The Effects of CMS on Rats Selectively-bred for Behavior Related to Bipolar-like and Depression-like Symptoms Público

Abstract

The chronic mild stress (CMS) paradigm often uses preference for sucrose as a measure of
hypothesized anhedonia in rats. However, this measure is rife with unreliability, an issue that
could be due to genetic differences between rats. This study tested this hypothesis by subjecting
rats selectively bred for affective disorder-like behavior to CMS. Five lines of rats selectively-
bred for behavior related to affective disorders were used: Hyperactive (HYPER), Swim-test
Susceptible (SUS), Swim-test Resistant (RES), Swim Low-active (SwLo), and Swim High-
active (SwHi) rats. The reactions of these selectively-bred lines to CMS were compared to the
reactions of non-selectively bred (NS) rats which were used as controls. In addition, both female
and male HYPER and NS rats were examined. Sucrose intake and preference for sucrose, as
determined by the proportion of total fluid intake that was water intake, were measured and
analyzed. Food intake and dark and light phase motor activity were also measured. During
CMS, stressed HYPER rats, both females and males, SUS, RES, and SwHi rats showed lower
preference for sucrose than did non-stressed rats of the same lines. In contrast, stressed female
NS rats did not show a different preference for sucrose than non-stressed female NS rats, and
stressed male NS rats tended to show higher preference for sucrose than non-stressed male NS
rats. Stressed SwLo rats also did not show a different preference for sucrose than non-stressed
SwLo rats. The effects on preference for sucrose could not be explained by a change in caloric
intake as evidenced by patterns in food and water intake. Taken together, these results suggest
that genetics can influence the outcome of CMS with respect to effects of stress on preference for
sucrose and thus the known behavioral characteristics of a rat line should be taken into
consideration when selecting animals for use in CMS experiments.

Table of Contents

Introduction - 1
Methods - 5
Animals and Housing Conditions - 5
Experimental Design - 6
Experiments - 7
Statistical Analyses - 9
Results - 11
Sucrose Intake - 11
Water Intake - 16
Total Fluid Intake - 19
Sucrose Preference - 19
Food Intake - 26
Dark Phase Motor Activity - 28
Light Phase Motor Activity - 32
Discussion - 36

References - 40
Table 1 - 44
Figure Captions - 45
Figure 1 - 55
Figure 2 - 56
Figure 3 - 57
Figure 4 - 58
Figure 5 - 59
Figure 6 - 60
Figure 7 - 61
Figure 8 - 62
Figure 9 - 63
Figure 10 - 64
Figure 11 - 65
Figure 12 - 66
Figure 13 - 67
Figure 14 - 68
Figure 15 - 69
Figure 16 - 70
Figure 17 - 71
Figure 18 - 72
Figure 19 - 73
Figure 20 - 74
Figure 21 - 75
Figure 22 - 76
Figure 23 - 77
Figure 24 - 78
Figure 25 - 79
Figure 26 - 80
Figure 27 - 81
Figure 28 - 82

About this Honors Thesis

Rights statement

• Permission granted by the author to include this thesis or dissertation in this repository. All rights reserved by the author. Please contact the author for information regarding the reproduction and use of this thesis or dissertation.

School	Emory College
Department	Neuroscience and Behavioral Biology
Degree	BS
Submission	Honors Thesis
Language	English
Research Field	Psychology, Behavioral Psychology, Experimental
Palabra Clave	CMS Depression Bipolar Chronic mild stress Selectively-bred rats Anhedonia
Committee Chair / Thesis Advisor	Weiss, Jay M, Emory University
Committee Members	Frenzel, Kristen E, Emory University Boss-Williams, Katherine,

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