scholarly journals Maintenance or stimulation of steroidogenic enzymes and testosterone production in rat Leydig cells by continuous and pulsatile infusions of luteinizing hormone during passive immunization against gonadotrophin-releasing hormone

Reproduction ◽  
1992 ◽  
Vol 95 (3) ◽  
pp. 657-667 ◽  
Author(s):  
D. J. Chase ◽  
J. A. Karle ◽  
R. E. Fogg
Keyword(s):  
Luteinizing Hormone ◽  
Leydig Cells ◽  
Passive Immunization ◽  
Steroidogenic Enzymes ◽  
Releasing Hormone ◽  
Testosterone Production ◽  
Gonadotrophin Releasing Hormone ◽  
Stimulation Of

scholarly journals The role of calcium in luteinizing hormone-releasing hormone agonist (ICI 118630)-stimulated steroidogenesis in rat Leydig cells

1984 ◽  
Vol 218 (2) ◽  
pp. 621-624 ◽  
Author(s):  
M H F Sullivan ◽  
B A Cooke
Keyword(s):  
Luteinizing Hormone ◽  
Cyclic Amp ◽  
Leydig Cells ◽  
Calcium Ionophore ◽  
Dependent Manner ◽  
Lhrh Agonist ◽  
Luteinizing Hormone Releasing Hormone ◽  
Releasing Hormone ◽  
Rat Testis ◽  
Testosterone Production

The luteinizing hormone-releasing hormone (LHRH) agonist ICI 118630 was found to increase testosterone production in purified rat testis Leydig cells in a concentration- and time-dependent manner, but no consistent changes in cyclic AMP levels were detectable. The stimulation of steroidogenesis by LHRH agonist was found to be dependent on the concentration of Ca2+ in the incubation medium; at least 1 mM was required. The calcium ionophore A23187 mimicked the effects of the LHRH agonist on steroidogenesis, and addition of both compounds together did not further increase testosterone production. The calcium ionophore caused a small increase in cyclic AMP which was independent of the concentration of the ionophore and of the calcium concentrations. The evidence obtained in this study indicates that LHRH agonist-stimulated steroidogenesis in rat testis Leydig cells is primarily mediated by calcium and not cyclic AMP.

scholarly journals Correlation of protein kinase activation and testosterone production after stimulation of Leydig cells with luteinizing hormone

1976 ◽  
Vol 160 (3) ◽  
pp. 439-446 ◽  
Author(s):  
B A Cooke ◽  
M L Lindh ◽  
F H A Janszen
Keyword(s):  
Protein Kinase ◽  
Luteinizing Hormone ◽  
Cyclic Amp ◽  
Protein Kinases ◽  
Leydig Cell ◽  
Leydig Cells ◽  
Kinase Activation ◽  
Testosterone Production ◽  
Protein Kinase Activation ◽  
Stimulation Of

The effect of different doses of luteinizing hormone on activation of protein kinases, cyclic AMP and testosterone production was studied in purified rat testis Leydig-cell preparations in the presence of 3-isobutyl-1-methylxanthine (a phosphodiesterase inhibitor). In addition, the nature of the protein kinases present in these cells and other tissues was investigated. The following results were obtained. 1. With all the amounts of luteinizing hormone used (0.1-1000 ng/ml), both activation of protein kinase and stimulation of testosterone production were demonstrated. With the lowest amount of luteinizing hormone (0.1 ng/ml), an 8.4±0.9% (S.E.M.,n=6) stimulation of protein kinase activation occurred, increasing to 100% with 1000 ng/ml, compared with 3.2±1.0%(S.E.M.,n=7) and 100% stimulation of testosterone production with 0.1 and 100 ng/ml respectively. 2. With amounts of luteinizing hormone up to 1 ng/ml (which gave half-maximal stimulation of testosterone production) no detectable increases in net cyclic AMP production were obtained. With higher amounts of luteinizing hormone, cyclic AMP production increased, but maximal production was not reached with 1000 ng/ml. 3. Two isoenzymic forms of protein kinase were present in Leydig cells and seminiferous tubules; type I was eluted with 0.075 M-and type II with 0.22-0.25 M-NaCl from DEAE-cellulose columns. 4. The protein kinase activity was not affected by the presence of erythrocytes in the Leydig-cell preparation, but varied depending on the type of histone used as substrate (histone F2b > mixed > histone F1).

scholarly journals Stimulation of cholesterol side-chain cleavage by a luteinizing-hormone-releasing hormone (luliberin) agonist (ICI 118630) in rat Leydig cells

1983 ◽  
Vol 216 (3) ◽  
pp. 747-752 ◽  
Author(s):  
M H F Sullivan ◽  
B A Cooke
Keyword(s):  
Luteinizing Hormone ◽  
Leydig Cells ◽  
Side Chain ◽  
Luteinizing Hormone Releasing Hormone ◽  
Releasing Hormone ◽  
Side Chain Cleavage ◽  
Chain Cleavage ◽  
Cleavage Enzyme ◽  
Cytochrome P 450 ◽  
Stimulation Of

The action of a luliberin (luteinizing-hormone-releasing hormone) agonist (ICI 118630) and lutropin (luteinizing hormone) on the activity of the cytochrome P-450 cholesterol side-chain cleavage enzyme in rat Leydig cells has been investigated. This has been carried out by studying the metabolism of exogenous (22R)-22- and 25-hydroxycholesterol to testosterone. It was found that both hydroxycholesterols increased testosterone production to higher levels than achieved by lutropin alone. Addition of luliberin agonist but not lutropin was found to increase further the metabolism of the hydroxycholesterol to testosterone; this occurred in the presence of saturating and subsaturating levels of the hydroxycholesterols. This effect of luliberin agonist was potentiated in the presence of lutropin. The protein synthesis inhibitor, cycloheximide, inhibited the luliberin agonist-induced stimulation of the hydroxycholesterol metabolism. At low calcium levels (1.1 microM), testosterone production was increased by addition of (22R)-22-hydroxycholesterol but the luliberin agonist effect was negated. The calmodulin inhibitor trifluoperazine inhibited (22R)-22-hydroxycholesterol-stimulated steroidogenesis and negated the luliberin agonist effect. These results indicate that luliberin agonist specifically increases the synthesis of the cytochrome P-450 cholesterol side-chain cleavage enzyme in rat testis Leydig cells.

Infertility

2013 ◽  
pp. 551-566
Author(s):  
John Reynard ◽  
Simon Brewster ◽  
Suzanne Biers
Keyword(s):  
Luteinizing Hormone ◽  
Male Infertility ◽  
Anterior Pituitary ◽  
Treatment Options ◽  
Follicle Stimulating Hormone ◽  
Reproductive Physiology ◽  
Seminiferous Tubules ◽  
Luteinizing Hormone Releasing Hormone ◽  
Releasing Hormone ◽  
Gonadotrophin Releasing Hormone

Male reproductive physiology 552 Aetiology and evaluation of male infertility 554 Investigation of male infertility 556 Oligozoospermia and azoospermia 560 Varicocele 562 Treatment options for male infertility 564 The hypothalamus secretes luteinizing hormone-releasing hormone (LHRH), also known as gonadotrophin-releasing hormone (GnRH). This causes the pulsatile release of anterior pituitary gonadotrophins called follicle-stimulating hormone (FSH) and luteinizing hormone (LH), which act on the testis. FSH stimulates the seminiferous tubules to secrete inhibin and produce sperm; LH acts on Leydig cells to produce testosterone (...

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