Arachidonic acid release from rat Leydig cells depends on the presence of luteinizing hormone/human chorionic gonadotrophin receptors

1997 ◽  
Vol 154 (2) ◽  
pp. 201-209 ◽  
Author(s):  
P F Moraga ◽  
M N Llanos ◽  
A M Ronco
Keyword(s):  
Arachidonic Acid ◽  
Luteinizing Hormone ◽  
Dose Response ◽  
Binding Sites ◽  
Leydig Cells ◽  
Chorionic Gonadotrophin ◽  
Human Chorionic Gonadotrophin ◽  
Receptor Interaction ◽  
Dependent Manner ◽  
Membrane Phospholipids

Abstract In this work, the involvement of arachidonic acid (AA) in the luteinizing hormone and human chorionic gonadotrophin (LH/hCG) action on Leydig cells was studied. Experiments were first designed to evaluate [14C]AA incorporation into membrane phospholipids. Subsequently, time-course, pulse-chase and dose–response studies of the effect of hCG on [14C]AA release were performed. Results indicated that 4 h was optimal for maximal incorporation of [14C]AA into membrane phospholipids of viable Leydig cells. Pulse-chase experiments and studies performed to evaluate the effect of different doses of hCG on [14C]AA release demonstrated that this hormone stimulates [14C]AA release in a dose–response and time-dependent manner. Furthermore, using a desensitised animal model, a link between the presence of LH/hCG receptors and LH/hCG-stimulated [14C]AA release in Leydig cells could be established. In fact, the amount of [14C]AA released was significantly dependent on, and directly proportional to, the concentration of LH/hCG binding sites. Thus [14C]AA released from intact rat Leydig cells decreased when animals had been previously injected with a high single dose of hCG (desensitised animals), which is known to cause a dramatic decrease in the number of LH/hCG binding sites. These results demonstrate that the mechanism of AA release in Leydig cells depends on LH/hCG–receptor interaction and also suggest that AA could act as an additional intracellular messenger associated with the hormonal action of LH/hCG. Journal of Endocrinology (1997) 154, 201–209

scholarly journals Arachidonic acid release from rat Leydig cells: the involvement of G protein, phospholipase A2 and regulation of cAMP production

2002 ◽  
Vol 172 (1) ◽  
pp. 95-104 ◽  
Author(s):  
AM Ronco ◽  
PF Moraga ◽  
MN Llanos
Keyword(s):  
Arachidonic Acid ◽  
Fatty Acid ◽  
G Protein ◽  
G Proteins ◽  
Pertussis Toxin ◽  
Leydig Cells ◽  
Inhibitory Effect ◽  
Receptor Interaction ◽  
Dependent Manner ◽  
Camp Production

We have previously demonstrated that the release of arachidonic acid (AA) from human chorionic gonadotropin (hCG)-stimulated Leydig cells occurs in a dose- and time-dependent manner. In addition, the amount of AA released was dependent on the hormone-receptor interaction and the concentration of LH-hCG binding sites on the cell surface. The present study was conducted to evaluate the involvement of phospholipase A(2) (PLA(2)) and G proteins in AA release from hormonally stimulated rat Leydig cells, and the possible role of this fatty acid in cAMP production. Cells were first prelabelled with [(14)C]AA to incorporate the fatty acid into cell phospholipids, and then treated in different ways to evaluate AA release. hCG (25 mIU) increased the release of AA to 180+/-12% when compared with AA released from control cells, arbitrarily set as 100%. Mepacrine and parabromophenacyl bromide (pBpB), two PLA(2) inhibitors, decreased the hormone-stimulated AA release to 85+/-9 and 70+/-24% respectively. Conversely, melittin, a PLA(2) stimulator, increased the release of AA up to 200% over control. The inhibitory effect of mepacrine on the release of AA was evident in hCG-treated Leydig cells, but not in the melittin-treated cells. To determine if the release of AA was also mediated through a G protein, cells were first permeabilized and subsequently treated with pertussis toxin or GTPgammaS, a non-hydrolyzable analog of GTP. Results demonstrate that GTPgammaS was able to induce a similar level of the release of AA as hCG. In addition, pertussis toxin completely abolished the stimulatory effect of hCG on the release of AA, indicating that a member of the G(i) family was involved in the hCG-dependent release of AA. Cells treated with PLA(2) inhibitors did not modify cAMP production, but exogenously added AA significantly reduced cAMP production from hCG-treated Leydig cells, in a manner dependent on the concentration of AA and hCG. Results presented here suggest an involvement of PLA(2) and G proteins in the release of AA from hCG-stimulated Leydig cells, and under particular conditions, regulation of cAMP production by this fatty acid in these cells.

ISOLATION OF RAT LEYDIG CELLS BY DENSITY GRADIENT CENTRIFUGATION

1982 ◽  
Vol 92 (2) ◽  
pp. 293-NP ◽  
Author(s):  
J. S. GALE ◽  
J. ST J. WAKEFIELD ◽  
H. C. FORD
Keyword(s):  
Density Gradient ◽  
Binding Sites ◽  
Leydig Cells ◽  
Interstitial Cell ◽  
Density Gradient Centrifugation ◽  
Gradient Centrifugation ◽  
Chorionic Gonadotrophin ◽  
Human Chorionic Gonadotrophin ◽  
Collagenase Treatment

A rapid method for preparing Leydig cells from rat testes is described. An interstitial cell suspension, prepared by collagenase treatment of decapsulated testes, was centrifuged for 10 min over a cushion of 60% (v/v) Percoll to remove red blood cells, and then centrifuged for 20 min in a 0–60% linear density gradient of Percoll. Seventy-four per cent of the cells present in that fraction of the gradient comprising 35–50% Percoll were Leydig cells; the yield from each testis was about 1·5 × 106 cells. The Leydig cells appeared viable, excluded Trypan blue, possessed high-affinity binding sites for human chorionic gonadotrophin (hCG) and synthesized increased quantities of testosterone in response to hCG. The cells could be stored overnight in 20% (v/v) glycerol at −20 °C, with only minimal effect on the specific activities of a number of enzymes used as markers of subcellular components. Testosterone production in vitro by the cells after storage for 20 h was greater than that of hCG-stimulated fresh cells and was not further increased by hCG.

THE PRECISION OF THE OVARIAN ASCORBIC ACID DEPLETION TEST FOR LUTEINIZING HORMONE

1963 ◽  
Vol 43 (1) ◽  
pp. 155-160
Author(s):  
Jørgen Falck Larsen ◽  
Christian Hamburger
Keyword(s):  
Ascorbic Acid ◽  
Luteinizing Hormone ◽  
Clinical Analysis ◽  
Chorionic Gonadotrophin ◽  
Human Chorionic Gonadotrophin

ABSTRACT Various modifications of the Parlow test for luteinizing hormone (ovarian ascorbic acid depletion in rats) were tried. Human chorionic gonadotrophin was used instead of hypophyseal luteinizing hormone. The precision of the method was found to be so low, however, that the test could not be used for routine clinical analysis. The low precision found in this and other laboratories is thought to be due to the strains of rats used.

In vivo acute testicular testosterone response to injection of luteinizing hormone in the rat fetus

1993 ◽  
Vol 128 (3) ◽  
pp. 268-273 ◽  
Author(s):  
René Habert
Keyword(s):  
Plasma Concentration ◽  
Luteinizing Hormone ◽  
Leydig Cells ◽  
Time Dependent ◽  
Fetal Life ◽  
Dependent Manner ◽  
Adult Rats ◽  
Rat Fetus ◽  
Age Related

The acute in vivo testosterone response to LH stimulation and its change during late fetal life were determined in the rat. In 18.5-day-old fetuses, testicular testosterone content was increased in a dose-and time-dependent manner after fetal subcutaneous LH injection. The maximum response was small: the testicular content and plasma concentration were increased by 200% and 2 50% over basal values respectively, while they were increased 1100% and 1200% in adult rats. Similarly, comparable low responses were obtained after subcutaneously injecting the fetuses with human chorionic gonadotropin (hCG) and after injecting LH into the vitelline vein. Between days 18.5 and 21.5 of fetal life, the testosterone levels in the testis and plasma of uninjected or PBS-injected fetuses decreased and were comparable in both groups. In maximally LH-stimulated fetuses, the testicular content did not change with age, and plasma concentration was lower on day 21.5 than on day 18.5. Since the number of Leydig cells increases 1.5 to 2-fold between days 18.5 and 21.5, these results show an age-related decrease in basal and maximally LH-stimulated in vivo testosterone secretions per Leydig cell during late fetal life.

scholarly journals Adrenaline Stimulation of Phospholipid Metabolism in Adipocyte Ghosts

1987 ◽  
Vol 40 (4) ◽  
pp. 405
Author(s):  
David Mann ◽  
Audrey M Bersten
Keyword(s):  
Fatty Acids ◽  
Arachidonic Acid ◽  
Linoleic Acid ◽  
Adenylate Cyclase ◽  
Phospholipid Metabolism ◽  
Dependent Manner ◽  
Long Chain Fatty Acids ◽  
Membrane Phospholipids ◽  
Dose Dependent ◽  
Stimulation Of

The incorporation of long-chain fatty acids into phospholipids has been detected in adipocyte ghosts that were incubated with [1_14 C] stearic, [1_14 C] linoleic or [l_14C] arachidonic acid. Adrenaline and adenosine activated this incorporation within 15 s of exposure of the ghosts to the hormones and the response was dose dependent. Maximum incorporation of labelled linoleic acid occurred at 10-5 M adrenaline and 10-7 M adenosine. The a-agonist phenylephrine and the ~-agonist isoproterenol were also shown to stimulate the incorporation of fatty acid in a dose dependent manner. Phosphatidylcholine, phosphatidylethanolamine, phosphatidylserine and phosphatidylinositol were each labelled preferentially with linoleic or arachidonic acid. p-Bromophenacylbromide, quinacrine and centrophenoxine inhibited the adrenaline-stimulated incorporation of fatty acids into ghost membrane phospholipids, and p-bromophenacylbromide also reduced the activation of adenylate cyclase by adrenaline. NaF, an activator of adenylate cyclase, like adrenaline, stimulated the incorporation of linoleic acid into ghost membrane phospholipids.

BINDING OF HUMAN CHORIONIC GONADOTROPHIN BY RAT TESTIS: EFFECT OF SEXUAL MATURATION, CRYPTORCHIDISM AND HYPOPHYSECTOMY

1975 ◽  
Vol 64 (1) ◽  
pp. 59-66 ◽  
Author(s):  
JOACHIM FROWEIN ◽  
WOLFGANG ENGEL
Keyword(s):  
Dissociation Constant ◽  
Sexual Maturation ◽  
Leydig Cells ◽  
Binding Capacity ◽  
Specific Binding ◽  
Chorionic Gonadotrophin ◽  
Human Chorionic Gonadotrophin ◽  
Scatchard Analysis ◽  
Rat Testis ◽  
Relative Binding

SUMMARY The specific binding of 125I-labelled human chorionic gonadotrophin (HCG) by rat testicular homogenate as compared with isolated Leydig cells differs with respect to total binding capacity but not to the dissociation constant (KD) as revealed by Scatchard analysis. The maximal binding capacity for [125I]HCG of crude testicular homogenate was 95 ng/g rat testis. Hypophysectomy causes a decline in binding capacity within the first three days but on the 20th and 30th day after hypophysectomy the relative binding capacity no longer differs from that of controls. Binding capacity is enhanced in cryptorchid testes relative to normal, and increases during sexual maturation to a peak shortly before puberty.

ANTIGONADOTROPHIC PROFILE OF ANTISERA AGAINST HUMAN GONADOTROPHIN PREPARATIONS

1971 ◽  
Vol 67 (2) ◽  
pp. 262-276 ◽  
Author(s):  
P. Petrusz ◽  
C. Robyn ◽  
E. Diczfalusy
Keyword(s):  
Biological Activity ◽  
Luteinizing Hormone ◽  
Total Dose ◽  
Follicle Stimulating Hormone ◽  
Chorionic Gonadotrophin ◽  
Human Chorionic Gonadotrophin ◽  
Immunological Activity ◽  
Human Menopausal Gonadotrophin ◽  
Stimulating Hormone

ABSTRACT Forty-two antisera were prepared in rabbits against human chorionic gonadotrophin (HCG), human hypophysial gonadotrophin (HHG), human urinary luteinizing hormone (LH) and human menopausal gonadotrophin (HMG) preparations. The gonadotrophic profiles of the antigens were previously characterized by bioassay, immunoassay and bioimmunoassay methods. The 25 most potent antisera were tested in statistically valid bioassays for their HCG and follicle stimulating hormone (FSH) neutralizing activities as well as for their neutralizing potencies against the FSH-like activity present in HCG preparations. The anti-HCG/anti-FSH ratios of the anti-HCG sera tested varied between 6.2 and > 254, while those of the anti-HHG, anti-LH and anti-HMG sera were close to 2. It was found that the total dose of immunological activity (anti-HCG neutralizing and anti-FSH neutralizing potency) rather than that of the biological activity administered to the rabbits was decisive for obtaining antisera with high anti-HCG and anti-FSH titers. Immunization with a highly purified HCG preparation (> 17 000 IU/mg) resulted in antisera exhibiting lower anti-HCG/anti-FSH ratios than did immunization with partially purified preparations. A highly purified urinary LH preparation which did not contain any detectable FSH activity gave rise to antisera exhibiting anti-HCG/anti-FSH ratios of approximately 2.0. These highly purified HCG and LH preparations were shown previously to possess high anti-FSH neutralizing potencies (Petrusz et al. 1971b). Booster injections did not change significantly the quality or the titer of the antigonadotrophic sera studied. The HCG neutralizing potency of anti-HCG sera was approximately 3 times higher when assayed against a highly purified HCG preparation (> 17 000 IU/mg) as compared to potency estimates obtained against the laboratory standard of HCG (about 2000 IU/mg). It is suggested that consideration should be given to the establishment of standard preparations of antigonadotrophic sera. It is concluded that bioimmunoassays are more suitably than conventional bioassay methods for the assessment of the antigenic purity of human gonadotrophin preparations.

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