Barrett, The Honors College Thesis/Creative Project Collection
Barrett, The Honors College at Arizona State University proudly showcases the work of undergraduate honors students by sharing this collection exclusively with the ASU community.
Barrett accepts high performing, academically engaged undergraduate students and works with them in collaboration with all of the other academic units at Arizona State University. All Barrett students complete a thesis or creative project which is an opportunity to explore an intellectual interest and produce an original piece of scholarly research. The thesis or creative project is supervised and defended in front of a faculty committee. Students are able to engage with professors who are nationally recognized in their fields and committed to working with honors students. Completing a Barrett thesis or creative project is an opportunity for undergraduate honors students to contribute to the ASU academic community in a meaningful way.
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- Creators: School of Life Sciences
found in the human and rat brain. In Rats, OCT3 is the only known monoamine transporter inhibited by physiological concentrations of corticosteroids. We hypothesized that CORT- mediated inhibition of OCT3 blocks the clearance of serotonin (5-HT) leading to an increase 5-HT receptor-mediated signaling. In experiment 1, due to conflicting reports on the location of OCT3 mRNA in the rat brain, in situ hybridization was performed on brain tissue sections. RNA was extracted from rat brain tissue, reverse transcribed into cDNA, and then polymerase chain reaction (PCR) was performed to generate riboprobe templates. The riboprobe templates were then used for in vitro transcription of digoxigenin (DIG)-labeled riboprobes complementary to OCT3. In experiment 2, 12 rats from an identical cohort were exposed to a chronic restraint stress paradigm (two hours/day for seven days, STRESS group), while the other 12 remained in their home cages (CTRL group). Twenty-four hours after the last stressor, all animals were euthanized and their brains immediately removed and frozen. Bilateral tissue punches were collected from 300μm coronal sections from the CA1 region of the dorsal hippocampus, basolateral amygdala (BLA), and dorsomedial hypothalamus (DMH). The relative OCT2, OCT3, and 5HT2a mRNA levels from each tissue punch were determined via quantitative real-time polymerase chain reaction (qPCR). The results of experiment 1 confirmed the presence of OCT3 mRNA in the CA1, amygdala, and the DMH. The results of experiment 2 show that chronic restraint stress did not alter gene expression for 5-HT2A, OCT2, and OCT3. These data may help reveal new information involving OCT3’s role in the hippocampus, amygdala and DMH in regards to localization and mRNA expression levels after exposure to a stressor.
This hypothesis is supported by previous studies demonstrating that stress-induced elevation of glucocorticoids increases the transcription of C4. I propose that activated glucocorticoid receptors directly increase C4 protein expression as a transcription factor activator. Additionally, I propose that activated glucocorticoid receptors inhibit the expression of the transcription factor nuclear factor-light-chain-enhancer of activated B cells (NF-κB), thereby leading to decreased expression of the C4 inhibitor CUB and Sushi multiple domains 1 (CSMD1).
Glucocorticoid receptors and C4 are richly expressed in the hippocampus, a region critical in memory consolidation, spatial, and declarative memory. I propose that stress-induced upregulation of C4 activity in the hippocampus promotes excessive synaptic pruning, contributing to specific deficits and hippocampal shrinkage seen in schizophrenia. Stress exposure during fetal development and adolescence likely acts through the proposed mechanisms to increase hippocampal C4 activity and subsequent schizophrenia risk. These mechanisms may reveal novel interactions between environmental and genetic risk factors in the etiology of schizophrenia through complement activation.