Skip to Main Content
 

Global Search Box

 
 
 
 

Files

File List


ucin1061305407.pdf (18.45 MB)

ETD Abstract Container

Abstract Header

THE ROLE OF ENDOGENOUS OPIOID PEPTIDES IN THE OVINE ESTROUS CYCLE

FORADORI, CHAD D.
http://rave.ohiolink.edu/etdc/view?acc_num=ucin1061305407

Abstract Details

2003, PhD, University of Cincinnati, Medicine : Interdisciplinary (Medical Science Scholars, Neuroscience).
Gonadotropin releasing hormone (GnRH) neurons play a central role in the control of mammalian reproductive function. Changes in the pulsatile secretion of GnRH and luteinizing hormone (LH) are critical for the regulation of events leading to ovulation, as well as to inhibition of ovulation prior to puberty and during other physiological periods of infertility. Based on recent data, we have developed a working hypothesis for the control of pulsatile GnRH/LH secretion by endogenous opioid peptides (EOP). This hypothesis states that one of the EOP systems in the brain, the dynorphin-kappa receptor system, mediates the inhibitory effect of progesterone on GnRH pulse frequency during the luteal phase of the ovine estrous cycle. We first tested one prediction of this hypothesis by determining whether or not dynorphin neurons contain progesterone receptors. We found that a very high percentage of dynorphin neurons in the arcuate nucleus of the hypothalamus, as well as in the anterior hypothalamic area and the preoptic area, contained immunoreactive nuclear progesterone receptors. We then asked whether or not progesterone could act upon these neurons to increase the transcription of dynorphin by using in situ hybridization to measure changes in the levels of mRNA encoding the precursor for dynorphin. We found that ovariectomy significantly decreased the number of PPD mRNA-expressing cells in the ARC, POA and AHA; progesterone replacement increased the number of cells back to those levels seen in intact luteal phase animals in the POA and AHA but not in the ARC, suggesting that in the latter nucleus, estradiol also plays a role in maintaining dynorphin levels. In the same experiment CSF dynorphin was found to be elevated in the progesterone treated group. We further determined that a very large proportion of dynorphin cells colocalize another neuropeptide, neurokinin B, previously shown to be sexually dimorphic and contain estradiol receptors. Finally, we implicated a novel opioid peptide, orphanin FQ/nociceptin, in the control of GnRH secretion by finding almost total colocalization of this peptide with GnRH cells and fibers.
Dr. Michael N. Lehman (Advisor)
164 p.
Biology, Neuroscience
progesterone; luteal phase; dynorphin; kappa opioid receptors; neurokinin B

Recommended Citations

Citations

  • FORADORI, C. D. (2003). THE ROLE OF ENDOGENOUS OPIOID PEPTIDES IN THE OVINE ESTROUS CYCLE [Doctoral dissertation, University of Cincinnati]. OhioLINK Electronic Theses and Dissertations Center. http://rave.ohiolink.edu/etdc/view?acc_num=ucin1061305407

    APA Style (7th edition)

  • FORADORI, CHAD. THE ROLE OF ENDOGENOUS OPIOID PEPTIDES IN THE OVINE ESTROUS CYCLE. 2003. University of Cincinnati, Doctoral dissertation. OhioLINK Electronic Theses and Dissertations Center, http://rave.ohiolink.edu/etdc/view?acc_num=ucin1061305407.

    MLA Style (8th edition)

  • FORADORI, CHAD. "THE ROLE OF ENDOGENOUS OPIOID PEPTIDES IN THE OVINE ESTROUS CYCLE." Doctoral dissertation, University of Cincinnati, 2003. http://rave.ohiolink.edu/etdc/view?acc_num=ucin1061305407

    Chicago Manual of Style (17th edition)

ucin1061305407
887
© 2003, all rights reserved.
This open access ETD is published by University of Cincinnati and OhioLINK.