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M A Drosdowsky

Publications and source records attributed to M A Drosdowsky.

At least 37 records · Page 2Linked to original sources
PubMed1989

[Role of a purified Sertoli cell protein (CMB-21) in the biosynthesis of Leydig cell testosterone in the immature rat].

The existence of Sertoli cell factors which modulate the rat Leydig cell function prompted us to study the biological activity of selected proteins called CMB proteins and produced by immature rat Sertoli cells. Percoll purified Leydig cells (10(5)) from 20 days-old rats have been incubated 5 h at 32 degrees C in 1 ml Ham F12/DME medium with increasing concentrations of partially purified CMB proteins (0-1,000 ng/ml) either in presence or absence of oLH (25 ng/ml). Among the CMB proteins tested, only CMB-21 produces a dose related increase of testosterone production: from 2 to 500 pg/ml of CMB-21, testosterone output is unchanged (51 pg/10(5) cells) but 1 to 1,000 ng/ml of this protein produces a linear increase of testosterone productions (86 to 870 pg). In the presence of oLH which induces a 10-fold increase of testosterone production (499 pg), increasing doses of CMB-21 further stimulate testosterone output (775 to 2.272 pg/10(5) cells). Whatever the concentration of oLH used (0 to 50 ng/ml), CMB-21 (500 ng/ml) leads to a further 2 fold augmentation of testosterone synthesis; similarly, in the presence of dbcAMP (1 mM), CMB 21 increases the testosterone production but no effect is observed when Leydig cells are incubated in the presence of 22R-hydroxycholesterol (30 microM). The cAMP levels which are increased more than 4 fold by oLH, remain unchanged in the presence of CMB-21 either alone or with oLH, as observed when Sertoli cell culture medium is used.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1988

Effects of cisplatin and bleomycin on mature rat Leydig cell testosterone production.

A single i.p. injection of either cisplatin or bleomycin affects the testosterone production by the Leydig cells in mature rats. It is noteworthy that on day 30 after treatment, a complete recovery of Leydig cell function is found in bleomycin-treated rats whereas in cisplatin-injected animals, 25-48% decreases of testosterone synthesis are still observed, respectively, under basal and LH-stimulated conditions. Together with the germ cell destruction, the low testosterone levels probably contribute to the sterility in cisplatin-treated rats.

Animals↗
PubMed1988

Changes in androgen binding protein (ABP) production following continuous low dose gamma irradiation (IR) of adult rat.

Continuous low dose gamma irradiation induces a progressive degeneration of germ cells with a concomittant increase in blood FSH; however, the Sertoli cell function is not too much altered since serum ABP level is normal and it is likely that the decrease of epididymal ABP content is the consequence of a reduction in seminiferous tubule fluid excretion. Obviously, spermatids seems to be involved in the regulation of Sertoli cell ABP synthesis.

Androgen-Binding Protein↗
PubMed1988

Validation of a new system for androgen binding protein measurement.

A new technique that permits measurement of Androgen-Binding Protein (ABP) is validated by reproducibility, linearity and correlation studies. Using this apparatus allowing Scatchard plot analysis, it is also possible to measure association and dissociation rate constants. In addition, it is a very useful tool for a rapid screening of ABP binding capacity during a chromatographic stepwise purification.

Androgen-Binding Protein↗
PubMed1988

Effect of continuous low-dose gamma-irradiation on rat Sertoli cell function.

Continuous low-dose gamma-irradiation of mature rats induced a progressive degeneration of the germ cells. Blood FSH increased by 127, 176 and 214%, respectively, after 55, 70 and 85 days of treatment when compared to FSH levels in control rats (8.50 +/- 0.60 ng/ml); conversely, serum LH and testosterone levels were unchanged. The Sertoli cell function was affected by the treatment from 70 days on, as attested by androgen binding protein (ABP) and transferrin secretions which diminished 35-40%. Serum ABP levels were not altered, whatever the duration of irradiation, even though epididymal ABP contents (as well as concentrations) diminished 34-60% when compared to those of the controls. Moreover, in purified Leydig cells, LH-stimulated intracellular cAMP levels, which were decreased by seminiferous tubule medium (STM) from control rats, were enhanced in presence of STM from treated animals. Testosterone output was stimulated 9-fold in presence of oLH and further increased (46-76%) from stages XIV-V by STM prepared from control and irradiated rats, respectively. After 85 days the STM effects on both cAMP and testosterone syntheses were zero. These results demonstrate a probable alteration of Sertoli cell function after irradiation, but also a role of the germ cells in the regulation of the synthesis of ABP, transferrin and Sertoli cell paracrine factors.

Androgen-Binding Protein↗
PubMed1988

Stimulation of adult rat Leydig cell aromatase activity by a Sertoli cell factor.

The paracrine control of adult rat Leydig cell aromatase activity was investigated in vitro. After a 24-h preculture period of Percoll-purified Leydig cells (2.5-5 X 10(5) cells), 17 beta-estradiol synthesis reached a maximum at 5 h in the presence of exogenous testosterone (200 ng/ml) as substrate, with or without LH (100 ng/ml), and remained stable for a further 24 h. Aromatase activity was stimulated 2.5-fold by LH. The addition of seminiferous tubule culture medium (STM) from normal, neonatally hemicastrated, or prepubertally irradiated rats as well as Sertoli cell culture medium prepared from these animals enhanced both basal and LH-dependent aromatase activities during 5 h; this effect was diminished after 24 h of culture. When seminiferous tubules (200 mm) were cocultured with Leydig cells, a greater stimulation of 17 beta-estradiol production was observed compared to culture with STM. The association of Sertoli and germ cells with purified Leydig cells further enhanced aromatase activity. These results demonstrate that a Sertoli cell factor regulates Leydig cell aromatase activity. This factor is of proteic nature, thermolabile, has a mol wt ranging between 10,000-50,000, and is different from the LHRH-like substance. This compound is tissue and species specific, since it is not present in rat serum, other cell line media, or guinea pig and mouse STM. Its secretion is independent from FSH and testosterone controls. The stimulation of aromatase activity by this factor requires protein synthesis.

Animals↗
PubMed1988

[Paracrine regulation of Leydig cell aromatase in the rat: development with age].

The paracrine regulation of rat testicular aromatase activity has been studied at various ages (20, 30, 45, 55, 70, 240 days); seminiferous tubule culture medium (STM) have been prepared at the above ages and added (40%, v/v) to the Percoll purified Leydig cells (150,000) for 5 h at 32 degrees C in presence or absence of oLH (25 ng/ml). In 20 day-old rat, the basal oestradiol-17 beta (E2) output is low (20 pg/10(6) Leydig cells), then gradually increases until day 70 (280 pg) without any change at 240 days (260 pg). In presence of oLH, a 2 fold increase of E2 output is observed whatever the age and the addition of STM further enhances both the basal (21-41%) and the LH-stimulated (14-65%) E2 syntheses. In conclusion, the Leydig cell aromatase activity, is in part regulated by STM factors, mainly after puberty. From 20 days onwards, it is noteworthy, that the Leydig cell testosterone (T) synthesis is highly stimulated by oLH (10 fold) and the addition of STM further increases T outputs (2 fold) which brings about a high intratesticular T level necessary for development of spermatogenesis.

Age Factors↗
PubMed1987

A minicolumn apparatus for androgen-binding protein measurement.

An easy, rapid, and sensitive assay that permits measurements of androgen-binding protein (ABP) in tissue as well as in spent media from Sertoli cells is described; this method involves the specific binding of labeled dihydrotestosterone (DHT) to ABP. The apparatus holds 36 minicolumns loaded with a DEAE Bio-Gel matrix. A peristaltic pump is used for the free fraction elution, taking into account the extremely rapid rate of dissociation of the ABP-DHT complexes. This technique, which allows Scatchard plot analysis, has been used to measure the rates of association (5.15 X 10(5)M-1 S-1 and dissociation (21.32 X 10(-4) S-1; t 1/2 = 5.5 min): the ratio of these rate constants is in perfect agreement with equilibrium dissociation constants determined by Scatchard plot analysis (KD = 4-4.5 nM). The intraassay and interassay coefficients of variation are 5 and 8%, respectively. A good correlation (r = 0.98) is obtained with the standard method of steady-state polyacrylamide gel electrophoresis below a value of 250 micrograms cytosolic proteins/gel. This apparatus, which allows either the measurement of ABP in 12 samples (in triplicates) at a saturating concentration or the analysis of two Scatchard plots (each of 6 points), is also very useful for a rapid localization of ABP during chromatographic purification.

Androgen-Binding Protein↗
PubMed1987

Effects of the transmethylation inhibitor S-adenosyl-homocysteine and of the methyl donor S-adenosyl-methionine on rat Leydig cell function in vitro.

In purified rat Leydig cells, the methyl donor S-adenosyl-methionine (SAM), increases significantly in a dose dependent manner the [125I]hCG binding as well as the productions of cAMP and of testosterone; the competitive inhibitor of methylations S-adenosyl-homocysteine (SAH), has an opposite effect. Associated to oLH, SAM further enhances the cAMP synthesis while SAH inhibits significantly the adenylate cyclase activity. With regard to testosterone synthesis, SAM potentiates the stimulating roles of oLH and dbcAMP (27 and 38% increases, respectively) although SAH diminishes testosterone productions (48 and 35%, respectively under oLH and dbcAMP stimulations). Scatchard analysis has shown that SAM (1.4 mM) increases the number of LH/hCG binding sites on Leydig cells while SAH (1.4 mM) decreases it; LH/hCG Ka values are not modified neither by SAM nor by SAH. These data suggest that the in vitro regulation of steroidogenesis in purified rat Leydig cells may involve methylation processes (presumably phospholipids are the potential substrates of these reactions) which modulates the transmission of the hormonal signal through the membrane and affects the testosterone synthesis at a step beyond the adenylate cyclase.

Animals↗
PubMed1987

Spent media from immature seminiferous tubules and Sertoli cells inhibit adult rat Leydig cell aromatase activity.

Adult rat Leydig cell aromatase activity is stimulated 2.5 fold by LH or dbcAMP. Spent media prepared from seminiferous tubules or Sertoli cells of immature rats depress both the basal and the LH stimulated estradiol syntheses (25 and 20% decreases, respectively). These inhibitory effects are further enhanced when FSH is added to the culture medium of seminiferous tubules or Sertoli cells. Rat serum as well as culture media from other cell lines are ineffective while seminiferous tubule media from other immature animals (mouse, guinea-pig, calf) inhibit the aromatase activity. This Sertoli cell factor is a heat stable protein (molecular weight greater than 10 kDa), different from the LHRH-like Sertoli cell compound, which acts on the aromatase activity at a step beyond the adenylate cyclase.

Animals↗
PubMed1987

Adult rat Sertoli cells secrete a factor or factors which modulate Leydig cell function.

Production of testosterone and oestradiol-17 beta by Leydig cells from adult rats was stimulated by LH or dibutyryl cyclic AMP (10 and 2.5-fold respectively). The addition of spent medium from normal, hemicastrated or gamma-irradiated rat seminiferous tubule cultures, as well as from Sertoli cell cultures, to purified Leydig cells further enhanced both basal (44 and 53% for testosterone and oestradiol-17 beta respectively) and LH-stimulated (56 and 18%) steroid output. Simultaneously, a decrease (20-30%) in intracellular cyclic AMP levels was observed. This stimulating factor (or factors) secreted by the Sertoli cells is different from LHRH, is of proteinic nature and has a molecular weight ranging between 10,000 and 50,000; its synthesis is not controlled by FSH nor by testosterone. This factor(s) involved in rat Leydig cell steroidogenesis, at a step beyond the adenylate cyclase, does not require protein synthesis for testosterone formation whereas it does for oestradiol-17 beta production. It should be noted that a germ cell-Sertoli cell interaction modulates the synthesis of this factor(s).

Animals↗
PubMed1986

Effects of seminiferous tubule secreted factor(s) on Leydig cell cyclic AMP production in mature rat.

The effects of spent media from seminiferous tubules (STM) on Percoll-purified rat Leydig cells were investigated. Intracellular and extracellular cyclic AMP (cAMP) accumulation and testosterone production were measured. After a 5 h incubation period, STM reduces both the basal and LH-dependent cAMP levels (38 and 20%, respectively for intra- and extracellular cAMP) while, simultaneously, a stimulation of testosterone production is observed (47 to 50%, respectively in the absence or presence of LH). The reduction of cAMP levels observed after 5 h is likely to be due to the potentiating effect of the STM factor on the LH-dependent initial rise of the cAMP level which, in turn, induces a desensitization of the Leydig cell adenylate cyclase. This substance is a thermolabile protein (Mr greater than 50 000) produced by the Sertoli cell, independent of FSH and testosterone controls, and different from the LHRH-like substance.

Animals↗
PubMed1986

Rat testis 17 beta-estradiol: identification by gas chromatography-mass spectrometry and age related cellular distribution.

The aromatization of testosterone into 17 beta-estradiol (E2) was assessed in purified Leydig and Sertoli cells from rats aged 10-80 days. E2 was identified by gas chromatography-mass spectrometry (GC-MS) and measured both by radioimmunoassay (RIA) and GC-MS associated with stable isotope dilution. A potent competitive inhibitor of the aromatase activity, 4-hydroxyandrostenedione (4-OH-A) was used to test the enzymatic specificity. The basal aromatase activity was present in both cell types whatever the age of the animals. The basal E2 levels did not vary in Sertoli cells while a gradual increase was noted in Leydig cells until day 40, followed by a slight decrease in mature rats. In 10-day old animals, the aromatase activity was localized in Sertoli cells and highly stimulated by FSH; on day 20, both Sertoli and Leydig cells synthesized E2 although E2 from Sertoli cell origin was still predominant. Starting on day 20 until adulthood, the aromatase activity was under LH control in Leydig cells with a maximum around 40 days. The FSH and LH effects were mediated by cyclic AMP.

Aging↗
PubMed1985

Effect of phorbol ester and phospholipase C on LH-stimulated steroidogenesis in purified rat Leydig cells.

When the phorbol ester, 4 beta-phorbol-12-myristate-13-acetate (PMA) or bacterial phospholipase C (PL-C) is added to a preparation of purified adult rat Leydig cells, containing 2 mM CaCl2, a time- and dose-dependent decreases of LH-stimulated testosterone production is observed. After a 3 h stimulation with oLH (100 ng/ml), PMA (100 ng/ml) and PL-C (1.6 U/ml) do not affect the cell viability or the hCG specific binding, while cAMP accumulation is significantly reduced; cAMP-stimulated steroidogenesis is diminished only in the presence of PL-C. These observations suggest that in vitro: (i) activated Ca2+- and phospholipid-dependent protein kinase is implicated in the regulation of rat Leydig cell steroidogenesis by LH at a step before the adenylate cyclase; (ii) phospholipids play an important role in cAMP-stimulated testosterone synthesis.

Animals↗
PubMed1985

[Male infertility in 1984].

The study of male sterility has not benefited as much from progress in fundamental research as that of female sterility, but nevertheless its diagnosis and, to a lesser extent, its treatment have developed considerably over the past few years. With respect to diagnosis, substantial progress has been made in sperm analysis. The techniques of the spermatogram and the spermocytogram, performed under the conditions defined by David et al. (Feuil. Biol., 15, 47, 1974) allow a better classification of the different anomalies of spermatozoa. Ultrastructural studies now being carried out in several laboratories should provide a more exact description of these anomalies. More precise studies of normal sperm have defined the limits of normality (Schwartz et al., J. Reprod. Fert., 57, 391, 1979). The study of the functional capacities of spermatozoa has also advanced considerably. The postcoital test is still routinely used, but it is subject to many causes of error. For this reason it must be complemented by an in vitro analysis of spermatozoon penetration into the zona pellucida, and possibly of spermatozoon penetration into the hamster ovum (Yanagimashi et al., Biol. Reprod., 15, 471, 1976). With respect to seminal plasma, research on antispermatic antibodies both in men and in women should expend with the help of simpler and more reliable techniques. The study of recently discovered constituents of seminal plasma (oligoelements, acetyl carnitine, specific proteins, etc.) should lead to a more accurate determination of the defective organ.(ABSTRACT TRUNCATED AT 250 WORDS)

Humans↗
PubMed1984

Androgen-binding proteins in sheep epididymis: characterization of a cytoplasmic androgen receptor in the ram epididymis.

An androgen receptor (Rc) was demonstrated in caput, corpus and cauda epididymal cytosols of the ram. This receptor had a high affinity for 5 alpha-dihydrotestosterone (Kd = 5.2 X 10(-9) mol/l) and could be distinguished from the androgen-binding protein (ABP) by several characteristics. On polyacrylamide-gel electrophoresis, Rc had a mobility of 0.37 and ABP 0.61; Rc sedimented in the 9S region of a linear sucrose gradient whereas ABP migrated in the 4.3S region; the molecular weights were 192 000 and 90 000 for Rc and ABP; their isoelectric points were 5.7 and 4.8-5.0; they were proteinaceous components since they were destroyed by proteolytic enzymes and heating (50 degrees C for Rc and 60 degrees C for ABP); they exhibited different half-times of dissociation:20 h at 0 degree C for Rc and 6 min for ABP, which is in agreement with their respective physiological roles, intra- and extracellular transport of androgens. The content of Rc-binding sites in caput epididymis was 18, in corpus 4 and in cauda 22 fmol/mg protein.

Androgen-Binding Protein↗
PubMed1984

Androgen-binding proteins in sheep epididymis: age-related effects on androgen-binding protein, cytosolic androgen receptor and testosterone concentrations. Correlations with histological studies.

The androgen-binding protein (ABP) and the cytosol androgen receptor (Rc) were measured in the epididymis of sheep aged 50, 120 and 200 days. Specific binding protein was not detected at 50 days (infantile); near puberty (120 days), ABP was more concentrated in caput and cauda epididymal cytosols (117 and 183 fmol/mg protein respectively) than in corpus (53 fmol/mg) although Rc levels were low (3-5 fmol/mg). In postpubertal rams (200 days), ABP and Rc concentrations were higher in caput and cauda than in corpus epididymis. Testosterone concentrations at 50 days were not statistically different along the epididymis and varied from 0.3 to 0.8 pmol/mg protein. In 120-day-old animals, testosterone was more concentrated in caput and corpus (0.45 and 0.41 pmol/mg) than in cauda (0.17 pmol/mg); at 200 days, the testosterone contents were low (0.10-0.17 pmol/mg) in all parts of the epididymis. A ten-fold increase in plasma testosterone concentrations was observed between 50 and 200 days (1.31 to 11.71 nmol/l). Histological studies of the epididymis in the three groups of animals showed that the cell differentiation started in the cauda where the principal epithelial cells were higher (47-56 micron) than in the caput (31-38 micron) at 50 days. The principal cells of the caput were two- to threefold higher in postpubertal rams than in infantile lambs, a finding which is correlated with the levels of ABP and Rc. This may suggest an important physiological role of this region in the induction of sperm maturation.

Aging↗