Friday, May 20, 2016

New Hormone Involved in Blood Glucose Control Discovered

New hormones are always being discovered, and the latest, called asprosin, is related to blood glucose control and insulin levels.

When blood glucose (BG) levels fall, for instance during the night, white adipose tissue (fat) releases asprosin, which increases BG levels. The increased BG levels then trigger the release of insulin, so BG levels don't get too high. That's how it's supposed to work.

But people with a rare disease called neonatal progeroid syndrome (NPS) that means they can't store fat can't produce asprosin because they have no fat. They can't use fat as an energy source between meals, because they don't have any, and hence they have to eat carbohydrates all day and even wake up during the night to eat to make sure their BG levels don't go too low. Without fat they don't have this trigger to keep BG levels up when they're not eating.

NPS patients can eat all the carbs they want without gaining weight, which might sound wonderful to anyone with a weight problem. It's not.  The woman in this article has never weighed more than 64 pounds, and cruel people make fun of her appearance. She says she has to eat constantly to keep her energy levels up.

Scientists discovered asprosin (which got its name from the Greek word for "white" because it's produced in white fat) by studying two people with NPS. Trying to find out what caused the disorder, the researchers did DNA sequencing of the NPS patients and discovered the new hormone.Then they figured out what it did.

Lipodystrophy (loss of fat tissue) is often associated with insulin resistance, so the researchers expected that the NPS patients would have elevated insulin levels. But they found that the NPS patients had two-fold lower insulin levels than normal. That's because they couldn't produce asprosin, which increases BG levels, which increases insulin levels.

Then they found that asprosin levels were doubled in obese insulin resistant men. Thus they wondered if blocking the action of asprosin could help control metabolic syndrome and type 2 diabetes. Indeed, in mice, an antibody against asprosin does reduce both glucose and insulin levels.

Of course we all know that what works in mice doesn't always work in humans. So only time will tell if this discovery has practical application. But it does sound promising. It also shows how complex the regulation of BG and insulin levels are, and different people with metabolic syndrome or type 2 diabetes may have defects in different systems. Thus it's not surprising that there's no one-size-all solution to these disorders.