
Description

Alzheimer’s disease (AD) is an irreversible brain disorder that plagues millions of people with no current cure. Current clinical research is slowly advancing to more definitive treatments in hopes of reducing the effects of progressive cognitive and behavioral decline, but none so far can slow AD’s onset. A brain area

Alzheimer’s disease (AD) is an irreversible brain disorder that plagues millions of people with no current cure. Current clinical research is slowly advancing to more definitive treatments in hopes of reducing the effects of progressive cognitive and behavioral decline, but none so far can slow AD’s onset. A brain area known as the nucleus incertus (NI) was recently discovered to potentially impact AD because of its connections to brain targets that degenerate; however, the NI’s role is unknown. This goal of this experiment was to use a transgenic mouse model (APP/PS1) that expresses AD pathology slowly as found in humans, and to test the mice in a variety of cognitive and anxiety assessments. Mice of both sexes and two different ages were used, with the first being young adult before AD pathology manifests (around 3-4 months old), and the second being around the cusp of when AD pathology manifests (late adult, 8-10 months old). The mice were tested in a variety of cognitive tasks that included the novel object recognition (NOR), Morris water maze (MWM), and the object placement (OP), with the latter being the focus of my thesis. Anxiety measures were taken from the open field (OF) and elevated plus maze (EPM) with the visible platform (VP) used to ensure mice could perform on the rigorous MWM task. In the OP, we found an age effect, where the older mice were less likely to explore the moved object during the OP compared to the younger mice; motor ability was unlikely to explain this effect. We did not find any significant age by genotype effects. These findings indicate that cognitive impairment only just started to affect the older cohort, since OP impairment was found on one measure and not another. Other measures currently being quantified will be helpful in understanding this data, and to see whether learning, memory, and anxiety are affected.

ContributorsDapon, Bianca (Author) / Conrad, Cheryl (Thesis director) / Bimonte-Nelson, Heather (Committee member) / Barrett, The Honors College (Contributor) / Department of Psychology (Contributor)
Created2023-05