SLEEP DISTURBANCES AFTER CHRONIC ALCOHOL CONSUMPTION: HOMEOSTATIC ...

187 Pages·2016·2.83 MB·English

by  Rong Guo

SLEEP DISTURBANCES AFTER CHRONIC ALCOHOL CONSUMPTION:

HOMEOSTATIC DYSREGULATION OR

CIRCADIAN DESYNCHRONY?

By

RONG GUO

A dissertation submitted in partial fulfillment of
the requirements for the degree of

DOCTOR OF PHILOSOPHY

WASHINGTON STATE UNIVERSITY
Program in Neuroscience

JULY 2016

©Copyright by RONG GUO, 2016
All Rights Reserved
©Copyright by RONG GUO, 2016
All Rights Reserved
To the Faculty of Washington State University:
The members of the Committee appointed to examine the dissertation of RONG GUO
find it satisfactory and recommend that it be accepted.

_____________________________________________________
Steven M. Simasko, Ph.D., Co-Chair

_____________________________________________________
Heiko T. Jansen, Ph.D., Co-Chair

_____________________________________________________
Barbara A. Sorg, Ph.D.

_____________________________________________________
Ilia Karatsoreos, Ph.D.

ii
ACKNOWLEDGEMENT

First, I would like to thank my mentors, Drs. Steven Simasko and Heiko Jansen. They
have not only helped me grow my knowledge in the field but also deepened my understanding of
science and research. They are supportive, encouraging, and inspiring. I’m glad that we were
able to work together and turn my initial research interest in sleep and alcohol into such a nice
project. I appreciate their help and guidance both in my studies and in my career. It is my
pleasure to be part of their team. I would also like to thank my committee members, Drs. Barbara
Sorg and Ilia Karatsoreos, for their help during numerous occasions in my research. They have
provided insightful thoughts that helped shape my project and this dissertation. They also have
given me great advice regarding my future career. I have learned a lot from them and it was an
honor to be able to work with them.
I would like to thank the past and present members of the Simasko lab and the Jansen lab,
especially Jamie Gaber, Christi Pedrow, and Brandon Hutzenbiler, and many others who were
willing to help me along the path of my graduate work. I’d like to give my special thanks to
Derrick Phillips, who has been a great classmate, lab-mate, office ‘roommate’, and dear friend. It
would not have been possible to accomplish much without all their enthusiastic help. I would
also like to thank all members of the department of Integrative Physiology and Neuroscience at
WSU, especially the office and vivarium staff. I appreciate their kindness and patience with me.
In addition, I would like to thank the financial support from the Alcohol & Drug Abuse
Program at WSU, which supported the initiation of my projects.
Finally, I would like to express my gratitude to my dear families and friends for their
unconditioned love, support, and faith. It means the world to me to have them in my life.
iii
SLEEP DISTURBANCES AFTER CHRONIC ALCOHOL CONSUMPTION:

HOMEOSTATIC DYSREGULATION OR

CIRCADIAN DESYNCHRONY?

Abstract

by Rong Guo, Ph.D.
Washington State University
July 2016

Co-Chairs: Steven M. Simasko
Heiko T. Jansen

Chronic alcohol use often leads to sleep disturbances such as insomnia and sleep
fragmentation, but the underlying mechanisms are not fully understood. Sleep is regulated by
two main processes: a homeostatic process representing the build-up of sleep pressure during
wake and a circadian process integrating sleep timing with environmental cues. It is possible that
chronic alcohol exposure impairs sleep through either process or both. This dissertation presents
investigations to address these possibilities.
We first determined if chronic alcohol exposure impaired the homeostatic regulation of
sleep by using a sleep deprivation challenge. We found that alcohol-treated rats showed robust
and relatively normal compensatory increase in sleep time and sleep intensity (as measured by
slow wave amplitude) within 24 hours after the challenge, but the recovery sleep of these rats
was delayed and fragmented. These results suggest that chronic alcohol exposure may weaken
the stability of sleep states, leading to sleep fragmentation, but the homeostatic regulatory
mechanisms were most likely intact. We next determined if chronic alcohol treatment altered the
integrity of circadian systems by examining diurnal rhythms of body temperature, locomotor,
iv
plasma corticosterone, and Per1 expression in the master pacemaker (suprachiasmatic nucleus,
SCN) and in the HPA axis (pituitary and adrenal glands). We found that after chronic alcohol
exposure these processes still exhibited a 24-hour cycle, but the cycles were less robust and more
variable. Most importantly, the phase relationships among diurnal physiological rhythms, and
between the central and peripheral molecular clocks, were significantly altered leading to
desynchronized circadian processes. Lastly, we placed rats under constant darkness to remove
the external light Zeitgeber and found that constant darkness stabilized the dampened rhythms
and normalized the blunted distribution of sleep/wake time caused by chronic alcohol exposure.
Taken together, our studies suggest that chronic alcohol exposure: 1) weakens the stability of
sleep states leading to unstable and fragmented sleep, 2) compromises the ability of SCN to
synchronize internal clocks and to integrate sleep timing with the external light Zeitgeber, and 3)
does not prevent the animal from responding to the build-up of sleep pressure.
v
TABLE OF CONTENTS
Page
ACKNOWLEDGEMENT ..................................................................................................... iii
ABSTRACT ............................................................................................................................ iv
LIST OF TABLES ................................................................................................................. ix
LIST OF FIGURES ................................................................................................................ x
DEDICATION....................................................................................................................... xii
CHAPTER ONE
GENERAL INTRODUCTION .............................................................................................. 1
Alcohol and Alcoholism ················································································· 3
A. Alcoholic Beverages ··············································································· 3
B. Alcoholism and Alcohol Use Disorder (AUD) ················································ 4
C. Alcohol-related Pathologies ······································································ 6
D. Alcohol and the Central Nervous System ······················································ 8
E. Summary ··························································································· 10
Alcohol-related Sleep Disturbances ··································································· 11
A. Acute Alcohol and Sleep ········································································· 12
B. Chronic Alcohol and Sleep ······································································ 15
C. Sleep Disturbances and Relapse ································································ 16
D. Treatment Options for Sleep Disturbances in AUD ·········································· 17
E. Possible Mechanisms ············································································· 18
Sleep and Sleep Regulation ············································································· 20
A. Sleep Measurements ·············································································· 20
vi
B. Sleep Stages ························································································ 21
C. Rodent Sleep vs. Human Sleep ·································································· 22
D. Sleep Regulation ·················································································· 23
E. Two-Process Model of Sleep Regulation ······················································ 24
Circadian Rhythms ······················································································· 27
A. Molecular Clocks and Circadian Genes ························································ 27
B. The Suprachiasmatic Nucleus (SCN) ·························································· 28
C. Interaction between Alcohol, Sleep, and Circadian Rhythms ······························ 28
References ································································································· 32
CHAPTER TWO
CHRONIC ALCOHOL CONSUMPTION DELAYS AND FRAGMENTS RECOVERY
SLEEP AFTER SLEEP DEPRIVATION IN RATS ....................................... 46
Abstract ···································································································· 47
Introduction ······························································································· 48
Materials and Methods ·················································································· 52
Results ····································································································· 57
Discussion ································································································· 62
References ································································································· 77
CHAPTER THREE
CHRONIC ALCOHOL CONSUMPTION IN RATS LEADS TO DESYNCHRONY IN
DIURNAL RHYTHMS AND MOLECULAR CLOCKS ............................... 82
Abstract ···································································································· 83
Introduction ······························································································· 84
vii
Materials and Methods ·················································································· 87
Results ····································································································· 92
Discussion ································································································· 96
References ······························································································· 110
CHAPTER FOUR
CONSTANT DARKNESS ALLEVIATES SLEEP AND CIRCADIAN DISRUPTIONS
AFTER CHRONIC ALCOHOL EXPOSURE IN RATS ............................. 115
Abstract ·································································································· 116
Introduction ····························································································· 118
Materials and Methods ················································································ 122
Results ··································································································· 126
Discussion ······························································································· 129
Reference ································································································ 140
CHAPTER FIVE
GENERAL DISCUSSION ................................................................................................. 143
Summary of Finding ··················································································· 143
Possible Candidate Mechanisms ····································································· 145
A. Body Temperature ·············································································· 145
B. The Corticotrophin-Releasing Factor (CRF) System, HPA Axis, and Glucocorticoids
(GCs) ··································································································· 147
Implications ····························································································· 157
Reference ································································································ 159

viii
LIST OF TABLES

CHAPTER TWO
Table 2. Sleep Parameters after Sleep Deprivation ................................................................ 75
CHAPTER THREE
Table 3-1. Light vs. Dark Characteristics of Body Temperature and Locomotor Activity . 107
Table 3-2. Rhythm Parameters for Body Temperature and Locomotor Activity ................ 108
Table 3-3. Results of Discrete Wavelet Transform (DWT) Analysis of Body Temperature
and Locomotor Activity ...................................................................................... 109
CHAPTER FOUR
Table 4. Rhythm Parameters for Body Temperature ........................................................... 139

ix