Glucose production and substrate cycle activity in a fasting adapted animal, the northern elephant seal

• DOI: 10.1242/jeb.01476
• Publication Date: 2005-03-08T19:57:48Z
• Authors: Cory D. Champagne; Dorian S. Houser; Daniel E. Crocker
• Keywords: Gluconeogenesis; Catabolism; Carbohydrate Metabolism

SUMMARY During prolonged fasting physiological mechanisms defend lean tissue from catabolism. In the state, glucose is derived solely gluconeogenesis, requiring some catabolism of amino acids for gluconeogenic substrates. This creates a conflict in animals undergoing fasts concurrently with metabolically challenging activities. study investigated metabolism and developing neonatal elephant seals. Glucose production cycle activity were measured early (2 weeks) late(6 postweaning period. Additionally role regulatory hormones on investigated. was highly variable throughout period, did not change over correlated insulin or glucagon level. Endogenous (EGP) 2.80±0.65 mg kg–1 min–1 2.21±0.12 during late fasting. Insulin to molar ratio decreased while cortisol levels increased fast (t=5.27,2.84; P=0.003, 0.04; respectively). There no relationship between EGP hormone levels. The values this high exceeded estimated substrate available. These data suggest extensive recycling via Cori occurring northern seals, we propose possible justification recycling.