Matching Items (5)
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- All Subjects: RASopathies
- All Subjects: Cocaine
- Creators: Newbern, Jason
- Creators: Hilbert, Alexander Robert
- Member of: Barrett, The Honors College Thesis/Creative Project Collection
Description
MicroRNAs are small, non-coding transcripts that control gene expression by preventing mRNA from translating into proteins. They have been implicated to play a role in many drug addictions. We previously found that miR-495 targets several addiction-related genes (ARGs) and is highly expressed in the nucleus accumbens (NAc). We also found miR-495 is downregulated in the NAc following acute cocaine administration, and cocaine motivation measured by breakpoint on a progressive ratio schedule of cocaine reinforcement is decreased when miR-495 is overexpressed. In this study, we manipulated the endogenous levels of miR-495 by using a viral vector. Using an animal model, rats were first trained for self-administration on a fixed ratio (FR) schedule of reinforcement. After they were infused with a lentivirus to overexpress (LV-miR-495) or decrease (LV-Sponge) miR-495, in the NAc shell. The rats were then tested for extinction and reinstatement of cocaine-seeking behavior, which are measures of motivation for cocaine. We measured the relative levels of miR-495 in the NAc shell using qRT-PCR. Our results show that overexpression of miR-495 decreased cocaine-seeking behavior during extinction and cocaine reinstatement, as we hypothesized. Surprisingly, miR-495 LV-sponge also decreased cocaine-seeking behavior in extinction, not as we hypothesized. However, we found that LV-Sponge failed to significantly decrease levels of miR-495 as intended. In conclusion, understanding why LV-Sponge decreased, rather than increased, miR-495 will need further study, however, the results with LV-miR-495 extend previous findings that miR-495 plays a vital role in the molecular mechanism that influences motivation to seek cocaine.
ContributorsChaudhury, Trisha (Author) / Neisewander, Janet (Thesis director) / Newbern, Jason (Committee member) / Powell, Gregory (Committee member) / Department of Psychology (Contributor) / School of Molecular Sciences (Contributor) / Barrett, The Honors College (Contributor)
Created2017-05
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 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
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 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
Description
The ERK1/2 cell signaling pathway is highly conserved and a prominent regulator of processes like cell proliferation, differentiation, and survival. During nervous system development, the ERK1/2 cascade is activated by the binding of growth factors to receptor tyrosine kinases, leading to the sequential phosphorylation of intracellular protein kinases in the pathway and eventually ERK1 and ERK2, the effectors of the pathway. Well-defined germline mutations resulting in hyperactive ERK1/2 signaling have been implicated in a group of neurodevelopmental disorders called RASopathies. RASopathic individuals often display features such as developmental delay, intellectual disability, cardio-facial abnormalities, and motor deficits. In addition, loss-of-function in ERK1/2 can lead to neurodevelopmental disorders such as autism spectrum disorder (ASD) and intellectual disability. To better understand the pathology of these neurodevelopmental disorders, the role of ERK1/2 must be examined during the development of specific neuronal and glial subtypes. In this study, we bred transgenic mice with conditional deletion of ERK1/2 in cholinergic neuronal populations to investigate whether ERK1/2 mediates the survival or activity of basal forebrain and striatal cholinergic neurons during postnatal development. By postnatal day 10, we found that ERK1/2 did not seem to mediate cholinergic neuron number within the basal forebrain or striatum. In addition, we showed that expression of FosB, a neuronal activity-dependent transcription factor and target of ERK1/2, was not yet observed in cholinergic neurons within either of these anatomical regions by P10. Finally, our preliminary data suggested that FosB expression within layer IV of the somatosensory cortex, a target domain for basal forebrain cholinergic projections, also did not appear to be mediated by ERK1/2 signaling. However, since cholinergic neuron development is not yet complete by P10, future work should explore whether ERK1/2 plays any role in the long-term survival and function of basal forebrain and striatal cholinergic neurons in adulthood. This will hopefully provide more insight into the pathology of neurodevelopmental disorders and inform future therapeutic strategies.
ContributorsBalasubramanian, Kavya (Author) / Newbern, Jason (Thesis director) / Velazquez, Ramon (Committee member) / Rees, Katherina (Committee member) / Barrett, The Honors College (Contributor) / Department of Psychology (Contributor)
Created2023-05
Description
Cocaine use remains a prevalent problem, yet there are no effective pharmacological treatments against cocaine use disorders. Cocaine is known to affect serotonin neurotransmission in the brain. Previous data has shown the modulatory role of CP 94,253, a serotonin 1B receptor (5-HT1BR) agonist on cocaine self-administration at different periods of the use-abstinence-relapse cycle. CP 94,253 facilitates cocaine self-administration in rats during the use maintenance phase, where rats are receiving daily intake of cocaine, yet attenuates it after a period of abstinence, when drug delivery is discontinued and rats are placed in home cages. Here we study the therapeutic potential of 5-HT1BR agonist pre-treatment on cocaine self-administration during these different time periods. Male and free-cycling female rats were trained to lever-press for cocaine (0.75 mg/kg i.v.) or sucrose pellets, until they met stable performance for total number of infusions on a fixed ratio 5 schedule of reinforcement. Rats were then tested with either the FDA-approved but less selective 5-HT1BR agonist zolmitriptan (3, 5.6, and 10 mg/kg s.c.; in descending order) prior to a period of abstinence or the more selective 5-HT1BR agonist CP 94,253 (5.6 mg/kg s.c.) after a period of prolonged abstinence and relapse (i.e. resumption of daily cocaine self-administration after a period of abstinence). Each session ran for 2 hours during which the training dose was available for the 1st hour and a low dose of cocaine (0.075 mg/kg i.v.) for the 2nd hour. Zolmitriptan was found to attenuate cocaine self-administration measures at a dose of 3 and 5.6 mg/kg when testing at the low dose of cocaine and at all three doses (3, 5.6, and 10 mg/kg) when testing at the training dose of cocaine. Zolmitriptan at the doses effective at attenuating cocaine intake did not alter sucrose self-administration. CP 94,253 (5.6 mg/kg s.c.) was found to have significant attenuative effects on self-administration measures both after a period of prolonged abstinence and after a period of relapse. Overall, these experiments showed that zolmitriptan decreased cocaine reinforcement without altering sucrose reinforcement as well as that CP 94,253 attenuates cocaine intake even after a period of relapse. These findings support the therapeutic potential of 5-HT1BR agonists as pharmacological treatments for cocaine use disorders.
ContributorsLe, Tien (Author) / Neisewander, Janet (Thesis director) / Newbern, Jason (Committee member) / Garcia, Raul (Committee member) / Chemical Engineering Program (Contributor, Contributor) / School of International Letters and Cultures (Contributor) / Barrett, The Honors College (Contributor)
Created2020-05