Investigating natural variation in the oxytocin system of prairie voles: Do levels of oxytocin differ between two naturally occurring genotypes? Public

Celeste, Julianna (Spring 2023)

Permanent URL: https://etd.library.emory.edu/concern/etds/47429b53z?locale=fr
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Abstract

Importance: Oxytocin (OT) is a neuropeptide that modulates many aspects of social behavior. Previously, our lab has demonstrated natural variation in the oxytocin receptor (OXTR) levels of prairie voles, which are strongly associated with noncoding single-nucleotide polymorphisms in the oxytocin receptor gene (Oxtr). This difference in genetic background might also be associated with altered levels of OT. As OT-signaling is involved in the regulation of social behavior, understanding the genetic background of this system could lead to a better understanding of mental conditions characterized by social deficits

Objective: To determine if there is a significant difference in protein levels of oxytocin within the paraventricular nucleus (PVN) between voles with two different genotypes

Main outcome and Measure: Genotyping through PCR, immunohistochemistry, and imaging

Subjects: 14 voles, 5 females and 9 males between ages 50 and 113 days old.

Results: We did not observe significant differences in the number of OT-positive cells in the PVN between genotypes. We did find a significant difference in OT-cell count across bregma positions, indicating that the medial part of the PVN contains most OT-positive cells. Manual and automated cell count methods delivered similar results.

Conclusion and Relevance: While we hypothesized that variation in OXTR levels in prairie voles may impact OT levels, our analyses did not deliver evidence to support this possibility. We found that OT protein levels do not vary between the two genotypes. Therefore, we could not confirm the differences that have been previously found in OT mRNA abundance between genotypes. A possible explanation is that differences in OT mRNA do not directly translate into differences in OT protein levels. In addition, it could be that confounding factors such as tissue isolation and/or processing could have affected experimental results. Overall, we did not observe any differences in OT levels between genotypes so it is unlikely that differences in OT levels are responsible for the differences in social strategies between the genotypes.

Table of Contents

Introduction………………………………………………………………………………………..1

Methods……………………………….………………………………………………………...…4

Results…………………………………………………………………………..……………..…..6

Discussion…………………………………………………………………………..……………..8

Tables and Figures………………………………………………………………………...……..11

Figure 1:Variation of OXTR and OT mRNA……………………………………………11

Figure 2: Example images of bregma position and shape……………………...………..12

Figure 3: Cell count according to Bregma position………………………………….…..13

Figure 4: Computer Cell count compared within bins…………………..…...…………..14

Figure 5: Intensity compared within bins…………..……………………………………15

Table 1: One-way ANOVA…………………………………………………………..…..16

Table 2: Welch two sample t-test - Cell to Computer Count………………...…………..16

Table 3: Welch two sample t-test - Computer Count…………………….………..……..17

Table 4: Shapiro-Wilk Normality test - Computer Count…..………………..…………..17

Table 5: Wilcoxon Rank Sum test - Computer Count (Medial Bin)……………………..18

Table 6: Welch two sample t-test - Intensity……………………………………………..18

Table 7: Shapiro-Wilk Normality test - Intensity…...………………………………..…..19

Table 8: Wilcoxon Rank Sum test - Intensity (Medial Bin)...……………………..……..19

References…………………………………………………………………………………….….20

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