Grizzlys in hibernation temporarily diabetics

Grizzlies temporarily become diabetics in hibernation

08/06/2014

Grizzly bears develop a type of diabetes during their hibernation, according to researchers from the United States. Before, however, if they eat the winter bacon and become very fat, they are free of symptoms. And after the break they are again „healed“. Obesity does not necessarily lead to diabetes.

Diabetes during hibernation - before and after
Grizzly bears develop a type of diabetes while they hibernate, but not before. Although the animals are very thick in the autumn, but symptom-free. But only a few weeks later they are diabetic during hibernation. This report researchers in the journal „Cell metabolism“. Accordingly, the animals are on waking up in the spring again „healed“. As the scientists write, obesity does not necessarily lead to diabetes.

Overweight as a major cause of diabetes
Characteristic of type 2 diabetes is that the body is barely responsive to the hormone insulin, which is referred to as insulin resistance. In the first place, the assumed causes are overweight. But also genetic predisposition, high blood sugar and lack of exercise could lead to the disease. For grizzly bears, the group led by Kevin Corbit from Amgen Inc., a biotechnology company in Thousand Oaks, California, wanted to find out how to eat Winterspeck without getting sick.

Unlike humans, insulin levels in the blood do not change in bears
As the researchers explained, it has been suggested that the bear's body regulates metabolism by the amount of insulin that pours out the pancreas. In bears, the level of insulin in the blood changes, unlike in humans, but not. Both the amount of insulin in the blood and the level of blood sugar remained approximately the same during the active time as well as during the hibernation. According to the scientists, the body does not react to insulin when hibernating instead. As Corbit and colleagues write, the bears are still very susceptible to insulin shortly before hibernation, when they have the most fat during the year.

Consume up to seven months of the fat reserves
A protein called PTEN, therefore, virtually shuts off the sensitivity of the fat cells to insulin so that the body can undisturbed fat loss. In spring, the body is then receptive to insulin again. The researchers took samples of bacon, liver and calf muscle from several Grizzlys (Ursus arctos horribilis) of different ages and sexes in October, January and May - before, during and after hibernation. It was found that the bears save energy for hibernation exclusively in the fatty tissue and not in the liver and muscles as many obese animals of other species. Grizzly bears hibernate for up to seven months. In time, they only consume their fat reserves. Their body temperature keeps the animals close to normal.

Therapies need to take better account of individual situations
The researchers write that the results showed yet again how complex the interaction of obesity and diabetes is and are proof that both phenomena never went hand in hand, as had long been assumed. For example, in some patients the cellular mechanism that makes them fat can protect against diabetes, such as a small amount of the PTEN protein. In other people, the diabetes mechanism leading to diabetes may be the factor that protects them from being overweight. According to the scientists, therapies should better take into account individual situations.

Enzyme is probably responsible for disease
Scientists from Germany, Austria and the USA were only in the beginning of July in the journal „Cell“ reports that the enzyme heme oxygenase-1 (HO-1) is probably responsible for the fact that obese people suffer from diabetes and not body weight, belly fat or fat. Thus, people with low HO-1 activity rarely develop complications, and people with high levels of HO-1 have diabetes more often. Insights into the metabolic correlations had been provided in mice. Thus, while animals in which HO-1 in the phagocytes of the immune system, the macrophages, was genetically switched off, as normal mice with intact enzyme. However, despite being overweight, they did not develop diabetes or fatty liver, but remained healthy and lived as long as normal-weight conspecifics. (Ad)