The Protective Effects of Exercise Against Acute Inflammatory and Metabolic Challenges

161 Pages·2017·2.23 MB·English

The Protective Effects of Exercise Against Acute Inflammatory and
Metabolic Challenges

By
Laura Nicole Castellani

A Thesis
presented to
The University of Guelph

In partial fulfilment of requirements
for the degree of
Doctor of Philosophy
in
Human Health and Nutritional Sciences

Guelph, Ontario, Canada

© Laura Nicole Castellani, June, 2017
ABSTRACT

THE PROTECTIVE EFFECTS OF EXERCISE AGAINST ACUTE
INFLAMMATORY AND METABOLIC CHALLENGES

Laura Nicole Castellani Advisor:
University of Guelph, 2017 Associate Professor D.C. Wright

It is well appreciated that exercise is associated with improvements in metabolic
health, though the specific mechanisms underlying these processes remain to be fully
understood. As such, the work presented in this thesis highlights the beneficial effects of
exercise with respect to protecting against acute inflammatory and metabolic challenges.

First, study one identified the protective effect of chronic exercise training against
an acute inflammatory challenge with the beta-3 adrenergic agonist CL 316,243.
Specifically, it was revealed that CL 316,243 activates markers of inflammation in white
adipose tissue of lean male mice and that this response was attenuated with 4-weeks of
exercise training. The blunted CL 316,243-induced inflammation was matched by
reductions in the protein content of the pro-inflammatory ion channel TRPV4.

To further explore the relationship between regular exercise training and adipose
tissue inflammation we next examined the inflammatory response associated with a
single, acute bout of moderate exercise. Notably, although IL-6 expression and signaling
were induced in response to acute exercise, this occurred independent of changes in other
traditional markers of adipose tissue inflammation (i.e. TNF-alpha, IL-1beta, JNK
phosphorylation). Moreover, activation of IL-6 signaling in response to an acute bout of
exercise is amplified with regular exercise training.

In study three, we found that a single bout of exercise protects against metabolic
disturbances associated with a single dose of the antipsychotic olanzapine. This was
paralleled by improvements in insulin tolerance, reductions in hepatic glucose output and
alterations in fuel utilization.

The studies in this thesis are the first to note i) that regular exercise training
protects against CL 316,243 induced activation of adipose tissue inflammation; ii) that
acute exercise-induced increases in IL-6 signaling are amplified in adipose tissue after
chronic exercise training; iii) That a single bout of exercise protects against olanzapine-
induced hyperglycemia. In all, this work contributes significantly to our understanding of
adipose tissue dependent and independent benefits of exercise.
iv
ACKNOWLEDGEMENTS

To the unknowing eye, this thesis may represent little more than 148 pages of exciting
data and extensive musings. But I believe with my whole heart that each piece of data is
as much a contribution to science as it is a reflection of the many wonderful, talented and
supportive people I have had the opportunity to work with, learn from, and share my life
as a scientist with.
The entirety of this thesis would not have been possible without the tireless support of my
advisor, Dr. David Wright. I’ve learned that to work with a mentor who encourages you
to be yourself each day fosters hard work, creativity and curiosity, and the thoughts
captured on these pages are a reflection of the many conversations and ideas we have
talked through. Thank you for guiding me through this process. I am forever grateful for
having called the Wright lab “home” for so long.
I consider myself incredibly fortunate to have worked alongside many talented, kind and
endearingly weird individuals and the work presented here captures the spirit of all my
wonderful labmates, friends and fellow researchers. I owe particular thanks to my friends
and mentors, Dr. Christopher Perry and Dr. Brennan Smith who have inspired me as a
scientist, taught me the true value of laughter, and have often held me to a higher
standard than I sometimes remembered to hold myself.
And finally I am thankful to my incredible family, for their unending support, enthusiasm
and fresh perspectives. Though my safe haven away from science, their continual interest
in IL-6, olanzapine and the wellbeing of my “subjects” meant everything to me. A special
thank you to Mom and Dad, who have been there every single step of the way.
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TABLE OF CONTENTS

ABSTRACT .............................................................................................................................................. II
ACKNOWLEDGEMENTS .................................................................................................................... IV
TABLE OF CONTENTS ......................................................................................................................... V
LIST OF FIGURES ................................................................................................................................. IX
LIST OF TABLES ................................................................................................................................... XI
LIST OF ABBREVIATIONS ............................................................................................................... XII

CHAPTER 1 ............................................................................................................................................... 1
INTRODUCTION AND LITERATURE REVIEW ............................................................................. 1
1.1 THE DEVELOPMENT OF OBESITY AND TYPE 2 DIABETES .................................................................. 2
1.1.1 Prevalence and costs of obesity and Type 2 Diabetes ................................................................. 2
1.2. INSULIN AND GLUCOSE HOMEOSTASIS: ................................................................................................. 2
1.2.1 Insulin Secretion ......................................................................................................................................... 3
1.2.2 Skeletal Muscle Insulin Signaling ....................................................................................................... 3
1.2.3 Hepatic Insulin Action ............................................................................................................................. 4
1.2.4 Adipose Tissue Lipolysis and Insulin Signaling ............................................................................. 5
1.3 INSULIN RESISTANCE AND INFLAMMATION IN GLUCOSE METABOLISM ...................................... 8
1.3.1 Tumour Necrosis Factor-α and Systemic Inflammation ............................................................. 9
1.3.2 Interleukin-1β and Inflammation in Metabolism ........................................................................... 9
1.3.3 Interleukin-6 and Inflammation in Metabolism ........................................................................... 10
1.4 ADIPOSE TISSUE MEDIATED INFLAMMATION ..................................................................................... 13
1.4.1 Adipose Tissue Remodeling and Inflammation ............................................................................ 13
1.4.2 Fatty Acid Release and Adipose Tissue Inflammation .............................................................. 15
1.4.3 Mitogen-Activated Protein Kinases and Inflammation ............................................................. 16
1.4.4 TRPV4 and adipose tissue inflammation ........................................................................................ 16
1.4.5 SGA-induced metabolic disturbances and adipose tissue accumulation ........................... 17
1.5 ANTIPSYCHOTICS AND DISTURBANCES IN GLUCOSE METABOLISM ........................................... 18
1.5.1 Antipsychotic-induced increases in blood glucose ..................................................................... 18
1.5.2 Anti-diabetic drugs to offset antipsychotic-induced glucose intolerance .......................... 18
1.6 EXERCISE AS A STRATEGY TO RECOVER GLUCOSE HOMEOSTASIS ............................................ 19
1.6.1 Inflammation and exercise ................................................................................................................... 20
1.6.2 Inflammation and acute exercise ....................................................................................................... 22
1.6.3 Exercise and adipose tissue-independent improvements in glucose homeostasis .......... 23
1.6.4 Exercise and Second-Generation Antipsychotic-induced glucose intolerance ............... 24
1.7 SUMMARY ....................................................................................................................................................... 24

CHAPTER 2: ........................................................................................................................................... 27
AIMS OF THESIS .................................................................................................................................. 27
2.1 SPECIFIC AIMS OF THESIS .......................................................................................................................... 28
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CHAPTER 3 ............................................................................................................................................ 31
EXERCISE TRAINING PROTECTS AGAINST AN ACUTE INFLAMMATORY INSULT IN
MOUSE EPIDIDYMAL ADIPOSE TISSUE ..................................................................................... 31
3.1 ABSTRACT ....................................................................................................................................................... 32
3.2 INTRODUCTION .............................................................................................................................................. 33
3.3 EXPERIMENTAL MATERIALS AND METHODS ...................................................................................... 35
3.3.1 Materials ..................................................................................................................................................... 35
3.3.2 Animals ........................................................................................................................................................ 36
3.3.3 Training Protocol .................................................................................................................................... 36
3.3.4 CL 316,243 Treatment ........................................................................................................................... 36
3.3.5 Plamsa IL-6, TNF-alpha, glycerol and NEFA ............................................................................. 37
3.3.6 Western Blotting ....................................................................................................................................... 37
3.3.7 Real Time PCR ......................................................................................................................................... 38
3.3.8 Statistical Analysis .................................................................................................................................. 39
3.4 RESULTS ........................................................................................................................................................... 39
3.4.1 Exercise training adaptations in muscle and adipose tissue .................................................. 39
3.4.2 Exercise training does not reduce markers of inflammation .................................................. 40
3.4.3 CL 316, 243 induces adipose tissue inflammation ...................................................................... 41
3.4.4 Prior exercise training dampens CL 316,243 induced inflammation in epididymal
adipose tissue ........................................................................................................................................................ 42
3.4.5 TRPV4 protein content is reduced in epididymal adipose tissue from trained mice ..... 45
3.5 DISCUSSION .................................................................................................................................................... 47
3.6 CONCLUSIONS ................................................................................................................................................ 51
3.6 FUTURE CONSIDERATIONS ........................................................................................................................ 52

CHAPTER 4 ............................................................................................................................................ 53
EXERCISE-MEDIATED IL-6 SIGNALING OCCURS INDEPENDENT OF INFLAMMATION
AND IS AMPLIFIED BY TRAINING IN MOUSE ADIPOSE TISSUE ....................................... 53
4.1 ABSTRACT ....................................................................................................................................................... 54
4.2 INTRODUCTION .............................................................................................................................................. 55
4.3 EXPERIMENTAL MATERIALS AND METHODS ...................................................................................... 56
4.3.1 Materials ..................................................................................................................................................... 56
4.3.2 Animals ........................................................................................................................................................ 57
4.3.3 Acute exercise in untrained mice ....................................................................................................... 57
4.3.4 Acute exercise in trained mice ............................................................................................................ 58
4.3.5 Intraperitoneal IL-6 injections in sedentary and trained mice .............................................. 59
4.3.6 Plasma NEFA and IL-6 ......................................................................................................................... 59
4.3.7 Western Blotting ....................................................................................................................................... 59
4.3.8 Real Time PCR ......................................................................................................................................... 60
4.3.9 Statistical Analysis .................................................................................................................................. 60
4.4 RESULTS ........................................................................................................................................................... 61
4.4.1 An acute bout of exercise increases markers of IL-6 signaling, but not inflammation in
mouse adipose tissue .......................................................................................................................................... 61
4.4.2 Exercise increases the mRNA expression and protein content of IL-6Rα and gp130 .. 64
4.4.3 Acute exercise causes a more rapid increase in markers of IL-6 signaling in adipose
tissue from trained compared to sedentary mice .................................................................................... 64
4.4.4 Markers of lipolysis are similar in response to an acute bout of exercise in sedentary
and exercise- trained mice ............................................................................................................................... 67
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4.4.5 Circulating levels of IL-6 are not different between sedentary and exercise trained
mice .......................................................................................................................................................................... 68
4.4.6 The effects of exercise training on exogenous IL-6 signaling ................................................ 68
4.5 DISCUSSION .................................................................................................................................................... 69
4.6 CONCLUSIONS ................................................................................................................................................ 74
4.7 FUTURE CONSIDERATIONS ........................................................................................................................ 74

CHAPTER 5 ............................................................................................................................................ 76
AN ACUTE BOUT OF EXERCISE PROTECTS AGAINST OLANZAPINE-INDUCED
HYPERGLYCEMIA IN MALE C57BL/6J MICE ............................................................................ 76
5.1 ABSTRACT ....................................................................................................................................................... 77
5.2 INTRODUCTION .............................................................................................................................................. 78
5.3 METHODS ........................................................................................................................................................ 80
5.3.1 Materials ..................................................................................................................................................... 80
5.3.3 Drug Preparation .................................................................................................................................... 81
5.3.4 Experimental Procedures ..................................................................................................................... 81
5.3.5 Serum IL-6, insulin, NEFA and glycerol ........................................................................................ 84
5.3.6 Muscle and Liver Glycogen Analysis ............................................................................................... 84
5.3.7 Statistical Analysis .................................................................................................................................. 84
5.4 RESULTS ........................................................................................................................................................... 84
5.4.1 A single session of acute high intensity exercise protects against the olanzapine-
induced rise in blood glucose. ........................................................................................................................ 84
5.4.2 Increases in circulating insulin do not explain the protective effects of exercise against
olanzapine-induced hyperglycemia .............................................................................................................. 87
5.4.3 Prior exercise attenuates blood glucose in response to pyruvate in olanzapine treated
mice. ......................................................................................................................................................................... 89
5.4.4 Prior Exercise Partially Protects Against Olanzapine-Induced Impairments in Insulin
Tolerance ................................................................................................................................................................ 90
5.4.5 Prior exercise and olanzapine-induced shifts in fuel oxidation ............................................ 91
5.4.6 Olanzapine-treatment does not alter the repletion of muscle and liver glycogen post-
exercise .................................................................................................................................................................... 91
5.5 DISCUSSION .................................................................................................................................................... 93

CHAPTER 6 ............................................................................................................................................ 97
INTEGRATIVE DISCUSSION ............................................................................................................ 97
6.0 INTEGRATIVE DISCUSSION ........................................................................................................................ 98
6.1 SUMMARY OF FINDINGS ............................................................................................................................. 98
6.2 INTERPRETATION AND DISCUSSION OF FINDINGS .......................................................................... 100
6.2.1 Advantages of Amplified IL-6 Signaling in Adipose Tissue ................................................. 100
6.2.2 “CL 316,243” vs “A Bout Of Exercise” as an acute challenge ......................................... 102
6.2.3 Defining Adipose Tissue Inflammation ........................................................................................ 103
6.2.4 High fat diet-induced obesity and acute olanzapine treatment ........................................... 104
6.2.5 Fasting and moderate intensity exercise to offset olanzapine-induced hyperglycemia
................................................................................................................................................................................. 105
6.2.6 Recombinant IL-6 and Olanzapine-induced Hyperglycemia ............................................... 106
6.2.7 Rodents as a Model for Human Depot-Specific Differences ............................................... 108
6.2.8 Consideration of Alternative Second-Generation Antipsychotics ..................................... 109
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6.3 FUTURE DIRECTIONS ................................................................................................................................ 110
6.3.1 Future Directions- Study 1 ................................................................................................................ 110
6.3.2 Future Directions- Study 2 ................................................................................................................ 111
6.3.3 Future Directions- Study 3 ................................................................................................................ 112
6.4 CONCLUDING REMARKS .......................................................................................................................... 114

REFERENCE LIST .............................................................................................................................. 115
APPENDIX A ....................................................................................................................................... 145
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LIST OF FIGURES

CHAPTER 1

Figure 1.1 Regulation of Lipolysis ………………………………….………...………………….7
Figure 1.2 IL-6 Signaling Cascade …………………………….……………………...………...12

CHAPTER 3

Figure 3.1 Exercise training adaptations in adipose tissue and skeletal muscle…........................40
Figure 3.2 CL 316, 243 induces markers of adipose tissue inflammation….…………….…...…42
Figure 3.3 The induction of inflammatory marker gene expression by CL 316, 243 is
attenuated in epididymal adipose tissue (eWAT) from trained mice………………………..........44
Figure 3.4 The attenuation in CL 316, 243 mediated induction of inflammatory markers is
not explained by alterations in markers of adipose tissue lipolysis…………………......………..45
Figure 3.5 Exercise training reduces the protein content of TRPV4 in adipose tissue…...……...47

CHAPTER 4

Figure 4.1 An acute bout of exercise increases indices of IL-6 signaling in epididymal but not
inguinal adipose tissue……………………………………………………………………………63
Figure 4.2 Acute exercise and markers of inflammation……………………………………..…65
Figure 4.3 Exercise training and the induction of IL-6………………………………………..…66
Figure 4.4 Indices of lipolysis are similar following an acute bout of exercise in sedentary and
trained mice……………………………………………………………………………………….67
Figure 4.5 STAT3 phosphorylation post-IL-6 injection…………………………………………69

CHAPTER 5

Figure 5.1 A single session of exhaustive exercise protects against olanzapine-induced
increases in blood glucose………………………………………………………………………..86
Figure 5.2. Exercise-mediated protection against olanzapine-induced hyperglycemia occurs
independent of changes in serum insulin………………………………………………………....88
Figure 5.3. Exercise improves pyruvate tolerance in mice treated with olanzapine…………......89
Figure 5.4 Insulin tolerance is improved in olanzapine-treated mice after intense exercise…….90
Figure 5.5 Acute high intensity exercise subtly modifies olanzapine-induced changes in
indirect calorimetry……………………………………………………………………………….92

CHAPTER 6

Figure 6.1 Summary of Findings………………………………………………………………...99
Figure 6.2 Exercise does not protect against olanzapine-induced increases in blood glucose
in high fat fed mice……......…………………………………………………………………….105
Figure 6.3 Fasting and moderate intensity exercise protect against olanzapine induced
increases in blood glucose……………………………………………………………………....106
Figure 6.4 IL-6 is not sufficient to protect against olanzapine-induced increases in blood
glucose…………………………………………………………………………………………..107
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APPENDIX

Figure A1 Study1 Experimental Design…………………….………………………………….145
Figure A2 Study 2 Experimental Design……………………………………………………….146
Figure A3 Study 3 Experimental Design……….……………………………………………....147
Figure A4 Study 3 Pyruvate Tolerance Test Experimental Design …………..………………..147
Figure A5 Study 3 Insulin Tolerance Test Experimental Design …………..…………...……..148