Expression and biological effects of endothelin-1 in human gonadotropin-releasing hormone-secreting neurons.
In a previous report, we demonstrated that in FNC-B4 cells, derived and characterized from a human fetal olfactory epithelium, both sex steroids and odorants regulate GnRH secretion. We now report the presence and biological activity of endothelin (ET)-1 in this GnRH-secreting neuronal cell. By in situ hybridization and immunohistochemistry, we found gene and protein expression of ET-1 and its converting enzyme ECE-1 in both fetal olfactory mucosa and FNC-B4 cells. The presence of authentic ET-1 in the conditioned media of FNC-B4 cells was further supported by combined RIAs and high-performance liquid chromatography studies. Experiments with radiolabeled ET-1 and ET-3 strongly indicated the presence of two classes of binding sites, corresponding to the ETA (16,500 sites/cell) and the ETB receptors (8,700 sites/cell). Functional studies, using selective analogs, indicated that these two classes of receptors subserve distinct functions in human GnRH-secreting cells. The ETA receptor subtype mediated an increase in intracellular calcium and GnRH secretion. Conversely, stimulation of the ETB subtype induced DNA synthesis and mitogen-activated protein kinase p44ERK1 expression. This is the first demonstration, in a human in vitro model, of a neuroendocrine role for ET-1 as regulator of GnRH-secreting neuron activity.
Maggi
M
M
Department of Anatomy Histology and Forensic Medicine, University of Florence, Firenze, Italy.
Barni
T
T
Fantoni
G
G
Mancina
R
R
Pupilli
C
C
Luconi
M
M
Crescioli
C
C
Serio
M
M
Vannelli
G B
GB
D002118:Calcium / Q000378:metabolism; D002478:Cells, Cultured; D017077:Culture Media, Conditioned; D004622:Embryo, Mammalian; D019332:Endothelin-1 / Q000032:analysis / Q000235:genetics* / Q000502:physiology*; D019334:Endothelin-3 / Q000378:metabolism; D007987:Gonadotropin-Releasing Hormone / Q000378:metabolism*; D006801:Humans; D017403:In Situ Hybridization; D009474:Neurons / Q000737:chemistry / Q000187:drug effects / Q000378:metabolism*; D009831:Olfactory Mucosa / Q000166:cytology* / Q000196:embryology / Q000378:metabolism; D044022:Receptor, Endothelin A; D044023:Receptor, Endothelin B; D017466:Receptors, Endothelin / Q000032:analysis / Q000378:metabolism
D017077:Culture Media, Conditioned; D019332:Endothelin-1; D019334:Endothelin-3; D044022:Receptor, Endothelin A; D044023:Receptor, Endothelin B; D017466:Receptors, Endothelin; D007987:Gonadotropin-Releasing Hormone; D002118:Calcium