Honors Theses

Title

Gene Expression Changes by Neuroprotectant Novel Antidotes to Organophosphates

College

College of Arts and Sciences

Department

Department of Biological Sciences

Degree

Bachelor of Science (B.S.)

Document Type

Honors Thesis

Abstract

Recent assassinations and terrorist attacks demonstrate the need for a more effective antidote against nerve agents and other organophosphate (OP) compounds which inhibit the nervous system enzyme acetylcholinesterase (AChE). This study explored the changes in gene expression induced by novel phenoxyalkyl pyridinium oximes (U.S. patent 9,277,937) that have demonstrated the ability to cross the blood-brain barrier and attenuate brain damage in a rat model. More specifically, this study determined whether rats treated with high levels of a surrogate for the nerve agent sarin (nitrophenyl isopropyl methylphosphonate; NIMP) and rats treated with NIMP followed by a novel oxime displayed significant differences in their levels of messenger RNA. First, RNA samples were drawn from brain regions susceptible to damage by seizureinducing OP exposure levels (piriform cortex and hippocampus), harvested from rats treated with NIMP alone or NIMP followed by a novel oxime. The samples of rat brain RNA were converted to complementary DNA (cDNA) via reverse transcription. The resultant cDNA was used in quantitative polymerase chain reaction (qPCR) to examine expression levels of genes that reflect inflammation (Ccl2) and nerve growth and repair (Ngfr) in the piriform cortex, along with expression levels of genes involved in potential brain damage repair (Bdnf) and astrocyte damage (Gfap) in the hippocampus. Following these initial four genes, two additional immediate early genes were evaluated, also in the hippocampus: Fos, associated with signal transduction, and Bcl2l1, which may provide neuroprotection. Changes in the levels of gene expression were quantified and compared across the experimental animal groups, i.e., NIMP alone, NIMP plus novel oxime, novel oxime alone, and vehicle controls. Bdnf, Fos, and Bcl2l1 showed statistically significant transcriptional changes between 4 several of the NIMP only and oxime combination groups, indicating that novel oximes may be able to directly affect these genes’ expression and thereby attenuate NIMP-related neural damage. While the other genes did not display statistical significance, average cycle threshold (Ct) values for NIMP, oxime, combination, and vehicle groups still demonstrated notable differences suggestive of oxime therapeutic efficacy. Ultimately, these comparisons should demonstrate whether novel oximes can remediate some of the damage from OP poisoning and stimulate tissue repair. The data produced also support the OP-induced neuropathological and behavioral changes, as well as the therapeutic effects following novel oxime treatment, observed in live rats.

Publication Date

11-1-2018

First Advisor

Chambers, Janice

Second Advisor

Dail, Mary Beth

Third Advisor

Oppenheimer, Seth

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