title: Investigation of the presence of ghrelin in the central nervous system of the rat and mouse.
abstract: Ghrelin and ghrelin receptor agonist have effects on central neurons in many locations, including the hypothalamus, caudal brain stem, and spinal cord. However, descriptions of the distributions of ghrelin-like immunoreactivity in the CNS in published work are inconsistent. We have used three well-characterized anti-ghrelin antibodies, an antibody to the unacylated form of ghrelin, and a ghrelin peptide assay in rats, mice, ghrelin knockout mice, and ghrelin receptor reporter mice to re-evaluate ghrelin presence in the rodent CNS. The stomach served as a positive control. All antibodies were effective in revealing gastric endocrine cells. However, no specific staining could be found in the brain or spinal cord. Concentrations of antibody 10 to 30 times those effective in the stomach bound to nerve cells in rat and mouse brain, but this binding was not reduced by absorbing concentrations of ghrelin peptide, or by use of ghrelin gene knockout mice. Concentrations of ghrelin-like peptide, detected by enzyme-linked immunosorbent assay in extracts of hypothalamus, were 1% of gastric concentrations. Ghrelin receptor-expressing neurons had no adjacent ghrelin immunoreactive terminals. It is concluded that there are insignificant amounts of authentic ghrelin in neurons in the mouse or rat CNS and that ghrelin receptor-expressing neurons do not receive synaptic inputs from ghrelin-immunoreactive nerve terminals in these species.
authors.affiliation: Department of Anatomy and Cell Biology, University of Melbourne, Parkville, Victoria 3010, Australia. j.furness@unimelb.edu.au
authors.forename: J B
authors.initials: JB
authors.lastname: Furness
authors.forename: B
authors.initials: B
authors.lastname: Hunne
authors.forename: N
authors.initials: N
authors.lastname: Matsuda
authors.forename: L
authors.initials: L
authors.lastname: Yin
authors.forename: D
authors.initials: D
authors.lastname: Russo
authors.forename: I
authors.initials: I
authors.lastname: Kato
authors.forename: M
authors.initials: M
authors.lastname: Fujimiya
authors.forename: M
authors.initials: M
authors.lastname: Patterson
authors.forename: J
authors.initials: J
authors.lastname: McLeod
authors.forename: Z B
authors.initials: ZB
authors.lastname: Andrews
authors.forename: R
authors.initials: R
authors.lastname: Bron
mesh_terms: D000818:Animals; D002490:Central Nervous System / Q000166:cytology / Q000378:metabolism*; D055098:Endocrine Cells / Q000378:metabolism; D004797:Enzyme-Linked Immunosorbent Assay / Q000379:methods; D005260:Female; D005753:Gastric Mucosa / Q000378:metabolism; D054439:Ghrelin / Q000378:metabolism*; D049452:Green Fluorescent Proteins / Q000235:genetics; D008297:Male; D051379:Mice; D008810:Mice, Inbred C57BL; D008822:Mice, Transgenic; D009412:Nerve Fibers / Q000378:metabolism; D009474:Neurons / Q000378:metabolism; D051381:Rats; D017207:Rats, Sprague-Dawley; D054440:Receptors, Ghrelin / Q000235:genetics; D013270:Stomach / Q000166:cytology
chemical_list: D054439:Ghrelin; D054440:Receptors, Ghrelin; D049452:Green Fluorescent Proteins