scholarly journals The effects of treatment with melatonin on the ultrastructure of mouse leydig cells: a quantitative study

2002 ◽  
Vol 62 (3) ◽  
pp. 517-523 ◽  
Author(s):  
C. A. REDINS ◽  
G. M. REDINS ◽  
J. C. NOVAES
Keyword(s):  
Pineal Gland ◽  
Leydig Cells ◽  
Direct Action ◽  
Secretory Activity ◽  
Nuclear Volume ◽  
Sham Control ◽  
Subcutaneous Injections ◽  
Testosterone Secretion ◽  
Transmission Electron

Both the presence of receptors for gonadal steroids in the pineal gland and in vitro observations of direct action of melatonin upon Leydig cells, inhibiting testosterone secretion, indicate a direct connection between pineal gland and gonadal function. In the present study, we used a transmission electron microscope to analyze the morphologic parameters of Leydig cells from adult Swiss outbred white mice treated with daily subcutaneous injections of 100 µg of melatonin (N-acetyl, 5-methoxytryptamine), during 22 consecutive days, compared with sham-control animals which had only received the melatonin vehicle. The melatonin group of mice showed a decrease in nuclear volume and fractional nuclear volume; smooth and rough endoplasmic reticulum; mitochondria; and Golgi complex. Our data also showed an increase in cytoplasmic volume, fractional cytoplasmic volume, and lysosomes in these same animals. The results suggest that melatonin, directly or indirectly, alters the ultrastructure of mouse Leydig cells and possibly influences their secretory activity by inhibiting their capacity to secrete steroids.

scholarly journals Mumps Virus Decreases Testosterone Production and Gamma Interferon-Induced Protein 10 Secretion by Human Leydig Cells

2003 ◽  
Vol 77 (5) ◽  
pp. 3297-3300 ◽  
Author(s):  
Ronan Le Goffic ◽  
Thomas Mouchel ◽  
Annick Ruffault ◽  
Jean-Jacques Patard ◽  
Bernard Jégou ◽  
...  
Keyword(s):  
Cell Cultures ◽  
Leydig Cell ◽  
Leydig Cells ◽  
Mumps Virus ◽  
Gamma Interferon ◽  
Testosterone Secretion ◽  
Testosterone Production

ABSTRACT Mumps virus is responsible for sterility. Here, we show that the mumps virus infects Leydig cells in vitro and totally inhibits testosterone secretion and that ribavirin in mumps virus-infected Leydig cell cultures completely restores testosterone production. Moreover, we show that gamma interferon-induced protein 10 (IP-10) is highly expressed by mumps virus-infected Leydig cells and that ribavirin does not block IP-10 production.

scholarly journals A novel mechanism for the melatonin inhibition of testosterone secretion by rat Leydig cells: reduction of GnRH-induced increase in cytosolic Ca2+

1999 ◽  
Vol 23 (3) ◽  
pp. 299-306 ◽  
Author(s):  
S Valenti ◽  
S Thellung ◽  
T Florio ◽  
M Giusti ◽  
G Schettini ◽  
...  
Keyword(s):  
Leydig Cells ◽  
Calcium Concentration ◽  
Inhibitory Effect ◽  
Adult Rat ◽  
Testosterone Secretion ◽  
Gi Protein ◽  
Hydroxy Progesterone ◽  
Induced Changes ◽  
Cells Cultured

The site of inhibition, by melatonin, of GnRH-dependent testosterone secretion was investigated in adult rat Leydig cells cultured in vitro. The various effects downstream of the binding of GnRH to its own receptor were isolated and mimicked by specific drugs. Testosterone secretion was then evaluated after 3 h stimulation with GnRH, thapsigargin (1 microM), phorbol-12-myristate-13-acetate (100 nM), arachidonic acid (20 microM), and ionomycin (1 microM) in the presence or absence of melatonin (215 nM). The effect of melatonin on the GnRH-induced changes in cytoplasmic calcium concentration ([Ca(2+)](i)) was also studied, using Fura-2 as fluorescent Ca(2+) indicator. Melatonin attenuated the increase in [Ca(2+)](i) and inhibited the testosterone secretion induced by GnRH, but not that induced by ionomycin. Both ionomycin and thapsigargin potentiated GnRH-induced testosterone secretion; however, ionomycin, but not thapsigargin, partially prevented the inhibitory effect of melatonin on cells stimulated with GnRH. The effect of melatonin was probably dependent on the binding of melatonin to its Gi-protein-coupled receptor, as the inhibitory effect on GnRH-induced secretion was supressed in cells pretreated with pertussis toxin in a concentration of 180 ng/ml for 20 h. Assay of 17-hydroxy-progesterone showed that, irrespective of the treatment, cells cultured with melatonin secreted greater amounts than controls. We conclude that melatonin reduces GnRH-induced testosterone secretion by 1) decreasing [Ca(2+)](i), through impairment of the GnRH-dependent release of Ca(2+) from intracellular stores and 2) blocking 17-20 desmolase enzymatic activity, an effect that occurs irrespective of changes in [Ca(2+)](i).

Effects of melatonin treatment on Leydig cell activity in the testis of the frog Rana esculenta

Zygote ◽  
2004 ◽  
Vol 12 (4) ◽  
pp. 293-299 ◽  
Author(s):  
Michela d'Istria ◽  
Ismene Serino ◽  
Gaia Izzo ◽  
Diana Ferrara ◽  
Gianluca De Rienzo ◽  
...  
Keyword(s):  
Leydig Cell ◽  
Leydig Cells ◽  
Morphological Changes ◽  
Cell Activity ◽  
Rana Esculenta ◽  
Cellular Adhesion ◽  
Morphological Observation ◽  
Melatonin Treatment ◽  
Testosterone Secretion

This study was conducted to verify the effect(s) of melatonin treatment on frog Leydig cells. Morphological observation after melatonin treatment indicates that many frog Leydig cells show degenerative changes (i.e. heterochromatic nuclei, loss of cellular adhesion) while in adjacent germinal tubules several Sertoli cells show heterochromatic nuclei, confirming the presence of a paracrine effect between interstitial and germinal compartments. The effect of melatonin on frog Leydig cell steroidogenesis was investigated in in vitro experiments; after 6 h of incubation melatonin severely inhibits both control and GnRH-induced testosterone secretion. In addition, in order to verify the effect of indolamine on frog Leydig cell activity, we investigated, by in situ hybridization, the presence of frog relaxin (fRLX, a transcript specifically expressed by these cells) in the testes of melatonin-injected animals after 48 h. fRLX signal completely disappeared from the testis of melatonin-injected frogs. The results of the present study indicate that melatonin treatment provokes Leydig cell morphological changes, blocks GnRH-antagonist-induced testosterone secretion and decreases fRLX expression. Taken together these results strongly indicate that melatonin acts on Leydig cells in the testis of the frog Rana esculenta.

Reversal of long-term LH deprivation on testosterone secretion and Leydig cell volume, number and proliferation in adult rats

1990 ◽  
Vol 127 (1) ◽  
pp. 47-NP ◽  
Author(s):  
D. S. Keeney ◽  
R. L. Sprando ◽  
B. Robaire ◽  
B. R. Zirkin ◽  
L. L. Ewing
Keyword(s):  
Cell Volume ◽  
Leydig Cell ◽  
Leydig Cells ◽  
Cell Number ◽  
Implant Removal ◽  
Adult Rats ◽  
Testosterone Secretion ◽  
Lh Secretion

ABSTRACT The purpose of this study was to determine whether Leydig cell volume and function could recover fully from long-term LH deprivation upon restoration of endogenous LH secretion, and whether the restoration of LH would elicit a mitogenic response, i.e. stimulate Leydig cell proliferation or affect Leydig cell number per testis. LH secretion was inhibited by treating adult rats with testosterone and oestradiol-filled (TO) silicone elastomer implants (16 weeks), and was restored by removing the implants. Changes in serum concentrations of LH and FSH, LH-stimulated testosterone secretion by testes perfused in vitro, Leydig cell volume and number per testis, average Leydig cell volume and Leydig cell [3H]thymidine incorporation were measured at weekly intervals following implant removal. The TO implants inhibited (P < 0·01) LH secretion, but serum concentrations of FSH were not significantly different (P > 0·10) from control values. After implant removal, serum LH returned to control values within 1 week, whereas serum FSH increased twofold (P < 0·01) and returned to control values at 4 weeks. LH-stimulated in-vitro testosterone secretion was inhibited by more than 99% in TO-implanted rats, but increased (P < 0·01) to 80% of control values by 8 weeks after implant removal. The total volume of Leydig cells per testis and the volume of an average Leydig cell were 14 and 19% of control values respectively, after 16 weeks of TO implantation (P < 0·01), but returned to 83 and 86% of controls (P > 0·10) respectively, by 6 weeks after implant removal. Leydig cell proliferation ([3H]thymidine labelling index) was low (< 0·1%) in both control and TO-implanted rats, increased (P < 0·01) fivefold from 1 to 4 weeks after implant removal and then declined to control values at 6 weeks. The increase in Leydig cell [3H]thymidine incorporation was mimicked by treating TO-implanted rats with exogenous LH, but not FSH. Leydig cells were identified in both the interstitium and the lamina propria of the seminiferous epithelium. The proportion of Leydig cell nuclei in the lamina propria was 30-fold greater (P < 0·01) at 1 and 3 weeks after implant removal (3%) compared with that for control and TO-implanted rats (0·1%). Total Leydig cell number per testis was marginally but not significantly (P = 0·06) decreased in rats treated with TO implants for 16 weeks when compared with controls (18·4±2·2 vs 25·4±1·2 × 106). Three weeks after implant removal, the numbers of Leydig cells per testis were identical (26·8±2·8 × 106) to those in control animals. These results not only demonstrate dramatic morphogenic effects of LH on mature rat Leydig cells, but also suggest that endogenous LH might be mitogenic at least to a subpopulation of Leydig cells. Journal of Endocrinology (1990) 127,47–58

ENDOTHELIN STIMULATES TESTOSTERONE SECRETION BY RAT LEYDIG CELLS

1993 ◽  
Vol 136 (2) ◽  
pp. R1-R4 ◽  
Author(s):  
D. Conte ◽  
P. Questino ◽  
S. Fillo ◽  
M. Nordio ◽  
A. Isidori ◽  
...  
Keyword(s):  
Binding Sites ◽  
Leydig Cells ◽  
Channel Blocker ◽  
Specific Binding ◽  
Human Chorionic Gonadotrophin ◽  
Paracrine Factor ◽  
Testosterone Secretion ◽  
Specific Binding Sites ◽  
Testicular Steroidogenesis

ABSTRACT The present study was designed to evaluate the effects of endothelin (ET) on rat testicular steroidogenesis in vitro and the involvement of prostaglandins (PG) and extracellular calcium in its mechanism of action. To this purpose we examined the effects of ET-1 and ET-3 on basal testosterone secretion, the influence of ET-1 on PGE2, release, the interaction of ET-1 and ET-3 with human chorionic gonadotrophin (hCG) and the interference of indomethacin (an inhibitor of cycloxygenase) and nifedipine (a calcium-channel blocker) in purified rat Leydig cells. The data indicate that ET-1 and ET-3 stimulate basal and hCG-induced testosterone production although the effects of ET-3 were less marked. In addition, a concomitant release of PGE2, was observed after exposure to ET-1. A sinergistic interaction between ET-1 and hCG in stimulating testicular steroidogenesis was revealed. Indomethacin was ineffective in modifying ET-1 evoked testosterone output, while in the presence of nifedipine the stimulatory effect of ET-1 was completely abolished. Since it has been shown by others that ET-1 is produced by rat Sertoli cells and specific binding sites are present in Leydig cells, the results of our study indicate that such a peptide may be regarded as a new paracrine factor able to influence steroidogenesis in Leydig cells. The action of ET-1 requires the activity of voltage-operated Ca2+ channels, while PGE2 activation is not essential for its steroidogenic effect.

A thymus factor influences the in vitro testosterone secretion of Leydig cells in the rat

Life Sciences ◽  
1986 ◽  
Vol 38 (9) ◽  
pp. 779-787 ◽  
Author(s):  
Enrique Pedernera ◽  
Jorge Díaz-Osuna ◽  
Mario Calcagno
Keyword(s):  
Leydig Cells ◽  
Testosterone Secretion ◽  
Thymus Factor

scholarly journals The effect of treatment with melatonin upon the ultrastructure of the mouse pineal gland: a quantitative study

2001 ◽  
Vol 61 (4) ◽  
pp. 679-684 ◽  
Author(s):  
G. M. REDINS ◽  
C. A. REDINS ◽  
J. C. NOVAES
Keyword(s):  
Electron Microscopy ◽  
Transmission Electron Microscopy ◽  
Pineal Gland ◽  
Quantitative Study ◽  
Subcutaneous Injection ◽  
Secretory Activity ◽  
Secretory Process ◽  
Volumetric Density ◽  
Transmission Electron ◽  
Effect Of Treatment

In order to evaluate melatonin implication in the regulating of its own secretory process by pinealocytes, we used morphometric techniques for transmission electron microscopy. In mice treated with 100 mg of melatonin (N-acetyl-5-methoxy-tryptamine) by daily subcutaneous injection, we observed a decrease in number and volumetric density of lysosomes. Our results showed that melatonin influences the secretory activity of pinealocytes and participates in a complex secretory regulating mechanism.

RNA synthesis in Leydig cells during sexual maturation in the rat: effect of LH

1986 ◽  
Vol 110 (3) ◽  
pp. 551-556 ◽  
Author(s):  
L. E. Valladares ◽  
A. M. Ronco ◽  
A. M. Pino
Keyword(s):  
Leydig Cells ◽  
Rna Synthesis ◽  
Marked Effect ◽  
Direct Action ◽  
Dependent Manner ◽  
Cellular Events ◽  
Age Dependent ◽  
Old Rats ◽  
Lh Releasing Hormone

ABSTRACT The trophic action of LH on Leydig cells involves the triggering of a number of cellular events including changes in protein synthesis. This latter change has led a number of workers to postulate an effect of LH on RNA synthesis. A direct action of LH on RNA synthesis, however, has been difficult to assess. The aim of the present work was to analyse the effect of LH on RNA synthesis in vitro during sexual development. Studies were performed using purified Leydig cells from rats of 20, 30, 40, 50, 60 and 90 days of age. The results obtained show that basal uridine incorporation into RNA increases in an age-dependent manner in rats from 20 to 60 days of age and then remains unchanged until 90 days of age. A stimulatory effect of LH on RNA synthesis was clearly demonstrated only in the youngest rats (20 and 30 days old). In order to differentiate the effect of LH on different RNA populations, the RNA synthesized by immature and mature rats was analysed using a poly(U)-Sepharose column. In 20-day-old rats, LH stimulated both unbound and poly(A) RNA, although a more marked effect was clearly demonstrated on the latter. On the other hand, LH had an identical effect on both unbound and poly(A) RNA obtained from Leydig cells of 60-day-old rats. This stimulatory effect of LH on RNA synthesis in Leydig cells from immature rats seemed specific, since effectors which act on interstitial cells, such as LH-releasing hormone, [Arg8]-vasopressin and FSH (which may act on macrophages) did not modify RNA synthesis. It is concluded that LH stimulates RNA synthesis in rat Leydig cells and that this effect is expressed differentially according to sexual maturity. J. Endocr. (1986) 110, 551–556

scholarly journals Role of AA-NAT and TPH1 in the Ghrelin-Dependent Regulation of Melatonin Secretion in Sheep during Different Seasons: An In Vitro Study

2017 ◽  
Author(s):  
Katarzyna Kirsz ◽  
Malgorzata Szczesna ◽  
Dorota A. Zieba
Keyword(s):  
Food Intake ◽  
Pineal Gland ◽  
Real Time Pcr ◽  
Secretory Activity ◽  
Melatonin Secretion ◽  
Independent Manner ◽  
Phosphorylated Form ◽  
Different Seasons

Several studies suggests that ghrelin (GHRL) has neurobiological effects that extend beyond control of food intake. Our previous results confirmed that GHRL modulates the secretory activity of the pineal gland (PG) through nocturnal melatonin (MEL) secretion in sheep, the seasonally reproductive animals. Here we investigated the effects of GHRL (10 ng/ml) on the expression of enzymes limiting synthesis of MEL, including tryptophan 5-hydroxylase 1 (TPH1), serotonin N-acetyltransferase (AA-NAT) and its phosphorylated form p31T-AA-NAT in sheep PG explants (n = 72) during the 4-hour incubation in a gas-liquid interface, at a short (SD) and long (LD) photoperiods. After each hour of incubation selected explants were frozen in liquid nitrogen and stored at -80&deg;C for subsequent analysis (real-time PCR, western-blotting, ELISA). Results show that GHRL regulates nightly MEL secretion in a TPH1-independent manner. The factor modulating GHRL activity was photoperiod. During SD photoperiod GHRL significantly reduced the expression of p31T-AA-NAT, AA-NAT and inhibited MEL secretion from PG explants. Whereas, during LD photoperiod no effect of GHRL on MEL secretion and expression of examined enzymes was noted. Studies indicate that GHRL directly affects PG under in vitro conditions and causes MEL secretion in animals which exhibit seasonality in reproductive and metabolic processes.

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