Interaction of luteinizing hormone-releasing hormone, cyproterone acetate and arginine vasotocin on plasma levels of luteinizing hormone in intact and castrated adult male rats

Mary K. Vaughan, Chatchai Trakulrungsi, Larry J. Petterborg, Linda Y Johnson, David E. Blask, Wantanee Trakulrungsi, Russel J Reiter

Research output: Contribution to journalArticle

3 Citations (Scopus)

Abstract

Treatment of unanesthetized castrated adult male rats every 3 h for 48 h with either 5 μg of arginine vasotocin (AVT) and/or 1μg luteinizing hormone-releasing hormone (LRH) caused a significant inhibition of plasma levels of luteinizing hormone (LH) compared to castrated control rats receiving diluent only. However, the intravenous (iv) injection of 1 μg of AVT into urethane-anesthetized male rats which had been castrated for 0, 24 or 48 h did not affect plasma levels of LH at 10, 20 or 60 min following injection compared to their respective diluent-treated castrated control rats. Similarly, the iv injection of either 100 ng, 1 μg or 10 μg AVT was unable to acutely affect plasma levels of LH in intact male rats. Following the iv injection of 2 doses of 50 ng LRH spaced 1 h apart in anesthetized castrated male rats, 2 peaks of equal magnitude in plasma LH were noted. Castrated rats treated with 2 injections spaced l h apart of LRH + AVT had significantly higher plasma levels of LH than did rats treated with LRH alone. In subsequent studies, both AVT and arginine vasopressin were observed to augment the plasma response of LH to an injection of LRH whereas oxytocin had no effect. A single injection of AVT + LRH significantly augmented the plasma titers of LH compared to levels observed in LRH-treated control rats as did a second injection l h later. The administration of cyproterone acetate sc for 2 days by itself had no effect on plasma LH but in conjunction with LRH caused a marked rise in plasma LH compared to intact rats treated with LRH alone. AVT in combination with LRH and cyproterone acetate caused a significant elevation in plasma LH at 60 min post-injection when compared to plasma levels of rats treated with LRH alone or the combination of LRH and cyproterone acetate. It is concluded that acute intravenous injections of AVT augment the LH-releasing activity of LRH; chronic treatment for 48 h, however, with LRH + AVT leads to a significant depression of plasma LH perhaps due to an exhaustion of the releasable pool of LH in the anterior pituitary.

Original languageEnglish (US)
Pages (from-to)59-71
Number of pages13
JournalMolecular and Cellular Endocrinology
Volume14
Issue number1
DOIs
StatePublished - 1979

Fingerprint

Vasotocin
Cyproterone Acetate
Luteinizing Hormone
Gonadotropin-Releasing Hormone
Rats
Plasmas
Rat control
Intravenous Injections
Injections
Arginine Vasopressin
Urethane
Oxytocin

Keywords

  • arginine vasopressin
  • arginme vasotocin
  • cyproterone acetate
  • luteinizing hormone
  • luteinizing hormone-releasing hormone
  • oxytocin

ASJC Scopus subject areas

  • Endocrinology
  • Endocrinology, Diabetes and Metabolism

Cite this

Interaction of luteinizing hormone-releasing hormone, cyproterone acetate and arginine vasotocin on plasma levels of luteinizing hormone in intact and castrated adult male rats. / Vaughan, Mary K.; Trakulrungsi, Chatchai; Petterborg, Larry J.; Johnson, Linda Y; Blask, David E.; Trakulrungsi, Wantanee; Reiter, Russel J.

In: Molecular and Cellular Endocrinology, Vol. 14, No. 1, 1979, p. 59-71.

Research output: Contribution to journalArticle

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abstract = "Treatment of unanesthetized castrated adult male rats every 3 h for 48 h with either 5 μg of arginine vasotocin (AVT) and/or 1μg luteinizing hormone-releasing hormone (LRH) caused a significant inhibition of plasma levels of luteinizing hormone (LH) compared to castrated control rats receiving diluent only. However, the intravenous (iv) injection of 1 μg of AVT into urethane-anesthetized male rats which had been castrated for 0, 24 or 48 h did not affect plasma levels of LH at 10, 20 or 60 min following injection compared to their respective diluent-treated castrated control rats. Similarly, the iv injection of either 100 ng, 1 μg or 10 μg AVT was unable to acutely affect plasma levels of LH in intact male rats. Following the iv injection of 2 doses of 50 ng LRH spaced 1 h apart in anesthetized castrated male rats, 2 peaks of equal magnitude in plasma LH were noted. Castrated rats treated with 2 injections spaced l h apart of LRH + AVT had significantly higher plasma levels of LH than did rats treated with LRH alone. In subsequent studies, both AVT and arginine vasopressin were observed to augment the plasma response of LH to an injection of LRH whereas oxytocin had no effect. A single injection of AVT + LRH significantly augmented the plasma titers of LH compared to levels observed in LRH-treated control rats as did a second injection l h later. The administration of cyproterone acetate sc for 2 days by itself had no effect on plasma LH but in conjunction with LRH caused a marked rise in plasma LH compared to intact rats treated with LRH alone. AVT in combination with LRH and cyproterone acetate caused a significant elevation in plasma LH at 60 min post-injection when compared to plasma levels of rats treated with LRH alone or the combination of LRH and cyproterone acetate. It is concluded that acute intravenous injections of AVT augment the LH-releasing activity of LRH; chronic treatment for 48 h, however, with LRH + AVT leads to a significant depression of plasma LH perhaps due to an exhaustion of the releasable pool of LH in the anterior pituitary.",
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