ZFIN ID: ZDB-PUB-100211-18
Ghrelin affects carbohydrate-glycogen metabolism via insulin inhibition and glucagon stimulation in the zebrafish (Danio rerio) brain
Cruz, S.A., Tseng, Y.C., Kaiya, H., Hwang, P.P., Cruz, S.A., Hwang, P.P., Kaiya, H., Tseng, Y.C., and Hwang, P.P.
Date: 2010
Source: Comparative biochemistry and physiology. Part A, Molecular & integrative physiology   156(2): 190-200 (Journal)
Registered Authors: Cruz, Shelly, Hwang, Pung Pung, Tseng, Yung-Che
Keywords: Brain, Ghrelin, Glucagon, Glycogen growth hormone secretagogue receptor, Insulin
MeSH Terms:
  • Animals
  • Brain/drug effects
  • Brain/metabolism*
  • Carbohydrate Metabolism*/drug effects
  • Cloning, Molecular
  • Gene Expression Profiling
  • Gene Expression Regulation/drug effects
  • Ghrelin/administration & dosage
  • Ghrelin/genetics
  • Ghrelin/metabolism*
  • Ghrelin/pharmacology
  • Glucagon/metabolism*
  • Glycogen/metabolism*
  • Goldfish
  • Insulin/metabolism*
  • Protein Transport/drug effects
  • RNA, Messenger/genetics
  • RNA, Messenger/metabolism
  • Receptors, Ghrelin/genetics
  • Receptors, Ghrelin/metabolism
  • Zebrafish/genetics
  • Zebrafish/metabolism*
  • Zebrafish Proteins/genetics
  • Zebrafish Proteins/metabolism
PubMed: 20138234 Full text @ Comp. Biochem. Physiol. A Mol. Integr. Physiol.
Carbohydrate-glycogen metabolism (CGM) is critical for emergency energy supplies in the central nervous system (CNS). Ghrelin (GHRL) in pancreas is known to significantly regulate a dominant player in CGM, insulin (INS). However, its regulatory effect on extrapancreatic INS synthesis is yet unknown. In this study, we used adult zebrafish to elucidate the expression and role of zebrafish GHRL (zGHRL) in genes primarily involved in the brain's CGM. Results showed that zebrafish brain expressed zghrl and its receptor, growth hormone secretagogue-receptor (GHS-R: zghs-r1a and zghs-r2a), according to RT-PCR and in situ hybridization. Protein localization coupled with mRNA spatial expression further verified zGHRL's presence in the brain. For the in vivo study, significant increases in zghs-r1a and zghs-r2a synthesis were observed after injection of synthetic peptide goldfish GHRL-12 (gGHRL) using brain templates analyzed by quantitative real time-PCR (qPCR). Ligand-receptor synthesis of INS (zinsa; zins-r1 and zins-r2) significantly decreased, while glucagon (GCG) (zgcgb1 and zgcgb2; zgcg-r1 and zgcg-r2) exhibited a significant transient increase. In CGM, subsequent processes indicate urgent glucose-sensing response that will balance glycogen degradation and energy storage. Taken together, these findings suggest that GHRL regulates INS synthesis by mediating its action on GHS-R in the CNS and partly involved in CGM.