Corticotropin-releasing hormone receptor expression and functional signaling in murine gonadotrope-like cells.
Corticotropin-releasing hormone (CRH) is a key regulator of the mammalian stress response, mediating a wide variety of stress-associated behaviors including stress-induced inhibition of reproductive function. To investigate the potential direct action of CRH on pituitary gonadotrope function, we examined CRH receptor expression and second messenger signaling in alpha T3-1 cells, a murine gonadotrope-like cell line. Reverse transcriptase PCR (RT-PCR) studies demonstrated that alpha T3-1 cells express mRNA for the two CRH receptor subtypes, CRHR1 and CRHR2, with CRHR2alpha as the predominant CRHR2 isoform. Stimulation of the cells with CRH or urocortin (UCN) resulted in rapid, transient increases in the intracellular levels of cAMP that were completely blocked by the addition of alpha-helical CRH 9-41 or astressin, non-selective CRH receptor antagonists. Stimulation of the cells with CRHR2-specific ligands, urocortin 2 (UCN2) or urocortin 3 (UCN3), resulted in rapid increases in intracellular cAMP levels to 50-60% of the levels observed with UCN. Treatment with a selective CRHR2 antagonist, antisauvagine, completely blocked UCN3-mediated increases in cAMP and significantly reduced, but did not completely block UCN-mediated increases in cAMP, demonstrating that both CRHR1 and CRHR2 are functionally active in these gonadotrope-like cells. Finally, UCN treatment significantly increased the transcriptional activity of the glycoprotein hormone alpha-subunit promoter as assessed by alpha-luciferase transfection assays. Together, these results demonstrate the functional signaling of CRH receptors in alpha T3-1 cells, suggesting that CRH may also modulate pituitary gonadotrope function in vivo.
Seasholtz
Audrey F
AF
Molecular and Behavioral Neuroscience Institute, University of Michigan, 109 Zina Pitcher Place, Ann Arbor, Michigan 48109, USA. aseashol@umich.edu
Ohman
Miina
M
Wardani
Amale
A
Thompson
Robert C
RC
D000818:Animals; D002460:Cell Line; D003346:Corticotropin-Releasing Hormone / Q000096:biosynthesis*; D000242:Cyclic AMP / Q000096:biosynthesis*; D015870:Gene Expression; D005786:Gene Expression Regulation; D052681:Gonadotrophs / Q000378:metabolism*; D047908:Intracellular Signaling Peptides and Proteins; D051379:Mice; D020033:Protein Isoforms; D018019:Receptors, Corticotropin-Releasing Hormone / Q000235:genetics*; D020133:Reverse Transcriptase Polymerase Chain Reaction; D015398:Signal Transduction
D047908:Intracellular Signaling Peptides and Proteins; D020033:Protein Isoforms; D018019:Receptors, Corticotropin-Releasing Hormone; D003346:Corticotropin-Releasing Hormone; D000242:Cyclic AMP