Luteinizing hormone differentially regulates the secretion of testicular oxytocin and testosterone by purified adult rat Leydig cells in vitro.

Endocrinology ◽  
1992 ◽  
Vol 130 (2) ◽  
pp. 671-677
Author(s):  
H D Nicholson ◽  
M P Hardy
Keyword(s):  
Luteinizing Hormone ◽  
Leydig Cells ◽  
Adult Rat

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).

Intragonadal regulation of immune system functions

1990 ◽  
Vol 2 (3) ◽  
pp. 263 ◽  
Author(s):  
MP Hedger ◽  
JX Qin ◽  
DM Robertson ◽  
Kretser DM de
Keyword(s):  
Immune System ◽  
Immune Responses ◽  
Germ Cell ◽  
Conditioned Medium ◽  
Leydig Cells ◽  
Seminiferous Tubules ◽  
Interstitial Tissue ◽  
Short Term ◽  
Adult Rat

Immune responses within the mammalian gonads, and in particular the testis, are deficient in spite of adequate lymphatic drainage and the presence of lymphocytes and MHC II+ macrophages. There is considerable evidence from in vivo and in vitro studies that this 'suppression' of the immune system may be due, at least in part, to localized inhibition or regulation of normal lymphocyte and/or macrophage functions within the gonads. In the testis, both steroidal and non-steroidal products of the Leydig cells, including androgens, endorphins, and inhibin-related proteins, have been implicated in mediating this activity. In turn, a number of immune cell cytokines affect steroidogenic cell function in vitro. The studies described in this paper indicated that [3H]-thymidine incorporation by adult rat thymocytes in vitro was inhibited by conditioned medium collected from short-term incubations of Percoll-purified adult rat Leydig cells, but stimulated by testicular interstitial fluid and by conditioned medium collected from short-term incubations of adult rat seminiferous tubules. The factors responsible for these effects on thymocyte function appeared to be of large molecular weight, as they were retained by ultrafiltration membranes with exclusion limits of 10,000 or 30,000 daltons. It is hypothesized that an 'immunosuppressive' mechanism, principally mediated by non-steroidal factors secreted by the steroidogenic cells of the gonadal interstitial tissue, exists within the gonads in order to prevent activation of the immune system by germ cell antigens and growth factors associated with germ cell proliferation and differentiation. This mechanism probably acts in parallel with normal antigen-specific tolerance mechanisms operating at the gonadal level. As immune responses to germ cells are believed to be a significant causative factor in infertility, particularly in men, this represents an important area for further study.

Ethan-1,2-dimethanesulphonate reduces testicular oxytocin content and seminiferous tubule movements in the rat

1987 ◽  
Vol 112 (2) ◽  
pp. 311-NP ◽  
Author(s):  
H. D. Nicholson ◽  
R. T. S. Worley ◽  
S. E. F. Guldenaar ◽  
B. T. Pickering
Keyword(s):  
Leydig Cell ◽  
Seminiferous Tubule ◽  
Leydig Cells ◽  
Contractile Activity ◽  
Histological Study ◽  
Interstitial Cells ◽  
Seminiferous Tubules ◽  
Adult Rats ◽  
Adult Rat

ABSTRACT An oxytocin-like peptide is present in the interstitial cells of the testis, and testicular concentrations of oxytocin have been shown to increase seminiferous tubule movements in vitro. We have used the drug ethan-1,2-dimethanesulphonate (EDS), which depletes the Leydig cell population of the adult rat testis, to examine further the relationships between the Leydig cell, testicular oxytocin and tubular movements. Adult rats were injected i.p. with a single dose of EDS (75 mg/kg) or of vehicle (25% dimethyl sulphoxide). Histological study 3 and 10 days after treatment with EDS showed a reduction in the number of interstitial cells, and levels of oxytocin immunoreactivity were undetectable by radioimmunoassay. Immunostaining revealed very few oxytocin-reactive cells. Spontaneous contractile activity of the seminiferous tubules in vitro was also dramatically reduced, but could be restored by the addition of oxytocin to the medium. Four weeks after EDS treatment, the interstitial cells were similar to those in the control animals both in number and in immunostaining; immunoassayable oxytocin was present and tubular movements were normal. The EDS effect, seen at 3 and 10 days, was not altered by daily treatment with testosterone. However, repopulation of the testes with oxytocin-immunoreactive cells was not seen until 6 weeks in the testosterone-treated animals. We suggest that the Leydig cells are the main source of oxytocin immunoreactivity in the testis and that this oxytocin is involved in modulating seminiferous tubule movements and the resultant sperm transport. The results also imply that testosterone does not play a major role in controlling tubular activity in the mature rat. J. Endocr. (1987) 112, 311–316

The effect of chronic luteinizing hormone treatment on adult rat Leydig cells

1998 ◽  
Vol 30 (1) ◽  
pp. 64-73 ◽  
Author(s):  
S.M.L.C. Mendis-Handagama ◽  
P.A. Watkins ◽  
T.J. Scallen
Keyword(s):  
Luteinizing Hormone ◽  
Leydig Cells ◽  
Hormone Treatment ◽  
Adult Rat

scholarly journals Immunocytochemical visualization of luteinizing hormone-human chorionic gonadotropin (LH-hCG) receptors in Leydig cells in primary culture.

1983 ◽  
Vol 31 (7) ◽  
pp. 898-904 ◽  
Author(s):  
M Begeot ◽  
C Mombrial ◽  
P M Dubois ◽  
M P Dubois ◽  
A Dazord ◽  
...  
Keyword(s):  
Luteinizing Hormone ◽  
Cell Surface ◽  
Chorionic Gonadotropin ◽  
Human Chorionic Gonadotropin ◽  
Leydig Cells ◽  
Defined Medium ◽  
Short Exposure ◽  
Receptor Complexes ◽  
Immunocytochemical Reaction

Visualization of human chorionic gonadotropin (hCG) binding sites was obtained by immunocytochemical reaction on Leydig cells cultured in chemically defined medium. After a short in vitro incubation with hCG or luteinizing hormone (LH), the cells were fixed and the bound molecules were revealed using anti-hCG or anti-LH antisera. In both cases the immunocytochemical reaction appeared as granulations at the cell surface. After prolonged (48 hr) culture in the presence of 0.5, 5, or 50 ng/ml of hCG, the hormone receptor complex is still visible. Similarly, following short exposure to hCG (0.5 or 50 ng/ml) and one or two days of culture without hCG, the immunocytochemical reaction is still present. These observations suggest that the half-life of the bound hormone is very long. This in vitro system in which the amount and time of hormone exposure are precisely defined provides arguments in favor of a long-term maintenance of the receptor complexes at the cell surface.

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