title: Plasma FGF21 concentrations, adipose fibroblast growth factor receptor-1 and β-klotho expression decrease with fasting in northern elephant seals.
abstract: 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.
authors: Department of Molecular & Cellular Biology, University of California Merced, Merced, CA 95343, USA; College of Bioresource Sciences, Nihon University, Fujisawa, Kanagawa 252-0880, Japan. Electronic address: suzuki.miwa@nihon-u.ac.jp.
authors: Miwa
authors: M
authors: Suzuki
authors: Department of Molecular & Cellular Biology, University of California Merced, Merced, CA 95343, USA.
authors: Andrew Y
authors: AY
authors: Lee
authors: Department of Molecular & Cellular Biology, University of California Merced, Merced, CA 95343, USA.
authors: José Pablo
authors: JP
authors: Vázquez-Medina
authors: Department of Molecular & Cellular Biology, University of California Merced, Merced, CA 95343, USA.
authors: Jose A
authors: JA
authors: Viscarra
authors: Department of Biology, Sonoma State University, Rohnert Park, CA 94928, USA.
authors: Daniel E
authors: DE
authors: Crocker
authors: Department of Molecular & Cellular Biology, University of California Merced, Merced, CA 95343, USA.
authors: Rudy M
authors: RM
authors: Ortiz
mesh_terms: D050154:Adiposity / Q000502:physiology; D000818:Animals; D001786:Blood Glucose / Q000378:metabolism*; D004797:Enzyme-Linked Immunosorbent Assay; D005215:Fasting / Q000502:physiology*; D005346:Fibroblast Growth Factors / Q000097:blood* / Q000235:genetics; D005508:Food Deprivation / Q000502:physiology; D005966:Glucuronidase / Q000097:blood* / Q000235:genetics; D000090265:Klotho Proteins; D009765:Obesity / Q000378:metabolism; D012333:RNA, Messenger / Q000235:genetics; D060888:Real-Time Polymerase Chain Reaction; D051496:Receptor, Fibroblast Growth Factor, Type 1 / Q000097:blood* / Q000235:genetics; D020133:Reverse Transcriptase Polymerase Chain Reaction; D046048:Seals, Earless / Q000378:metabolism*
chemical_list: D001786:Blood Glucose; D012333:RNA, Messenger; C414620:fibroblast growth factor 21; D005346:Fibroblast Growth Factors; D051496:Receptor, Fibroblast Growth Factor, Type 1; D005966:Glucuronidase; D000090265:Klotho Proteins
keywords: Elephant seal; Fasting; Fibroblast growth factor 21; Food deprivation