Metabolism of androstenedione by guinea-pig peritoneal macrophages: synthesis of testosterone and 5 alpha-reduced metabolites

Redox features of the cell: a gender perspective

Reactive oxygen and nitrogen species have been implicated in diverse subcellular activities, including cell proliferation,differentiation and, in some instances, cell injury and death. The implications of reactive species inhuman pathology have also been studied in detail. However, although the role of free radicals in the pathogenesis of human diseases has been extensively analyzed in different systems (i.e., in vitro, ex vivo, and in vivo),it is still far from elucidated. In particular, the possible role of gender 4 differences in human pathophysiology associated with reactive species is a promising new field of investigation. Although the complex scenario this presents is still incomplete, important gender-associated "redox features" of cells have already been described in the literature. Here we summarize the different aspects of redox-associated molecules and enzymes in regard to gender differences in terms of the intracellular production and biochemical activity of reactive species. These are often associated with the pathogenetic mechanisms underlying several human morbidities(e.g., degenerative diseases) and can represent a specific target for new pharmacologic strategies. Gender differences may thus pose an important challenge for future studies aimed at the clinical management of diseases characterized by a redox imbalance.

Testosterone is responsible for enhanced susceptibility of males to ischemic renal injury

Female mice are much more resistant to ischemia/reperfusion (I/R)-induced kidney injury when compared with males. Although estrogen administration can partially reduce kidney injury associated with I/R, we demonstrated that the presence of testosterone, more than the absence of estrogen, plays a critical role in gender differences in susceptibility of the kidney to ischemic injury. Testosterone administration to females increases kidney susceptibility to ischemia. Dihydrotestosterone, which can not be aromatized to estrogen, has effects equal to those of testosterone. Castration reduces the I/R-induced kidney injury. In contrast, ovariectomy does not affect kidney injury induced by ischemia in females. Testosterone reduces ischemia-induced activation of nitric oxide synthases (NOSs) and Akt and the ratio of extracellular signal related kinase (ERK) to c-jun N-terminal kinase (JNK) phosphorylation. Pharmacological (Nomega-nitro-L-arginine) or genetic (endothelial NOS or inducible NOS) inhibition of NOSs in females enhances kidney susceptibility to ischemia. Nitric oxide increases Akt phosphorylation and protects Madin-Darby canine kidney epithelial cells from oxidant stress. Antagonists of androgen or estrogen receptors do not affect the gender differences. In conclusion, testosterone inhibits the post-ischemic activation of NOSs and Akt and the ratio of ERK to JNK phosphorylation through non-androgen receptor-medicated mechanisms, leading to increased inflammation and increased functional injury to the kidney. These findings provide a new paradigm for the design of therapies for ischemia/reperfusion injury and may be important to our understanding of the pathophysiology of acute renal failure in pregnancy where plasma androgen levels are elevated.

Influence of blood monocytes and lymphocytes on progesterone production by granulosa cells from small and large follicles in the pig

The objectives of this study were 1) to determine the influence of lymphocytes and monocytes on progesterone secretion by porcine granulosa cells in culture, and 2) to compare the responses of granulosa cells obtained from small versus large follicles. Granulosa cells were cocultured with lymphocytes, monocytes, and unfractionated mononuclear cells in serum-free culture medium. Progesterone content of media and cellular DNA were determined after 6, 12, and 24 hrs of culture. Progesterone production by granulosa cells alone or in coculture with erythrocytes increased (P less than .001) up to 12 hrs and plateaued thereafter. Cells from large follicles produced approximately two-fold (P less than .01) more progesterone as compared to those isolated from small follicles. Cell numbers, as indicated by DNA, did not change with time in any of the cultures. Lymphocytes stimulated (P less than .05) progesterone production by granulosa cells from large follicles but not from small follicles. Similar results were seen when unfractionated mononuclear cells were cocultured with granulosa cells. Monocytes stimulated progesterone production by granulosa cells from both large and small follicles. Lymphocytes and monocytes influence steroid secretion by granulosa cells in the pig in vitro. These effects are not mediated through cell proliferation and are influenced by follicle size.

Postnatal development of the tubular lamina propria and the intertubular tissue in the bovine testis

The postnatal development of intertubular cells and vessels and of the tubular lamina propria was studied in three locations of perfusion-fixed bovine testes from 31 animals ranging from 4 to 78 weeks. The postnatal morphological differentiation of the testis is not uniform, regional differences have to be considered. The intertubular cell population is composed of mesenchyme-like cells, fibrocytes, Leydig cells, peritubular cells and mononuclear cells. In 4- and 8-week-old testes mesenchyme-like cells are the dominating element. These pluripotent cells proliferate by frequent mitoses and are the precursors of Leydig cells, contractile peritubular cells and fibrocytes. Morphologically differentiated Leydig cells are encountered throughout the entire period of postnatal development. In 4-week-old testes degenerating fetal and newly formed postnatal Leydig cells are seen in juxtaposition to each other. From the 8th week on, only postnatal Leydig cells are present. Between 16 and 30 weeks large-scale degeneration of prepuberal Leydig cells is observed. The Leydig cells that survive this degenerative phase constitute the long-lasting adult population. 20-30% (numerically) of all intertubular cells at all ages are free mononuclear cells. These are found as lymphocytes, plasma cells, monocytes, macrophages and light intercalated cells (LIC). The latter are monocyte-derived, Leydig cell-associated typical cells of the bovine testis. The differentiation of the two main components of the tubular lamina propria, (i) basal lamina and (ii) peritubular cell sheath, seems to be effected rather independent from each other and also from hormonal signals important for the development of the germinal cells. The laminated basal lamina reaches nearly 3 micron at 16 weeks and is later on continuously reduced. At 25 weeks the peritubular cells have transformed into contractile myofibroblasts. At this period the germinal epithelium is still in a prepuberal state.

Androgen metabolism by human peritoneal macrophages

Peritoneal macrophages (PM) were obtained by peritoneal dialysis from a regularly menstruating woman with renal failure. Macrophages (10(6) cells) were incubated at 37 degrees C for various periods of time (0-4 hr) in the presence of 14C-androstenedione or 3H-androstenedione and various concentrations (0.06-5.06 microM) of nonradiolabeled androstenedione (A). Testosterone (T) formed was purified by column chromatography, thin layer chromatography, acetylation, and recrystalization to constant 3H:14C ratios. The rate of formation of T from A was linear for nearly 2 hr. Conversion of A to T was linear at cell numbers in the incubation up to 1 x 10(6). The formation of T from A followed Michaelis-Menten kinetics at concentrations of A between 0.06 and 5.06 microM. The apparent Km of the enzyme for A was 0.75 microM and the Vmax for T formation from A in these cells was 33.9 pmol x hr-1 x 10(6) cells-1. PM were obtained also from normal patients (n = 6) and patients with endometriosis (n = 5). The rate of T synthesis from A in PM obtained from patients with endometriosis [527 +/- 263 pmol x hr-1 x 10(6) cells-1 (mean +/- SEM, n = 5)] was similar to that observed in PM obtained from normal patients [518 +/- 226 pmol x hr-1 x 10(6) cells-1 (mean +/- SEM, n = 6)]. We observed a near 30-fold variation in the rate of formation of T from A by PM obtained from different individuals (range 54 to 1580 pmol x hr-1 x 10(6) cells-1). Further study is needed to elucidate the physiologic significance of PM androgen metabolism and its relationship to reproductive function.

Steroid 5 alpha-reductase activity in endothelial cells from human umbilical cord vessels

The metabolism of radiolabeled progesterone and androstenedione was evaluated in endothelial cells from human umbilical cord vein and arteries maintained in culture. The predominant metabolite of progesterone was 5 alpha-pregnane-3,20-dione and that of androstenedione was 5 alpha-androstane-3,17-dione. Thus, the major pathway of progesterone and androstenedione metabolism within these cells is via steroid 5 alpha-reductase. The rate of formation of 5 alpha-pregnane-3,20-dione from progesterone by venous endothelial cells was linear with incubation time up to 4 h and with cell number up to 1.6 X 10(6) cells/ml. The apparent Km of 5 alpha-reductase for progesterone was 0.4 microM; and, the Vmax was 55 pmol 5 alpha-pregnane-3,20-dione formed/mg protein X h. The rate of 5 alpha-androstane-3,17-dione formation from androstenedione also was linear with incubation time up to 4 h. In addition to 5 alpha-androstane-3,17-dione, the metabolism of androstenedione by either venous or arterial cells resulted in the formation of various minor metabolites, including testosterone and 5 alpha-reduced steroids, viz. 5 alpha-dihydrotestosterone, androsterone, isoandrosterone, 5 alpha-androstane-3 alpha, 17 beta-diol, and 5 alpha-androstane-3 beta, 17 beta-diol. Estrogens (i.e. estradiol-17 beta and estrone) were not detected as products of androstenedione metabolism. The formation of these metabolites are indicative that the steroid-metabolizing enzymes present in endothelial cells are: 5 alpha-reductase, 17 beta-hydroxysteroid oxidoreductase, 3 alpha-hydroxysteroid oxidoreductase, and 3 beta-hydroxysteroid oxidoreductase.

Metabolism of testosterone to 17 beta-hydroxy-5 alpha-androstane-3-one and 5 alpha-androstane-3 alpha, 17 beta-diol in alveolar macrophages from rat lung--II. Effects of intratracheal instillation of 3.4 mumol K2Cr2O7

Activity of the steroid 5 alpha-reductase in pulmonary alveolar macrophages from adult male rats has been investigated in vitro. Intratracheal instillation of 3.4 mumol K2Cr2O7 lowered the enzyme activity within 6 h, and the reduction was significant on the subsequent 2, 4 and 7 days. The activity of this enzyme was significantly decreased only 6 and 24 h after instillation when measured in the 800 g supernatant fraction of whole lung. Instillation of 3.4 mumol K2Cr2O7 increased serum levels of corticosterone. Serum levels of triiodothyronine and thyroxine decreased except for a transient increase 3 h after the K2Cr2O7 instillation. Subcutaneous administration of 200 micrograms dexamethasone/100 g b.wt, 200 micrograms/100 g b.wt of testosterone, 17 beta-hydroxy-5 alpha-androstane-3-one (5 alpha-DHT), dehydroepiandrosterone or corticosterone had no effect on the 5 alpha-reductase activity of the pulmonary alveolar macrophages within 12 h. The combined treatment with dexamethasone s.c. and intratracheal instillation of 3.4 mumol K2Cr2O7 reduced the steroid 5 alpha-reductase activity in the pulmonary alveolar macrophages to about 25% of controls. Measurement of the steroid 5 alpha-reductase activity in pulmonary alveolar macrophages as an index of lung damage when exposed to toxic material is discussed.

Metabolism of dehydroisoandrosterone and androstenedione by human A-549 alveolar type II epithelial-like cells

The A-549 cell line was initiated from an explant of human lung carcinoma tissue. The biochemical characteristics of these cells are similar to those of normal alveolar type II epithelial cells. To gain some insight into the steroid-metabolizing capabilities of A-549 cells, the metabolism of tritium-labeled dehydroisoandrosterone and androstenedione by these cells was studied. The metabolism of dehydroisoandrosterone led to the exclusive formation of 5-androstene-3 beta,17 beta-diol. The major product of androstenedione metabolism was testosterone; and, 5 alpha-reduced steroids also were formed, viz. 5 alpha-androstane-3,17-dione, androsterone, isoandrosterone, 5 alpha-dihydrotestosterone, 5 alpha-androstane-3 alpha,17 beta-diol and 5 alpha-androstane-3 beta,17 beta-diol. Estrogens, viz., estrone and estradiol-17 beta, were not products of androstenedione metabolism by A-549 cells. The rates of metabolite formation from either dehydroisoandrosterone or androstenedione were linear as a function of incubation time up to 3 h, and with cell number up to 1 X 10(6) cells/ml. The apparent Km of 17 beta-hydroxysteroid oxidoreductase for dehydroisoandrosterone was 11 microM, and that for androstenedione was 13 microM. The predominant formation of 5-androstene-3 beta,17 beta-diol from dehydroisoandrosterone, and testosterone from androstenedione is a likely indication that the principal C19-steroid-metabolizing enzyme in A-549 cells is 17 beta-hydroxysteroid oxidoreductase; the other steroid-metabolizing enzymes expressed in these cells are 5 alpha-reductase, 3 beta-hydroxysteroid oxidoreductase and 3 alpha-hydroxysteroid oxidoreductase. The findings of this study demonstrate that A-549 cells express steroid-metabolizing enzymatic activities that are qualitatively similar to those found in other human pneumonocytes and human lung tissue, except for 3 beta-hydroxysteroid oxidoreductase-5----4-isomerase activity, which is not expressed in these cells with dehydroisoandrosterone as the substrate.

Stage-specific inhibition of interstitial cell testosterone secretion by rat seminiferous tubules in vitro

The stage-specific influence of the secretions from rat seminiferous tubules on the LH-stimulated testosterone production by rat Leydig cells in vitro was studied. The spent media from incubated seminiferous tubules (SMST) from stages VII-VIII of the seminiferous epithelial cycle caused about 50% inhibition of the LH-dependent testosterone production by a crude preparation of rat interstitial cells. The SMST from other stages had no effect on testosterone production. Mixed tubules of unidentified stages gave an intermediate response. When SMST from ten different stages of the seminiferous wave were compared, the most pronounced inhibitory activity was found in stages VI and VIII-XI, while SMST from stages I, VII and XIII-XIV had no inhibitory effects on interstitial cell testosterone production. No stimulation was found in this system. Prolonged incubation of the interstitial cells with SMST from stages VIII-XI resulted in loss of inhibitory activity after 12 h of incubation. Maximum inhibitory activity was noted after 3 h of incubation. The inhibitory activity of the SMST from stages VIII-XI was retained after prolonged dialysis, and was unchanged after heating the medium at 60 degrees C for 1 h. The activity did not seem to be due to the presence of proteolytic enzymes, since it was not influenced by addition of protease inhibitors. SMST from stages VIII-XI had no effect on the metabolism of [3H]testosterone added to the interstitial cell preparations. No inhibitory effect was observed when Leydig cells were incubated with dibutyryl cAMP instead of LH, suggesting an early influence on the LH-receptor-adenylate cyclase chain of events.(ABSTRACT TRUNCATED AT 250 WORDS)

The mononuclear phagocyte system of the mouse defined by immunohistochemical localization of antigen F4/80: macrophages of endocrine organs

Macrophages of endocrine organs have been identified by immunohistochemical localization of the macrophage-specific antigen F4/80. F4/80+ cells line vascular sinuses and capillaries in anterior and posterior pituitary, adrenal cortex, corpus luteum, parathyroid, pineal gland, and islets of Langerhans. In testis approximately 20% of interstitial cells are F4/80+. F4/80+ cells infiltrate corpus luteum in increased numbers during luteolysis.

Metabolism of testosterone to 17 beta-hydroxy-5 alpha-androstane-3-one and 5 alpha-androstane-3 alpha, 17 beta-diol in alveolar macrophages from rat lung

5 alpha-Reduction of testosterone was observed in lung cells obtained by bronchoalveolar lavage (greater than 95% macrophages) from the rats. This activity was inhibited by progesterone and corticosterone. Production of 17 beta-hydroxy-5 alpha-androstane-3-one and 5 alpha-androstane-3 alpha, 17 beta-diol from testosterone was higher in rat pulmonary alveolar macrophages than by the 800 g supernatant fraction of whole lung homogenate from the same animals. Alveolar macrophages from rats treated with the 5 alpha-reductase inhibitor 17 beta-N,N-diethylcarbamoyl-4-aza-4-methyl-5 alpha-androstane-3-one (5 mg/100 g b.w., s.c.) showed decreased metabolism of testosterone to 17 beta-hydroxy-5 alpha-androstane-3-one and 5 alpha-androstane-3 alpha, 17 beta-diol 4 h after treatment. This metabolism was also decreased in alveolar macrophages from rats exposed to potassium dichromate by intratracheal instillation. When bovine alveolar macrophages were incubated with potassium dichromate, 5 alpha-reduction of testosterone decreased significantly. The function of steroid 5 alpha-reduction in alveolar macrophages is currently not known.

Conversion of androstenedione to testosterone and other androgens in guinea-pig alveolar macrophages

Alveolar macrophages obtained by bronchoalveolar lavage of lungs of male and female guinea pigs were incubated with tritium-labelled androstenedione to evaluate the steroid metabolizing enzymes in these cells. The radiolabeled metabolites were isolated and thereafter characterized as testosterone, 5 alpha-androstanedione, 5 alpha-dihydrotestosterone, androsterone, isoandrosterone, 5 alpha-androstane-3 alpha, 17 beta-diol and 5 alpha-androstane-3 beta, 17 beta-diol. Thus, the following androstenedione metabolizing enzymes are present in guinea-pig alveolar macrophages: 17 beta-hydroxysteroid dehydrogenase, 5 alpha-reductase, 3 beta-hydroxysteroid dehydrogenase and 3 alpha-hydroxysteroid dehydrogenase. The predominant androstenedione metabolizing enzyme activity present in alveolar macrophages was 17 beta-hydroxysteroid dehydrogenase. The rate of testosterone formation increased with incubation time up to 4 h, and with macrophage number up to 1.6 X 10(7) cells per ml. Androstenedione metabolism was similar in alveolar macrophages obtained both from male and female guinea pigs. These results suggest that alveolar macrophages may be a site of peripheral transformation of blood-borne androstenedione to biologically potent androgens in vivo and, therefore, these cells may contribute to the plasma levels of testosterone in the guinea pig.