But the powerful venom of the Gila monster (Heloderma suspectum), one of the featured species in the new exhibition The Power of Poison, has medicinal capabilities as well: one of its components has been used to develop a diabetes drug.
The key ingredient is exendin-4, a peptide that may slow the lizard’s digestion and allow it to go for long periods without food. Gila (pronounced “Hee-lah”) monsters, which are native to the southwestern U.S. and northern Mexico, are slow-moving and shy, spending most of their time concealed in underground retreats in deserts and other relatively dry habitats.
These carnivorous lizards prey on nesting young rodents and rabbits, and the eggs of birds and reptiles. They can consume more than one-third of their body weight in a single feeding and endure many months between meals, by storing fat in their thick tails and bodies. (The lizard at the Museum is fed one weekly meal consisting of two dead mice.)
As it turns out, exendin-4 is similar to a human peptide that stimulates insulin production and lowers blood sugar. A synthetic version of the hormone was developed for use in a drug to treat type 2 diabetes. In addition to regulating blood sugar, exendin-4 may also reduce appetite and help control obesity.
In the wild, venom may help Gila monsters immobilize prey or defend themselves when a predator or human disturbs them. If a quick slashing bite fails to deter a bothersome intruder, a Gila monster will grip the offender in its jaws and hold on for several minutes, forcing venom into the victim through grooves in the long teeth of its lower jaw. Although not fatal to humans it nevertheless acts a powerful deterrent: it causes extreme pain, swelling, reduced blood pressure, and internal bleeding.
A version of this article first appeared in the Spring 2014 issue of Rotunda, the Member magazine.