Platypus venom ingredient may help treat type 2 diabetes
The egg-laying mammals evolved remarkable insulin regulation techniques which may have stemmed from fighting over females. Jake Port reports.
Platypuses aren’t entirely the cuddly creatures they appear to be. They boast spurs loaded with excruciating venom – but these painful compounds could be good news for people with diabetes.
Researchers in Australia found a hormone in platypus venom called GLP-1 is also produced in their gut to regulate blood glucose levels. And while the human form of the hormone degrades within minutes, the platypus version lasts hours – which could form the basis of long-lasting diabetes treatment.
The work was published in Scientific Reports.
In animals such as humans and platypuses (Ornithorhynchus anatinus), GLP-1, or glucagon-like peptide-1, stimulates production of insulin, a hormone that signals cells to scoop sugar from the bloodstream.
But patients with type 2 diabetes – a condition that will develop in at least one in three Americans (PDF download) – are unable to use insulin properly. And the short period that GLP-1 stimulates insulin before breaking apart isn’t long enough to regulate sugar levels.
It turns out a longer lasting form of GLP-1 is found in monotremes – a group of egg-laying mammals comprising platypuses and echidnas (family Tachyglossidae).
(Like platypuses, echidnas wield spurs on their hind legs, but unlike platypuses, they aren’t venomous, so echidna GLP-1 is found only in the gut.)
Normally, GLP-1 is degraded by a protein called dipeptidyl peptidase-4. But to the surprise of the University of Adelaide’s Enkhjargal Tsend-Ayush, Chuan He and their colleagues, monotreme GLP-1 resisted dipeptidyl peptidase-4 degradation, surviving at least four hours.
The team believes that this dual-purpose form of GLP-1 may have evolved from a biological arms race within the species.
During mating season, males fight off competitors using their spurs, around 1.5 centimetres long, that inject poison produced in a gland in their thigh.
If a platypus cops a dose of venom, its blood sugar levels drop – not a great thing to happen in a fight.
To counteract this, monotreme GLP-1 is 50 times less potent than human GLP-1 so they don't die of hypoglycaemia.
"The lack of a spur on echidnas remains an evolutionary mystery, but the fact that both platypus and echidnas have evolved the same long-lasting form of the hormone GLP-1 is in itself a very exciting finding," says study senior author Frank Grutzner, also from the University of Adelaide.
By better understanding the differences between monotreme and human GLP-1, it’s hoped that a long-lasting form of the hormone could be developed for use in type 2 diabetes medication.