Platypus venom for insulin regulation

Everyone knows the platypus and the echidna are two of a kind, as the world’s only egg-laying mammals. But as research led by the University of Adelaide has uncovered, Australia’s iconic monotremes have another unusual ability that could pave the way for new treatments for type 2 diabetes in humans.

The hormone glucagon-like peptide-1 (GLP-1) is normally secreted in the gut of both humans and animals, stimulating the release of insulin to lower blood glucose. The problem is that GLP-1 typically degrades within minutes, so this short stimulus isn’t sufficient to help diabetics maintain a proper blood sugar balance. As a result, medication that includes a longer lasting form of the hormone is needed to help provide an extended release of insulin.

So what does this have to do with Australian animals? As stated by Professor Frank Grutzner, co-lead author on the study, “Our research team has discovered that monotremes … have evolved changes in the hormone GLP-1 that make it resistant to the rapid degradation normally seen in humans.”

Professor Grutzner, from the University of Adelaide’s School of Biological Sciences and Robinson Research Institute, explained that GLP-1 is “degraded in monotremes by a completely different mechanism”. Not only is the hormone produced in the gut of the two species, but also in their venom.

During breeding season the platypus produces a powerful venom, which is secreted from a spur in its hind leg and used in competition among males for females. The echidna has no such spur from which to deliver its venom.

“We’ve discovered conflicting functions of GLP-1 in the platypus: in the gut as a regulator of blood glucose and in venom to fend off other platypus males during breeding season,” said co-lead author Associate Professor Briony Forbes, from Flinders University’s School of Medicine. “This tug of war between the different functions has resulted in dramatic changes in the GLP-1 system.

“The function in venom has most likely triggered the evolution of a stable form of GLP-1 in monotremes. Excitingly, stable GLP-1 molecules are highly desirable as potential type 2 diabetes treatments.”

The study has been published in the journal Scientific Reports.

Image courtesy of Eddy under CC BY-NC-ND 2.0