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Decreased Protein Expression of Lipoprotein Lipase in Late Fasting Elephant Seals
Author(s) -
Wiener Adam,
Viscarra Jose,
Crocker Daniel,
Ortiz Rudy M
Publication year - 2011
Publication title -
the faseb journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.709
H-Index - 277
eISSN - 1530-6860
pISSN - 0892-6638
DOI - 10.1096/fasebj.25.1_supplement.1095.12
Subject(s) - lipolysis , lipoprotein lipase , medicine , endocrinology , adipose tissue , glycerol , weaning , insulin resistance , glycogen , lipase , adipose triglyceride lipase , lipid metabolism , chemistry , insulin , metabolism , biology , enzyme , biochemistry
During prolonged food deprivation, glycogen stores are depleted, and mammals rely on oxidation of fatty acids for energy. Thus, the breakdown of triglycerides (TG) becomes a critical process by which metabolic substrates become available to support energy requirements. Prolonged fasting is associated with the onset of insulin resistance so it should be expected that content of insulin‐responsive enzymes such as lipoprotein lipase (LpL) which cleave TG would decrease resulting in decreased free fatty acids (FFA) and glycerol. Prolonged fasting in northern elephant seals is associated with decreased insulin but elevated FFA; the changes in LpL have not been examined. To address the hypothesis that LpL decreases in fasting seals, we measured adipose LpL in Early (n=9; 2–3 weeks post weaning) and Late (n=8; 6–8 weeks post weaning) fasted pups. LpL decreased (8%), but plasma FFA, glycerol and TG all increased 41%, 27% and 40%, respectively late in fast. This suggests that LpL does not contribute significantly to metabolism of TG in adipose of prolong‐fasted seals. Increased TG may be necessary to provide sufficient substrate for increased lipolysis, resulting in increased FFA and glycerol. This pattern of substrate‐product utilization suggests elephant seals have a robust mechanism to maintain TG levels to maintain energetic demands during their fast. This project was funded by NIH NCMHD 9T37MD001480 & P20MD005049.