These tools will no longer be maintained as of December 31, 2024. Archived website can be found here. PubMed4Hh GitHub repository can be found here. Contact NLM Customer Service if you have questions.


Pubmed for Handhelds

PUBMED FOR HANDHELDS

Search MEDLINE/PubMed

  • Title: GnRH secretion throughout the ovine estrous cycle.
    Author: Clarke IJ, Thomas GB, Yao B, Cummins JT.
    Journal: Neuroendocrinology; 1987 Jun; 46(1):82-8. PubMed ID: 3302748.
    Abstract:
    In order to define the patterns of gonadotropin-releasing hormone (GnRH) secretion during the estrous cycle of the sheep we sampled hypophysial portal blood from conscious animals on day 1 of the cycle (n = 1), during the luteal phase (n = 8), during the follicular phase (n = 6) and during the preovulatory luteinizing hormone (LH) surge (n = 6). At the same time, we sampled jugular blood to measure plasma LH concentrations. During day 1 we noted regular GnRH pulses, whereas GnRH pulse amplitude and frequency were more variable in the luteal phase of the cycle. In the transition from the luteal phase to the follicular phase the GnRH pulse frequency increased and the amplitude decreased. Around the time of the LH surge we noted 3 types of secretory profiles for GnRH. In one sheep (type 1) there was a large GnRH pulse at the onset of the LH surge followed by very little activity during the surge. In two sheep (type 2) the GnRH profile did not change between the late follicular phase and the onset of the LH surge. In the remaining three sheep (type 3) there was a clear increase in the secretion of GnRH at the onset of the LH surge. With the exclusion of the type 1 sheep the GnRH pulse frequency was maximal (2 pulses/h) at the time of the LH surge; average portal GnRH levels were also maximal at this time.(ABSTRACT TRUNCATED AT 250 WORDS)
    [Abstract] [Full Text] [Related] [New Search]