Brain mechanism may explain glucose cravings
Published in the Journal of Clinical Investigation, the team said the discovery could help develop ways to reduce cravings for glucose in humans, including changes in how we eat, as well as the development of new drugs to treat obesity.
Dr James Gardiner, from the Department of Medicine, who led the study, said: “This is the first time anyone has discovered a system in the brain that responds to a specific nutrient, rather than energy intake in general. It suggests that when you’re thinking about diet, you have to think about different nutrients, not just count calories.”
Glucokinase is present in the hypothalamus, and it detects glucose in the liver and pancreas.
“Appetite for glucose is an important driver of overall food intake,” the researchers wrote, adding that although glucokinase’s role in appetite has been suggested previously, it had not been demonstrated.
In rats, the study’s authors found that glucokinase activity in the brain was low after a 24-hour fasting period. When they stimulated glucokinase activity using a virus in a separate experiment, the rats consumed more glucose instead of their regular chow. When glucokinase activity was decreased, they consumed less glucose.
The researchers said this suggested that glucokinase was involved in our desire for glucose, a main component of carbohydrate-rich sweet and starchy foods. They suggested that when the brain detects that it is not receiving enough glucose, this mechanism prompts animals to seek more.
Referring to the study’s relevance for humans, Gardiner said: “People are likely to have different levels of this enzyme, so different things will work for different people. For some people, eating more starchy foods at the start of a meal might be a way to feel full more quickly by targeting this system, meaning they eat less overall.”
The study was funded by the Biotechnology and Biological Sciences Research Council.
Source: Journal of Clinical Investigation
doi:10.1172/JCI77172
“Glucokinase activity in the arcuate nucleus regulates glucose intake”
Authors: Syed Hussain, Errol Richardson, Yue Ma, Christopher Holton, Ivan De Backer, Niki Buckley, Waljit Dhillo, Gavin Bewick, Shuai Zhang, David Carling, Steve Bloom, and James Gardiner
