title: Cobalt complex with GnRH stimulates the LH release and PKA signaling pathway in pig anterior pituitary cells in vitro.
abstract: Metal complexes with GnRH were shown to interact with GnRH receptors in pituitary cells. In the present study we examined the effects of GnRH and its cobalt complex form (Co-GnRH) on LH secretion and generation of second messengers, namely inositol phosphates (IPs) and cAMP, in porcine pituitary cells in vitro. The cells were obtained from gilt pituitary at the pre-ovulatory phase of estrous cycle and cultured for 72 h before challenge with GnRH or Co-GnRH. Both substances induced a significant increase in LH release that was detectable after 60 min (P<0.05) of treatment, with the Co-GnRH complex being more efficient than GnRH at 180 min (P<0.01). GnRH and Co-GnRH were equally effective at 10(-8)M (P<0.01), however, at the lowest (10(-9)M) as well as the highest (10(-7)M) concentrations tested, Co-GnRH was more potent than its native counterpart (P<0.01). Interestingly, Co-GnRH revealed twice more efficient than GnRH at stimulating cAMP production, an effect which was detectable in cells after 1h-incubation (P<0.001). In contrast, while native GnRH induced a rapid increase (P<0.05) in IPs no such effect of Co-GnRH was observed. These data demonstrate that Co-GnRH and GnRH differentially effect on the signaling pathway in porcine gonadotropes and suggest that in these cells, the releasing action of Co-GnRH results from the mediation via the cAMP/protein kinase A second messenger system.
authors.affiliation: Institute of Animal Reproduction and Food Research, Polish Academy of Sciences, 10-747 Olsztyn, Poland.
authors.forename: Agnieszka
authors.initials: A
authors.lastname: Blitek
authors.forename: Adam
authors.initials: A
authors.lastname: Ziecik
authors.forename: Alina
authors.initials: A
authors.lastname: Gajewska
authors.forename: Masato
authors.initials: M
authors.lastname: Kodaka
authors.forename: Raymond
authors.initials: R
authors.lastname: Counis
authors.forename: Kazimierz
authors.initials: K
authors.lastname: Kochman
mesh_terms: D000704:Analysis of Variance; D000818:Animals; D002478:Cells, Cultured; D003035:Cobalt / Q000494:pharmacology*; D005576:Colforsin / Q000494:pharmacology; D000242:Cyclic AMP / Q000378:metabolism; D017868:Cyclic AMP-Dependent Protein Kinases / Q000378:metabolism*; D004305:Dose-Response Relationship, Drug; D004347:Drug Interactions; D007987:Gonadotropin-Releasing Hormone / Q000494:pharmacology*; D007124:Immunoenzyme Techniques / Q000379:methods; D066298:In Vitro Techniques; D007986:Luteinizing Hormone / Q000378:metabolism; D010744:Phosphoric Monoester Hydrolases / Q000378:metabolism; D010903:Pituitary Gland, Anterior / Q000166:cytology*; D015398:Signal Transduction / Q000187:drug effects* / Q000502:physiology; D013552:Swine; D013997:Time Factors
chemical_list: D005576:Colforsin; D007987:Gonadotropin-Releasing Hormone; D003035:Cobalt; D007986:Luteinizing Hormone; D000242:Cyclic AMP; D017868:Cyclic AMP-Dependent Protein Kinases; D010744:Phosphoric Monoester Hydrolases; C021822:myo-inositol-1 (or 4)-monophosphatase