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Research Interests
Reproductive Endocrinology
Research Summary
Feedback of estradiol on the hypothalamic-pituitary axis is a major factor which alters pulsatile release of gonadotropin-releasing hormone (GnRH) and luteizing hormone (LH). That estradiol both inhibits and stimulates secretion of LH has been known for decades. Recently it was shown that membrane impermeable forms of estrogen can mimic the rapid decrease, < 15 min, in pulsatile release of LH in sheep. Furthermore, we have shown that these same membrane impermeable forms of estrogen can increase the numbers of GnRH receptors in a time similar to that of estradiol in ovine gonadotropes. The long-term goal of my laboratory is to determine the role of estradiol signaling via nuclear receptors or receptors associated with the plasma membrane in altering the sensitivity of the pituitary to GnRH and subsequent release of LH. The regulation of membrane estrogen receptors during different states of reproduction will also be examined.
Research Publications
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Davis TL, Mussard ML, Jiménez-Severiano H, Enright W, Kinder JE. Chronic treatment with an agonist of gonadotropin-releasing hormone enhances luteal function in cattle. Biol Reprod 2003; 69:398-403. Niswender, GD, Davis, TL, Griffith, RJ, Bogan, RL, Monser, K, Bott, RC, Bruemmer, JE, Nett, TM, 2006. Judge, jury and executioner: The auto-regulation of luteal function. In: Reproduction in Domestic Ruminants VI. J.L. Juengel, J.F. Murray & M.F. Smith (eds.), Nottingham University Press, Nottingham, UK., pp.191-206. Bogan RL, Davis TL, Niswender GD. Peripheral-type benzodiazepine receptor (PBR) aggregation and absence of steroidogenic acute regulatory protein (StAR)/PBR association in the mitochondrial membrane as determined by bioluminescence resonance energy transfer (BRET). J Steroid Biochem Mol Biol 2007; 104:61-67. Arreguin-Arevalo JA, Davis TL, Nett TM. Differential modulation of gonadotropin secretion by selective estrogen receptor 1 and estrogen receptor 2 agonists in ovariectomized ewes. Biol Reprod 2007; 77:320-328. Davis TL, Pate JL. Bovine luteal cells stimulate proliferation of major histocompatibility nonrestricted gamma delta T cells. Biol Reprod 2007; 77:914-922. Breen KM, Davis TL:, Doro LC, Nett TM, Oakley AE, Padmanabhan V, Rispoli LA, Wagenmaker ER, Karsch FJ. Insight into the neuroendocrine site and cellular mechanism by which cortisol suppresses pituitary responsiveness to gonadotropin-releasing hormone. Endocrinology 2008; 149:767-773. |
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