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- Title
Hormonal Control of Metabolic Substrate Use by Birds and Reptiles.
- Authors
Sweazea, Karen L.; McMurtry, John P.; Elsey, Ruth M.; Redig, Patrick; Braun, Eldon J.
- Abstract
The differential use of metabolic substrates by birds is not well understood. Therefore, to clarify which substrates are preferentially utilized, studies were conducted on birds with divergent dietary habits and on close non-avian relatives of birds, alligators. Fasting plasma substrate and hormone levels were compared for Mourning doves (omnivorous), Bald Eagles, Great Homed Owls, Red-tailed Hawks, and American alligators (all carnivorous). The plasma of carnivorous birds and alligators had the highest concentrations of ketone bodies (10 to 21 mg/dl) concomitant with low levels of triglycerides (62 to 79 mg/dl) indicative of free fatty acid (FFA) utilization. Elevated FFAs have been correlated with decreased utilization of glucose and insulin resistance in mammals. This may also occur in birds as doves, eagles, and hawks were less sensitive to insulin as indicated by high glucose (325 to 350 mg/dl) levels in all three species, as well as increased insulin levels in eagles and hawks (1.1 to 1.2 ng/ml). In contrast, owls had high glucose (361 mg/dl) but low insulin (0.2 ng/ml) levels. More studies are required to determine if owls release insulin in response to a glucose load. Interestingly, previous studies have demonstrated that pancreatectomy of Great Homed Owls results in hyperglycemia and death suggesting they, like alligators and mammals, rely on insulin more than the other birds examined in this study.
- Subjects
METABOLISM; HORMONES; BIRDS; REPTILES; KETONES; TRIGLYCERIDES; FATTY acids; INSULIN resistance
- Publication
FASEB Journal, 2007, Vol 21, Issue 6, pA1397
- ISSN
0892-6638
- Publication type
Article
- DOI
10.1096/fasebj.21.6.a1397