Aldosterone and dexamethasone activate African lungfish mineralocorticoid receptor: Increased activation after removal of the amino-terminal domain

Aldosterone, the main physiological mineralocorticoid in humans and other terrestrial vertebrates, first appears in lungfish, which are lobe-finned fish that are forerunners of terrestrial vertebrates. Aldosterone activation of the MR regulates internal homeostasis of water, sodium and potassium, which was critical in the conquest of land by vertebrates. We studied transcriptional activation of the slender African lungfish MR by aldosterone, other corticosteroids and progesterone and find that aldosterone, 11-deoxycorticosterone, 11-deoxycortisol and progesterone have half-maximal responses (EC50 s) below 1 nM and are potential physiological mineralocorticoids. In contrast, EC50 s for corticosterone and cortisol were 23 nM and 66 nM, respectively. Unexpectedly, truncated lungfish MR, consisting of the DNA-binding, hinge and steroid-binding domains, had a stronger response to corticosteroids and progesterone than full-length lungfish MR, indicating that the N-terminal domain represses steroid activation of lungfish MR, unlike human MR in which the N-terminal domain contains an activation function. BLAST searches of GenBank did not retrieve a GR ortholog, leading us to test dexamethasone and triamcinolone for activation of lungfish MR. At 10 nM, both synthetic glucocorticoids are about 4-fold stronger than 10 nM aldosterone in activating full-length lungfish MR, leading us to propose that lungfish MR also functions as a GR.

11-Deoxycortisol controls hydromineral balance in the most basal osmoregulating vertebrate, sea lamprey (Petromyzon marinus)

It is unknown whether and how osmoregulation is controlled by corticosteroid signaling in the phylogenetically basal vertebrate group Agnatha, including lampreys and hagfishes. It is known that a truncated steroid biosynthetic pathway in lampreys produces two predominant circulating corticosteroids, 11-deoxycortisol (S) and 11-deoxycorticosterone (DOC). Furthermore, lampreys express only a single, ancestral corticosteroid receptor (CR). Whether S and/or DOC interact with the CR to control osmoregulation in lampreys is still unknown. We examined the role of the endogenous corticosteroids in vivo and ex vivo in sea lamprey (Petromyzon marinus) during the critical metamorphic period during which sea lamprey increase osmoregulatory capacity and acquire seawater (SW) tolerance. We demonstrate in vivo that increases in circulating [S] and gill CR abundance are associated with increases in osmoregulatory capacity during metamorphosis. We further show that in vivo and ex vivo treatment with S increases activity and expression of gill active ion transporters and improves SW tolerance, and that only S (and not DOC) has regulatory control over active ion transport in the gills. Lastly, we show that the lamprey CR expresses an ancestral, spironolactone-as-agonist structural motif and that spironolactone treatment in vivo increases osmoregulatory capacity. Together, these results demonstrate that S is an osmoregulatory hormone in lamprey and that receptor-mediated discriminative corticosteroid regulation of hydromineral balance is an evolutionarily basal trait among vertebrates.

Cortexolone 17α-propionate (Clascoterone) Is a Novel Androgen Receptor Antagonist that Inhibits Production of Lipids and Inflammatory Cytokines from Sebocytes In Vitro

Cortexolone 17α-propionate (clascoterone) is a novel topical androgen antagonist that is being analyzed for its ability to treat acne. The pathogenesis of acne is attributed to multiple factors, including altered sebum production, inflammatory processes, dysregulation of the hormone microenvironment, and the proliferation of the skin commensal bacteria, Propionibacterium acnes (P. acnes). Androgens induce the proliferation and differentiation of sebocytes, (cells that comprise the sebaceous gland), help regulate the synthesis of the lipids that are incorporated into sebum and stimulate the production of cytokines that are found in inflammatory acne lesions. Several studies have established that clascoterone is a potent antiandrogen that is well tolerated and has selective topical activity. Its potency as an acne therapeutic is currently being analyzed in a large phase 3 clinical trial. The study described herein elucidates for the first time the mechanism of action of clascoterone. Clascoterone was found to bind the androgen receptor (AR) with high affinity in vitro, inhibit AR-regulated transcription in a reporter cell line, and antagonize androgen-regulated lipid and inflammatory cytokine production in a dose-dependent manner in human primary sebocytes. In particular, when compared to another AR antagonist, spironolactone, clascoterone was significantly better at inhibiting inflammatory cytokine synthesis from sebocytes. Therefore, clascoterone may be an excellent candidate to be the first topical antiandrogen to treat acne. J Drugs Dermatol. 2019;18(5):412-418.

Cortexolone 17α-Propionate (Clascoterone) is an Androgen Receptor Antagonist in Dermal Papilla Cells In Vitro

Cortexolone 17α-propionate (clascoterone) is a novel androgen antagonist that is currently being analyzed in a large phase 2 clinical trial for the topical treatment of androgenetic alopecia (AGA). While the pathogenesis of AGA is still debated, the consensus is that AGA is an androgen-dependent hair disorder with strong genetic links, and that the testosterone metabolite, dihydrotestosterone (DHT), plays a causal role in its development. DHT binds to the androgen receptor (AR) in scalp dermal papilla cells (DPC) to induce AR-mediated transcription of genes that contribute to AGA in genetically predisposed individuals. Several studies have established that clascoterone is a potent antiandrogen that is well tolerated and has selective topical activity. The study described herein elucidates a potential mechanism of clascoterone in AGA. Clascoterone was found to inhibit AR-regulated transcription in a reporter cell line with similar efficacy to the 5α-reductase inhibitor, finasteride. More importantly, when compared with another direct AR antagonist, enzalutamide, clascoterone was significantly better at inhibiting IL-6 synthesis from DHT-stimulated primary cultures of human scalp DPC. Therefore, clascoterone may be an excellent candidate to be the first topical antiandrogen for treating AGA. J Drugs Dermatol. 2019;18(2):197-201.

Involvement of epidermal growth factor receptors and mitogen-activated protein kinase in progestin-induction of sperm hypermotility in Atlantic croaker through membrane progestin receptor-alpha

The intracellular pathways mediating rapid, nongenomic progestin stimulation of sperm motility remain unclear. The role of epidermal growth factor receptors (Egfr and ErbB2) and mitogen-activated protein kinase (Mapk) in membrane progestin receptor-alpha (mPRα)-mediated progestin stimulation of sperm hypermotility was examined in a teleost, Atlantic croaker. Inhibition of upstream regulators of Egfr, intracellular tyrosine kinase (Src) with PP2, and matrix metalloproteinase (MMP) with Ilomastat, abolished progestin-initiated sperm hypermotility by 17,20β,21-trihydroxy-4-pregnen-3-one (20β-S; 20 nM) and a specific mPRα agonist, Org OD 02-0 (20 nM). Pretreatment of croaker sperm with EGFR inhibitors, AG1478 (5 μM) and RG13022 (50 μM), the ErbB2 inhibitor, AG879 (5 nM), or the MEK1/2 inhibitor, U0126 (500 nM) blocked progestin stimulation of sperm motility. Levels of phosphorylated extracellular-related kinase 1 and 2 (P-Erk1/2) were increased after 20β-S treatment. These results demonstrate that progestin-mediated hypermotility via mPRα in croaker sperm involves activation of the Egfr, ErbB2 and Mapk pathways.

Membrane progestin receptor alpha mediates progestin-induced sperm hypermotility and increased fertilization success in southern flounder (Paralichthys lethostigma)

Progestin hormones stimulate sperm motility in teleosts but their mechanisms of action remain unclear. Preliminary results suggest that progestin upregulation of sperm motility in southern flounder and several other marine species is mediated through a sperm membrane progestin receptor with the characteristics of membrane progestin receptor alpha (mPRα, also known as Paqr7b). The hypothesis that mPRα has an important role in progestin regulation of southern flounder sperm motility and fertility was tested in the present study. The specific mPRα agonist, 10-ethenyl-19-norprogesterone (Org OD 02-0, 100nM), mimicked the stimulatory actions of the endogenous progestin, 17,20β, 21-trihydroxy-4-pregnen-3-one (20β-S, 100nM) on flounder sperm motility. The concentration of the mPRα protein on sperm plasma membranes was positively correlated to sperm motility as well as the responsiveness of sperm to progestin stimulation. Acute in vitro progestin treatment of sperm with high mPRα protein levels increased both sperm motility and fertilization success in strip spawning experiments. However, in vitro progestin treatments were ineffective on sperm with low receptor abundance. A single injection of the superactive gonadotropin-releasing hormone analog (LHRHa, 100μg/kg) increased sperm motility and fertilization success in strip spawning experiments 72h post-injection which was accompanied by an increase in mPRα protein concentrations on sperm plasma membranes. These results provide clear evidence that southern flounder sperm hypermotility is mediated through mPRα. Stimulatory G proteins, but not inhibitory G proteins, were identified in flounder sperm plasma membrane fractions. The finding that treatment of flounder sperm plasma membrane fractions with either 20β-S or Org OD 02-0 increases cAMP levels suggests progestins stimulate flounder sperm motility by activating an mPRα/stimulatory G protein/membrane adenylyl cyclase pathway. A similar mechanism has been identified in Atlantic croaker, suggesting that the signaling pathway mediated by mPRα in sperm is highly conserved in advanced teleosts. Collectively, our results indicate that progestin-stimulation of flounder sperm hypermotility and fertility is dependent on a sufficient concentration of mPRα which can be upregulated by in vivo LHRHa treatments. These findings potentially have practical applications for enhancing the fertility of male flounder broodstock.

Identification of 17,20β,21-trihydroxy-4-pregnen-3-one (20β-S) receptor binding and membrane progestin receptor alpha on southern flounder sperm (Paralichthys lethostigma) and their likely role in 20β-S stimulation of sperm hypermotility

The existence of direct progestin actions on teleost sperm to stimulate hypermotility is not widely acknowledged because it has only been demonstrated in members of the family Sciaenidae. In the present study, progestin stimulation of sperm hypermotility was investigated in a non-sciaenid, southern flounder, and the potential role of membrane progestin receptor alpha (mPRα or Paqr7b) in mediating this action was examined. The major progestin produced in vitro by flounder testicular fragments co-migrated with 17,20β,21-trihydroxy-4-pregnen-3-one (20β-S) during thin-layer chromatography. Treatment of flounder sperm with 5 nM-100 nM 20β-S significantly increased sperm velocity in vitro, whereas 17,20β-dihydroxy-4-pregnen-3-one and other steroids were ineffective. A single class of high affinity (K(d) 22.95 nM), saturable, limited-capacity binding sites (B(max) 0.013 nM) specific for 20β-S was identified on sperm membranes. Treatment of sperm membranes with guanosine 5'-(3-O-thio)triphosphate reduced [(3)H]-20β-S binding, suggesting the 20β-S receptor couples to a G protein. The membrane adenylyl cyclase inhibitor 2',5'-dideoxyadenosine blocked 20β-S-induced sperm hypermotility, indicating 20β-S activates stimulatory G proteins. Finally, flounder paqr7b was cloned and characterized from testicular tissues. The Paqr7b protein is expressed on the midpiece of flounder sperm and is more abundant in individuals with high sperm motility than low motility donors. These findings suggest that 20β-S stimulates sperm hypermotility in flounder through activation of stimulatory G proteins, likely through Paqr7b. The finding that progestins directly stimulate sperm hypermotility in a flatfish, a highly derived species not belonging to the teleost family Sciaenidae, suggests this phenomenon is widespread among advanced fishes.

Biotransformation of cortexolone to hydrocortisone by molds using a rapid color development assay

Capabilities of 22 molds were assessed for 11beta-hydroxylation of cortexolone (Reichstein's compound S) to hydrocortisone. The biotransformation capability was compared for solid-state and submerged monocultures of the molds under otherwise identical conditions. A novel rapid color development assay and thin layer chromatography were used to qualitatively establish the ability of the fungi to convert cortexolone to hydrocortisone. These assays were validated and supplemented with data from high performance liquid chromatography to obtain quantitative information on the biotransformation. Nearly all the fungi consumed a significant fraction of the cortexolone fed, but only four (i.e. two isolates of Cunninghamella blakesleeana, C. echinulata and Curvularia lunata) yielded measurable quantities of hydrocortisone. Submerged cultures generally gave significantly greater yield of hydrocortisone compared to equivalent solid-state cultures.

The effect of the corticosteroid hormone cortexolone on the metabolites produced during phenanthrene biotransformation in Cunninghamella elegans

The metabolism of phenanthrene and the mammalian corticosteroid hormone cortexolone by the fungus Cunninghamella elegans was studied. The amounts of the cortexolone transformation products, cortisol and epicortisol, were affected by the presence of phenanthrene. Approximately 40% more cortisol was produced by C. elegans in cultures with phenanthrene. In contrast, epicortisol formation decreased. C. elegans transformed phenanthrene to phenanthrene trans-1,2-,3,4-, and 9,10-dihydrodiols, phenols, diphenols (diols) and glucoside conjugates of 1-, 2-, 3-, 4-, and 9-phenanthrols. Almost all of the phenanthrene initially added was metabolized to ethyl acetate extractable metabolites. In the mycelia and culture medium extracts, phenanthrol glucosides represented 80% and 94% of the total metabolites, respectively. The major metabolite was the glucoside conjugate of 1-phenanthrol. The presence of cortexolone affected the biodegradation of phenanthrene by decreasing the amounts of phenanthrene metabolites compared to control cultures.

Immunoenzymometric Assay for a Small Molecule,11-Deoxycortisol, with Attomole-Range Sensitivity Employing an scFv−Enzyme Fusion Protein and Anti-Idiotype Antibodies

To overcome the sensitivity limit in immunoassays for small molecules (haptens), we established a noncompetitive immunoenzymometric assay (IEMA) format that can detect attomole-range hapten molecules. We selected 11-deoxycortisol (11-DC; Mr 346.5), a corticosteroid serving a diagnostic index for pituitary-adrenal function, as a model target hapten. A fusion of a single-chain Fv fragment (scFv) specific for 11-DC and alkaline phosphatase (ALP) was generated for use as an enzyme-labeled antibody, instead of the conventional chemically linked enzyme-antibody conjugates. After binding reaction of 11-DC and fixed amounts of the fusion protein (scFv-ALP), the unbound fusion protein was removed by incubation with a mouse beta-type anti-idiotype antibody recognizing the scFv paratope. These complexes were captured by magnetic separation using anti-mouse IgG antibody-coated magnetic beads. Following magnetic sedimentation of the beads, immune complexes of scFv-ALP and 11-DC remained in the supernatant were further purified by capture on microtiter plates with immobilized alpha-type anti-idiotype antibody. As measured fluorometrically, ALP activity from bound immune complexes on the plates increased with increasing 11-DC, which is characteristic of a noncompetitive relationship. This IEMA afforded an extremely low detection limit (20 amol/assay), a very wide measurable range, and practical specificity. The plasma 11-DC levels determined for healthy subjects were validated as reliable.

In the ventral tegmental area, progestins' membrane-mediated actions for lordosis of hamsters and rats involve protein kinase A

Progestin-facilitated lordosis of hamsters and rats is enhanced by activation of dopamine type 1 (D1) or GABAA/benzodiazepine receptor complexes (GBRs) in the ventral tegmental area (VTA) and these effects involve G-proteins and second messengers, such as adenosine 3',5'-monophosphate (cAMP). We examined whether D1- and/or GBR-mediated increases in progestin-facilitated lordosis of female hamsters and rats involve the cAMP-dependent protein kinase, protein kinase A (PKA), in the VTA. In experiment 1, ovariectomized hamsters, primed with estradiol (E2; 10 microg at h 0) + progesterone (P; 100 microg at h 45), were first pre-tested for lordosis and motor behavior (h 48) and then infused with the PKA inhibitor, Rp-cAMP (100 ng/side), or vehicle. Thirty minutes later, hamsters were retested and then received infusions of the D1 agonist, SKF38393 (100 ng/side), the GBR agonist, muscimol (100 ng/side), or vehicle to the VTA. Hamsters were post-tested for lordosis and motor behavior 30 min later. In Experiment 2, ovariectomized rats, primed with E2 (10 microg at h 0), were first pre-tested for lordosis and then infused with Rp-cAMP (100 ng/side) or vehicle to the VTA at h 44. Immediately after testing, rats received infusions of SKF38393 (100 ng/side), muscimol (100 ng/side), or vehicle and were retested for lordosis. Rats were then infused with the neurosteroid, 5alpha-pregnan-3alpha-ol-20-one (3alpha,5alpha-THP; 100 or 200 ng/side), or beta-cyclodextrin vehicle and were post-tested for lordosis and motor behavior 10 and 60 min later. The enhancing effects of progestins or progestins plus D1 or GBR activation on lordosis of E2-primed hamsters and rats were blocked by the PKA inhibitor, Rp-cAMP. Thus, in the VTA, progestins' membrane actions involving D1 or GBRs are mediated, in part, by PKA.

Pharmacological profile of 9,11-dehydrocortexolone 17alpha-butyrate (CB-03-04), a new androgen antagonist with antigonadotropic activity

A series of new cortexolone-related derivatives has been synthesized and investigated for potential anti-androgenic activity. Among the steroids evaluated, 9,11-dehydrocortexolone 17alpha-butyrate (CB-03-04) was the most promising one. The compound displayed a strong local antiandrogenic activity in hamster's flank organ test, and it was also found to be effective in the rat after subcutaneous injection. When compared to other well known androgen antagonists, the rank order of topical anti-androgenic activity in that test was: cyproterone acetate (CAS 427-51-0) > or = CB-03-04 > finasteride (CAS 98319-26-7) > flutamide (CAS 13311-84-7). In addition, the steroid had selective antigonadotropic activity, when injected into parabiotic rats, and was about as active as progesterone. The activity of CB-03-04 was ascribed mainly to its ability to compete with the stimulating effects of testosterone and dihydrotestosterone and, concurrently, to inhibit the gonadotropins hypersecretion. This bimodal mechanism of action could be predictive for the clinical usefulness of the steroid in the treatment of prostate cancer and benign prostate hypertrophy.

Activation of a pertussis toxin-sensitive, inhibitory G-protein is necessary for steroid-mediated oocyte maturation in spotted seatrout

Oocyte maturation (OM) is initiated in lower vertebrates and echinoderms when maturation-inducing substances (MIS) bind oocyte membrane receptors. This study tested the hypothesis that activation of a G(i) protein is necessary for MIS-mediated OM in spotted seatrout. Addition of MIS significantly decreased adenylyl cyclase activity in a steroid specific, pertussis toxin (PTX)-sensitive manner in oocyte membranes and microinjection of PTX into oocytes inhibited MIS-induced OM, suggesting the steroid activates a G(i) protein. MIS significantly increased [(35)S]GTPgammaS binding to ovarian membranes, confirming that MIS receptor binding activates a G-protein, and immunoprecipitation studies showed the increased [(35)S]GTPgammaS binding was associated with Galpha(i1-3) proteins. Radioligand binding studies in ovarian membranes using GTPgammaS and PTX demonstrated that the MIS binds a receptor coupled to a PTX-sensitive G-protein. This study provides the first direct evidence in a vertebrate model that MIS-induced activation of a G(i) protein is necessary for OM. These results support a mechanism of MIS action involving binding to a novel, G-protein coupled receptor and activation of an inhibitory G-protein, the most comprehensive and plausible model of MIS initiation of OM proposed to date.

Steroid-induced oocyte maturation in Atlantic croaker (Micropogonias undulatus) is dependent on activation of the phosphatidylinositol 3-kinase/Akt signal transduction pathway

Exposure of fully grown fish and amphibian oocytes to a maturation-inducing steroid (MIS) activates numerous signal transduction pathways to initiate the final stage of oocyte maturation. These events culminate in the activation of maturation-promoting factor and germinal vesicle breakdown (GVBD). In most species, exposure to MIS causes a transient decrease in oocyte cAMP levels. Whether this reduction in oocyte cAMP concentration is sufficient to induce GVBD is unclear. The current study tested the hypothesis that activation of cAMP-independent signal transduction pathways by the naturally occurring MIS, 17,20beta,21-trihydroxy-4-pregnen-3-one (20beta-S), is necessary for GVBD in Atlantic croaker (Micropogonias undulatus) oocytes. Results indicate that although 20beta-S treatment of oocyte membranes significantly reduced cAMP production, incubation of follicles with the cell-permeable cAMP-dependent protein kinase (Prka) inhibitors Rp-cAMP or KT5720 did not promote GVBD in the absence of 20beta-S. Additionally, treatment of follicles with the phosphodiesterase (Pde) inhibitors Cilostamide (Pde3) or Rolipram (Pde4) significantly reduced GVBD, but they were not able to completely block it. In contrast, pharmacologic inhibition of the cAMP-independent phosphatidylinositol 3-kinase (Pik3)/Akt signal transduction pathway using the Pik3 inhibitors Wortmannin or LY294002, or the Akt inhibitor ML-9, blocked 20beta-S-induced GVBD. Finally, mitogen-activated protein kinase (Mapk1/3) activity increased after treatment with 20beta-S; however, inhibition of Mapk1/3 activity using PD98059 or U0126 had no effect on GVBD. These results demonstrate that activation of cAMP-independent signaling pathways, especially the Pik3/Akt pathway, is necessary for 20beta-S-induced GVBD in Atlantic croaker oocytes.

3alpha,5beta-Reduced cortisol exhibits antagonist properties on cerebral cortical GABA(A) receptors

The tetrahydro-reduced derivatives of progesterone and deoxycorticosterone, allopregnanolone, and tetrahydrodeoxycorticosterone are potent positive modulators of GABA(A) receptors that are elevated by hypothalamic-pituitary-adrenal axis activation in rodents. In humans, 11-deoxycortisol and cortisol are important hypothalamic-pituitary-adrenal axis steroids. We hypothesized that C(3,5) reduction of 11-deoxycortisol and cortisol generates steroids with GABA(A) receptor activity. 3alpha,5beta-Reduced cortisol dose-dependently inhibited muscimol-stimulated chloride flux and tetrahydrodeoxycorticosterone potentiation of muscimol responses. Cortisol, 11-deoxycortisol, 5alpha-dihydrocortisol, 3alpha,5alpha-reduced cortisol, 3alpha,5alpha-reduced 11-deoxycortisol, and 3alpha,5beta-reduced 11-deoxycortisol had no activity at 1 muM and weaker negative modulatory activity at 10 muM. We conclude that cortisol metabolism may produce antagonistic GABAergic activity.

Effects of external pH on hormonally regulated ovarian follicle maturation and ovulation in Atlantic croaker

In vitro studies of ovarian follicle maturation and ovulation in teleost fishes typically are conducted within a narrow range (7.5-7.8) of constant external (medium) pH, although there is evidence that pH can influence ovulation. Therefore, this study with Atlantic croaker investigated the effects of external pH on hormonally regulated in vitro maturation and ovulation as well as changes in the pH of ovarian fluid during in vivo maturation and ovulation. For the in vitro experiments, follicles were first incubated with human chorionic gonadotropin (hCG) to induce maturational and ovulatory competencies, and then with maturation-inducing hormone (MIH) to induce completion of maturation and ovulation. At a constant external pH within the range of 7.0-8.2, the lower pH levels (7.0-7.3) generally inhibited or slowed down hormonally induced maturation and ovulation whereas higher pH (7.6-8.2) facilitated these processes. When ovarian follicles were incubated at a constant pH of 7.6 during the priming incubation with hCG, changing the external pH during the incubation with MIH had relatively little effect on oocyte maturation or ovulation. Thus, the inhibitory effect of constant low levels of external pH (7.0-7.3) on maturation and ovulation may be primarily due to disruptions in the gonadotropin-dependent acquisition of maturational and ovulatory competencies. The pH of ovarian fluid remained constant at 8.5 during in vivo ovarian follicle maturation and ovulation. Subsequent in vitro tests showed that external pH of 8.5 enhances hormonally induced maturation and ovulation relative to pH of 7.6. These observations suggest that attention should be paid to the pH of incubation media used in basic research and in biotechnological applications relying on in vitro maturation and ovulation in teleosts. Further, an understanding of the physiological significance of the enhancing effect of alkaline pH on maturation and ovulation will require determination of the intrafollicular pH around the oocyte during the periovulatory period.

Biological profile of cortexolone 17alpha-propionate (CB-03-01), a new topical and peripherally selective androgen antagonist

The aim of this study was to investigate the antiandrogenic activity of a new monoester of cortexolone, cortexolone 17alpha-propionate (CAS 19608-29-8, CB-03-01). Although the compound displayed a strong local antiandrogenic activity in hamster's flank organ test, it did not exhibit antiandrogenic activity in rats after subcutaneous injection, nor did it affect gonadotropins hypersecretion when injected to parabiotic rats. As topical antiandrogen, the steroid resulted about 4 times more active than progesterone (CAS 57-83-0) and, when compared to known antiandrogen standards, it was about 3 times more potent than flutamide (CAS 13311-84-7), about 2 times more effective than finasteride (CAS 98319-26-7) and approximately as active as cyproterone acetate (CAS 427-51-0). Its pharmacological activity seemed to be primarily related to its ability to antagonistically compete at androgen receptor level; nevertheless its primary pharmacological target needs to be further investigated. Its topical activity, along with the apparent absence of systemic effects, anticipates this compound to have the potential of representing a novel and safe therapeutic approach for androgen-dependent skin disorders.

Insulin-like growth factor-I induces oocyte maturational competence but not meiotic resumption in white bass (Morone chrysops) follicles in vitro: evidence for rapid evolution of insulin-like growth factor action

A combination of recombinant human (rh) insulin-like growth factor-I (IGF-I) (25 nM) and the maturation-inducing hormone (MIH), 17,20beta,21-trihydroxy-4-pregnen-3-one (20beta-S; 72.5 nM), induced germinal vesicle breakdown (GVBD) in ovarian follicles of white bass incubated in vitro, whereas a four times greater concentration of each hormone was ineffective alone. These results indicate that IGF-I induces oocyte maturational competence (OMC) but not meiotic resumption in white bass. Culture medium concentrations of 20beta-S remained below detection limits for ovarian fragments incubated with rhIGF-I. Actinomycin D blocked GVBD in response to hCG but not to rhIGF-I plus 20beta-S, suggesting that IGF-I requires de novo translation but not transcription to induce OMC. Gap junction uncouplers, 1-octanol and 1-heptanol, and the phosphatidylinositiol 3-kinase (PI 3-K) inhibitors, wortmannin and LY 294002, attenuated hCG-, 20beta-S-, and rhIGF-I plus 20beta-S-induced GVBD. Although these inhibitors reduced hCG-induced progestin release, PI 3-K inhibitors did not alter MIH synthesis in some incubations and addition of 20beta-S to the incubations did not fully overcome the effects of either class of inhibitors, suggesting that decreasing MIH production is not their only inhibitory effect on gonadotropin (GtH) action. Our data suggest that gap junctions and PI 3-K activity are necessary for GtH and IGF-I to induce and maintain OMC in white bass. The induction of OMC but not meiotic resumption by IGF-I in white bass, compared with the induction of meiotic resumption but not OMC by IGF-I discovered in the congeneric striped bass suggests rapid evolution of the reproductive actions of IGF-I among temperate basses (genus Morone).

11-deoxycorticosterone is a potent agonist of the rainbow trout (Oncorhynchus mykiss) mineralocorticoid receptor

The teleost fish are thought to lack the mineralocorticoid hormone aldosterone but possess mineralocorticoid receptor (MR) homologs. Here we describe the characterization of two rainbow trout (Oncorhynchus mykiss) MRs, called rtMRa and rtMRb. The open reading frame of rtMRa cDNA encoded a protein of 1041 amino acids. The rtMRb predicted protein sequence is similar, differing in only 10 amino acids in the nonconserved A/B domain and lacking a three-amino acid insertion between the two zinc fingers of the C domain. Expression of rtMR mRNA (sum of both forms), measured in juvenile trout by real-time RT-PCR, shows that the transcripts are ubiquitous. Expression was significantly higher in brain than the other tissues studied (eye, trunk kidney, head kidney, gut, gills, liver, spleen, ovary, heart, white muscle, skin). Hormonal stimulation of receptor transactivation activity was studied in COS-7 cells transiently cotransfected with receptor cDNA and a mouse mammary tumor virus-luciferase reporter. The mineralocorticoids 11-deoxycorticosterone and aldosterone were more potent enhancers of rtMRa transcriptional activity (EC50 = 1.6 +/- 0.5 x 10(-10) and 1.1 +/- 0.4 x 10(-10) M, respectively) than the glucocorticoids cortisol and 11-deoxycortisol (EC50 = 1.1 +/- 0.3 x 10(-9) and 3.7 +/- 1.9 x 10(-9) M, respectively). A similar response was observed in transactivation assays with rtMRb. These results are discussed in the view of reported circulating levels of corticosteroids in trout.

Evidence that 4-pregnen-17,20beta,21-triol-3-one functions as a maturation-inducing hormone and pheromonal precursor in the percid fish, Gymnocephalus cernuus

Behavioral, biochemical, and electrophysiological studies suggest that the trihydroxylated progestin steroid, 4-pregnen-17,20beta,21-triol-3-one (20beta-S) stimulates oocyte maturation and pheromone release in the Eurasian ruffe, a freshwater percid fish. Behavioral observations found that female ruffe undergoing oocyte maturation (OM) release a pheromonal cue that stimulates swimming activity and social interactions among conspecific males. Neither vitellogenic nor ovulated females released the cue. Pheromone production was directly associated with elevated plasma levels of 20beta-S in maturing female ruffe which in vitro incubation suggested to be a possible maturation-inducing hormone (MIH) in this species along with 4-pregnen-17,20beta-diol-3-one (17,20betaP). However, neither of these steroids appear to be the pheromone because electrophysiological and behavioral studies found them to lack olfactory (EOG) and behavioral activity. Instead, studies of the odor of steroid-injected fish suggest the pheromone is a metabolite of 20beta-S. In particular, inter-peritoneal injection of 20beta-S (but not 17,20betaP) consistently induced release of a urinary cue with strong behavioral activity. The pheromone may be a highly polar and novel metabolite because it could not be extracted using octadecylsilane resin (C18) which has proven effective for other teleost hormonal pheromones.

Molecular determinants of glucocorticoid receptor mobility in living cells: the importance of ligand affinity

The actions of glucocorticoids are mediated by the glucocorticoid receptor (GR), which is activated upon ligand binding, and can alter the expression of target genes either by transrepression or transactivation. We have applied FRAP (fluorescence recovery after photobleaching) to quantitatively assess the mobility of the yellow fluorescent protein (YFP)-tagged human GR alpha-isoform (hGRalpha) in the nucleus of transiently transfected COS-1 cells and to elucidate determinants of its mobility. Addition of the high-affinity agonist dexamethasone markedly decreases the mobility of the receptor in a concentration-dependent manner, whereas low-affinity ligands like corticosterone decrease the mobility to a much lesser extent. Analysis of other hGRalpha ligands differing in affinity suggests that it is the affinity of the ligand that is a major determinant of the decrease in mobility. Similar results were observed for two hGRalpha antagonists, the low-affinity antagonist ZK98299 and the high-affinity antagonist RU486. The effect of ligand affinity on mobility was confirmed with the hGRalpha mutant Q642V, which has an altered affinity for triamcinolone acetonide, dexamethasone, and corticosterone. Analysis of hGRalpha deletion mutants indicates that both the DNA-binding domain and the ligand-binding domain of the receptor are required for a maximal ligand-induced decrease in receptor mobility. Interestingly, the mobility of transfected hGRalpha differs among cell types. Finally, the proteasome inhibitor MG132 immobilizes a subpopulation of unliganded receptors, via a mechanism requiring the DNA-binding domain and the N-terminal part of the ligand-binding domain. Ligand binding makes the GR resistant to the immobilizing effect of MG132, and this effect depends on the affinity of the ligand. Our data suggest that ligand binding induces a conformational change of the receptor which is dependent on the affinity of the ligand. This altered conformation decreases the mobility of the receptor, probably by targeting the receptor to relatively immobile nuclear domains with which it transiently associates. In addition, this conformational change blocks immobilization of the receptor by MG132.

Endocrine control of diurnal oocyte maturation in the kyusen wrasse, Halichoeres poecilopterus

The present study examined diurnal cycles of oocyte development and maturation in the kyusen wrasse, Halichoeres poecilopterus, and investigated the sensitivity of oocytes to maturation-inducing hormone (MIH) and gonadotropic hormone (GTH). Female fish were sampled at fixed intervals throughout the day, revealing that final oocyte maturation and ovulation were completed by 6:00 hr, and that spawning occurred daily between 6:00 and 9:00 hr. In vitro experiments showed that the steroids 17,20beta-dihydroxy-4-pregnen-3-one (17,20beta-P) and 17,20beta,21-trihydroxy-4-pregnen-3-one (20beta-S) were equally potent and highly effective inducers of germinal vesicle breakdown (GVBD) in kyusen wrasse oocytes. Additionally, circulating levels of 17,20beta-P and 20beta-S increased around the time of GVBD and ovulation, suggesting that 17,20beta-P and 20beta-S act as MIHs in the kyusen wrasse. Moreover, in vitro experiments clearly showed that kyusen wrasse oocytes had a daily developmental cycle of GTH and MIH sensitivity, and that oocytes that completed vitellogenesis acquired GTH-induced maturational competence. An endogenous GTH surge likely occurs between 12:00 and 15:00 hr, and this daily pre-maturational GTH surge probably controls the diurnal maturation cycles of kyusen wrasse oocytes.

Effects of the maturation-inducing steroid on LH secretion and the GnRH system at different stages of the gonadal cycle in Atlantic croaker

The effects of treatment with the maturation-inducing steroid 17,20beta,21-trihydroxy-4-pregnen-3-one (20beta-S) on luteinizing hormone-releasing hormone analog (LHRHa)-induced LH secretion were examined during several phases of the gonadal cycle in Atlantic croaker, Micropogonias undulatus. 20beta-S (1 and 5 microg/g of body wt) was administered by intraperitoneal (ip) injection, 24 h prior to injection with LHRHa (10-50 ng/g of body wt) and fish were bled 1 h after LHRHa injection. Treatment with both doses of 20beta-S resulted in plasma concentrations of the steroid within the normal physiological range for this species during final oocyte maturation and ovulation. The 20beta-S treatments altered the LH response to LHRHa throughout the reproductive cycle in both sexes, but the direction and magnitude of the response varied. 20beta-S treatment decreased the LH response to LHRHa in fish with recrudescing and fully recrudesced gonads and in females with regressed gonads. On the other hand, 20beta-S treatment significantly increased the LH response to LHRHa in males with regressing or regressed gonads. 20beta-S treatment also altered preoptic anterior hypothalamic (POAH) and pituitary seabream gonadotropin-releasing hormone (sbGnRH) contents, and the patterns of these changes were similar to those observed in LH secretion. The finding that moderate increases in plasma 20beta-S concentrations, similar to those occurring during final oocyte maturation, significantly inhibit the LH response to LHRHa at the end of the reproductive cycle suggests that this action of 20beta-S is of physiological importance during the periovulatory period. Moreover, the fact that concurrent changes occur in POAH and pituitary sbGnRH contents suggests that the actions of 20beta-S on LH secretion are at least partly mediated via the GnRH system.

Effects of maturation-inducing hormone on heterologous gap junctional coupling in ovarian follicles of Atlantic croaker

A previous ultrastructural study of heterologous (granulosa cell-oocyte) gap junction (GJ) contacts in ovarian follicles of Atlantic croaker suggested that these contacts disappear late during the process of resumption of oocyte meiosis. This observation suggested that, unlike scenarios proposed for a number of other species, uncoupling of GJ is not necessary for the onset of meiotic resumption in croaker follicles. However, the functionality of heterologous GJ contacts and the temporal association between maturation-inducing hormone (MIH)-induced changes in heterologous coupling and resumption of oocyte meiosis have not been examined in Atlantic croaker. These questions were addressed with a cell-cell coupling assay that is based on the transfer of a GJ marker, Lucifer Yellow, from oocytes to granulosa cells. Follicle-enclosed oocytes injected with Lucifer Yellow allowed transfer of the dye into the follicle cell layer, thus confirming that there is functional heterologous coupling between the oocyte and the granulosa cells. Dye transfer was observed in vitellogenic, full-grown/maturation-incompetent, and full-grown/maturation-competent follicles. Treatment of maturation-competent follicles with MIH caused a time-dependent decline in the number of follicles transferring dye. However, although GJ uncoupling in some of the follicles was observed before germinal vesicle breakdown (GVBD, index of meiotic resumption), about 50% of the follicles maintained the ability to transfer dye even after GVBD had occurred. Further, a known GJ inhibitor (phorbol 12-myristate 13-acetate) blocked heterologous GJ within a time frame similar to that seen with MIH but without inducing any of the morphological changes (including GVBD) associated with follicular maturation. In conclusion, uncoupling of heterologous GJ seems insufficient and unnecessary for the onset of meiotic resumption in ovarian follicles of Atlantic croaker.

Steroids differentially inhibit the nicotinic acetylcholine receptor

The effect of various natural and synthetic steroids on the function of the nicotinic acetylcholine receptor (AChR) was studied at the single-channel level. AChR channel kinetics was affected by some substitutions in the cyclopentaneperhydrophenantrene ring. Functionally relevant substitutions shortened channel open state duration, an effect that varied for different steroids. The presence of a polar group at C11 contributed to the inhibitory potency of the steroid. Among mono-hydroxylated steroids such as 11- and 17-OH progesterone, the highest potency was displayed by the former showing a level similar to that of the reference compound, hydrocortisone. When the effects were analyzed in terms of the octanol-water partition coefficient, a linear relationship was unexpectedly found between the hydrophilicity of the steroids and their inhibitory potency.

In vitro effects of different steroid hormones on superoxide anion production of human neutrophil granulocytes

Neutrophil granulocytes play an important role in atherogenesis also through their free radical generation. According to recent studies, a point of action by which estrogens can provide protection against atherosclerosis is their inhibiting effect on superoxide anion production. The aim of our study was to test whether this means a common effect of steroids on superoxide production, or whether various steroid hormones have different action on superoxide generation of human granulocytes. Neutrophils were separated from the blood samples of twelve healthy volunteers. Isolated cells were incubated with different concentrations (10(-9), 10(-8), 10(-7) M) of hydrocortisone, aldosterone, cortexolone, 17-beta-estradiol, progesterone, and testosterone. Superoxide anion production was determined by photometry using the reduction of ferricytochrome-C. Compared to that of control cells neutrophils incubated with 17-beta-estradiol, progesterone, testosterone and hydrocortisone showed significantly reduced superoxide production. No significant alteration of superoxide anion production was found after the incubation of cells with aldosterone and cortexolone. It is concluded that similarly to estradiol other sex steroids and cortisol can inhibit the free radical production of human granulocytes, but mineralocorticoid aldosterone and Reichstein's substance S do not show such activity. Our results provide new evidence supporting the theory that certain types of steroid hormones have antioxidant capacity. This may give further reasons for investigating the molecular background of the existence or absence of this property and thus might lead to the development of new free radical scavengers.

Induction of ovulation of mature oocytes by the maturation-inducing steroid 17,20beta,21-trihydroxy-4-pregnen-3-one in the spotted seatrout

Incubation of mature, hydrated, follicle-enclosed oocytes of the spotted seatrout, Cynoscion nebulosus, with the maturation-inducing steroid (MIS), 17,20beta,21-trihydroxy-4-pregnen-3-one (20beta-S), for 9-12 h resulted in the appearance of ovulated oocytes in the culture media. The ovulation response was concentration-dependent and steroid-specific. The other teleost MIS, 17, 20beta-dihydroxy-4-pregnen-3-one (17,20beta-P), was also a potent inducer of ovulation, whereas progesterone and 11-deoxycorticosterone did not stimulate ovulation above control levels and partially antagonized the action of 20beta-S. The agonist and antagonist activities of these steroids on ovulation are consistent with their relative binding affinities for the ovarian nuclear progestogen receptor previously characterized in this species. Both the RNA synthesis inhibitor actinomycin D and the protein synthesis inhibitor cycloheximide blocked MIS-induced ovulation. This suggests that induction of ovulation by the MIS is through a genomic mechanism of action, and potentially involves the previously characterized nuclear progestogen receptor. Gonadotropin (hCG)-induced ovulation was blocked by addition of the steroid synthesis inhibitor cyanoketone, which was overcome by the addition of 20beta-S, but not pregnenolone. Thus, the most likely mechanism of gonadotropin-induced ovulation is an increase in the synthesis of the MIS. It is concluded that the processes of final oocyte maturation and ovulation are both regulated by the MIS. Whereas final oocyte maturation is mediated by the 20beta-S membrane receptor (P. Thomas and S. Das, 1997, Biol. Reprod. 57, 999-1007), ovulation is regulated by a genomic mechanism and is potentially mediated by the previously characterized nuclear progestogen receptor.

Pesticides interfere with the nongenomic action of a progestogen on meiotic maturation by binding to its plasma membrane receptor on fish oocytes

Although many environmental contaminants disrupt endocrine function by binding to nuclear steroid receptors, it is not known whether they are capable of binding to steroid membrane receptors and interfering with nongenomic actions of steroids. The binding of several organochlorine pesticides to the plasma membrane receptor for the maturation-inducing steroid, 17,20beta,21-trihydroxy-4-pregnen-3-one (20beta-S), in the ovaries of spotted seatrout (Cynoscion nebulosus) was investigated in in vitro competition assays. Kepone and o,p'-DDD were competitive inhibitors of 20beta-S binding and caused concentration-dependent displacement of [3H]-20beta-S from its receptor site over the range of 10(-4) to 10(-6) or 10(-7) M, whereas several other pesticides had lower affinities for the receptor. Interference with the nongenomic actions of 20beta-S on final meiotic maturation of spotted seatrout oocytes (final oocyte maturation, FOM) was examined in an in vitro bioassay. A concentration-dependent inhibition of FOM in response to 20beta-S was observed after 5 min and 12 h exposure to the same range of Kepone and o,p'-DDD concentrations (10(-4) to 10(-6) or 10(-7) M). The close correspondence between competitive binding of the two pesticides to the 20beta-S membrane receptor and their inhibition of 20beta-S induced FOM suggests a mechanism of endocrine disruption mediated by binding to a steroid membrane receptor and antagonism of a nongenomic steroid action.

Agonist-specific modulation of glucocorticoid receptor-mediated transcription by immunosuppressants

Although the immunosuppressive drugs FK506, rapamycin and cyclosporin A have been reported to potentiate transcriptional activation mediated by a non-saturating concentration of the glucocorticoid receptor agonist dexamethasone, the precise mechanism(s) underlying these responses remains unclear. The murine L-929-derived LMCAT cell line stably transfected with the mouse mammary tumor virus promoter-chloramphenicol acetyl transferase reporter gene construct was utilized in the present study to further investigate the mechanism(s) underlying this dexamethasone potentiation as well as the possible agonist specificity of this potentiation. The present data demonstrate that pretreatment (2 h) of LMCAT cells with 10 microM FK506, rapamycin or cyclosporin A results in the potentiation of reporter gene transcription mediated not only by dexamethasone (approximately 12-fold), but also by hydrocortisone (approximately 6-fold) and triamcinolone acetonide (approximately 2.5-fold). In sharp contrast, the data show for the first time that pretreatment with any one of these immunosuppressive drugs suppresses (approximately 2-8-fold) the transcriptional responses mediated by corticosterone, deoxycorticosterone, and cortexolone. Pretreatment of intact LMCAT cells with FK506 increases the subsequent whole cell specific binding of [3H]dexamethasone, but does not increase specific cytoplasmic binding when the tritiated agonist is added directly to cytosolic extracts prepared from the pretreated cells. These data suggest that the FK506-mediated potentiation of the transcriptional responses induced by some agonists, like dexamethasone, may be related to the ability of this immunosuppressant to inhibit the membrane-associated multidrug resistance (MDR) P-glycoprotein, which actively extrudes some steroids from cells. Identical pretreatment with FK506 has no detectable effect on the subsequent whole cell specific binding of [3H]corticosterone, a steroid which is not effectively extruded by the MDR pump. Two additional MDR pump inhibitors, verapamil and quinidine, potentiate (30-fold) the dexamethasone-mediated transcriptional response as expected, but have no detectable effects on a corticosterone-mediated transcriptional response. Unlike immunosuppressive drugs, these ion channel blockers do not bind to receptor-associated immunophilins (FK506-binding proteins or cyclophilins). Collectively, these results suggest that immunosuppressants potentiate a dexamethasone-mediated transcriptional response in LMCAT cells by inhibiting efflux of this steroid. In contrast, these drugs appear to suppress a corticosterone-mediated transcriptional response by a different mechanism, perhaps one involving their binding to glucocorticoid receptor-associated immunophilins.

Synthesis and biological evaluation of 2-amino-2-deoxy- and 6-amino-6-deoxy-cyclomaltoheptaose polysulfates as synergists for angiogenesis inhibition

2-Amino-2-deoxy-cyclomaltoheptaose was prepared from beta-cyclodextrin perbenzoate [heptakis(2,3,6-tri-O-benzoyl)cyclomaltoheptaose] by a series of reactions including selective de-O-benzoylation at C-2 of one of the perbenzoylated D-glucopyranosyl moieties, oxidation to the 2-ulose derivative, oxime formation, and reduction to the 2-amino-2-deoxy-D-glucose moiety. This compound and 6-amino-6-deoxycyclomaltoheptaose accessible from beta-cyclodextrin through the known procedure were sulfated to give polysulfated aminocyclomaltoheptaose derivatives (3, 5). Employing beta-cyclodextrin polysulfate as a reference compound, the synergistic effects of 3 and 5 for cortexolone or angiogenesis inhibitory activity were examined by rabbit-corneal micropocket assay system. In contrast to the significant anti-angiogenesis activity of the beta-cyclodextrin polysulfate-cortexolone pair, neither 3 nor 5 showed any cooperative activity with cortexolone in the inhibition of basic FGF-induced angiogenesis.

Glucocorticoids prolong rat sciatic nerve blockade in vivo from bupivacaine microspheres

BACKGROUND

Previous work showed that incorporation of dexamethasone (0.05 weight/weight percentage) into bupivacaine microspheres prolonged blockade by eight to 13 times compared with that produced by bupivacaine microspheres alone. The determinants of dexamethasone's block-prolonging effect were examined and reported here.

METHODS

Polylactic-co-glycolic acid polymer microspheres (65/35) with 75 weight/weight percentage bupivacaine were prepared. Microspheres were injected adjacent to the rat sciatic nerve, and sensory and motor blockade were assessed. A procedure was developed to test drugs for block-prolonging ability in vivo by placing test drugs in the injection fluid along with a suspension of bupivacaine microspheres.

RESULTS

Dexamethasone alone in suspension did not produce blockade, nor did it prolong blockade induced by aqueous bupivacaine. Bupivacaine microspheres (150 mg drug/kg rat weight) produced blockade for 6 to 10 h. Dexamethasone in the suspending solution of microspheres prolonged block by up to five times. Glucocorticoids prolonged block in proportion to glucocorticoid/antiinflammatory potency. The corticosteroid antagonist cortexolone inhibited dexamethasone's blockade-prolonging action. Durations of blockade with or without dexamethasone were unaltered by hydroxyurea-induced neutrophil depletion. Microspheres were extracted from rats at time points ranging from 7 h to 7 days, and residual microsphere dry weight and bupivacaine content were similar in groups of rats injected with either bupivacaine microspheres or bupivacaine microspheres containing dexamethasone, respectively.

CONCLUSIONS

Glucocorticoids prolong blockade from bupivacaine microspheres. The mechanism appears unrelated to the kinetics of bupivacaine release in vivo.

Evaluation of angiogenic inhibitors with an in vivo quantitative angiogenesis method using agarose microencapsulation and mouse hemoglobin enzyme-linked immunosorbent assay

In the present work, using a previously reported in vivo quantitative tumor-angiogenesis model, we attempted to ascertain whether this animal model is suitable for practical use in monitoring inhibitors of tumor angiogenesis. Mouse sarcoma-180 cells, human A431 cells or rat C6 cells microencapsulated in agarose beads were implanted s.c. into C57BL/6 mice. The level of blood vessel induction at the agarose pellet site was evaluated using mouse hemoglobin enzyme-linked immunosorbent assay on day 10 after implantation. Hydrocortisone, tetrahydro-S, medroxyprogesterone acetate, pentosan polysulfate and suramin inhibited blood vessel growth in our in vivo tumor-angiogenesis assay system, and heparin enhanced the antiangiogenic effects of hydrocortisone and tetrahydro-S. These results are almost entirely consistent with those observed in common assay systems, and suggest that this method may be useful for the identification and quantitative evaluation of inhibitors of tumor angiogenesis.

Potent inhibitory effects of steroids in an in vitro model of angiogenesis

The regulation of angiogenesis in the ovarian follicle and corpus luteum is unclear. Steroids are produced at very high concentrations in these tissues and we therefore examined the effect of steroids on angiogenesis in vitro. Explants of rat aorta were embedded in collagen gel and cultured in serum-free medium. Capillary-like microvessels were produced from the explants and microvessel number and length were measured in the presence and absence of steroids. At a concentration of 10 micrograms/ml, cortisol, progesterone, 17 alpha-hydroxyprogesterone and medroxyprogesterone acetate produced degeneration of microvessels after 7 days of steroid treatment (P < 0.01). Androstenedione and tetrahydro-S-(11-deoxytetrahydrocortisol) (tetrahydro S) produced degeneration at a slower rate: androstenedione inhibited microvessel growth after 11 days (P < 0.01) and tetrahydro S after 14 days (P < 0.05). Oestriol had no effect on microvessels; oestrone had a slow degenerative effect with significant inhibition seen after 14 days (P < 0.01). Oestradiol-17 beta at a concentration of 10 micrograms/ml completely inhibited microvessel growth from the explant cultures (P < 0.01) while at 1 microgram/ml it caused degenerative effects on growing microvessels. The effects of oestradiol and cortisol were reversible on removal of steroid-containing medium and replacement with 10% serum. We conclude that oestradiol may modulate angiogenesis in tissues in which the steroid concentration is high.

Heparin-steroid conjugates lacking glucocorticoid or mineralocorticoid activities inhibit the proliferation of vascular endothelial cells

A new class of angiogenesis inhibitors consist of a non-anticoagulating derivative of heparin, which binds to vascular endothelial cells, coupled to a steriod (e.g., cortisol) which suppresses endothelial cell division. We linked heparin to a further 10 steroids in an effort to identify ones which would yield more effective or safer angiogenesis inhibitors. Steroids having a C3 ketone group were linked by reaction with a hydrazide derivative of heparin. Steroids having a C20 ketone group and lacking a C3 ketone could not be prepared by this method, necessitating the development of alternative methods. The most efficient was to convert the steroid into a derivative having a hydrazone group at C20 and then link the steroid hydrazone to heparin. Conjugates prepared from steroids having C3 ketones were at most 6-fold more inhibitory than the free steroids to endothelial cells in tissue culture. In contrast, steroids having a C20 ketone but lacking a C3 ketone (tetrahydrocortisone, tetrahydrocortisol and tetrahydro S) became highly inhibitory to endothelial cells only after conjugation to heparin. They inhibited [3H]thymidine incorporation by 50% at a steroid concentration of 18-30 microM and by 95% at 300 microM. Since tetrahydrocortisone, tetrahydrocortisol and tetrahydro S lack glucocorticoid and mineralocorticoid activity, they may prove safer alternatives to cortisol for prolonged administration, as is likely to be necessary with anti-angiogenic therapies.

The scarlet letter: Reichstein's Substance S. A comparison of the angiostatic properties of 5 alpha-tetrahydro S and 5 beta-tetrahydro S

5 beta-Tetrahydro-Reichstein's Substance S (3 alpha, 5 beta-THS) from different sources yielded variable bioassay activity in the chick chorio-allantoic membrane assay system. Physical characterization showed impure products. Synthesis of this compound by two different routes yielded active and inactive 3 alpha, 5 beta-THS. Of the other two epimers, 3 beta, 5 beta-THS (epi-THS) and 3 alpha, 5 alpha-THS (allo-THS), only the latter was active. These results suggest that the impurities present in 3 alpha, 5 beta-THS synthesized by reduction of the alpha, beta-unsaturated ketone of Substance S might be either or both the epi-/allo-epimers (3 beta, 5 beta-THS and 3 alpha, 5 alpha-THS, respectively), with only the latter contributing the positive angiostatic activity to the mixture. Of the two synthetically derived compounds, only the latter was shown to maintain the activity, whereas 3 alpha, 5 beta-THS was not antiangiogenic.

Influence of adrenal steroid hormones on sodium appetite of Balb/c mice

The effects of adrenal steroid hormones on sodium appetite were determined in female Balb/c mice by the subcutaneous implantation for 7 days of slow-release pellets containing aldosterone, corticosterone, deoxycorticosterone (DOC) or 11-deoxycortisol, separately or in a "cocktail" combination. Placebo pellets were also implanted. The daily intake of 0.3 M NaCl was increased for 2 days by aldosterone (calculated 2.9 micrograms/day released) or corticosterone (240 micrograms/day) and for 7 days by DOC (4.8 micrograms/day). The combination of these steroids plus 11-deoxycortisol (95 micrograms/day) increased daily sodium intake nine-fold (days 3-7) and also increased water intake 1.5-fold. Placebo pellets had small effects on water intake on three days. Subcutaneous infusion of ACTH (Synacthen) at 2.8 micrograms/day for 7 days by mini-osmotic pump increased sodium intake five-fold and water intake three- or four-fold. Thus, several adrenal steroids evoked sodium appetite in Balb/c mice, DOC being the most potent at the doses used. The effects of individual steroids are consistent with their contribution to the effect of ACTH on sodium appetite.

Human papillomavirus (HPV) type 18 E7 protein is a short-lived steroid-inducible phosphoprotein in HPV-transformed cell lines

We used a capture ELISA to quantify the E7 protein of human papillomavirus type 18 (HPV-18). In HeLa cells, which express low levels of immunoreactive E7 protein (iE7), iE7 had a mean half-life of 13.5 min. In HPV-18 E7 recombinant baculovirus (E7rec BV)-infected Sf21 cells, which express higher levels of E7, the half-life of iE7 was much longer (90 min and > 24 h, with two different E7rec BVs). For two transformed human cervical cell lines expressing HPV-18 E7, exposure of the cells to hydrocortisone resulted in a twofold increase in steady-state levels of the E7 protein: no similar effect was observed with progesterone, oestrogen or testosterone. The half-life of iE7 was unaltered by hydrocortisone or progesterone exposure. An immunoassay which distinguished Ser33-phosphorylated E7 from E7 not phosphorylated at this residue (Ser33dephospho-E7), showed that in HeLa and Sf21 cells the majority of E7 was phosphorylated: the half-life of both species of E7 was similar in HeLa cells, but the half-life of Ser33dephospho-E7 was much shorter (90 min) in Sf21 cells than that of Ser33phospho-E7 (> 24 h). A HeLa-fibroblast fusion cell line with tumorigenic potential (CGL-1) had a similar ratio of dephospho-E7 to total E7 (0.06), as a similar fusion cell line (CGL-4) with no tumorigenic potential (0.03). We conclude that E7 is a labile phosphoprotein, and that the expression and steady-state level of the E7 protein in eukaryotic cells may be influenced by the hormonal environment of the cells.

Other physiological considerations of protective mechanisms of mineralocorticoid action

Mineralocorticoid receptors (MR) are protected from the effects of endogenous glucocorticoids (GC) in mineralocorticoid (MC) target tissues such as the kidney and the parotid gland. This protection is thought to be provided by 11 beta-hydroxysteroid dehydrogenase (11 beta-OHSD). 11 beta-OHSD metabolizes cortisol (in humans) and corticosterone (B) (in the rat) to cortisone and 11-dehydro-B, their respective inactive dehydro products. We have previously shown that the antinatriuretic actions of the MC deoxycorticosterone (DOC) are amplified in carbenoxolone (CBX) treated adrenalectomized (ADX) rats. CBX is believed to inhibit 11 beta-OHSD activity; DOC, however, is not a substrate for this enzyme. We now report on 11-desoxycortisol (11-desoxy-F) and 2 alpha-methylcortisone, substances which possess no intrinsic antinatriuretic activity, are not metabolized by 11 beta-OHSD and yet cause Na+ retention in CBX-treated ADX rats. Given that none of the above steroids are substrates for 11 beta-OHSD it is unlikely that the inhibition of this enzyme is involved in the unmasking of the Na+ retention observed when these substances are given to CBX-treated animals. These results provide further evidence for an additional protective mechanism, that protects MR from the inappropriate binding of excessive amounts of endogenous MCs.

Efficacy of pyridoxal treatment in controlling the growth of melanomas in cell culture and an animal pilot study

We have demonstrated, using confocal laser scanning microscopy, that pyridoxal treatment of B16C3 murine melanoma cells inhibits triamcinolone acetonide induced translocation of the glucocorticoid receptor to the nucleus of intact cells. In addition to inhibiting glucocorticoid receptor nuclear translocation, pyridoxal kills B16C3 murine melanoma cells and WM983A human melanoma cells in culture. Cortexolone, a glucocorticoid antagonist, also kills cells in culture. This mechanism, however, appears to initiate in the glucocorticoid receptor signal transducing cascade at a point prior to the impact of pyridoxal treatment alone. The glucocorticoid antagonist RU486 has no detrimental effect on melanoma cell viability, however, in combination with pyridoxal, RU486 extends cell viability. Since pyridoxal kills melanoma cells in culture, a pilot study was carried out examining the efficacy of topical application of a pyridoxal cream to inhibit the growth and/or cause regression of (B16C3) xenograft melanoma tumors in an immunocompetent (Hairless Rhino-J3) and an immunocompromised (Crl: nu/nu (CD1)BR) murine animal model. The results of the study with immunocompetent animals are encouraging. While tumors are brought under control by pyridoxal treatment, further work is needed to determine the most efficacious treatment regimen and to establish formal concentrations for pyridoxal in topical ointments. Trials using immunocompromised animals indicated that although some qualitative differences may be detected between the control and experimental animals, tumor growth in these animals is so aggressive that multiple applications or higher concentrations of pyridoxal may be needed to obtain useful data.

Opioid footshock-induced analgesia in mice acutely falls by stress prolongation

The application of 80 footshocks (S-80) to mice induces a decrease in nociceptive responses as measured by the tail-flick test, which is opioid mediated as well as prevented by naloxone (10 mg/kg, SC). When the stress is prolonged up to 240 shocks (S-240) (i.e., from 6 min 40 s to 20 min), no analgesia can be seen immediately after the stress. We have examined the two most obvious possibilities, but they do not seem to be responsible for this fact. When morphine (1-5 mg/kg IP) is injected in the S-240 situation, a potentiation of its analgesic effects is seen, so that a desensitization of mu opioid receptors is unlikely. On the other hand, although cortisol (3-30 mg/kg IP) inhibits the analgesic response to S-80, metyrapone (40 and 80 mg/kg IP) and cortexolone (3-18 mg/kg IP) do not cause S-240 to be analgesic. Thus, an increase of endogenous glucocorticoids released during the long-duration stress does not seem responsible for the lack of analgesia after S-240.

Cortisol is transported by the multidrug resistance gene product P-glycoprotein

The physiology of the multidrug transporter P-glycoprotein (Pgp) is still poorly understood. We now show evidence that cell lines with a high expression of Pgp display a reduced accumulation of cortisol and an ATP-dependent outward transport of the hormone. Cortisol efflux from Pgp negative cells does not have such an active component. Further we show that the steroid hormones cortisol, testosterone, and progesterone cause an immediate, dose-dependent increase of daunorubicin accumulation in Pgp overexpressing cells. These effects are particularly apparent for the more lipophilic steroids. These results demonstrate that Pgp may function as a transporter for cortisol and suggest a physiological role of the protein in steroid handling by organs such as the adrenal.

Low sodium intake enhances sensitivity of 11-deoxycortisol and deoxycorticosterone to ACTH in ACTH-suppressed normal subjects

Continued administration of ACTH to patients with hypopituitarism produced normal increases in steroids dependent on microsomal cytochrome P450(21) and P450(17 alpha) but reduced responses of steroids dependent on mitochondrial cytochrome P450(11 beta-18). To explore possible mechanisms and to determine whether this dissociation occurs with short-term ACTH suppression, we have examined the steroid responses to ACTH after 1 h in 12 normal subjects after equilibration on sodium intakes of 124 mmol/d [normal sodium diet (NSD)], 22 mmol/d [low sodium diet (LSD)], and 240 mmol/d [high sodium diet (HSD)] before and during continued ACTH suppression with dexamethasone (DEX). Two distinct patterns of steroid responses were observed. Deoxycorticosterone (DOC) responses were initially reduced during LSD-DEX but eventually returned to the NSD-control (NSD-CONT) values; in contrast 18-hydroxydeoxycorticosterone and corticosterone remained suppressed. 11-Deoxycortisol and 21-deoxycortisol showed patterns similar to DOC, with a return to normal ACTH responses on LSD-DEX. Basal cortisol levels were reduced and the ACTH response was unchanged by LSD. HSD-DEX reduced basal levels of all steroids as well as their ACTH responses. LSD and/or increased activity of the renin-angiotensin system have a significant impact on 17 alpha- and 21-hydroxylation functions in the zona fasciculata to maintain a normal ACTH response of microsomally dependent steroids under these conditions. In contrast, on HSD-DEX with the renin-angiotensin system suppressed, there is generalized impairment of steroid responses to ACTH.

The effects of dexamethasone on fibronectin expression in cultured human trabecular meshwork cells

Topical administration of glucocorticoids to the eye can lead to the development of ocular hypertension. This increase in intraocular pressure is caused by the heightened resistance to flow of aqueous humor from the eye, presumably at the trabecular meshwork (TM). This study reports the effects of dexamethasone (DEX) on the expression of the extracellular matrix protein fibronectin (FN) in cultured human TM cells (HTM). The expression of FN was evaluated in four HTM cell strains by epifluorescence microscopy and immunoblotting and autofluorography of electrophoretically separated cell proteins. There was a heterogeneous response of the four cell strains tested. Treatment of cell strain HTM4 with DEX (10(-7) mol/l) for 17 d caused an approximate doubling of cell-associated and secreted FN. This DEX-induced increase in FN expression was progressive after the first 7 d of treatment and was blocked partially with a glucocorticoid antagonist, cortexolone. By contrast, DEX treatment induced an intermediate 50-60% increase in FN expression in cell strains HTM10 and HTM2; in HTM6, FN was unchanged after exposure to the glucocorticoid. This model system may be useful to examine molecular changes associated with corticosteroid-induced ocular hypertension and evaluate glaucomatous changes in the TM because increased FN deposition occurs in the aqueous humor outflow pathway of patients with open-angle glaucoma.

Glucocorticoids inhibit the induction of nitric oxide synthase and the related cell damage in adenocarcinoma cells

Lipopolysaccharide (LPS) induced a time-dependent synthesis of nitric oxide (NO) in EMT6 adenocarcinoma cells, assayed by accumulation of NO-derived nitrite in the medium. The induction of NO synthesis was inhibited in a concentration-dependent manner by the glucocorticoids dexamethasone (IC50 = 5 nM) and hydrocortisone (IC50 = 20 nM) and this effect was partially antagonized by progesterone and cortexolone. If addition of dexamethasone was delayed 6 h or more, inhibition of nitrite accumulation over 24 h was substantially reduced, indicating a lack of direct effect of glucocorticoids on the NO synthase. Nitrite accumulation was accompanied by cell damage, which was increased by L-arginine and inhibited by NG-monomethyl-L-arginine (L-NMMA) and dexamethasone. These data show that NO is a primary cytotoxic mediator and that suppression of its formation by glucocorticoids explains some of their anti-inflammatory and cytoprotective effects.

L-arginine, the precursor of nitric oxide, abolishes the effect of estrogens on bleeding time in experimental uremia

We have reported previously that conjugated estrogens that are effective in shortening the prolonged bleeding time in uremic patients are also effective on bleeding time in a rat model of uremia. Using such a rat model we have recently demonstrated that nitric oxide (NO), an endothelium-derived vasodilator, is involved in mediating the bleeding tendency of uremia. With the present study we wanted to investigate whether conjugated estrogen mixture or its active component, 17 beta-estradiol, reduce uremic bleeding by interfering with the NO pathway. Our results showed that the shortening effect of conjugated estrogen and 17 beta-estradiol on bleeding time of uremic rats was completely reversed by giving the animals the NO precursor L-arginine, but not D-arginine, which is not a precursor of NO. Dexamethasone which at variance to progesterone inhibits the process of induction of NO-forming enzyme, shortened the prolonged bleeding time of uremic rats within 4 hours from injection. This effect was eliminated by L-arginine but not D-arginine administration. The glucocorticoid receptor antagonist cortexolone prevented the shortening of bleeding time induced by dexamethasone, suggesting that a receptor-mediated mechanism is involved in the hemostatic effect of dexamethasone as previously reported for estrogens. Unlike conjugated estrogens and dexamethasone, progesterone had no effect on bleeding time. All these findings would indicate that the effect of estrogens and dexamethasone on primary hemostasis in uremia might be mediated by changes in NO synthetic pathway.

11 beta-hydroxylase deficiency in hyperandrogenism

OBJECTIVE

to determine the 11-deoxycortisol (S) response and incidence of 11 beta-hydroxylase deficiency in hyperandrogenism.

DESIGN

Hyperandrogenic women prospectively and consecutively underwent acute adrenal stimulation studies.

SETTING

Tertiary institution.

PATIENTS

Two hundred sixty women complaining of hirsutism and/or hyperandrogenic oligomenorrhea were studied, excluding five unrelated families (1.9% of total) suffering from 21-hydroxylase deficient late-onset adrenal hyperplasia. Forty-one healthy premenopausal eumenorrheic women served as controls.

MAIN OUTCOME MEASURES

Only two unrelated women (0.8%) had a poststimulation or net increment S level value greater than or equal to threefold the upper 95th percentile of controls and were presumed to suffer from 11 beta-hydroxylase deficient late-onset adrenal hyperplasia. One hundred nine (42%) of hyperandrogenic women had at least one S value above the 95th percentile of controls. These women also demonstrated higher basal (F0) and stimulated cortisol levels, but a similar increment compared with controls.

RESULTS

Patients with high S measures had higher testosterone, dehydroepiandrosterone sulfate, and androstenedione levels, but similar luteinizing hormone/follicle-stimulating hormone ratios, than hyperandrogenic cohorts with no abnormal S measures. Basal values of S (S0), F0, or S0/F0 were not useful to predict an abnormal S response to stimulation.

CONCLUSIONS

Although adrenocortical hyperactivity was present in 42% of our hyperandrogenic patients, only 0.8% were presumed to suffer from 11 beta-hydroxylase deficient late-onset adrenal hyperplasia. A systemic search for this deficiency in hyperandrogenism is probably unwarranted.

A quantitative in vivo mouse model used to assay inhibitors of tumor-induced angiogenesis

An in vivo model of tumor-induced angiogenesis was used to monitor two known inhibitors of angiogenesis, protamine sulfate and the steroid tetrahydro S. Tumor cells entrapped in alginate beads were injected s.c. into mice. Blood vessel induction was measured by two quantitative methods: measurement of hemoglobin at the alginate pellet site, and pooling of radiolabeled RBC to the alginate pellet site. The two methods gave parallel results. Tetrahydro S with or without heparin inhibited blood vessel growth by 50%, and protamine sulfate inhibited blood vessel growth by 85%. These results were supported by gross morphology and histological analysis of the alginate pellet site.

Glucocorticoid receptor monoclonal antibodies define the biological action of RU 38486 in intact B16 melanoma cells

The mechanism of action of the synthetic glucocorticoid antagonist, RU 38486, has yet to be completely elucidated. Although RU 38486 is a potent antiglucocorticoid in vivo, several studies have indicated that it has some agonist activities in vitro, such as high-affinity steroid binding to the receptor, activation, and DNA binding. Nevertheless, these in vitro postbinding events do not lead to any known gene expression. To understand the action of the glucocorticoid antagonist RU 38486, we studied glucocorticoid receptor localization on a mouse melanoma cell line (B16C3) by indirect immunofluorescent staining techniques, using monoclonal antibodies to the glucocorticoid receptor. Our data in intact cells suggest that, unlike glucocorticoid agonists such as triamcinolone acetonide, and similar to the glucocorticoid antagonist cortexolone, RU 38486-bound receptors do not translocate to the nucleus and hence do not allow for transcription of glucocorticoid-regulated genes to occur. Passage through the nuclear membrane may be a rate-limiting step in the action of glucocorticoid antagonists, and translocation may in itself be an important regulatory mechanism of steroid hormone action.

Effects of gonadotropin on ovarian intrafollicular processes during the development of oocyte maturational competence in a teleost, the Atlantic croaker: evidence for two distinct stages of gonadotropin control of final oocyte maturation

Full-grown oocytes of Atlantic croaker are insensitive to maturation-inducing steroid (MIS) unless they are primed with gonadotropin (GtH). The objective of this study was to examine the mechanism of GtH-induced maturational competence in croaker oocytes. Specifically, we determined the in vitro secretion of steroids by intact ovarian follicles of unprimed or hCG-primed fish, the direct effects of steroids on maturational competence, and the effects of steroid (cyanoketone), protein (cycloheximide), and RNA (actinomycin D) synthesis inhibitors on hCG-induced maturational competence and steroidogenesis in vitro. The steroid content of the incubation medium after hCG treatment was measured by RIA. The effects of hCG or exogenous steroid treatment on maturational competence were determined by recording the incidence of germinal vesicle breakdown (GVBD) after MIS-induced GVBD in a standard bioassay. Our major findings were: (1) induction of maturational competence occurred after exposure of ovarian follicles to hCG either in vivo or in vitro; (2) MIS secretion was detected in follicles of hCG-primed fish but not unprimed fish, and no MIS secretion was observed during hCG induction of maturational competence in vitro; (3) treatment with cyanoketone blocked the hCG-dependent secretion of testosterone and estradiol but not the development of maturational competence; (4) treatment with MIS or various other exogenous steroids in the absence of hCG did not induce maturational competence; and (5) hCG-induced maturational competence was inhibited by cycloheximide and actinomycin D. Therefore, the mechanisms of GtH induction of oocyte maturation in Atlantic croaker can be described in two distinct stages: a delta-4 steroid-(including MIS) and estrogen-independent priming stage followed by a MIS-mediated GVBD stage. The priming stage may involve mechanisms requiring RNA as well as protein synthesis.