Cardiovascular Journal of Africa: Vol 25 No 5 (September/October 2014)

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CARDIOVASCULAR JOURNAL OF AFRICA • Volume 25, No 5, September/October 2014 248 AFRICA
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Glucose ‘control switch’ in the brain key to both types of diabetes
Researchers at Yale School of Medicine have pinpointed a
mechanism in part of the brain that is key to sensing glucose
levels in the blood, linking it to both type 1 and type 2
diabetes. The findings were published in the July 28 issue of
Proceedings of the National Academies of Sciences.
’We’ve discovered that the prolyl endopeptidase
enzyme’ located in a part of the hypothalamus known as
the ventromedial nucleus, sets a series of steps in motion
that control glucose levels in the blood’, said lead author
Sabrina Diano, professor in the Departments of Obstetrics,
Gynecology and Reproductive Sciences, Comparative
Medicine, and Neurobiology at Yale School of Medicine.
‘Our findings could eventually lead to new treatments for
diabetes.’
The ventromedial nucleus contains cells that are glucose
sensors. To understand the role of prolyl endopeptidase
in this part of the brain, the team used mice that were
genetically engineered with low levels of this enzyme. They
found that in the absence of this enzyme, mice had high levels
of glucose in the blood and became diabetic.
Diano and her team discovered that this enzyme is
important because it makes the neurons in this part of the
brain sensitive to glucose. The neurons sense the increase in
glucose levels and then tell the pancreas to release insulin,
thus preventing diabetes.
‘Because of the low levels of endopeptidase, the neurons
were no longer sensitive to increased glucose levels and could
not control the release of insulin from the pancreas, and the
mice developed diabetes’, said Diano, who is also a member
of the Yale program on integrative cell signalling and the
neurobiology of metabolism.
Diano said the next step in this research is to identify the
targets of this enzyme by understanding how the enzyme
makes the neurons sense changes in glucose levels. ‘If we
succeed in doing this, we could be able to regulate the
secretion of insulin, and be able to prevent and treat type 2
diabetes’, she said.
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