Effects of luteinizing hormone withdrawal on Leydig cell smooth endoplasmic reticulum and steroidogenic reactions which convert pregnenolone to testosterone

T. Y. Wing, L. L. Ewing, Barry R Zirkin

Research output: Contribution to journalArticle

Abstract

Depletion of endogenous LH with sc implants of testosterone-17β-estradiol (T-E) caused a reduction in the Leydig cell smooth endoplasmic reticulum (SER) over a 10-day treatment period. Decreases also occurred in some, but not all, of the testicular steroidogenic reactions responsible for the conversion of pregnenolone (PREG) to testosterone. The conversions of progesterone (PROG) to 17α-hydroxyprogesterone, 17α-hydroxyprogesterone to androstenedione, and androstenedione to testosterone were significantly correlated (P <0.05) with the loss of Leydig cell SER. In contrast, the testicular converions of PREG to PROG in rats deprived of endogenous LH for up to 10 days was identical to that in intact controls. Similar results were obtained when rats were hypophysectomized for 10 days. These results indicate that the Leydig cell enzyme activities responsible for converting PREG to PROG are distributed in the Leydig cell SER fraction which remains in Leydig cell cytoplasm 10 days after LH withdrawal, and thus, the bulk of these enzyme activities are sequested in a SER compartment that is resistant to LH withdrawal.

Original languageEnglish (US)
Pages (from-to)2290-2296
Number of pages7
JournalEndocrinology
Volume115
Issue number6
StatePublished - 1984

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Smooth Endoplasmic Reticulum
Pregnenolone
Leydig Cells
Luteinizing Hormone
Testosterone
17-alpha-Hydroxyprogesterone
Progesterone
Androstenedione
Conversion Disorder
Enzymes
Estradiol
Cytoplasm

ASJC Scopus subject areas

  • Endocrinology
  • Endocrinology, Diabetes and Metabolism

Cite this

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title = "Effects of luteinizing hormone withdrawal on Leydig cell smooth endoplasmic reticulum and steroidogenic reactions which convert pregnenolone to testosterone",
abstract = "Depletion of endogenous LH with sc implants of testosterone-17β-estradiol (T-E) caused a reduction in the Leydig cell smooth endoplasmic reticulum (SER) over a 10-day treatment period. Decreases also occurred in some, but not all, of the testicular steroidogenic reactions responsible for the conversion of pregnenolone (PREG) to testosterone. The conversions of progesterone (PROG) to 17α-hydroxyprogesterone, 17α-hydroxyprogesterone to androstenedione, and androstenedione to testosterone were significantly correlated (P <0.05) with the loss of Leydig cell SER. In contrast, the testicular converions of PREG to PROG in rats deprived of endogenous LH for up to 10 days was identical to that in intact controls. Similar results were obtained when rats were hypophysectomized for 10 days. These results indicate that the Leydig cell enzyme activities responsible for converting PREG to PROG are distributed in the Leydig cell SER fraction which remains in Leydig cell cytoplasm 10 days after LH withdrawal, and thus, the bulk of these enzyme activities are sequested in a SER compartment that is resistant to LH withdrawal.",
author = "Wing, {T. Y.} and Ewing, {L. L.} and Zirkin, {Barry R}",
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AU - Zirkin, Barry R

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N2 - Depletion of endogenous LH with sc implants of testosterone-17β-estradiol (T-E) caused a reduction in the Leydig cell smooth endoplasmic reticulum (SER) over a 10-day treatment period. Decreases also occurred in some, but not all, of the testicular steroidogenic reactions responsible for the conversion of pregnenolone (PREG) to testosterone. The conversions of progesterone (PROG) to 17α-hydroxyprogesterone, 17α-hydroxyprogesterone to androstenedione, and androstenedione to testosterone were significantly correlated (P <0.05) with the loss of Leydig cell SER. In contrast, the testicular converions of PREG to PROG in rats deprived of endogenous LH for up to 10 days was identical to that in intact controls. Similar results were obtained when rats were hypophysectomized for 10 days. These results indicate that the Leydig cell enzyme activities responsible for converting PREG to PROG are distributed in the Leydig cell SER fraction which remains in Leydig cell cytoplasm 10 days after LH withdrawal, and thus, the bulk of these enzyme activities are sequested in a SER compartment that is resistant to LH withdrawal.

AB - Depletion of endogenous LH with sc implants of testosterone-17β-estradiol (T-E) caused a reduction in the Leydig cell smooth endoplasmic reticulum (SER) over a 10-day treatment period. Decreases also occurred in some, but not all, of the testicular steroidogenic reactions responsible for the conversion of pregnenolone (PREG) to testosterone. The conversions of progesterone (PROG) to 17α-hydroxyprogesterone, 17α-hydroxyprogesterone to androstenedione, and androstenedione to testosterone were significantly correlated (P <0.05) with the loss of Leydig cell SER. In contrast, the testicular converions of PREG to PROG in rats deprived of endogenous LH for up to 10 days was identical to that in intact controls. Similar results were obtained when rats were hypophysectomized for 10 days. These results indicate that the Leydig cell enzyme activities responsible for converting PREG to PROG are distributed in the Leydig cell SER fraction which remains in Leydig cell cytoplasm 10 days after LH withdrawal, and thus, the bulk of these enzyme activities are sequested in a SER compartment that is resistant to LH withdrawal.

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