Inhibiting Substance Research Articles

Mullerian inhibiting substance in humans: normal levels from infancy to adulthood.

Mullerian-inhibiting substance (MIS) is a gonadal hormone synthesized by Sertoli cells of the testis and granulosa cells of the ovary. To facilitate the use of MIS for the evaluation of intersex disorders and as a tumor marker in women with MIS-expressing ovarian tumors, we measured MIS in 600 serum samples from males and females. These data show that mean MIS values for males rise rapidly during the first year of life and are highest during late infancy, then gradually decline until puberty. In contrast, MIS values in females are lowest at birth and exhibit a minimal increase throughout the prepubertal years. Whereas MIS is uniformly measurable in all prepubertal boys studied, it is undetectable in most prepubertal female subjects. These data reveal an easily discernible sexually dimorphic pattern of expression and confirm that MIS can be used as a testis-specific marker during infancy and early childhood. MIS values that are above the upper limits for females are discriminatory for the presence of testicular tissue or ovarian tumor, and those below the lower limits for males are consistent with dysgenetic or absent testes or the presence of ovarian tissue. These data will enable normal and abnormal levels of MIS to be differentiated with higher precision and will facilitate the use of MIS in the management of gonadal disorders.

Müllerian inhibiting substance

Müllerian inhibiting substance

Ejaculate substances that affect female insect reproductive physiology and behavior: Honest or arbitrary traits?

Males of many insect species transfer, within the ejaculate, substances that render females sexually unreceptive and promote ovulation and oviposition. In this paper, I propose hypotheses for the evolutionary origin of these substances and discuss how selection may have modified them subsequently. Two hypotheses are considered. According to the handicap hypothesis, receptivity inhibition substances (RIS) and ovulation and oviposition stimulating substances (OSS) are used by females to evaluate the quality of the ejaculate received, the last being a function of the genetic or phenotypic quality of sperm, and of the nutritional or protective (to the female or her offspring) quality of its chemical constituents. This hypothesis predicts that RIS and OSS must be reliable indictors of ejaculate quality, reliability being the result of the high RIS/OSS production costs and specific chemical composition. The second hypothesis proposes that RIS/OSS are selected only in regard to their effectiveness as stimulators through Fisher's sexual selection runaway process. According to this hypothesis, RIS/OSS are not necessarily are reliable indicators of sperm or ejaculate chemical constituents quality (other than ability to stimulate), and must show a high species-specificity (rapid evolutionary divergence). Empirical evidence is reviewed, and the kind of information necessary to evaluate the relative importance of each hypothesis is indicated.

Müllerian inhibiting substance: New perspectives and future directions

MIS, as a differentiate and antiproliferative agent, is precisely regulated, for example, at the transcriptional level by such transacting factors as SRY, and posttranslationally by testosterone. Processing of MIS most likely requires an as yet unknown in vivo protease which probably serves to control cleavage of MIS and hence its activation at specific sites wherein a localized program of cell death is initiated via a receptor mediated event. Progress has been made in understanding the molecular domains of MIS; current efforts are focused on characterizing the wild type MIS receptor as well as cloning and expressing the MIS receptor. We need now to understand how to target and efficiently activate MIS at its projected site of action. We must focus, after structural analysis of its receptor, on elucidating the MIS initiated intracellular signals which result in localized cell inhibition. Understanding of these mechanisms will permit design of antitumor agents and therapeutic strategies. Similarly, understanding regulation of MIS expression may lead to therapeutic induction of expression in those states where depressed expression is associated with tumorigenesis, sexual ambiguity, or infertility.

Mullerian inhibiting substance: a gonadal hormone with multiple functions

Mullerian inhibiting substance: a gonadal hormone with multiple functions

Mullerian inhibiting substance: a gonadal hormone with multiple functions.

Mullerian inhibiting substance (MIS) is the gonadal hormone that causes regression of the Mullerian ducts, the anlagen of the female internal reproductive structures, during male embryogenesis. MIS is a member of the large transforming growth factor-beta (TGF beta) multigene family of glycoproteins that are involved in the regulation of growth and differentiation. The proteins in this gene family are all produced as dimeric precursors and undergo posttranslational processing for activation, requiring cleavage and dissociation to release bioactive C-terminal fragments. Similarly, the 140 kilodalton (kDa) disulfide-linked homodimer of MIS is proteolytically cleaved to generate its active C-terminal fragments. The sexually dimorphic expression of MIS in Sertoli cells of the testis and granulosa cells of the ovary is critical for normal differentiation of the internal reproductive tract structures. A number of extra-Mullerian functions such as control of germ cell maturation and gonadal morphogenesis, induction of the abdominal phase of testicular descent, suppression of lung maturation, and growth inhibition of transformed cells have also been proposed for this growth-inhibitory hormone and will be discussed. This article will summarize the current understanding of the biology and multiple functions of MIS including its activation, regulation, and mechanism of action and discuss areas of interest in ongoing research.

Müllerian inhibiting substance in the diagnosis and management of intersex and gonadal abnormalities

Müllerian inhibiting substance (MIS), a gonadal hormone important in sexual differentiation, is high (10 to 70 ng/mL) in human male serum postnatally for several years before declining during the peripubertal period, but is undetectable in female serum until the onset of puberty. The sexually dimorphic secretion of MIS suggested possibilities for its use in several clinical settings. Thirty-one patients with intersex and gonadal anomalies from 17 institutions were therefore evaluated between 1989 and 1992 with an MIS enzyme-linked immunosorbent assay (ELISA). Serum MIS levels correlated with the presence of testicular tissue in two patients with suspected anorchia, five patients with male pseudohermaphroditism, and eight other intersex patients with undescended testes, dysgenetic gonads, or ovotestes. In these latter patients, serial MIS values were also helpful to confirm complete removal of gonadal tissue postoperatively. MIS may be a more sensitive marker for the presence of testicular tissue than serum testosterone levels, both before and after the neonatal androgen surge, and, consequently, may obviate the need for human chorionic gonadotropin stimulation in the evaluation of certain intersex disorders. In patients with the persistent Müllerian duct syndrome, MIS values were useful in differentiating the underlying etiology of the disorder. Four patients with undetectable levels have presumptive MIS gene mutations, while 7 others with MIS values of 2 to 45 ng/mL may have bioinactive hormone or MIS receptor defects. Finally, two young girls with ovarian granulosa cell tumors had elevated MIS values that fell from 18 to 2 ng/mL and from 6.5 to 1 ng/mL during postoperative follow-up. The MIS level in the latter patient has recently increased to 7.2 ng/mL, raising the question of residual tumor. Data in adults with similar sex cord tumors suggest that serum MIS can be followed in these patients as a marker for persistent or recurrent disease. Thus, the determination of serum MIS concentrations is useful in the diagnosis and management of patients with a variety of intersex and gonadal abnormalities.

Mullerian inhibiting substance requires its N-terminal domain for maintenance of biological activity, a novel finding within the transforming growth factor-beta superfamily

Mullerian inhibiting substance requires its N-terminal domain for maintenance of biological activity, a novel finding within the transforming growth factor-beta superfamily

Mullerian inhibiting substance requires its N-terminal domain for maintenance of biological activity, a novel finding within the transforming growth factor-beta superfamily.

Mullerian inhibiting substance (MIS)/anti-Mullerian hormone is a differentiation factor that causes regression of the Mullerian duct in the developing male fetus and an apparent sex reversal of the fetal ovary when inappropriately exposed to it. The purified product is a 140-kilodalton glycoprotein composed of two identical subunits. We show that a C-terminal fragment of MIS, which shares homology with transforming growth factor-beta, causes regression of the Mullerian duct and inhibits the biosynthesis of aromatase in the fetal ovary. However, both activities are enhanced dramatically by addition of the N-terminal portion of MIS. Under conditions where potentiation occurs, the N- and C-terminal domains of MIS reassociate. These results indicate that the N-terminus of MIS, unlike that of the other members of the transforming growth factor-beta family, plays a role in maintaining the biological activity of the C-terminus.

Directed expression of an oncogene to Sertoli cells in transgenic mice using mullerian inhibiting substance regulatory sequences

Directed expression of an oncogene to Sertoli cells in transgenic mice using mullerian inhibiting substance regulatory sequences

Directed expression of an oncogene to Sertoli cells in transgenic mice using mullerian inhibiting substance regulatory sequences.

Mullerian inhibiting substance (MIS) is a glycoprotein hormone expressed by Sertoli cells that induces the regression of Mullerian ducts during development of the male reproductive tract. Transgenic mice carrying a fusion gene composed of human MIS transcriptional regulatory sequences linked to the SV40 T-antigen gene specifically develop testicular tumors composed of a cell type histologically resembling the Sertoli cell. The lack of pathology at other sites suggests tissue-restricted expression of the transgene. A cell line derived from one of the testicular tumors has been established that continues to express markers associated with Sertoli cells, such as transferrin, sulfated glycoprotein-2, and inhibin-beta B. The cell line does not express detectable levels of inhibin-alpha, MIS, or FSH receptor. However, the cells have retained forskolin responsiveness. As adult Sertoli cells cannot be propagated in vitro, the availability of an immortal cell line displaying features characteristic of normal Sertoli cells should aid in subsequent analyses of the biology of this cell type.

Mullerian inhibiting substance messenger ribonucleic acid expression in granulosa and Sertoli cells coincides with their mitotic activity

Mullerian inhibiting substance messenger ribonucleic acid expression in granulosa and Sertoli cells coincides with their mitotic activity

Mullerian inhibiting substance messenger ribonucleic acid expression in granulosa and Sertoli cells coincides with their mitotic activity.

In males, Mullerian inhibiting substance (MIS) mRNA was first detected on the medial aspect of the urogenital ridge early on the morning of day 13 of gestation before testicular differentiation was evident, and localized to the more obvious Sertoli cells later on embryonic day 13. MIS transcripts remained at maximal levels between 14.5 and 17.5 days gestation, while the Mullerian duct involutes, and remained high until birth. MIS gene expression decreased progressively after birth and, as germ cell meiosis increased, became barely detectable in the Sertoli cells of the seminiferous tubules. In female rats, MIS mRNA was first detected in the single layer of cuboidal granulosa cells surrounding larger primary follicles 3 days after birth, coincident with the initiation of follicular growth. As follicular growth progressed, MIS mRNA expression was high in preantral and small antral follicles, especially in those granulosa cells closest to the oocyte. MIS mRNA expression decreased gradually in larger antral follicles, remaining prominent only in the cumulus cells and the dividing population of granulosa cells closest to the lumen. MIS gene expression was absent in follicles with features of atresia and in the larger antral follicles. The expression of MIS mRNA in actively dividing Sertoli and granulosa cells correlates with the stages of germ cell division. These findings are suggestive of a role for MIS in the control of germ cell maturation.

Müllerian inhibiting substance in reproduction and cancer.

During embryogenesis normal male phenotypic development requires the action of Müllerian Inhibiting Substance (MIS) which is secreted by Sertoli cells of the fetal testis. As testes differentiate in genetic (XY) males, they produce MIS which causes regression of the Müllerian ducts, the anlagen of the female reproductive tract. Soon thereafter, testicular androgens stimulate the Wolffian ducts. In females, on the other hand, MIS is not produced by grandulosa cells until after birth, before which, estrogens induce Müllerian duct development, while the Wolffian ducts passively atrophy in the absence of androgenic stimulation. High serum MIS levels in males are maintained until puberty, whereupon they fall to baseline levels. In females MIS is undetectable in serum until the peripubertal period when values approach the baseline levels of males. This distinct pattern of sexual and ontogenic expression presupposes and requires tight regulation. MIS may play a role in gonadal function and development. Our laboratory has shown that an important role for ovarian MIS is to inhibit oocyte meiosis, perhaps providing maximal oocyte maturation prior to selection for ovulation and subsequent fertilization. Furthermore, Vigier et al. (Development 100:43-55) have recently obtained evidence that MIS may influence testicular differentiation, coincident with inhibition of aromatase activity. Current structure-function studies demonstrate that MIS, like other growth regulators in its protein family, requires proteolytic cleavage to exhibit full biological activity. MIS can be inhibited by epidermal growth factor. This antagonism, which is common to all MIS functions so far investigated, is associated with inhibition of EGF receptor autophosphorylation. We have provided evidence that bovine MIS can inhibit female reproductive tract tumors arising in adults.(ABSTRACT TRUNCATED AT 250 WORDS)

Cellular localization of müllerian inhibiting substance messenger ribonucleic acid during human ovarian follicular development

Müllerian inhibiting substance is expressed in the human reproductive system and has been associated with oocyte meiotic arrest. In situ hybridization was used to selectively localize ovarian cells containing high levels of müllerian inhibiting substance messenger ribonucleic acid, a müllerian inhibiting substance precursor, during different stages of human follicular development. Müllerian inhibiting substance transcript was noted in the granulosa cells of primordial, primary, and antral follicles. Surprisingly, transcript was also identified within the cytoplasm of oocytes and throughout the ovarian stroma. Controls included sense oligoprobe, positive and negative tissue controls, and treatments minus the detection antibody. Localization of transcript within the cytoplasm demonstrates that active transcription of müllerian inhibiting substance messenger ribonucleic acid occurs within both fetal and adult human female gonads. The presence of müllerian inhibiting substance messenger ribonucleic acid within oocyte cytoplasm could implicate an autocrine role for müllerian inhibiting substance-derived peptides in the establishment of oocyte competence. (AM J OBSTET GYNECOL 1991;165:1881-6.)

Müllerian inhibiting substance blocks epidermal growth factor receptor phosphorylation in fetal rat lung membranes

Neonatal males develop respiratory distress syndrome more frequently than females for unknown reasons. The fetal testis secretes testosterone and müllerian inhibiting substance (MIS); MIS has been shown to inhibit fetal lung maturation in vitro and in vivo and to block phosphorylation of epidermal growth factor (EGF) receptors in A431 cells. We hypothesized that MIS would also inhibit membrane phosphorylation of EGF receptors in fetal lung, and that ultrastructural study of MIS-exposed lung might complement the biochemical data by assessing the effect of MIS on tissue morphology. Lung membranes were prepared from 19.5-day fetal rats and phosphorylation assays performed with 3 to 4 μg of membrane protein, with or without EGF (26 nmol/L), 0.025 mCi AT 32P (0.136 μmol/L), and either recombinant human MIS (rhMIS, 30 pmol) from media of Chinese hamster ovary (CHO) cells, rhMIS dialysis buffer, or wild-type CHO media. The 170,000 molecular weight EGF receptor, visualized by autoradiography of polyacrylamide gels, was phosphorylated in both female and male membranes. rhMIS, when added to EGF-stimulated membranes, caused significant inhibition of EGF receptor phosphorylation (females: 32.42% ± 11.5%; males: 32.3% ± 19.1%, P < 0.001; rhMIS-treated v EGF-stimulated state, P = NS, male v female, Cerenkov counting). Electron microscopy (EM) of rhMIS-exposed lung showed decreased lamellar bodies (LB) in both male alveolar spaces and female parenchyma, and, unexpectedly, increased numbers in female alveoli. Immunoabsorption experiments using coincubation of rhMIS with anti-rhMIS IgG polyclonal antibodies or equiprotein normal IgG demonstrated MIS antibody-specific reversal of rhMIS activity in membrane phosphorylation. These observations in fetal rat lung membranes extend the previous data showing inhibitory effects by MIS in fetal lung, confirm findings in natural tissue previously confined to tumor cells (A431), and suggest that rhMIS signal transduction could be mediated via inhibition of EGF receptor autophosphorylation.

Lipid solubility is not the sole criterion for the inhibition of a Ca 2+-activated K + channel by alcohols

The effect of a homologous series of n-alkanols (C 2-C 8) on the 86Rb + influx through charybdotoxin sensitive Ca 2+-activated K + channels of rat glioma C6 cells was investigated. The lipid solubility of the n-alkanols was not the sole determinant of the inhibitory potency of these substances for ion flux inhibition. 1-Hexanol for example was about 8-times less potent than one would expect on the basis of its lipid solubility. The introduction of a second OH-group in this molecule (giving 1,6-hexanediol) or a structural shift in the OH-group of 1-hexanol from position 1 to 3 strongly increased the potency of the alcohol. The above data cannot be explained by a pure lipid site of action of the alcohols. Therefore it seems likely that direct effects on protein are involved in the inhibitory action of some of the alcohols.

Müllerian inhibiting substance production and testicular migration and descent in the pouch young of a marsupial.

The ontogeny of Müllerian inhibiting substance (MIS) production by the developing testis of an Australian marsupial, the tammar wallaby (Macropus eugenii), was determined during pouch life using an organ-culture bioassay of mouse fetal urogenital ridge. This information was related to the morphological events during testicular migration and descent. MIS biological activity was found in testes (but not ovaries or liver) of pouch young from 2 to 85 days of age. MIS production had commenced by day 2, which is within a day of the first gross morphological signs of testicular differentiation. Müllerian duct regression occurred between 10 and 30 days, which partly coincided with testicular migration to the inguinal region and enlargement of the gubernacular bulb (15 to 30 days). These observations are consistent with the hypothesis that MIS may be involved in testicular transabdominal migration. The epididymis commenced development and growth only after the testis had descended through the inguinal ring. This provides no support for the suggestion that the epididymis is involved in testicular descent into the scrotum. The basic sequence of events in post-testicular sexual differentiation in the wallaby is sufficiently similar to that seen in eutherian mammals to make it an excellent experimental model for future studies of testicular differentiation, migration and descent.

Müllerian inhibiting substance depresses accumulation in vitro of disaturated phosphatidylcholine in fetal rat lung

Respiratory distress syndrome and associated pulmonary surfactant deficiency are more common in male neonates. Androgens have been shown to depress surfactant production. We tested the hypothesis that müllerian inhibiting substance, another fetal testicular product, might inhibit lung maturation measured as disaturated phosphatidylcholine accumulation. Initially, female fetal rat lungs were incubated with fetal testis or ovary or nanomolar concentrations of bovine müllerian inhibiting substance. Cultured lungs produced less disaturated phosphatidylcholine after incubation for 5 days with either testis (p = 0.012) or müllerian inhibiting substance than after coculture with ovary. In more comprehensive experiments, female lung fragments of 17.5 days' gestation, when incubated with nanomolar concentrations of bovine müllerian inhibiting substance or picomolar concentrations of human recombinant müllerian inhibiting substance, showed significant suppression of disaturated phosphatidylcholine accumulation (p < 0.004) when compared with incubation with vehicle buffer. The suppression of surfactant accumulation produced in vitro by müllerian inhibiting substance, a potent male-specific fetal regressor, may be a factor in the increased susceptibility of male infants to respiratory distress syndrome.

Fluoxetine vs Amitriptyline in the Treatment of Depressed Out-patients

As a result of research in recent years, therapeutic possibilities for the treatment of depressive illnesses have been significantly expanded. Monoamine oxidase inhibitors and selective noradrenaline (e.g. oxaprotiline) or serotonin-reuptake inhibiting (e.g. fluoxetine, fluvoxamine) substances have been added to the classical tricyclic antidepressants, whose mode of action is primarily based upon combined noradrenaline and serotonin reuptake inhibition. Furthermore, the extent to which benzodiazepine derivatives or neuroleptics can be successfully used at low dosages for the treatment of depressive illness is currently being investigated.For these compounds to be used in an individualised manner, however, agreed diagnostic criteria must be taken into consideration, as well as other factors such as the severity and type of depressive syndrome (mild, marked, or severe, retarded or agitated). For example, the benzodiazepine derivative alprazolam has a therapeutic efficacy comparable to amitriptyline for the treatment of milder depressive syndromes, but is significantly less effective for a severe depressive disorder.We undertook a study of fluoxetine, a selective serotonin-reuptake inhibitor (Wong et al, 1974, 1975), in a double-blind comparison with amitriptyline. We particularly wanted to know if the efficacy of fluoxetine was comparable to that of amitriptyline, and whether fluoxetine caused less adverse effects as a result of its selectivity, which remains unchanged even after its metabolisation to desmethyl fluoxetine (Fuller et al, 1978).