The relationship between pulsatile GnRH secretion and cAMP production in immortalized GnRH neurons.
Am J Physiol Endocrinol Metab
; 300(6): E1022-30, 2011 Jun.
Article
em En
| MEDLINE
| ID: mdl-21447787
ABSTRACT
In perifused immortalized GnRH neurons (GT1-7), simultaneous measurements of GnRH and cAMP revealed that the secretory profiles for both GnRH and cAMP are pulsatile. An analysis of GnRH and cAMP pulses in 16 independent experiments revealed that 25% of pulses coincide. Inversion of the peak and nadir levels was found in 33% and random relationship between GnRH and cAMP found in 42% of analyzed pulses. The random relation between GnRH and cAMP pulse resets to synchronous after an inverse relation between pulses occurred during the major GnRH release, indicating that GnRH acts as a switching mechanism to synchronize cAMP and GnRH release in perifused GT1-7 neurons. Activation of GnRH receptors with increasing agonist concentrations caused a biphasic change in cAMP levels. Low nanomolar concentrations increased cAMP production, but at high concentrations the initial increase was followed by a rapid decline to below the basal level. Blockade of the GnRH receptors by peptide and nonpeptide antagonists generated monotonic nonpulsatile increases in both GnRH and cAMP production. These findings indicate that cAMP positively regulates GnRH secretion but does not participate in the mechanism of pulsatile GnRH release.
Texto completo:
1
Base de dados:
MEDLINE
Assunto principal:
Hormônio Liberador de Gonadotropina
/
AMP Cíclico
/
Neurônios
Limite:
Animals
/
Humans
Idioma:
En
Ano de publicação:
2011
Tipo de documento:
Article