PubMed Health⌕ Search

Biomedical subjects

J R McFarlane

Publications and source records attributed to J R McFarlane.

At least 19 recordsLinked to original sources
PubMed1999

Serum activin A and follistatin concentrations during human pregnancy: a cross-sectional and longitudinal study.

Activin A, a dimer of the betaA-subunit of inhibin, has been shown to have multiple biological activities and sites of production. Follistatin is a high-affinity binding protein for activin, which neutralizes its activity. This study provides the first data, using a cross-sectional design, on the measurement of both these proteins in the maternal circulation of a large cohort of women (6-39 weeks of gestation, n = 2-20 women/time point) during normal pregnancies, and confirms that similar patterns are seen in nine women studied longitudinally during pregnancy. The concentrations of total activin A were measured using a specific two-site enzyme-linked immunosorbent assay (ELISA), and a new radioimmunoassay for measuring total follistatin in serum utilizing dissociating reagents to eliminate the interference of activin is described. At 38-39 weeks gestation, both activin A and follistatin concentrations rose to a peak (4.59 +/- 0.54 ng/ml and 72.7 +/- 3.31 ng/ml, respectively). The activin A and follistatin concentrations were highly correlated both in the cross-sectional study (P <0.0001) and in individual women in the longitudinal study (P <0.05-0.0001). Concentrations of follistatin showed a greater increase in the second trimester of pregnancy relative to activin A concentrations. The parallel increase in the secretion of these two proteins throughout pregnancy probably reflects feto-placental secretion.

Activins↗
PubMed1999

Uterine milk protein, a novel activin-binding protein, is present in ovine allantoic fluid.

Activins are pluripotent growth factors that have recently been shown to be present in placental and fetal membrane preparations. Our previous studies have identified and purified activin A from ovine amniotic and allantoic fluids. In this study, ligand blots of side fractions from the isolation of activin A from allantoic fluid suggested the presence of activin-binding proteins other than follistatin. Further purification of one of these fractions involved two sequential reverse phase HPLC steps and a Superose 12HR fractionation. SDS-PAGE revealed a single protein band of 55 kDa, which was identified by NH2-terminal sequencing as ovine uterine milk protein (UTMP), a member of the serine protease inhibitor (serpin) superfamily of proteins. Further binding studies, using ligand blot techniques and Superose 12HR fractionation in the presence of [125I]activin, demonstrated UTMP to be an activin-binding protein with a lower affinity for activin than that of follistatin. A study of the specific binding behavior of UTMP to activin, using surface plasmon resonance, revealed an apparent equilibrium dissociation constant (Kd) of 49 +/- 25 nM, compared with the follistatin-activin Kd of 379 +/- 51 pM. Similar to another activin-binding protein, alpha2-macroglobulin, UTMP was unable to neutralize the bioactivity of activin in a bioassay based on the capacity of activin to inhibit the proliferation of an MPC-11 plasmacytoma cell line. The high concentrations of this protein in uterine fluid during pregnancy and its ability to bind activin suggest that UTMP may act as a low affinity, high capacity binding protein to sequester activin in the local uterine environment.

Activins↗
PubMed1999

A switch in the cellular localization of macrophage migration inhibitory factor in the rat testis after ethane dimethane sulfonate treatment.

Macrophage migration inhibitory factor (MIF), one of the first cytokines to be discovered, has recently been localized to the Leydig cells in adult rat testes. In the following study, the response of MIF to Leydig cell ablation by the Leydig cell-specific toxin ethane dimethane sulfonate (EDS) was examined in adult male rats. Testicular MIF mRNA and protein in testicular interstitial fluid measured by ELISA and western blot were only marginally reduced by EDS treatment, in spite of the fact that the Leydig cells were completely destroyed within 7 days. Immunohistochemistry using an affinity-purified anti-mouse MIF antibody localized MIF exclusively to the Leydig cells in control testes. At 7 days post-EDS treatment, there were no MIF immunopositive Leydig cells in the interstitium, although distinct MIF immunostaining was observed in the seminiferous tubules, principally in Sertoli cells and residual cytoplasm, and some spermatogonia. A few peritubular and perivascular cells were also labelled at this time, which possibly represented mesenchymal Leydig cell precursors. At 14 and 21 days, Sertoli cell MIF immunoreactivity was observed in only a few tubule cross-sections, while some peritubular and perivascular mesenchymal cells and the re-populating immature Leydig cells were intensely labeled. At 28 days after EDS-treatment, the MIF immunostaining pattern was identical to that of untreated and control testes. The switch in the compartmentalization of MIF protein at 7 days after EDS-treatment was confirmed by western blot analysis of interstitial tissue and seminiferous tubules separated by mechanical dissection. These data establish that Leydig cell-depleted testes continue to produce MIF, and suggest the existence of a mechanism of compensatory cytokine production involving the Sertoli cells. This represents the first demonstration of a hitherto unsuspected pattern of cellular interaction between the Leydig cells and the seminiferous tubules which is consistent with an essential role for MIF in male testicular function.

Animals↗
PubMed1999

Sexual differentiation of oestradiol-LH positive feedback in a marsupial.

The surge of LH that induces ovulation in mammals showing spontaneous ovulation is precipitated by the positive feedback of increasing oestrogens from the developing follicles in the ovary. In eutherians, exogenous oestrogens can mimic this effect by eliciting an LH surge in females, but not usually in males. The absence of a positive LH response to eutherian males is either due to an acute suppression by the secretory products of the testes during adulthood or the permanent disabling of the system by testosterone during early development. This phenomenon is examined in tammar wallabies, Macropus eugenii. The results show that the oestradiol-LH positive feedback response is sexually dimorphic in this marsupial. A surge in plasma LH occurred between 15 and 28 h after injection of 2.5 micrograms oestradiol benzoate kg-1 in 13 of 16 intact females and 4 of 4 ovariectomized females, but in none of 11 intact males. Five females each implanted with a 100 mg testosterone pellet 3 months earlier failed to produce an LH surge. Four males castrated in adulthood and three adult males castrated before puberty also failed to show an LH surge. However, three males castrated 24-26 days after birth showed an unambiguous LH surge when challenged with oestradiol benzoate during adulthood. Thus, in tammar wallabies, the ability to generate an LH surge to oestradiol is a sexually dimorphic response that is suppressed in the male by the organizational effects of the testes in early life and presumably supplemented by an inhibitory effect of circulating testosterone in adulthood.

Animals↗
PubMed1999

Isolation and characterization of rat sperm tail outer dense fibres and comparison with rabbit and human spermatozoa using a polyclonal antiserum.

Rat outer dense fibres were isolated from cauda epididymal spermatozoa using mechanical and chemical dissection methods. Sperm tail isolation procedures were monitored by phase-contrast microscopy and the purity of the outer dense fibres was verified by electron microscopy. SDS-PAGE of isolated outer dense fibres revealed at least nine Coomassie brilliant blue stained bands, and 12 silver staining bands. The most abundant proteins were a large band between 26.5 and 32.5 kDa, and 84 kDa, 21.5 kDa and 15.5 kDa bands. The amino acid composition of the total rat outer dense fibres and seven isolated proteins showed similar compositions, being abundant in aspartic and glutamic acid, serine, glycine and leucine. However, the content of cysteine and proline was highly variable among the isolated proteins. Immunofluorescence microscopy demonstrated that a polyclonal antiserum to isolated rat outer dense fibres showed positive staining localized to the mid-piece of rat and rabbit spermatozoa. However, there was crossreactivity in the principal piece as well as the mid-piece of the human spermatozoa. The antiserum also showed crossreactivity in the perforatorium of rat sperm heads and the acrosome and equatorial segment of rabbit sperm heads. These data indicate that it is technically possible to isolate proteins from the outer dense fibres that will enable further studies of the amino acid sequences of sperm tail proteins.

Amino Acids↗
PubMed1998

Identification of a rat testis-specific gene encoding a potential rat outer dense fibre protein.

Screening of a rat testis expression library with an antiserum specific for an outer dense fibre (ODF) has led to the identification of a gene encoding for a putative protein previously unknown as a component of the sperm tail. This gene has been designated tpx-1 by virtue of its homology with the mouse and human gene of the same name (79 and 73%, respectively). The tpx-1-like gene encoded a 1.6-kb mRNA and a 243-amino-acid protein that had significant homology with members of the cysteine-rich secretory protein (CRISP) family and partial homology with several venom/allergen proteins from both plants and insects. During rat spermatogenesis, the tpx-1-like transcript was first detected by in situ hybridization in low levels in late pachytene spermatocytes. Low but detectable levels of expression continued up to step 5 round spermatids, after which expression levels increased dramatically to a maximum in step 11-12 spermatids. Progressively decreasing levels of expression were detected in up to step 17 elongating spermatids. Testicular somatic cells did not contain detectable tpx-1-like transcript. This pattern of expression is consistent with published data on the development of the ODF in spermatogenesis and, when taken together with a comparison of the predicted amino acid sequence of tpx-1 with the amino acid analysis of a 29-kDa rat ODF protein, suggests that the tpx-1-like gene may encode for this protein.

Amino Acid Sequence↗
PubMed1998

Ovine allantoic fluid contains high concentrations of activin A: partial dissociation of immunoactivity and bioactivity.

In a preliminary study, allantoic fluid collected from pregnant sheep across gestational ages of 20-124 days contained significantly higher levels of activin bioactivity (189 +/- 74 ng/ml, mean +/- SE) than did amniotic fluid (3.2 +/- 0.6 ng/ml). Using a combination of chromatography steps, we isolated from 5 L of allantoic fluid approximately 612 microg of immunoactive activin, which eluted over 10 fractions from a C8 reversed-phase column. When these fractions were assayed in a rat pituitary cell culture bioassay, in a specific RIA, and in an activin A two-site ELISA, the RIA activity was skewed to the less hydrophobic side of the activin profile, while the bioactivity was skewed to the more hydrophobic forms. The activity measured in the two-site ELISA more closely matched the mass of activin as determined by laser densitometry. Amino-terminal sequencing of fractions containing either peak immunoactivity or bioactivity showed each to be identical to activin A. This was confirmed by internal sequences from a fraction that eluted in the area of overlapping immunoactivity and bioactivity. A peptide containing at least 18 amino acids at its amino terminus, which were identical to the conserved region of the acute-phase protein serum amyloid A, was identified in the most immunoactive activin fractions.

Activins↗
PubMed1998

Localization of follistatin in the rat testis.

The cellular localization of the activin-binding protein, follistatin, in the rat testis has been a matter of some controversy with different investigators claiming that Sertoli cells, Leydig cells or germ cells are the primary cell types containing this protein. The localization of mRNA encoding follistatin was re-examined using reverse transcription-polymerase chain reaction (RT-PCR) and in situ hybridization as well as the distribution of follistatin by immunohistochemistry. The results demonstrate that mRNA encoding follistatin is located in many germ cells including type B spermatogonia, primary spermatocytes with the exception of the late leptotene and early zygotene stages, and spermatids at steps 1 to 11. It is also found in Sertoli cells and endothelial cells but not in Leydig cells. Immunohistochemistry, using two different antisera to follistatin, showed that this protein was localized to spermatogonia, primary spermatocytes at all stages except the zygotene stage, spermatids at all stages and to endothelial cells and Leydig cells in the intratubular regions. The failure to detect mRNA for follistatin in Leydig cells using RT-PCR and in situ hybridization suggests that the immunohistochemical localization in these cells reflects binding of follistatin produced elsewhere. The widespread localization of follistatin, taken together with its capacity to neutralize the actions of activin, may indicate that follistatin modulates a range of testicular actions of activin, many of which remain unknown.

Animals↗
PubMed1997

Developmental response by Leydig cells to acidic and basic fibroblast growth factor.

The present study examines the effects of acidic (FGF-1) and basic (FGF-2) fibroblast growth factors on Leydig cell steroidogenesis by cells from 5-, 21- and 90-day-old rats. These ages represent three distinct time points in Leydig cell development: fetal Leydig cells (day 5), immature Leydig cells (day 21) and adult Leydig cells (day 90). The results demonstrate that the actions of the two growth factors on steroidogenesis are developmentally regulated, and require the presence of heparan sulphate proteoglycans (HSPG). FGF-1 and FGF-2 both had stimulatory effects on basal, but not maximally LH-stimulated, testosterone production by fetal Leydig cells, and both growth factors stimulated basal 5 alpha-androstane-3 alpha, 17 beta-diol production by immature Leydig cells. These effects were mediated by heparan sulphate-proteoglycans (HSPG), as they were blocked by the addition of protamine sulphate and sodium chlorate. FGF-1 and FGF-2 had no effect on basal testosterone production by adult Leydig cells, however, FGF-1 alone inhibited LH-stimulated testosterone production by adult Leydig cells in a dose-dependent manner. These data demonstrate that the effects of FGF-1 and FGF-2 are dependent on the specific stage of Leydig cell differentiation and development and may vary accordingly. Furthermore, although FGF-1 and FGF-2 are closely related structurally, a different effect of these two growth factors can be observed on the same type of Leydig cells. The data therefore suggest that these growth factors may have different but specific roles in the regulation of Leydig cell steroidogenesis, at different stages of development.

Age Factors↗
PubMed1997

Isolation and partial characterization of tammar wallaby luteinizing hormone and development of a radioimmunoassay.

Tammar wallaby (Macropus eugenii) luteinizing hormone (LH) was purified from pituitaries collected from wild and captive populations by salt sequential precipitation, ion exchange chromatography and gel filtration. Pituitary tissue (5 g) yielded 1.8 mg of purified wallaby luteinizing hormone (ME-14B), as verified by sodium dodecyl sulfate polyacrylamide gel electrophoresis (SDS-PAGE). A heterologous radioimmunoassay has been developed for measurement of LH in plasma of marsupials using a monoclonal antibody raised against bovine LH (518B7). This assay system was able to measure basal LH concentrations in male and female tammars and detected a significant rise in plasma LH in response to oestradiol benzoate in female tammars and luteinizing hormone-releasing hormone (LHRH) in males. Parallel dose-response curves were also obtained from pituitary extracts from four other species of marsupial (brushtail possum, Trichosurus vulpecula; brown antechinus, Antechinus stuartii; kowari, Dasyuroides byrnei; and Eastern pygmy possum, Cercartetus nanus) in this assay, which suggests its usefulness in the measurement of LH in other marsupial species.

Animals↗
PubMed1997

Isolation and characterization of human and rabbit sperm tail fibrous sheath.

Using mechanical and chemical dissection methods, fibrous sheath was isolated both from normal ejaculated human spermatozoa and from rabbit cauda epididymal spermatozoa. The same techniques did not produce a pure preparation of fibrous sheath from ejaculated rabbit spermatozoa, suggesting that further cross-linking and stabilization of sperm structures occurs in response to components of the seminal plasma. The isolation procedures were monitored by phase contrast microscopy and the purity of the fibrous sheath was verified by electron microscopy. Sodium dodecyl sulphate-polyacrylamide gel electrophoresis (SDS-PAGE) of isolated human fibrous sheath revealed at least 14 protein bands of which the most intensely stained were of molecular weight 84, 72, 66.2, 57, 32 and 28.5 kDa. The rabbit fibrous sheath revealed at least 10 protein bands, of which the most intensely stained were 35.2, 32.7 and 28.5 kDa. The amino acid composition of the purified fibrous sheath from human and rabbit spermatozoa was similar, being high in aspartic acid and/or asparagine and glutamic acid and/or glutamine, serine, alanine, leucine, lysine and glycine, but low in histidine, tyrosine and isoleucine. This composition is similar to that reported for the rat and suggests that mammalian sperm tail fibrous sheaths are composed of similar types of proteins, although there are apparent differences in protein components between species.

Amino Acids↗
PubMed1997

Source of inhibin in ovine fetal plasma and amniotic fluid during late gestation: half-life of fetal inhibin.

Immunoactive inhibin (ir-inhibin) concentrations were determined in chronically catheterized sheep between 120 and 145 days gestation. Maternal plasma ir-inhibin concentrations remained basal (0.19 +/- 0.05 ng/ml) throughout the period of study. Immunoactive inhibin concentrations in male and female fetal plasma were elevated above those observed in maternal plasma, with the concentrations in plasma of male fetuses (7.38 +/- 0.04 ng/ml) being significantly greater (p < 0.001) than those in female fetuses (1.07 +/- 0.14 ng/ml). The concentrations of ir-inhibin in amniotic fluid of ewes bearing male fetuses (10.93 +/- 1.55 ng/ml) were significantly greater than in ewes bearing female fetuses (2.81 +/- 0.32 ng/ml; p < 0.05) but not significantly different from the concentrations in male fetal plasma. Immunoactive inhibin concentrations decreased following surgery in gonadectomized fetuses, to 3.25 +/- 0.99 ng/ml within 6 h, and remained at a mean value of 0.75 +/- 0.38 ng/ml from 24 h after gonadectomy. The half-life of circulating inhibin in fetal plasma, estimated from the decay curve during the first 6 h after surgery, was 3.94 +/- 0.88 h. There was a significant (p < 0.05) decrease in the concentration of ir-inhibin in amniotic fluid after gonadectomy; however, this decrease occurred gradually over 7 days, and ir-inhibin concentrations did not fall to those concentrations observed in fetal circulation at any time after gonadectomy. It is concluded that the major source of circulating ir-inhibin in male fetal plasma, but not in amniotic fluid, is the gonads.

Amniotic Fluid↗
PubMed1997

Inhibin, activin and follistatin bind preferentially to the transformed species of alpha 2-macroglobulin.

alpha 2-Macroglobulin (alpha 2-M), a major serum glycoprotein, has been implicated as a low-affinity binding protein for inhibin and activin. In serum, alpha 2-M exists as two major species, a native form that is abundant and stable, and a transformed ('fast') species that is rapidly cleared from the circulation via alpha 2-M receptors. In this study inhibin, activin and their major binding protein follistatin were investigated for their ability to bind to the native or transformed species of purified human alpha 2-M. Using native PAGE and size exclusion chromatography, radiolabelled inhibin, activin and follistatin bound to the transformed alpha 2-M. Inhibin and follistatin did not bind significantly to native alpha 2-M, whereas activin was able to bind to the native species but with a lower capacity compared with that to transformed alpha 2-M. Under reducing conditions, binding of these hormones to alpha 2-M was abolished. These findings implicate alpha 2-M as a mechanism whereby inhibin, activin and follistatin may be removed from the circulation through alpha 2-M receptors, but also whereby activin can be maintained in the circulation through its ability to bind to native alpha 2-M.

Activins↗
PubMed1996

Evidence that heparin binding autocrine factors modulate testosterone production by the adult rat Leydig cell.

Androgen production by adult rat Leydig cells is stimulated by pituitary LH but can also be modulated in vitro by paracrine stimulatory and inhibitory factors, many of which belong to growth factor families. Their actions are mediated through cell surface or extracellular matrix proteoglycans and the aim of this study was to determine the role of cell surface heparan sulfate proteoglycans in the regulation of testosterone secretion by adult rat Leydig cells. The presence of sodium chlorate (25 mM) and protamine sulfate (10 micrograms/ml) inhibited testosterone production by LH stimulated cells by over 50%, but had no effect on unstimulated cells. The LH responsiveness and testosterone production returned to normal after these agents were removed from the culture media. No significant difference in LH receptor numbers at the end of the culture period was seen between sodium chlorate treated and untreated cells. Testosterone production by dibutryl-cAMP stimulated Leydig cells was also inhibited by sodium chlorate. The addition of heparin inhibited testosterone production by LH stimulated cells in a dose-dependent manner, however, in unstimulated Leydig cells heparin stimulated testosterone production to up to 50% of that seen in LH stimulated cells. These data suggest that cell surface heparan sulfate proteoglycans modulate testosterone production by adult Leydig cells in vitro, and that this may involve the autocrine actions of heparin binding growth factors on the Leydig cells.

Animals↗
PubMed1996

Functional integrity of granulosa cells from polycystic ovaries.

OBJECTIVE: The polycystic ovarian syndrome is frequently associated with human infertility and is a partially characterized syndrome of unknown aetiology. The aim of this study was to describe the functional integrity of granulosa cells from polycystic ovaries. PATIENTS: Follicular aspirates were collected from polycystic ovaries of ovulatory (n = 24) and anovulatory (n = 7) patients. Follicular aspirates were also collected from normal ovaries of untreated (n = 24) and superovulated (n = 10) subjects. All patients were enrolled for the recovery of their oocytes for in vitro maturation and fertilization. MEASUREMENTS: FSH receptors and apoptosis were measured in the granulosa cells of the different patients. FSH-stimulated oestradiol and LH-stimulated progesterone production by granulosa cells of the different patients were also measured. RESULTS: The binding of 125I-labelled human recombinant FSH to granulosa cells from anovulatory subjects with polycystic ovaries was significantly higher than that found in granulosa cells from normal (180%) and superovulated (163%) ovaries. However, the ligand binding to granulosa cells from ovulatory subjects with polycystic ovaries was not significantly higher than that found in normal granulosa cells. Also, granulosa cells obtained from anovulatory subjects with polycystic ovaries cultured with FSH produced more oestradiol than normal granulosa cells but oestradiol production was similar to that of granulosa cells from superovulated ovaries (mean +/- SEM, 224.94 +/- 22.02, 24.23 +/- 2.92, 211.87 +/- 50.39 nmol/l/24 h, respectively). Flow cytometric analysis showed that the proportions of viable and apoptotic granulosa cells (mean +/- SDM, 70 +/- 5 and 7 +/- 1%, respectively) were similar in normal subjects and in those with polycystic ovaries. CONCLUSION: We conclude that most of the granulosa cells of polycystic ovaries are healthy and non-apoptotic, expressing high levels of FSH receptors and highly responsive to this hormone in culture. These data provide direct evidence that most of the follicles of polycystic ovaries are not atretic.

Adult↗
PubMed1996

Microtubule-associated protein-2 in the rat testis: a novel site of expression.

The testis is one of the most abundant sources of microtubule networks. These networks include mitotic and meiotic spindles, the spermatid manchette and axoneme, and the Sertoli cell cytoskeleton. Microtubules are composed of alpha- and beta-tubulin subunits that are polymerized and stabilized by a variety of microtubule-associated proteins (MAPs). One of these, MAP2, has been extensively characterized as a brain-specific protein with the capacity to bind tubulin, cAMP-dependent kinase, and calmodulin. MAP2 mRNA is processed into at least two variants encoding proteins designated MAP2a, MAP2b, and MAP2c. Of the 5.7 kb of coding sequence in the 9-kb mRNA that encodes MAP2a and MAP2b, a deletion of approximately 4 kb produces mRNA encoding MAP2c, which consists of only the N- and C- terminal regions of MAP2b. To determine whether MAP2 was present in the rat testis, microtubule preparations were isolated from adult rat testis and brain by means of taxol-mediated polymerization and analyzed by gel filtration, ELISA, and Western blotting using polyclonal and monoclonal antibodies reactive with MAP2. A 74-kDa protein corresponding to MAP2c was detected in the testis. These results were confirmed by Northern blot analysis of total RNA from adult rat brain and testis with cDNA probes that distinguish between the known MAP2 splice variants. The predominant mRNAs in testis of 6 kb and 2.5-3.5 kb corresponded to MAP2c. A single 6-kb mRNA with the potential to encode MAP2c was detected in enriched preparations of immature Sertoli cells and adult Leydig cells. Round spermatids contained at least two MAP2 mRNAs between approximately 2.5 and 3.5 kb in size that displayed a stage-specific pattern of expression. Immunohistochemistry showed a MAP2-like protein in both somatic and germ cells, with a particularly distinct localization within the cytoplasm of primary and secondary spermatocytes at stage XIV of the seminiferous cycle during meiotic metaphase. In addition to cytoplasmic staining, a novel localization of this protein was observed in the nucleus of many testicular cells.

Animals↗
PubMed1996

Macrophage migration inhibitory factor production by Leydig cells: evidence for a role in the regulation of testicular function.

Macrophage migration inhibitory factor (MIF), described originally as a product of activated T lymphocytes, recently has been found to be released by monocytes/macrophages and the anterior pituitary gland. Immunohistochemical studies of the adult rat testis using an affinity-purified polyclonal antimurine MIF antibody demonstrated strong staining for MIF in Leydig cells and their putative precursors. Peritubular myoid cells and the seminiferous epithelium were negative for MIF staining; however, a weak reaction around the heads of elongated spermatids also was observed. The expression of MIF messenger RNA and protein in whole rat testis was demonstrated by Northern blot and Western blot analyses, respectively. Both MIF messenger RNA and protein immunoreactivity in Leydig cells was observed in testes obtained from long term hypophysectomized rats. Significant concentrations of intracellular MIF were detected in lysates of the TM3 Leydig cell line (7.23 +/- 2.6 pg/microgram protein), and testicular interstitial fluid contained 14.7 +/- 1.6 ng/ml MIF protein, as measured by MIF-specific enzyme-linked immunosorbent assay. To gain insight into the possible biological role of MIF in the testis, cultures of adult rat seminiferous tubules and purified Leydig cells were incubated together with recombinant murine MIF (rMIF). Neither rMIF (50 ng/ml) nor a neutralizing anti-MIF antiserum was found to affect basal or LH-stimulated Leydig cell steroidogenesis in vitro. However, a dose-dependent decrease in the secretion of inhibin by the seminiferous tubules was observed at rMIF concentrations ranging from 10-100 ng/ml. Taken together, these data indicate that Leydig cells produce MIF in vivo and suggest an important regulatory role for this newly discovered mediator of testicular function.

Animals↗