1
|
Fanelli G, Belardo A, Savino R, Rinalducci S, Zolla L. Testosterone replacement therapy in insulin-sensitive hypogonadal men restores phosphatidylcholine levels by regulation of arachidonic acid metabolism. J Cell Mol Med 2020; 24:8266-8269. [PMID: 32491269 PMCID: PMC7348168 DOI: 10.1111/jcmm.15392] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/16/2020] [Revised: 04/18/2020] [Accepted: 04/27/2020] [Indexed: 12/27/2022] Open
Abstract
Male hypogonadism is notoriously associated with altered lipid metabolism. In this study, we performed an untargeted mass spectrometry-based profiling of plasma lipids from twenty healthy and twenty hypogonadal men before and after testosterone replacement therapy (TRT) for 60 days. Results demonstrated that hypogonadism was associated with a significant increase in sphingomyelin (SM), whereas phosphatidylcholine (PC) was mainly cleaved by activated phospholipase-A2 into lysophosphatidylcholine (LPC). In hypogonadal patients, arachidonic acid (AA), also produced through the latter cleavage, was prevalently bio-transformed into leukotriene B4 (LTB4) and not into endoperoxides from which prostaglandins and thromboxanes are derived. Interestingly, upon testosterone treatment SM, PC and LPC returned to levels similar to controls. Also, AA was newly converted into prostaglandin-A2, thromboxane-A2 and 5(S)-hydroxyeicosatetraenoic acid (HETE), suggesting that testosterone probably plays a role in controlling hypogonadal alterations above reported.
Collapse
Affiliation(s)
- Giuseppina Fanelli
- Department of Ecological and Biological Sciences (DEB)University of TusciaViterboItaly
| | - Antonio Belardo
- Department of Ecological and Biological Sciences (DEB)University of TusciaViterboItaly
| | - Rocco Savino
- Department of Medical and Surgical SciencesMagna Graecia UniversityCatanzaroItaly
| | - Sara Rinalducci
- Department of Ecological and Biological Sciences (DEB)University of TusciaViterboItaly
| | - Lello Zolla
- Department of Science and Technology for Agriculture, Forestry, Nature and Energy (DAFNE)University of TusciaViterboItaly
| |
Collapse
|
2
|
Cooke M, Di Cónsoli H, Maloberti P, Cornejo Maciel F. Expression and function of OXE receptor, an eicosanoid receptor, in steroidogenic cells. Mol Cell Endocrinol 2013; 371:71-8. [PMID: 23159987 DOI: 10.1016/j.mce.2012.11.003] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/15/2012] [Revised: 11/05/2012] [Accepted: 11/06/2012] [Indexed: 10/27/2022]
Abstract
Hormonal regulation of steroidogenesis involves arachidonic acid (AA) metabolism through the 5-lipoxygenase pathway. One of the products, 5-hydroperoxy-eicosatetraenoic acid (5-HpETE), acts as a modulator of the activity of the steroidogenic acute regulatory (StAR) protein promoter. Besides, an oxoeicosanoid receptor of the leukotriene receptor family named OXE-R is a membrane protein with high affinity and response to 5-HpETE, among other AA derivatives. The aim of our work was to elucidate whether this receptor may be involved in steroidogenesis. RT-PCR and western blot analysis demonstrated the presence of the mRNA and protein of the receptor in human H295R adrenocortical cells. The treatment of H295R or MA-10 cells (murine Leydig cell line) with 8Br-cAMP together with docosahexaenoic acid (DHA, an antagonist of the receptor) partially reduced StAR induction and steroidogenesis. On the contrary, 5-oxo-ETE - the prototypical agonist, with higher affinity and potency on the receptor - increased cAMP-dependent steroid production, StAR mRNA and protein levels. These results lead us to conclude that AA might modulate StAR induction and steroidogenesis, at least in part, through 5-HpETE production and activation of a membrane receptor, such as the OXE-R.
Collapse
Affiliation(s)
- Mariana Cooke
- INBIOMED - UBA/CONICET, Department of Biochemistry, School of Medicine, University of Buenos Aires, Paraguay 2155, C1121ABG Buenos Aires, Argentina
| | | | | | | |
Collapse
|
3
|
Maternal use of acetaminophen, ibuprofen, and acetylsalicylic acid during pregnancy and risk of cryptorchidism. Epidemiology 2011; 21:779-85. [PMID: 20805751 DOI: 10.1097/ede.0b013e3181f20bed] [Citation(s) in RCA: 131] [Impact Index Per Article: 10.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
Abstract
BACKGROUND Cyclooxygenase (COX) inhibitors-acetaminophen, ibuprofen and acetylsalicylic acid-have endocrine-disruptive properties in the rainbow trout. In humans, aspirin blocks the androgen response to human chorionic gonadotropin (hCG), and, because hCG-stimulated androgen production in utero is crucial for normal testicular descent, exposure to COX inhibitors at vulnerable times during gestation may impair testicular descent. We examined whether prenatal exposure to acetaminophen, ibuprofen, and acetylsalicylic acid was associated with increased occurrence of cryptorchidism. METHODS Our study used data on 47,400 live-born singleton sons of mothers enrolled in the Danish National Birth Cohort during 1996-2002. Cryptorchidism was identified in 980 boys during childhood, of whom 565 underwent orchiopexy. The use of acetaminophen, ibuprofen, and acetylsalicylic acid during pregnancy was assessed in 3 computer-assisted telephone interviews and 1 self-administered questionnaire. We estimated adjusted hazard ratios (HRs) of cryptorchidism by Cox regression analysis. RESULTS Exposure to acetaminophen during both the first and second trimesters was associated with increased occurrence of cryptorchidism (HR = 1.33 [95% confidence interval = 1.00-1.77]). Exposure for more than 4 weeks within the postulated time-window of programming testicular descent (gestational weeks 8-14) was associated with a HR of 1.38 (1.05-1.83) for cryptorchidism. Exposure to ibuprofen and acetylsalicylic acid was not associated with cryptorchidism. CONCLUSION Maternal intake of acetaminophen for more than 4 weeks during pregnancy, especially during the first and second trimesters, may moderately increase the occurrence of cryptorchidism.
Collapse
|
4
|
Sheng Y, Tsai-Morris CH, Li J, Dufau ML. Lessons from the gonadotropin-regulated long chain acyl-CoA synthetase (GR-LACS) null mouse model: a role in steroidogenesis, but not result in X-ALD phenotype. J Steroid Biochem Mol Biol 2009; 114:44-56. [PMID: 19167491 DOI: 10.1016/j.jsbmb.2008.12.011] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/19/2008] [Accepted: 12/31/2008] [Indexed: 10/21/2022]
Abstract
Gonadotropin-regulated long chain fatty acid Acyl-CoA synthetase (GR-LACS), is a member of the LACS family that is regulated by gonadotropin in the rat Leydig cell (LC). Its mouse/human homologs, lipidosin/bubblegum, have been suggested to participate in X-linked adrenoleukodystrophy (X-ALD), an adreno/neurodegenerative disorder with accumulation of very long chain fatty acids (VLCFA) in tissues and plasma. To further gain insights into its regulatory function, a GR-LACS/lipidosin null mouse was generated. No apparent phenotypic abnormalities were observed in the X-ALD target tissues (brain, testis, adrenal). Nuclear inclusions seen in mice >15 month-old, were present in LC of 9 month-old GR-LACS(-/-) mice. LC of the null mice showed refractoriness to the gonadotropin-induced desensitization of testosterone production that is observed in adult animals. LCFAs were moderately increased in the testis, ovary and brain, but not in the adrenal gland of GR-LACS(-/-) mice, with no major changes in VLCFA. No change in LACS activity was observed in these tissues, suggesting a compensatory mechanism exhibited by other LACS members. The GR-LACS(-/-) model did not support its association with X-ALD. These studies revealed a role of GR-LACS in reducing the aging process of the LC, and its participation in gonadotropin-induced testicular desensitization of testosterone production.
Collapse
Affiliation(s)
- Yi Sheng
- Program in Developmental Endocrinology and Genetics, Eunice Kennedy Shriver National Institute of Child Health and Human Development, National Institutes of Health, Bethesda, MD 20892-4510, United States
| | | | | | | |
Collapse
|
5
|
Selmanoğlu G, Koçkaya EA, Akay MT, Kismet K. Subacute toxicity of celecoxib on thyroid and testis of rats: Hormonal and histopathological changes. ENVIRONMENTAL TOXICOLOGY AND PHARMACOLOGY 2006; 22:85-89. [PMID: 21783692 DOI: 10.1016/j.etap.2005.12.004] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/17/2005] [Accepted: 12/13/2005] [Indexed: 05/31/2023]
Abstract
Celecoxib is an effective agent in the treatment of signs and symptoms of inflammation, rheumatoid arthritis and osteoarthritis. The purpose of this study is to assess the effects of two different doses of celecoxib on some hormones and endocrine glands of male rats. In this study, the doses of 10 and 50mg/kg/day of celecoxib were given to male rats orally for 28 days. At the end of the study, serum total triiodothyronine (T(3)), total thyroxine (T(4)), thyroid stimulating hormone (TSH), testosterone and luteinizing hormone (LH) levels of rats were analyzed by radioimmunoassay technique using RIA kits. Thyroid and testis tissues of male rats were examined histopathologically. While there was no a change in serum T(3), T(4) and LH levels of celecoxib-treated rats, there were differences in serum TSH and testosterone levels of rats treated with 50mg/kg/day celecoxib for 28 days compared with those of control rats. In histopathological examinations, celecoxib-related changes were found in thyroid glands of the rats.
Collapse
Affiliation(s)
- Güldeniz Selmanoğlu
- Hacettepe University, Faculty of Science, Department of Biology, 06800 Beytepe Campus, Ankara, Turkey
| | | | | | | |
Collapse
|
6
|
Moreau C, Froment P, Tosca L, Moreau V, Dupont J. Expression and regulation of the SCD2 desaturase in the rat ovary. Biol Reprod 2005; 74:75-87. [PMID: 16207839 DOI: 10.1095/biolreprod.105.044545] [Citation(s) in RCA: 30] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/01/2022] Open
Abstract
Despite the significant role of the lipid reserve in cell structure and function, very few studies have provided detailed descriptions of unsaturated fatty acid synthesis in the ovary. In the present study, we have shown by RT-PCR, Northern blot, and Western blot analyses the mRNA and protein expression of SCD2 (stearoyl-coenzyme A desaturase 2; also named delta 9 desaturase) in rat ovary. We also have localized Scd2 mRNA by in situ hybridization, mainly in granulosa cells of antral follicles, cumulus oophorus, and corpus luteum. Interestingly, either no or very weak SCD2 expression was observed in primordial follicles and oocytes. After eCG injection for 24 h in immature rats (age, 22 days), the level of SCD2 expression and SCD activity in ovary was increased by approximately fourfold (P < 0.05), and the response was further increased 48 h after hCG treatment. As expected, eCG/hCG treatment increased expression of the steroidogenesis enzymes (CYP11A1 and HSD3B) and STAR. We also found a decrease in the SCD2 expression and SCD activity in the corpus luteum at Days 10 and 15 compared to Day 3 of gestation, paralleled by a decrease in the expression of the steroidogenesis enzymes and STAR. To investigate the molecular mechanisms involved in the regulation of SCD2 expression in ovary, we performed primary culture of rat granulosa cells. We observed that both insulin-like growth factor 1 (IGF1) (7.5 x 10(-8)g/ml) and FSH (350 x 10(-8)g/ml) increased SCD2 expression and SCD activity by approximately threefold. Using specific inhibitors, we demonstrated that the MAPK3/MAP1 and PIK3R1/AKT pathways are involved in the IGF1- and FSH-induced SCD2 expression, respectively. The SCD2 is expressed and active in rat ovary, and it may be involved in the regulation of follicular growth and/or the oocyte maturation.
Collapse
Affiliation(s)
- Céline Moreau
- Unité de Physiologie de la Reproduction et des Comportements, Institut National de la Recherche Agronomique, 37380 Nouzilly, France
| | | | | | | | | |
Collapse
|
7
|
Abstract
Ligand-protein docking has been developed and used in facilitating new drug discoveries. In this approach, docking single or multiple small molecules to a receptor site is attempted to find putative ligands. A number of studies have shown that docking algorithms are capable of finding ligands and binding conformations at a receptor site close to experimentally determined structures. These algorithms are expected to be equally applicable to the identification of multiple proteins to which a small molecule can bind or weakly bind. We introduce a ligand-protein inverse-docking approach for finding potential protein targets of a small molecule by the computer-automated docking search of a protein cavity database. This database is developed from protein structures in the Protein Data Bank (PDB). Docking is conducted with a procedure involving multiple-conformer shape-matching alignment of a molecule to a cavity followed by molecular-mechanics torsion optimization and energy minimization on both the molecule and the protein residues at the binding region. Scoring is conducted by the evaluation of molecular-mechanics energy and, when applicable, by the further analysis of binding competitiveness against other ligands that bind to the same receptor site in at least one PDB entry. Testing results on two therapeutic agents, 4H-tamoxifen and vitamin E, showed that 50% of the computer-identified potential protein targets were implicated or confirmed by experiments. The application of this approach may facilitate the prediction of unknown and secondary therapeutic target proteins and those related to the side effects and toxicity of a drug or drug candidate. Proteins 2001;43:217-226.
Collapse
Affiliation(s)
- Y Z Chen
- Department of Computational Science, National University of Singapore, Blk S17, Level 7, 3 Science Drive 2, Singapore 117543.
| | | |
Collapse
|
8
|
Abstract
Ligand-protein docking has been developed and used in facilitating new drug discoveries. In this approach, docking single or multiple small molecules to a receptor site is attempted to find putative ligands. A number of studies have shown that docking algorithms are capable of finding ligands and binding conformations at a receptor site close to experimentally determined structures. These algorithms are expected to be equally applicable to the identification of multiple proteins to which a small molecule can bind or weakly bind. We introduce a ligand-protein inverse-docking approach for finding potential protein targets of a small molecule by the computer-automated docking search of a protein cavity database. This database is developed from protein structures in the Protein Data Bank (PDB). Docking is conducted with a procedure involving multiple-conformer shape-matching alignment of a molecule to a cavity followed by molecular-mechanics torsion optimization and energy minimization on both the molecule and the protein residues at the binding region. Scoring is conducted by the evaluation of molecular-mechanics energy and, when applicable, by the further analysis of binding competitiveness against other ligands that bind to the same receptor site in at least one PDB entry. Testing results on two therapeutic agents, 4H-tamoxifen and vitamin E, showed that 50% of the computer-identified potential protein targets were implicated or confirmed by experiments. The application of this approach may facilitate the prediction of unknown and secondary therapeutic target proteins and those related to the side effects and toxicity of a drug or drug candidate. Proteins 2001;43:217-226.
Collapse
Affiliation(s)
- Y Z Chen
- Department of Computational Science, National University of Singapore, Blk S17, Level 7, 3 Science Drive 2, Singapore 117543.
| | | |
Collapse
|
9
|
Affiliation(s)
- M P Hedger
- Monash University Institute of Reproduction and Development, Monash Medical Centre, Clayton, Victoria, Australia
| | | |
Collapse
|
10
|
Conte D, Romanelli F, Fillo S, Guidetti L, Isidori A, Franceschi F, Latini M, di Luigi L. Aspirin inhibits androgen response to chorionic gonadotropin in humans. THE AMERICAN JOURNAL OF PHYSIOLOGY 1999; 277:E1032-7. [PMID: 10600792 DOI: 10.1152/ajpendo.1999.277.6.e1032] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Eicosanoids play an important role in the regulation of the hypothalamic-pituitary axis; less clear is their role in testicular steroidogenesis. To evaluate the involvement of cyclooxygenase metabolites, such as prostaglandins, in the regulation of human testicular steroidogenesis, we examined the effects of a prostaglandin-blocker, aspirin, on plasma testosterone, pregnenolone, progesterone, 17OH-progesterone, androstenedione, dehydroepiandrosterone, and 17beta-estradiol response to human chorionic gonadotropin (hCG) in normal male volunteers in a placebo-controlled, single-blinded study. To test the efficacy of aspirin, seminal prostaglandin E(2) levels were also determined. hCG stimulation increased peripheral levels of testosterone, 17OH-progesterone, androstenedione, dehydroepiandrosterone, and 17beta-estradiol, without affecting circulating pregnenolone and progesterone values. Aspirin significantly lowered seminal prostaglandin E(2) levels, whereas it did not modify steroid concentrations not exposed to exogenous hCG. Moreover, the drug significantly reduced the response of testosterone, 17OH-progesterone, androstenedione, and dehydroepiandrosterone to hCG, as assessed by the mean integrated area under the curve, whereas it did not influence 17beta-estradiol response. In conclusion, aspirin treatment inhibits androgen response to chorionic gonadotropin stimulation in normal humans. The action of aspirin is probably mediated via an effective arachidonate cyclooxygenase block.
Collapse
Affiliation(s)
- D Conte
- Division of Andrology, Department of Medical Pathophysiology, University "La Sapienza," 00161 Rome, Italy.
| | | | | | | | | | | | | | | |
Collapse
|
11
|
Cooke BA. Signal transduction involving cyclic AMP-dependent and cyclic AMP-independent mechanisms in the control of steroidogenesis. Mol Cell Endocrinol 1999; 151:25-35. [PMID: 10411317 DOI: 10.1016/s0303-7207(98)00255-x] [Citation(s) in RCA: 71] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 10/17/2022]
Abstract
The control of steroidogenesis via signal transduction mechanisms involving cAMP-dependent and cAMP-independent mechanisms is reviewed. Several structurally unrelated factors that are potent stimulators of steroidogenesis whose actions do not require cAMP and/or synthesis of proteins have been identified. These include various interleukins, a lipophilic factor from macrophages, a steroidogenic inducing protein from follicular fluid and an imidazole compound, calmidazolium. All of these factors are capable of inducing maximum steroidogenesis. Calcium is required for steroidogenesis in all steroidogenic cells. With the exception of the effects of angiotensin II, there is little evidence for a role of IP3 in the stimulation of the release of calcium from intracellular stores in steroidogenic cells under physiological conditions. There may however, be a cAMP-mediated activation of a plasma membrane calcium channel. Chloride channels that can be regulated by cAMP-dependent and -independent mechanisms, are present in steroidogenic cells. Chloride ions exert a negative effect on steroidogenesis because exclusion of chloride from the extracellular medium markedly enhances cAMP-stimulated steroidogenesis. Arachidonic acid and its lipoxygenase products are involved in the control of steroidogenesis via cAMP mediated processes. An arachidonic acid related thioesterase has been isolated that is activated by ACTH and which may be involved in the release of arachidonic acid. It is concluded that while cAMP is a second messenger for LH/ACTH in the control of steroidogenesis, other signalling systems exist which are potentially equally effective in controlling steroidogenesis. In addition, the action of cAMP requires other signalling pathways involving calcium and chloride ions, as well as arachidonic acid and its lipoxygenase products.
Collapse
Affiliation(s)
- B A Cooke
- Department of Biochemistry and Molecular Biology, Royal Free and University College Medical School, University College London, UK.
| |
Collapse
|
12
|
Marinero MJ, Penalva V, Oliva JL, Colás B, Prieto JC, López-Ruiz MP. Specific effect of arachidonic acid on 17beta-hydroxysteroid dehydrogenase in rat Leydig cells. FEBS Lett 1998; 422:10-4. [PMID: 9475159 DOI: 10.1016/s0014-5793(97)01584-6] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
Abstract
It is well known that arachidonic acid (AA) acts as an intratesticular factor regulating luteinizing hormone-mediated testicular steroidogenesis. The present studies were conducted to determine the effect of AA on steroidogenic enzymes in rat Leydig cells. Exogenously added AA significantly inhibited 22(R)-hydroxy-cholesterol-stimulated testosterone production, which is a clear indication that AA is acting at some point after cholesterol transport to the inner mitochondrial membrane. AA failed to block the conversion of 22(R)-hydroxycholesterol to pregnenolone, indicating that the cytochrome P-450 side-chain cleavage enzyme complex is not the site of inhibition. The present results demonstrate that only 17beta-hydroxysteroid dehydrogenase seems to be involved in the AA action, since nearly 60% inhibition of testosterone production was found when the cells were incubated with androstenedione. Furthermore, no effect of AA was found when androstenediol was used as substrate in the testosterone synthesis, which indicates that 3beta-hydroxysteroid dehydrogenase is not affected by AA. The conversion of AA to its metabolites is not required for its action on 17beta-hydroxysteroid dehydrogenase and the activation of protein kinase C is not involved in the inhibitory effect.
Collapse
Affiliation(s)
- M J Marinero
- Unidad de Neuroendocrinologia Molecular, Departamento de Bioquímica y Biología Molecular, Universidad de Alcalá, Alcalá de Henares-Madrid, Spain
| | | | | | | | | | | |
Collapse
|
13
|
Kühn H. Biosynthesis, metabolization and biological importance of the primary 15-lipoxygenase metabolites 15-hydro(pero)XY-5Z,8Z,11Z,13E-eicosatetraenoic acid and 13-hydro(pero)XY-9Z,11E-octadecadienoic acid. Prog Lipid Res 1996; 35:203-26. [PMID: 9082450 DOI: 10.1016/s0163-7827(96)00008-2] [Citation(s) in RCA: 75] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/04/2023]
Affiliation(s)
- H Kühn
- Institute of Biochemistry, University Clinics Charité, Humboldt University, Berlin, Germany
| |
Collapse
|
14
|
Marinero MJ, Colas B, Prieto JC, López-Ruiz MP. Different sites of action of arachidonic acid on steroidogenesis in rat Leydig cells. Mol Cell Endocrinol 1996; 118:193-200. [PMID: 8735605 DOI: 10.1016/0303-7207(96)03784-7] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/01/2023]
Abstract
The present study in purified rat Leydig cells shows that arachidonic acid may act as an intratesticular factor regulating LH-mediated testicular steroidogenesis. Arachidonic acid decreased, in a dose-dependent manner, the LH-stimulated cAMP and testosterone levels, over 2 h incubation. Incubation of Leydig cells with arachidonic acid did not modify 125I-hCG binding to the cells as compared to control, showing that the action of arachidonic acid is not related to a decrease of hCG binding to the cells. Forskolin-stimulated cAMP and testosterone production were inhibited by 51.65 and 70.9%, respectively, in the presence of arachidonic acid (100 microM), although the ED50 for the diterpene was not changed. When isobutyl-methyl-xanthine was added to the incubation medium, the same percentage of inhibition was found indicating that arachidonic acid inhibition of cAMP production is not due to stimulation of Leydig cell phosphodiesterase activity. Pretreatment of the cells with pertussis toxin, to inactivate Gi, was also without effect on arachidonic acid inhibition of LH-stimulated cAMP production, but pertussis toxin abolished the inhibitory effects of arachidonic acid when adenylate cyclase was stimulated with forskolin. However, arachidonic acid addition resulted in inhibition of LH- and forskolin-stimulated testosterone production, even if the cells were pretreated with pertussis toxin. It can be concluded that: (1) The inhibitory effect of arachidonic acid is neither due to a decrease of hCG binding to Leydig cells nor to a stimulation of cell phosphodiesterase activity; (2) arachidonic acid modulates cAMP production at two different levels, either by activation of Gi protein and by inhibition of Gs protein or adenylate cyclase; (3) the effect of arachidonic acid on steroidogenesis is also beyond cAMP formation.
Collapse
Affiliation(s)
- M J Marinero
- Departmento de Bioquímica y Biologia Molecular, Universidad de Alcalá, Alcalá de Henares, Madrid, Spain
| | | | | | | |
Collapse
|