Hormone that causes insulin resistance discovered
Washington: A hormone that plays a key role in triggering insulin resistance in the body has been found by Japanese scientists in what they say could lead to new class of drugs to treat the condition and type 2 diabetes.
Insulin resistance (IR) is a physiological condition in which the natural hormone, insulin, becomes less effective at lowering blood sugars, leading to the development of type 2
Researchers at the Kanazawa University Graduate School of Medical Science in Japan found the hormone secreted naturally in the liver is abundant among people suffering from type 2 diabetes compared to that of healthy people.
The new study, published in the journal Cell Metabolism, "sheds light on a previously underexplored function of the liver" which "participates in the pathogenesis of insulin resistance through hormone secretion", said lead researcher Hirofumi Misu.
The researchers had earlier discovered that genes encoding secretory proteins are abundantly expressed in the livers of people with type 2 diabetes.
On the basis of those findings, Misu and colleagues began to suspect that, similar to the role of fat tissue, the liver might contribute to the development of type 2 diabetes and insulin resistance via secretory proteins known as hepatokines.
They found that the liver expresses higher levels of the gene encoding "selenoprotein P" (SeP) in people with type 2 diabetes who are more insulin resistant. Blood levels of SeP are also increased in people with diabetes compared to healthy people.
Further studies in mice added support to the notion that the connection between SeP and insulin resistance is causal.
When the researchers gave SeP to normal mice, they became insulin resistant and their blood sugar levels rose. And when a treatment blocked the activity of SeP in their livers, obese and diabetic mice improved their sensitivity to insulin and their blood sugar levels are lowered.
Misu said that SeP was known previously as a protein produced mainly in the liver where it transports the essential trace element "selenium" from the liver to other parts of the body. But the protein`s clinical significance and, more specifically, its role in glucose homeostasis weren`t known.
In the development of insulin resistance, the researchers don`t think SeP acts on its own. The fat tissue is a main contributor to the development of insulin resistance by producing fat-derived hormones called adipokines, they said.
First Published: Wednesday, November 03, 2010, 00:00
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