Anatomical distribution and biochemical characterization of the novel RFamide peptide 26RFa in the human hypothalamus and spinal cord

J Neurochem. 2006 Oct;99(2):616-27. doi: 10.1111/j.1471-4159.2006.04090.x. Epub 2006 Aug 8.


26RFa is a novel RFamide peptide originally isolated in the amphibian brain. The 26RFa precursor has been subsequently characterized in various mammalian species but, until now, the anatomical distribution and the molecular forms of 26RFa produced in the CNS of mammals, in particular in human, are unknown. In the present study, we have investigated the localization and the biochemical characteristics of 26RFa-like immunoreactivity (LI) in two regions of the human CNS--the hypothalamus and the spinal cord. Immunohistochemical labeling using specific antibodies against human 26RFa and in situ hybridization histochemistry revealed that in the human hypothalamus 26RFa-expressing neurons are located in the paraventricular and ventromedial nuclei. In the spinal cord, 26RFa-expressing neurons were observed in the dorsal and lateral horns. Characterization of 26RFa-related peptides showed that two distinct molecular forms of 26RFa are present in the human hypothalamus and spinal cord, i.e. 26RFa and an N-terminally elongated form of 43 amino acids designated 43RFa. These data provide the first evidence that 26RFa and 43RFa are actually produced in the human CNS. The distribution of 26RF-LI suggests that 26RFa and/or 43RFa may modulate feeding, sexual behavior and transmission of nociceptive stimuli.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Aged
  • Aged, 80 and over
  • Amino Acid Sequence / physiology
  • Animals
  • Chromatography, High Pressure Liquid / methods
  • Female
  • Humans
  • Hypothalamus / anatomy & histology
  • Hypothalamus / metabolism*
  • Immunohistochemistry
  • Male
  • Neurons / cytology
  • Neurons / metabolism*
  • Neuropeptides / analysis
  • Neuropeptides / chemistry
  • Neuropeptides / metabolism*
  • PC12 Cells
  • Paraventricular Hypothalamic Nucleus / anatomy & histology
  • Paraventricular Hypothalamic Nucleus / metabolism
  • Posterior Horn Cells / anatomy & histology
  • Posterior Horn Cells / metabolism
  • Protein Isoforms / analysis
  • Protein Isoforms / chemistry
  • Protein Isoforms / metabolism
  • Protein Structure, Tertiary / physiology
  • Radioimmunoassay
  • Rats
  • Spinal Cord / anatomy & histology
  • Spinal Cord / metabolism*
  • Ventromedial Hypothalamic Nucleus / anatomy & histology
  • Ventromedial Hypothalamic Nucleus / metabolism


  • Neuropeptides
  • Protein Isoforms
  • prepro-26RFa protein, human