Characterization of serotonin and gut microbiota following exposure to antibiotics in white-tailed deer (Odocoileus virginianus)



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In this thesis we will be discussing the importance of developing baseline serotonin concentrations in white-tailed deer serum and urine samples, both are minimally invasive tissues. An analytical method for the detection and confirmation of serotonin, 5-hydroxytryptamine (5-HT), in white-tailed deer tissues was developed and validated. Serum and urine samples were extracted with acetonitrile. Liquid chromatography separation was attained on a Phenomenex C18 column with a Security Guard ULTRA guard column with gradient elution using a mobile phase of 0.1% formic acid in water and 0.1% formic acid in acetonitrile. This methodology was applied to baseline (control), chlortetracycline (CTC) treated, florfenicol treated and tulathromycin treated white-tailed deer serum and urine samples. We will also be discussing the impact chlortetracycline, an antibiotic growth promoter (AGP), has on serotonin concentrations as well as on the white-tailed deer gut microbiota. Florfenicol and tulathromycin impacts on serotonin concentration changes were also investigated. Next-generation sequencing of 16S rRNA was used to characterize the bacterial communities in the rumen and fecal samples of white-tailed deer treated with chlortetracycline. This research will aid the white-tailed deer breeders and other researchers toward the characterization of “normal” concentrations of serotonin in healthy animals. This characterization will allow for the development of a biomarker using non-invasive sample tissues in sick animals, for example, non-clinical cases of chronic wasting disease. It will also allow some further insight into whether the use of antibiotics as growth promoters (AGP), such as chlortetracycline, is affecting serotonin concentrations in white-tailed deer. If serotonin concentrations are being affected by the use of AGPs, it could indirectly affect behaviors that are associated with serotonin and overall herd health. Antibiotics inhibit the growth of microorganisms so characterizing the gut microbiota in white-tailed deer in control and chlortetracycline treated samples will also allow insight into whether the use of AGPs impact the abundance and/or diversity of bacterial communities in the gut of white-tailed deer.



Serotonin, Neurotransmitter, Gut microbiota, Antibiotics, White-tailed deer, Chromatography, LC-MS/MS