Kayla Lemons

Lemons, Head shot DSC_5108 (1)





Participant: PROMISE AGEP Research Symposium, 2014

Kayla Lemons
: Department of Biological Sciences
Institution: University of Maryland, Baltimore County (UMBC)




The Effects of Hydrocortisone on Tryptophan-2,3 dioxygenase and the Kynurenine Pathway

The Kynurenine pathway (KP) is a biochemical enzyme cascade responsible for metabolizing the essential amino acid Tryptophan. The hepatic enzyme Tryptophan-2,3 dioxygenase (TDO) is one of two enzymes that catalyze the initial breakdown of L-Tryptophan to N-Formylkynurenine in the first step of the pathway. It has previously been established in the literature that the steroid hormone Hydrocortisone induces TDO activity; however, the effects of Hydrocortisone on the KP as a whole have not yet been examined. Thus, given the role of TDO in the initial Tryptophan degradation step of the KP, we hypothesized that Hydrocortisone administration and the subsequent induction of TDO may cause significant changes in the levels of downstream KP metabolites. To test this hypothesis, Hydrocortisone was administered to 3 groups of mice which were sacrificed 1, 6, or 24 hours post-injection. High Performance Liquid Chromatography (HPLC) was then used to determine if there were any resulting differences in the levels of particular downstream KP metabolites in the liver, plasma and brain tissues of treated mice versus a saline-treated control group. This study has potentially great implications for the field of Neuropsychiatry, as several downstream KP metabolites are capable of influencing brain function by acting on various receptors and cell types in the brain. Given the known association between stress (which increases Hydrocortisone production) and the development of mental disorders, research into this topic could help clarify the proposed role of stress-related changes in the KP as a potential causative factor in the etiology of mental disorders.



I am currently a graduate student in the Neuroscience & Cognitive Science (NACS) doctoral program in the UMBC Biology Department. Originally a native of Virginia, I earned my Bachelor’s degree in Biology and Cognitive Science from the University of Virginia in Charlottesville, Virginia. During my time as an undergraduate at there, I served as a psychology research assistant in both the Virginia Affective Neuroscience (VAN) Lab and the Virginia Cognitive Aging Lab. Transitioning into graduate school, I look forward to gaining technical skills in bench research that deals with molecular and physiological questions in the field of Neuroscience.



Thus far, I have gained invaluable research experience through my work on a variety of graduate rotation projects. Utilizing immunohistochemistry and western blotting, I have studied the role of specific protein interactions in microtubule transport during the neural tube development of Zebrafish embryos. Additionally, I learned to use High Performance Liquid Chromatography in order to study the induction of Tryptophan 2,3 dioxygenase by hydrocortisone at the Maryland Psychiatric Research center. My current research project involves conducting behavioral studies in order to  assess the olfactory capabilities of mice in response to irritant exposure.


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