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Reproductive Sciences

, Volume 18, Issue 3, pp 277–285 | Cite as

Long-Term Hypoxia Enhances Cortisol Biosynthesis in Near-Term Ovine Fetal Adrenal Cortical Cells

  • Vladimir E. Vargas
  • Kanchan M. Kaushal
  • Tshepo Monau
  • Dean A. Myers
  • Charles A. DucsayEmail author
Original Articles

Abstract

This study was designed to determine the potential mechanism/mechanisms of previously observed enhanced fetal cortisol secretion following exposure to long-term hypoxia (LTH). Pregnant ewes were maintained at high altitude (3820 m) for approximately the last 100 days of gestation. Between the gestation days of 138 and 141, adrenal glands were collected from LTH and age-matched normoxic control fetuses. Cyclic adenosine monophosphate (cAMP), cortisol, and steroidogenic acute regulatory (StAR) protein were measured in response to adrenocorticotropic hormone (ACTH) stimulation. Cortisol responses to ACTH were also measured in the presence of the protein kinase (PKA) inhibitor H-89, proopiomelanocortin (POMC), or 22-kDa pro-ACTH. Cortisol output was higher in the LTH group compared to the control (P <.05), following ACTH treatment while the cAMP response was similar in both groups. Although PKA inhibition decreased cortisol production in both groups, however no differences were observed between groups. Western analysis revealed a significant increase in protein expression for StAR in the LTH group (P <.05, compared to control). Proopiomelanocortin and 22-kDa pro-ACTH did not alter the cortisol response to ACTH treatment. Results from the present study taken together with those of previous in vivo studies suggest that the enhanced cortisol output in the LTH group is not the result of differences in cAMP generation or PKA. We conclude that enhanced cortisol production in LTH adrenals is the result of enhanced protein expression of StAR and potential downstream signaling pathways.

Keywords

22-kDa pro-ACTH ACTH cAMP PKA StAR POMC 

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References

  1. 1.
    Liggins GC, Fairclough RJ, Grieves SA, Kendall JZ, Knox BS. The mechanism of initiation of parturition in the ewe. Recent Prog Horm Res. 1973;29:111–159.PubMedPubMedCentralGoogle Scholar
  2. 2.
    Meaney MJ, Viau V, Bhatnagar S, et al. Cellular mechanisms underlying the development and expression of individual differences in the hypothalamic-pituitary-adrenal stress response. J Steroid Biochem Mol Biol. 1991;39(2):265–274.PubMedCrossRefPubMedCentralGoogle Scholar
  3. 3.
    Challis JR, Richardson BS, Rurak D, Wlodek ME, Patrick JE. Plasma adrenocorticotropic hormone and cortisol and adrenal blood flow during sustained hypoxemia in fetal sheep. Am J Obstet Gynecol. 1986;155(6):1332–1336.PubMedCrossRefPubMedCentralGoogle Scholar
  4. 4.
    Fletcher AJ, Gardner DS, Edwards CM, Fowden AL, Giussani DA. Development of the ovine fetal cardiovascular defense to hypoxemia towards full term. Am J Physiol Heart Circ Physiol. 2006;291(6):H3023–H3034.PubMedCrossRefPubMedCentralGoogle Scholar
  5. 5.
    Raff H, Wood CE. Effect of age and blood pressure on the heart rate, vasopressin, and renin response to hypoxia in fetal sheep. Am J Physiol. 1992;263(4 pt 2):R880–R884.PubMedPubMedCentralGoogle Scholar
  6. 6.
    Towell ME, Figueroa J, Markowitz S, Elias B, Nathanielsz P. The effect of mild hypoxemia maintained for twenty-four hours on maternal and fetal glucose, lactate, cortisol, and arginine vasopressin in pregnant sheep at 122 to 139 days’ gestation. Am J Obstet Gynecol. 1987;157(6):1550–1557.PubMedCrossRefPubMedCentralGoogle Scholar
  7. 7.
    Myers DA, Bell PA, Hyatt K, Mlynarczyk M, Ducsay CA. Long-term hypoxia enhances proopiomelanocortin processing in the near-term ovine fetus. Am J Physiol Regul Integr Comp Physiol. 2005;288(5):R1178–R1184.PubMedCrossRefPubMedCentralGoogle Scholar
  8. 8.
    Myers DA, Hyatt K, Mlynarczyk M, Bird IM, Ducsay CA. Long-term hypoxia represses the expression of key genes regulating cortisol biosynthesis in the near-term ovine fetus. Am J Physiol Regul Integr Comp Physiol. 2005;289(6):R1707–R1714.PubMedCrossRefPubMedCentralGoogle Scholar
  9. 9.
    Schwartz J, Kleftogiannis F, Jacobs R, Thorburn GD, Crosby SR, White A. Biological activity of adrenocorticotropic hormone precursors on ovine adrenal cells. Am J Physiol. 1995;268(4 pt 1):E623–E629.PubMedPubMedCentralGoogle Scholar
  10. 10.
    Imamura T, Umezaki H, Kaushal KM, Ducsay CA. Long-term hypoxia alters endocrine and physiologic responses to umbilical cord occlusion in the ovine fetus. J Soc Gynecol Investig. 2004;11(3):131–140.PubMedCrossRefPubMedCentralGoogle Scholar
  11. 11.
    Adachi K, Umezaki H, Kaushal KM, Ducsay CA. Long-term hypoxia alters ovine fetal endocrine and physiological responses to hypotension. Am J Physiol Regul Integr Comp Physiol. 2004;287(1):R209–R217.PubMedCrossRefPubMedCentralGoogle Scholar
  12. 12.
    Sewer MB, Waterman MR. ACTH modulation of transcription factors responsible for steroid hydroxylase gene expression in the adrenal cortex. Microsc Res Tech. 2003;61(3):300–307.PubMedCrossRefPubMedCentralGoogle Scholar
  13. 13.
    Stocco DM. Star protein and the regulation of steroid hormone biosynthesis. Annu Rev Physiol. 2001;63:193–213.PubMedCrossRefPubMedCentralGoogle Scholar
  14. 14.
    Bell ME, McDonald TJ, Myers DA. Proopiomelanocortin processing in the anterior pituitary of the ovine fetus after lesion of the hypothalamic paraventricular nucleus. Endocrinology. 2005;146(6):2665–2673.PubMedCrossRefPubMedCentralGoogle Scholar
  15. 15.
    Ducsay CA, Mlynarczyk M, Kaushal KM, Hyatt K, Hanson K, Myers DA. Long-term hypoxia enhances ACTH response to arginine vasopressin but not corticotropin-releasing hormone in the near-term ovine fetus. Am J Physiol Regul Integr Comp Physiol. 2009;297(3):R892–R899.PubMedPubMedCentralCrossRefGoogle Scholar
  16. 16.
    Monau TR, Vargas VE, Zhang L, Myers DA, Ducsay CA. Nitric oxide inhibits ACTH-induced cortisol production in nearterm, long term hypoxic ovine fetal adrenocortical cells. Reprod Sci. 2010;17(10):955–962.PubMedPubMedCentralCrossRefGoogle Scholar
  17. 17.
    Daniel PB, Walker WH, Habener JF. Cyclic AMP signaling and gene regulation. Annu Rev Nutr. 1998;18:353–383.PubMedCrossRefPubMedCentralGoogle Scholar
  18. 18.
    Kamenetsky M, Middelhaufe S, Bank EM, Levin LR, Buck J, Steegborn C. Molecular details of camp generation in mammalian cells: A tale of two systems. J Mol Biol. 2006;362(4):623–639.PubMedPubMedCentralCrossRefGoogle Scholar
  19. 19.
    Myers DA, Hyatt K, Mlynarczyk M, Bird IM, Ducsay CA. Long-term hypoxia represses the expression of key genes regulating cortisol biosynthesis in the near-term ovine fetus. Am J Physiol Regul Integr Comp Physiol. 2005;289(6):R1707–R1714.PubMedCrossRefPubMedCentralGoogle Scholar
  20. 20.
    Darbeida H, Durand P. Glucocorticoid enhancement of adrenocorticotropin-induced 3’,5’-cyclic adenosine monophosphate production by cultured ovine adrenocortical cells. Endocrinology. 1987;121(3):1051–1055.PubMedCrossRefPubMedCentralGoogle Scholar
  21. 21.
    Su Y, Rose JC. The impact of acth receptor knockdown on fetal and adult ovine adrenocortical cell function. Reprod Sci. 2008;15(3):253–262.PubMedPubMedCentralCrossRefGoogle Scholar
  22. 22.
    Valego NK, Rose JC. A specific crh antagonist attenuates acth-stimulated cortisol secretion in ovine adrenocortical cells. Reprod Sci. 2010;17(5):477–486.PubMedCrossRefPubMedCentralGoogle Scholar
  23. 23.
    Manna PR, Dyson MT, Eubank DW, et al. Regulation of steroidogenesis and the steroidogenic acute regulatory protein by a member of the camp response-element binding protein family. Mol Endocrinol. 2002;16(1):184–199.PubMedCrossRefPubMedCentralGoogle Scholar
  24. 24.
    Raff H, Hong JJ, Oaks MK, Widmaier EP. Adrenocortical responses to acth in neonatal rats: Effect of hypoxia from birth on corticosterone, star, and pbr. Am J Physiol Regul Integr Comp Physiol. 2003;284(1):R78–R85.PubMedCrossRefPubMedCentralGoogle Scholar
  25. 25.
    Gorostizaga A, Cornejo Maciel F, Brion L, Maloberti P, Podesta EJ, Paz C. Tyrosine phosphatases in steroidogenic cells: regulation and function. Mol Cell Endocrinol. 2007;265–266:131–137.PubMedCrossRefPubMedCentralGoogle Scholar
  26. 26.
    Cohen P. The structure and regulation of protein phosphatases. Annu Rev Biochem. 1989;58:453–508.PubMedCrossRefPubMedCentralGoogle Scholar
  27. 27.
    Ford SL, Abayasekara DR, Persaud SJ, Jones PM. Role of phosphoprotein phosphatases in the corpus luteum: I Identification and characterisation of serine/threonine phosphoprotein phosphatases in isolated rat luteal cells. J Endocrinol. 1996;150(2):205–211.PubMedCrossRefPubMedCentralGoogle Scholar
  28. 28.
    Sayed SB, Whitehouse BJ, ones PM. Phosphoserine/threonine phosphatases in the rat adrenal cortex: a role in the control of steroidogenesis?. J Endocrinol. 1997;154(3):449–458.PubMedCrossRefPubMedCentralGoogle Scholar
  29. 29.
    Burns CJ, Gyles SL, Persaud SJ, Sugden D, Whitehouse BJ, Jones PM. Phosphoprotein phosphatases regulate steroidogenesis by influencing star gene transcription. Biochem Biophys Res Commun. 2000;273(1):35–39.PubMedCrossRefPubMedCentralGoogle Scholar
  30. 30.
    Jones PM, Sayed SB, Persaud SJ, Burns CJ, Gyles S, Whitehouse BJ. Cyclic amp-induced expression of steroidogenic acute regulatory protein is dependent upon phosphoprotein phosphatase activities. J Mol Endocrinol. 2000;24(2233–239.Google Scholar
  31. 31.
    Poderoso C, Maciel FC, Gorostizaga A, Bey P, Paz C, Podesta EJ. The obligatory action of protein tyrosine phosphatases in acth-stimulated steroidogenesis is exerted at the level of star protein. Endocr Res. 2002;28(4):413–417.PubMedCrossRefPubMedCentralGoogle Scholar
  32. 32.
    Sewer MB, Waterman MR. cAMP-dependent transcription of steroidogenic genes in the human adrenal cortex requires a dual-specificity phosphatase in addition to protein kinase a. J Mol Endocrinol. 2002;29(1):163–174.PubMedCrossRefPubMedCentralGoogle Scholar
  33. 33.
    Arakane F, King SR, Du Y, et al. Phosphorylation of steroidogenic acute regulatory protein (star) modulates its steroidogenic activity. J Biol Chem. 1997;272(51):32656–32662.PubMedCrossRefPubMedCentralGoogle Scholar
  34. 34.
    Fleury A, Mathieu AP, Ducharme L, Hales DB, LeHoux JG. Phosphorylation and function of the hamster adrenal steroidogenic acute regulatory protein (star). J Steroid Biochem Mol Biol. 2004;91(4):259–271.PubMedCrossRefPubMedCentralGoogle Scholar
  35. 35.
    LeHoux JG, Fleury A, Ducharme L, Hales DB. Phosphorylation of the hamster adrenal steroidogenic acute regulatory protein as analyzed by two-dimensional polyacrylamide gel electrophoreses. Mol Cell Endocrinol. 2004;215(1–2):127–134.PubMedCrossRefPubMedCentralGoogle Scholar
  36. 36.
    Manna PR, Stocco DM. Regulation of the steroidogenic acute regulatory protein expression: functional and physiological consequences. Curr Drug Targets Immune Endocr Metabol Disord. 2005;5(1):93–108.PubMedCrossRefPubMedCentralGoogle Scholar
  37. 37.
    Orme-Johnson NR. Distinctive properties of adrenal cortex mitochondria. Biochim Biophys Acta. 1990;1020(3):213–231.PubMedCrossRefPubMedCentralGoogle Scholar
  38. 38.
    Pon LA, Hartigan JA, Orme-Johnson NR. Acute ACTH regulation of adrenal corticosteroid biosynthesis. Rapid accumulation of a phosphoprotein. J Biol Chem. 1986;261(28):13309–13316.PubMedPubMedCentralGoogle Scholar
  39. 39.
    Yuen BS, Owens PC, Symonds ME, et al. Effects of leptin on fetal plasma adrenocorticotropic hormone and cortisol concentrations and the timing of parturition in the sheep. Biol Reprod. 2004;70(6):1650–1657.PubMedCrossRefPubMedCentralGoogle Scholar
  40. 40.
    Pralong FP, Roduit R, Waeber G, et al. Leptin inhibits directly glucocorticoid secretion by normal human and rat adrenal gland. Endocrinology. 1998;139(10):4264–4268.PubMedCrossRefPubMedCentralGoogle Scholar
  41. 41.
    Ducsay CA, Hyatt K, Mlynarczyk M, Kaushal KM, Myers DA. Long-term hypoxia increases leptin receptors and plasma leptin concentrations in the late-gestation ovine fetus. Am J Physiol Regul Integr Comp Physiol. 2006;291(5):R1406–R1413.PubMedCrossRefPubMedCentralGoogle Scholar
  42. 42.
    Vargas VE, Myers DA, Kaushal KM, Ducsay CA. ACTH induced cortisol synthesis in ovine fetal adrenocortical cells is mediated in part by extracellular signal regulated kinase (erk) 1 and 2: effect of long term hypoxia (lth). Reprod Sci. 2009;16(3):250A.Google Scholar

Copyright information

© Society for Reproductive Investigation 2011

Authors and Affiliations

  • Vladimir E. Vargas
    • 1
  • Kanchan M. Kaushal
    • 1
  • Tshepo Monau
    • 1
  • Dean A. Myers
    • 2
  • Charles A. Ducsay
    • 1
    Email author
  1. 1.Center for Perinatal BiologyLoma Linda University School of MedicineLoma LindaUSA
  2. 2.Department of Obstetrics and GynecologyUniversity of Oklahoma Health Sciences CenterOklahoma CityUSA

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