Lowering cyclic adenosine-3',5'-monophosphate (cAMP) levels by expression of a cAMP-specific phosphodiesterase decreases intrinsic pulsatile gonadotropin-releasing hormone secretion from GT1 cells.
Pulsatile GnRH secretion is an intrinsic property of GnRH neurons. Since increases in cAMP levels increase excitability and GnRH secretion in the GT1-1 GnRH cell line, we asked whether cAMP levels play a role in timing excitability and intrinsic pulsatile GnRH secretion. The expression of the cAMP-specific phosphodiesterase (PDE4D1) was used in a genetic approach to lower cAMP levels. Cells were infected with an adenovirus vector (Ad) expressing PDE4D1 (PDE-Ad), or for controls with an empty Ad (Null-Ad) or an Ad expressing green fluorescent protein (GFP-Ad). Infection with the PDE-Ad significantly inhibited forskolin-induced increases in cAMP production, GnRH secretion, and Ca2+ oscillations. Infection of GT1-1 cells with the PDE-Ad vs. GFP-Ad or Null-Ad controls significantly decreased spontaneous Ca2+ oscillations and inhibited the frequency of GnRH pulses. These data support the hypothesis that the level of cAMP in GT1 neurons is a component of the biological clock timing neuron excitability and pulsatile GnRH secretion. Genetically targeted expression of PDE4D1 represents a powerful approach to study the role of cAMP levels in specific populations of neurons in transgenic animals.
Yoshida
Hiroshi
H
Department of Obstetrics, Gynecology and Reproductive Sciences, University of California San Francisco, San Francisco, California 94143, USA.
Beltran-Parrazal
Luis
L
Butler
Paul
P
Conti
Marco
M
Charles
Andrew C
AC
Weiner
Richard I
RI
D015105:3',5'-Cyclic-AMP Phosphodiesterases / Q000235:genetics / Q000378:metabolism*; D000262:Adenylyl Cyclases / Q000378:metabolism; D000818:Animals; D002118:Calcium / Q000378:metabolism; D015220:Calcium Channels / Q000378:metabolism; D045744:Cell Line, Tumor; D005576:Colforsin / Q000494:pharmacology; D000242:Cyclic AMP / Q000378:metabolism*; D017868:Cyclic AMP-Dependent Protein Kinases / Q000378:metabolism; D054703:Cyclic Nucleotide Phosphodiesterases, Type 4; D005260:Female; D005786:Gene Expression Regulation / Q000187:drug effects; D007987:Gonadotropin-Releasing Hormone / Q000378:metabolism*; D006801:Humans; D007473:Ion Channels / Q000502:physiology; D008297:Male; D051379:Mice; D009474:Neurons / Q000378:metabolism*; D018408:Patch-Clamp Techniques; D015398:Signal Transduction
D015220:Calcium Channels; D007473:Ion Channels; D005576:Colforsin; D007987:Gonadotropin-Releasing Hormone; D000242:Cyclic AMP; D017868:Cyclic AMP-Dependent Protein Kinases; D015105:3',5'-Cyclic-AMP Phosphodiesterases; D054703:Cyclic Nucleotide Phosphodiesterases, Type 4; D000262:Adenylyl Cyclases; D002118:Calcium