Food Reward in Dopamine β-Hydroxylase Knockout Mice 公开

Abstract

While dopamine (DA) has been implicated as an essential neurotransmitter for reward,
norepinephrine (NE) has largely been ignored. To examine the role of NE in food
reward, we tested mice that have been genetically altered to lack an enzyme necessary for
NE synthesis (dopamine β-hydroxylase; DBH-/-) using fixed ratio (FR) responding for 14
mg food pellets. The results suggest that genetic depletion of DBH produces effects on
responding for food that, in males, are highly dependent on the ratio requirement of the
schedule. When the number of responses required were low, FR1-FR14, male DBH-/-
mice responded significantly more than DBH+/- controls. However, as the ratio
requirement increased to FR16 through FR30, there were no differences between the two
genotypes. There were no differences in low or high ratio requirements between
genotypes in females and a post hoc analysis demonstrated the only significant difference
between female genotypes was at FR1. 24-hour food intake was also measured and it
was determined that male DBH-/- consumed more food per body weight than male
controls, but that female DBH-/- mice consumed less than controls. At the behavioral
level, these results were interpreted as reflecting two factors: the physiological need for
food intake, and the incentive value of the food. At the neuroscience level, it is proposed
that the chronic lack of NE causing an upregulation of DA receptors, resulting in at low
FR values.

Table of Contents

Food Reward in Dopamine β-Hydroxylase Knockout Mice............................................................ 1
Methods .......................................................................................................................................... 7
Animals ....................................................................................................................................... 7
Apparatus .................................................................................................................................... 8
Training ....................................................................................................................................... 8
Testing ........................................................................................................................................ 9
Results ............................................................................................................................................. 9
Operant Responding..................................................................................................................... 9
Food Intake ............................................................................................................................... 10
Sex Differences .......................................................................................................................... 11
Discussion ..................................................................................................................................... 12
References ..................................................................................................................................... 17
Figures…………………………………………………………………………………………….29

About this Master's Thesis

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School	Laney Graduate School
Department	Psychology
Subfield / Discipline	Neuroscience and Animal Behavior
Degree	MA
Submission	Master's Thesis
Language	English
Research Field	Biology, Genetics Psychology, Behavioral Psychology, Physiological
关键词	dopamine norepinephrine food intake dopamine β-hydroxylase reward food reward mice
Committee Chair / Thesis Advisor	Neill, Darryl B, Emory University
Committee Members	Rodman, Hillary R, Emory University Brennan, Patricia, Emory University

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