Elsevier

Life Sciences

Volume 34, Issue 8, 20 February 1984, Pages 743-749
Life Sciences

Effect of adrenalectomy and 5-hydroxytryptophan on phasic release of luteinizing hormone

https://doi.org/10.1016/0024-3205(84)90381-3Get rights and content

Abstract

The effect of 5-hydroxytryptophan (5-HTP) on serum progesterone and the possible role of adrenal progesterone in mediating stimulation by 5-HTP of phasic release of luteinizing hormone (LH) were investigated in estradiol benzoate (EB)-treated ovariectomized rats. LH surges were induced in long-term (at least two weeks) ovariectomized rats by two injections of EB (20 μg/rat, s.c.) with an interval of 72 hrs. Administration of 5-HTP (50 mg/kg, i.p.) at 1000 hr in EB-treated ovariectomized rats resulted in a four-fold increase in serum progesterone within 30 mins, and significantly stimulated the LH surge at 1600 hr. This facilitative effect of 5-HTP on serum LH, but not progesterone, was further potentiated in rats pretreated with P-chlorophenylalanine (PCPA) 72 hrs earlier. Adrenalectomy shortly before 5-HTP administration attenuated the LH surge in saline treated controls, and completely blocked the facilitative effect of 5-HTP on the afternoon surge of LH in rats pretreated with PCPA 72 hrs earlier. On the other hand, chronic adrenalectomy (for 6 days) followed by hydrocortisone (0.2 mg/rat/day) replacement not only had no effect on the LH surge in saline treated controls, but also failed to prevent 5-HTP from facilitating the LH surge in PCPA pretreated rats. On the first day of bleeding, the basal LH value at 1000 hr in sham operated controls was significantly suppressed by PCPA pretreatment 48 hrs earlier. The second dose of 5-HTP administered on the next day failed to potentiate LH surges in either sham operated or adrenalectomized rats. The results from the chronic adrenalectomy study indicate that adrenal progesterone is not required for 5-HTP to exert its facilitative action on the phasic release of LH, and suggest that the failure of the second dose of 5-HTP to potentiate LH surges in PCPA pretreated rats is not due to increased secretion of adrenal progesterone following the first dose of 5-HTP. The complete blockade of the facilitative action of 5-HTP in acutely adrenalectomized rats is discussed.

References (23)

  • M. Hery et al.

    Endocrinology

    (1976)
  • C.W. Coen et al.

    J. Endocrinol.

    (1976)
  • D.C. Meyer

    Endocrinology

    (1978)
  • R.W. Fuller et al.

    Life Sci.

    (1976)
  • J.C. Rose et al.
  • R.W. Fuller et al.
  • I.A. Kamberi et al.

    Endocrinology

    (1971)
  • H.J. Chen et al.

    Endocrinology

    (1975)
  • J.A. Clemens et al.

    Endocrinology

    (1977)
  • H.H. Feder et al.

    Endocrinology

    (1969)
  • H.H. Feder et al.

    J. Endocrinol.

    (1971)
  • Cited by (0)

    Published with the approval of the Agricultural Experiment Station as Journal Article No.

    2

    Present address: Department of Physiology and Biophysics, University of Alabama in Birmingham, Alabama 35294.

    3

    Aided by NIH research fellowship AG05062 from the National Institute on Aging.

    4

    Aided by NIH research grants CA10771 from the National Cancer Institute, and AM04784 from the National Institute for Arthritis, Metabolism and Digestive Diseases.

    View full text