Direct effect of the luteinizing hormone releasing hormone analog D-Trp6-Pro9-Net-LHRH on rat testicular steroidogenesis

Rosario D'Agata, Fernando Cassorla, Abraham K. Munabi, Veronica Mericq, Marie C. Gelato, Barry D. Albertson, D. Lynn Loriaux.

Research output: Contribution to journalArticle

1 Scopus citations

Abstract

The luteinizing hormone releasing hormone analog D-Trp6-Pro9-Net-LHRH (LHRHa) inhibits rat testicular testosterone secretion. To determine whether LHRHa decreases serum testosterone concentrations solely by inhibiting gonadotropin secretion or, in addition, by influencing directly testicular testosterone biosynthesis, we examined the effects of LHRHa on the activities of 5 key testicular steroidogenic enzymes. Thirty hypophysectomized, hCG treated rats were given either LHRHa (1 μg sc/day) or saline during 7 days. The LHRHa treated animals exhibited a significant decrease of serum testosterone when compared to the control group (498 ± 37 ng/dl vs 2044 ± 105 ng/dl, mean ± SEM, P 〈0.001). 17-Hydroxyprogesterone serum levels were also decreased in the LHRHa treated rats (61 ± 6 ng/dl vs 93 ± 7 ng/dl, P 〈0.005), while serum progesterone levels were similar in both groups of animals. These changes in steroid concentrations were associated with decreases in the musomal enzyme activities of 17-hydroxylase (37 ± 9 vs 654 ± 41 pmol/mg protein/min, P 〈0.001), 17, 20-desmolase (103 ± 9 vs 522 ± 47 pmol/mg protein/min, P 〈0.001), 3β-hydroxysteroid dehydrogenase (1.7 ± 0.02 vs 4.1 ± 0.1 nmol/mg protein/min, P 〈0.001), aromatase (95 ± 7 vs 228 ± 6 pmol/mg protein/ min, P 〈0.001) and 17-ketosteroid reductase (167 ± 9 vs 290 ± 18 pmol/mg protein/min, P 〈0.01) in the LHRHa treated animals. These findings indicate that LHRHa can inhibit directly rat testicular testosterone biosynthesis.

Original languageEnglish (US)
Pages (from-to)201-207
Number of pages7
JournalSteroids
Volume43
Issue number2
DOIs
StatePublished - Feb 1984

ASJC Scopus subject areas

  • Biochemistry
  • Molecular Biology
  • Endocrinology
  • Pharmacology
  • Clinical Biochemistry
  • Organic Chemistry

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