Effects of long-term administration of a superactive agonistic and an antagonistic GnRH analog on the pituitary-gonad system

Magdolna Kovács, Imre Mezö, János Seprödi, Valér Csernus, István Teplán, Béla Flerkó

Research output: Contribution to journalArticle

18 Citations (Scopus)

Abstract

A powerful GnRH antagonist: [Ac-D-Trp1,3,D-Cpa2,D-Lys6,D-Ala10]-GnRH (MI-1544) and a superactive GnRH agonist: [D-Phe6,desGly10]-GnRH(1-9)EA (OVURELIN) were used in long-term administration to compare their effects on the inhibition of ovulation, LH and progesterone (P) release, LH content of pituitaries as well as on the recovery period. Both analogs showed 100% inhibitory effects on ovulation in very low doses during the daily treatment for 21 days. The antagonist prevented LH release already after the first injection, decreased the serum P level to 40%, and increased the LH content of the pituitary up to 180%, inhibiting only the release but not the synthesis of LH. The agonist showed marked LH-releasing effects on the first day of the treatment, which were reduced to 12% on the 7th day. Serum P concentration was dropped to 68% by the end of the treatment. No change was found in the LH content of pituitaries in the group treated with the agonist. Ovaries showed polifollicular pictures in the antagonist-treated group, and persistent corpora lutea were seen in the ovaries from the agonist-treated group. Regular estrous cycles returned 13-15 days after ceasing the treatment with the antagonist and 3-5 days after ceasing the treatment with the agonist. No edema-inducing effect was observed after the injections of the antagonist in doses of 100 times higher than the single antiovulatory dose.

Original languageEnglish
Pages (from-to)925-931
Number of pages7
JournalPeptides
Volume10
Issue number5
DOIs
Publication statusPublished - Jan 1 1989

Keywords

  • GnRH agonist
  • GnRH antagonist
  • Long-term effect
  • Pituitary LH
  • Serum progesterone

ASJC Scopus subject areas

  • Biochemistry
  • Physiology
  • Endocrinology
  • Cellular and Molecular Neuroscience

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