Physiological and Behavioral Effects of High Fat Diet Removal and Wheel Running in C57BL/6J Mice

The possibility of developing Type 2 Diabetes Mellitus (T2DM) is determined by a combination of genetic factors and the lifestyle of the individual. Higher risks of T2DM diagnosis occur when individuals are exposed to lifestyle factors such as physical inactivity and high fat diet consumption. Animal models, including mice, are consistently used in laboratory studies to understand T2DM in humans due to genetic and physiological similarities. This study focuses on whether change of diet and increased exercise can reduce obesity and alleviate T2DM symptoms in C57BL/6J (B6) mice. Changes in weight, anxiety-like behaviors, leptin and insulin levels and glucose tolerance during a 12:12 light/dark circadian rhythm will be measured when B6 mice are given a high fat diet ad libtium with and without a running wheel. One half of the mice initially weaned on a high-fat diet were switched to a regular chow (lower calorie food) half way through the study to observe physiological changes. Physiological parameters such as body mass, kilocalories (kcal) consumed, food and water intake were measured weekly over a 20 week period and then analyzed statistically. High fat recovery (HFR) groups showed improvements in body mass, insulin and leptin levels after switching to a regular chow in association with daily exercise. Glucose tolerance tests were performed before and after the food switch. HFR mice exhibited improved glucose tolerance, lower insulin levels and lower triglyceride levels in whole blood upon reducing dietary fat intake. Explorative and anxiety behaviors were assessed with light-dark box and open-field box assays. Mice without running wheels were more active in open-field anxiety test, and spent increased time in the dark with light-dark (LD) box tests. Results suggest that incorporating a healthy diet along with daily exercise improves quality of health and can suppress T2DM symptoms and related conditions

6-hour Advances Alter Circadian Activity Patterns, Fasting Glucose and Insulin Levels in C57BL6/J Mice

Chronobiological disruptions, including shift-work, have been linked to a number of disorders such as fatigue and diabetes. Additionally, there is evidence to support that exercise can not only counteract fatigue and the onset of diabetes, but also alleviate the other negative symptoms associated with shift-work. Therefore, the present study investigated the effects of wheel-running and monthly 6-hour phase advances on the circadian locomotor activity patterns and glucose and insulin levels in C57BL6/J mice. 6-hour phase advances produced decreases in fasting glucose and increases in insulin, and wheel-running was able to alleviate the spike in insulin secretion. Additionally, mice experiencing the shift increased their food intake, despite having no change in body mass. Circadian wheel-running activity was also altered in phase advanced mice. These results provide further evidence that chronobiological disruptions can lead to alterations in physiology and behavior, and that exercise can alleviate some of those symptoms

Long-term Wheel-running and Acute 6-h Advances Alter Glucose Tolerance and Insulin Levels in TALLYHO/JngJ Mice

Studies have shown a relationship between circadian rhythm disruptions and type-2 diabetes. This investigation examined the effects of circadian disruption (6-h phase advances) on the progression of diabetes in a type-2 diabetic mouse model – TALLYHO/JngJ – and whether wheel-running can alleviate the effects of the phase advances. 6-h advances alter fasting glucose, glucose tolerance and insulin production. Wheel-running reduced body mass, improved glucose tolerance and reduced insulin in TALLYHO/JngJ and alleviated some of the changes in diabetic symptoms due to 6-h advances. These results indicate that individuals with type-2 diabetes can benefit from physical activity and exercise can be a countermeasure to offset the effects of an acute phase advance

Voluntary Wheel-running Attenuates Insulin and Weight Gain and Affects Anxiety-like Behaviors in C57BL6/J Mice Exposed to a High-fat Diet

It is widely accepted that lifestyle plays a crucial role on the quality of life in individuals, particularly in western societies where poor diet is correlated to alterations in behavior and the increased possibility of developing type-2 diabetes. While exercising is known to produce improvements to overall health, there is conflicting evidence on how much of an effect exercise has staving off the development of type-2 diabetes or counteracting the effects of diet on anxiety. Thus, this study investigated the effects of voluntary wheel-running access on the progression of diabetes-like symptoms and open field and light-dark box behaviors in C57BL/6J mice fed a high-fat diet. C57BL/6J mice were placed into either running-wheel cages or cages without a running-wheel, given either regular chow or a high-fat diet, and their body mass, food consumption, glucose tolerance, insulin and c-peptide levels were measured. Mice were also exposed to the open field and light-dark box tests for anxiety-like behaviors. Access to a running-wheel partially attenuated the obesity and hyperinsulinemia associated with high-fat diet consumption in these mice, but did not affect glucose tolerance or c-peptide levels. Wheel-running strongly increased anxiety-like and decreased explorative-like behaviors in the open field and light-dark box, while high-fat diet consumption produced smaller increases in anxiety. These results suggest that voluntary wheel-running can assuage some, but not all, of the physiological problems associated with high-fat diet consumption, and can modify anxiety-like behaviors regardless of diet consumed

Removal of a High-fat Diet, but not Voluntary Exercise, Reverses Obesity and Diabetic-like Symptoms in Male C57BL/6J Mice

OBJECTIVE: Both the consumption of high-fat diets and exercise are known to produce alterations in metabolism and behavior. This study focuses on the effects of a change to a low-fat diet from a high-fat diet and voluntary exercise on obesity, type-2 diabetic-like symptoms, and locomotor behavior in male C57BL/6J mice. DESIGN: Mice were initially given either a high-fat diet or regular chow, along with a cage with a running-wheel to mimic exercise, or one without, to determine to what extend exercise affects these symptoms. Then half of the mice given a high-fat diet were switched to regular chow to ascertain if the switch in diet would improve type-2 diabetic-like and obesity symptoms. RESULTS:Wheel-running alone produced an improvement in insulin in mice continuously fed a high-fat diet (p=0.006), but running-wheels did not produce any further improvements in mice with regular chow replacement (p=0.999) or in controls (p=0.996). Replacement of a high-fat diet with regular chow led to physiological improvements in insulin (p=0.012) and leptin (p CONCLUSIONS: These results suggest that exercise is only partially beneficial to improving health outcomes in mice consuming a high-fat diet, whereas incorporating a better diet, even without exercise, improves quality of health and can suppress T2DM symptoms and related conditions more so than exercise alone