title: Mast cells in the rat brain synthesize gonadotropin-releasing hormone.
abstract: Mast cells occur in the brain and their number changes with reproductive status. While it has been suggested that brain mast cells contain the mammalian hypothalamic form of gonadotropin-releasing hormone (GnRH-I), it is not known whether mast cells synthesize GnRH-I de novo. In the present study, mast cells in the rat thalamus were immunoreactive to antisera generated against GnRH-I and the GnRH-I associated peptide (GAP); mast cell identity was confirmed by the presence of heparin, a molecule specific to mast cells, or serotonin. To test whether mast cells synthesize GnRH-I mRNA, in situ hybridization was performed using a GnRH-I cRNA probe, and the signal was identified as being within mast cells by the binding of avidin to heparin. GnRH-I mRNA was also found, using RT-PCR, in mast cells isolated from the peritoneal cavity. Given the function of GnRH-I in the regulation of reproduction, changes in the population of brain GnRH-I mast cells were investigated. While housing males with sexually receptive females for 2 h or 5 days resulted in a significant increase in the number of brain mast cells, the proportion of mast cells positive for GnRH-I was similar to that in males housed with a familiar male. These findings represent the first report showing that mast cells synthesize GnRH-I and that the mast cell increase seen in a reproductive context is the result of a parallel increase in GnRH-I positive and non-GnRH-I positive mast cells.
authors.affiliation: Department of Biochemistry and Molecular Biophysics, Columbia University College of Physicians and Surgeons, New York, New York 10032, USA.
authors.forename: Mona H
authors.initials: MH
authors.lastname: Khalil
authors.forename: Ann-Judith
authors.initials: AJ
authors.lastname: Silverman
authors.forename: Rae
authors.initials: R
authors.lastname: Silver
mesh_terms: D000818:Animals; D015415:Biomarkers; D001921:Brain / Q000166:cytology*; D001923:Brain Chemistry / Q000502:physiology*; D002452:Cell Count; D015550:Cell Degranulation / Q000502:physiology; D007987:Gonadotropin-Releasing Hormone / Q000096:biosynthesis*; D007150:Immunohistochemistry; D017403:In Situ Hybridization; D008297:Male; D008407:Mast Cells / Q000378:metabolism*; D010477:Perfusion; D011498:Protein Precursors / Q000096:biosynthesis; D051381:Rats; D020318:Rats, Long-Evans; D020133:Reverse Transcriptase Polymerase Chain Reaction
chemical_list: D015415:Biomarkers; D011498:Protein Precursors; C050502:gonadotropin releasing hormone associated peptide; D007987:Gonadotropin-Releasing Hormone