Meeting Abstract
66.4 Jan. 7 Gila monster digestion and exendin-4: absence of exendin-4 effect on metabolism, intestinal performance, or plasma nutrient concentrations CHRISTEL, Carolyn M.*; DENARDO, Dale F.; SECOR, Stephen M.; Arizona State University; Arizona State University; University of Alabama carolyn.christel@asu.edu
Gila monsters, one of two venomous lizard species, actively forage in their desert environment for eggs and litters of small mammals. Known to feed relatively infrequently on large meals (up to 35% of body mass), Gila monsters may require extraordinary regulation of digestive performance. One potential regulatory hormone is the peptide exendin-4, which was isolated from the saliva of Gila monsters and has demonstrated prolonged plasma glucose-lowering properties in mammals. Although exendin-4 has often been labeled a venom protein, circulating plasma levels of exendin-4 have been shown to increase in response to feeding. Thus, we examined the Gila monster�s metabolic responses to feeding and the possible regulation of these responses by exendin-4. Specifically, we explored the effect of feeding and exendin-4 on Gila monster metabolic rate, intestinal mass, intestinal performance, and circulating nutrient concentrations. In response to rodent meals, Gila monsters experienced approximately a 5-fold increase in metabolic rate and maintained significantly elevated metabolic rates for up to 7 days post-prandially. Small intestine mass and nutrient transport rates increased by 50% irrespective of circulating exendin-4 concentration. Similarly, glucose and triglyceride levels increased significantly over time, but did not correspond to either a post-prandial or a delayed increase in circulating exendin-4 concentration. Our results demonstrate that while Gila monsters experience a significant increase in intestinal performance and circulating glucose and triglycerides after feeding, exendin-4 does not affect these physiological events. Therefore, the question remains whether exendin-4 is involved in regulating digestive events or is a venom protein.
