Plasma FGF21 concentrations, adipose fibroblast growth factor receptor-1 and β-klotho expression decrease with fasting in northern elephant seals.

• Main Authors: Suzuki, Miwa, Lee, Andrew Y, Vázquez-Medina, José Pablo, Viscarra, Jose A, Crocker, Daniel E, Ortiz, Rudy M
• Format: Article in Journal/Newspaper
• Language: unknown
• Published: eScholarship, University of California 2015
• Subjects: Animals; Seals; Earless; Obesity; Glucuronidase; Blood Glucose; Fibroblast Growth Factors; RNA; Messenger; Enzyme-Linked Immunosorbent Assay; Fasting; Reverse Transcriptase Polymerase Chain Reaction; Food Deprivation; Adiposity; Receptor; Fibroblast Growth Factor; Type 1; Real-Time Polymerase Chain Reaction; Klotho Proteins; Elephant seal; Fibroblast growth factor 21; Nutrition; Diabetes; Metabolic and endocrine; Physiology; Zoology; Veterinary Sciences; Endocrinology & Metabolism; Elephant Seal; Elephant Seals
• Online Access: https://escholarship.org/uc/item/25x8j9nw

Fibroblast growth factor (FGF)-21 is secreted from the liver, pancreas, and adipose in response to prolonged fasting/starvation to facilitate lipid and glucose metabolism. Northern elephant seals naturally fast for several months, maintaining a relatively elevated metabolic rate to satisfy their energetic requirements. Thus, to better understand the impact of prolonged food deprivation on FGF21-associated changes, we analyzed the expression of FGF21, FGF receptor-1 (FGFR1), β-klotho (KLB; a co-activator of FGFR) in adipose, and plasma FGF21, glucose and 3-hydroxybutyrate in fasted elephant seal pups. Expression of FGFR1 and KLB mRNA decreased 98% and 43%, respectively, with fasting duration. While the 80% decrease in mean adipose FGF21 mRNA expression with fasting did not reach statistical significance, it paralleled the 39% decrease in plasma FGF21 concentrations suggesting that FGF21 is suppressed with fasting in elephant seals. Data demonstrate an atypical response of FGF21 to prolonged fasting in a mammal suggesting that FGF21-mediated mechanisms have evolved differentially in elephant seals. Furthermore, the typical fasting-induced, FGF21-mediated actions such as the inhibition of lipolysis in adipose may not be required in elephant seals as part of a naturally adapted mechanism to support their unique metabolic demands during prolonged fasting.