The Role Of The Endothelium In Insulin's In Vivo Action Upon Skeletal Muscle Metabolism.
Funder
National Health and Medical Research Council
Funding Amount
$451,500.00
Summary
A number of studies using novel techniques developed in association with our USA collaborators, indicate that insulin has a major stimulatory effect on blood flow within muscle in both animals and humans to improve access for itself as well as nutrients such as glucose. As much as 50% of the glucose taken up by muscle in vivo during continual exposure to insulin may be attributed to this effect. Moreover, this haemodynamic effect of insulin in muscle is impaired in a number of animal models and ....A number of studies using novel techniques developed in association with our USA collaborators, indicate that insulin has a major stimulatory effect on blood flow within muscle in both animals and humans to improve access for itself as well as nutrients such as glucose. As much as 50% of the glucose taken up by muscle in vivo during continual exposure to insulin may be attributed to this effect. Moreover, this haemodynamic effect of insulin in muscle is impaired in a number of animal models and in obese humans when insulin mediated muscle glucose uptake is also impaired. What is not known is how insulin mediates this haemodynamic effect of recruiting capillary blood flow. Thus in the present study a number of aspects are to be explored, with particular focus on the cells that line the blood vessels and constitute the capillaries, the so called endothelium. First, we will explore the specific role of the endothelium in insulin's action by using the novel approach of attaching insulin to a large molecule that prevents it leaving the lumen of the blood vessel. This will mean that insulin will be confined to interacting only with insulin receptors on the muscle endothelium. Similarly, non activating anti insulin receptor antibody will be used in the presence of insulin to selectively prevent activation of the endothelial insulin receptors. In addition, we will investigate whether homocysteine, an amino acid found to impair endothelial dependent vasodilatation, impairs the haemodynamic effects of insulin. The impact that normal insulin release after a meal has upon the haemodynamic actions in muscle and the role this has in muscle glucose uptake will also be investigated by using the techniques developed in the first part of the project. Our over riding hypothesis is that the endothelium plays a key role in controlling insulin and possibly glucose access to muscle cells and thus a significant proportion of insulin mediated metabolic events in muscle.Read moreRead less
The Regulation Of Insulin Action In Liver And Skeletal Muscle By Protein Kinase C Epsilon
Funder
National Health and Medical Research Council
Funding Amount
$647,604.00
Summary
We have identified an enzyme, protein kinase C epsilon, which has a major negative impact on the control of blood glucose levels. We will now examine the mechansisms by which it affects insulin action in liver and muscle, two major target tissues of the hormone responsible for glucose disposal. This work is expected to validate PKCepsilon or its downstream effectors as therapeutic targets in the treatment of the insulin resistance which accompanies obesity and Type 2 diabetes.
The Role Of Liver Fructose-1,6-phosphatase (FBPase) In Body Weight Regulation
Funder
National Health and Medical Research Council
Funding Amount
$494,718.00
Summary
We have shown that fructose-1,6-bisphosphatase (FBPase), an enzyme important in producing sugar from the liver and one that is connected to Type 2 diabetes, does not cause an increase in sugar production when there is more of the enzyme in mouse livers. It does, however, lower both body weight and the amount of food the mice consume. We therefore hypothesise that liver FBPase is important in controlling body weight in humans and our project aims to find out exactly how and why this happens.
Reversal Of Diabetes In Pigs Using Liver-directed Gene Therapy
Funder
National Health and Medical Research Council
Funding Amount
$573,807.00
Summary
Type I diabetes mellitus is caused by the autoimmune destruction of the beta cells of the pancreas that secrete insulin. We have shown that we can cure diabetes in spontaneously diabetic mice by delivery of the insulin gene to the liver using a non-pathogenic viral delivery system. The study aims to repeat this work in pigs which have similar physiology to humans. If successful this would be proof-of-principle that we could theoretically control blood glucose levels in humans.