Peripheral ghrelin participates in glucostatic feeding mechanisms and in the anorexigenic signalling mediated by CART and CRF neurons

Nutr Neurosci. 2005 Oct-Dec;8(5-6):287-95. doi: 10.1080/10284150500502546.

Abstract

Ghrelin is upregulated under negative energy balance conditions, including starvation and hypoglycemia, while it is downregulated under situations of positive energy balance, such as feeding, hyperglycemia and obesity. The aims of this study were to assess potential ghrelin interactions with glucose levels in appetite control and to identify potential mechanisms involving orexigenic and anorexigenic ghrelin mediated signals by using a specific anti-ghrelin antibody. Our results confirm that peripheral ghrelin is an important signal in meal initiation and food intake stimulation. C-fos positive neurons in the PVN increased after insulin or 2-deoxyglucose administration. Moreover, we also demonstrate that peripheral ghrelin blockade with a specific anti-ghrelin antibody reduces, in part, the orexigenic signal induced by insulin and 2-DG administration. Furthermore, when we blocked peripheral ghrelin, c-fos positive CRF neurons and CART expression increased in the PVN, both under hypoglycemia or cytoglycopenia conditions, suggesting a neuronal activation (anorexigenic signalling) in this hypothalamic region. In summary, our findings imply that peripheral ghrelin plays an important role in regulatory "glucostatic" feeding mechanisms due to its role as a "hunger" signal affecting the PVN area, which may contribute to energy homeostasis through both orexigenic/anorexigenic pathways.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Animals
  • Antibodies / pharmacology
  • Appetite Regulation / physiology
  • Blood Glucose / metabolism*
  • Corticotropin-Releasing Hormone / analysis*
  • Corticotropin-Releasing Hormone / physiology
  • Energy Metabolism / physiology
  • Ghrelin
  • Homeostasis / physiology
  • Immunohistochemistry
  • Male
  • Nerve Tissue Proteins / analysis*
  • Nerve Tissue Proteins / physiology
  • Neurons / chemistry
  • Neurons / physiology*
  • Paraventricular Hypothalamic Nucleus / physiology
  • Peptide Hormones / immunology
  • Peptide Hormones / physiology*
  • Proto-Oncogene Proteins c-fos / analysis
  • Rats
  • Rats, Wistar
  • Signal Transduction / physiology*
  • alpha-MSH / analysis

Substances

  • Antibodies
  • Blood Glucose
  • Ghrelin
  • Nerve Tissue Proteins
  • Peptide Hormones
  • Proto-Oncogene Proteins c-fos
  • cocaine- and amphetamine-regulated transcript protein
  • alpha-MSH
  • Corticotropin-Releasing Hormone