Blocking peptide hormone may be answer, say U of T researchers
by Paul Cantin
Researchers at the University of Toronto have discovered that new hope for diabetics fighting to control their blood sugar may lie in blocking a common peptide hormone.
Under the leadership of Professor Mladen Vranic, a 2009 Canadian Medical Hall of Fame inductee, the team from the Faculty of Medicine's Departments of Physiology and Medicine looked at one of the biggest challenges facing people with diabetes - the control of blood sugar. The team's findings were presented June 6 at the American Diabetes Association conference in New Orleans.
Low blood sugar - or hypoglycemia - is one of the most worrying consequences of diabetes and can cause irritability, loss of consciousness, seizures and in extreme cases, coma. Frequent hypoglycemic attacks can affect many brain functions including the hippocampus - the area that controls cognitive functions. Diabetes complications include blindness, terminal kidney disease, stroke and neuropathy. Although the amount of insulin administered to diabetes patients can be calculated based on blood sugar, it is not exact and the consequence of that imprecision can be hypoglycemia. The risk of hypoglycemia can be decreased by decreasing the tightness of blood glucose control. This however increases danger of complications. Thus hypoglycemia is the limiting factor for precise glucose control in diabetics.
Vranic and his team focused on the complex relationship between insulin, the hormone glucagon and the hormone peptide somatostatin. In people with diabetes, researchers have noted higher levels of somatostatin, which inhibits glucagon. Using mouse models, Vranic's team introduced a peptide - developed by Dr. David Coy at Tulane University - that acts as a blocking inhibitor to somatostatin's effect on the pancreatic alpha cell, which in turn permitted glucagon and insulin to interact normally. The result is better control of blood sugar.
"There is great potential for the introduction of the somatostatin antagonist as part of the diabetes control regime," Vranic said. "If people with diabetes were to take the antagonist along with their insulin treatment, the result could be much healthier patients with fewer long-term negative effects of hypoglycemia."
Vranic's team, which has patented its discovery, has already discussed the possibility of developing a commercial application for the findings, once further research and testing has been completed.
Vranic's team included graduate student Jessica Yue and research partners Suad Efendic (Karolinska Institute, Stockholm) and David Coy (Tulane University, New Orleans).