Aminoglutethimide Research Articles

Progestin and adipoQ receptor 7 (PAQR7) mediate the anti-apoptotic effect of P4 on human granulosa cells and its deficiency reduces ovarian function in female mice

PurposePAQR7 plays a key role in cell apoptosis as a progesterone membrane receptor. The physiological mechanism of PAQR7 in ovarian function and its anti-apoptotic action in mammals remain poorly understood.MethodsWe first added 0.2 µM aminoglutethimide (AG), an inhibitor of endogenous progesterone (P4) secretion, and transfected siPAQR7 co-incubated with P4 in human KGN cells to identify granulosa cell apoptosis, respectively. Additionally, we used Paqr7 knockout (PAQR7 KO) mice to assess the role of PAQR7 in the ovary.ResultsThe PAQR7 deficiency significantly increased apoptosis of KGN cells, and this significant difference disappeared following P4 supplementation. The Paqr7−/− female mice showed a prolonged estrous cycle, reduced follicular growth, increased the number of atresia follicles, and decreased the concentrations of E2 and AMH. The litters, litter sizes, and spontaneous ovulation in the Paqr7−/− mice were significantly decreased compared with the Paqr7+/+ mice. In addition, we also found low expression of PAQR7 in GCs from human follicular fluids of patients diagnosed with decreased ovarian reserve (DOR) and ovaries of mice with a DOR-like phenotype, respectively.ConclusionsThe present study has identified that PAQR7 is involved in mouse ovarian function and fertilization potential. One possible mechanism is mediating the anti-apoptotic effect of P4 on GC apoptosis via the BCL-2/BAX/CASPASE-3 signaling pathway. The mechanism underlying the effect of PAQR7 on ovarian development and aging remains to be identified.

Histopathological and immunohistochemical evaluation for detecting changes in blood hormone levels caused by endocrine disruptors in a 28-day repeated-dose study in rats.

Although measurements of blood hormone levels in rodent toxicological studies can provide important information on the mechanisms of toxicity and extrapolation to humans, there are several difficulties such as large individual differences and limited sample volume. To develop a more simplified method that does not depend solely on blood samples, we examined the possible application of immunohistochemistry for detecting endocrine disruptors in short-term studies. Aminotriazole (AMT), propylthiouracil (PTU), phenobarbital, aminoglutethimide (AGT), estradiol, and vitamin D3 were administered orally to 6-week-old male and female SD rats (five/group) for 28 days. Measurements of serum hormone levels revealed decreases in triiodothyronine (T3) and thyroxine (T4) in the AMT and PTU groups, an increase in thyroid stimulating hormone (TSH) in the AMT, PTU, and AGT groups, and an increase in adrenocorticotrophic hormone in the AGT group. Increased thyroid, pituitary, and adrenal gland weights; histopathological lesions, including follicular hypertrophy/hyperplasia, hypertrophy/vacuolation of anterior pituitary cells, and increased adrenocortical vacuolation were observed in association with the hormone level changes. Immunohistochemical analysis revealed a decreased T4 level in the thyroid gland of the AMT and PTU groups and an increased area of TSH positive immunostaining in the pituitary gland of the AMT, PTU, and AGT groups, consistent with the changes in serum T4 and TSH levels, respectively. These results suggest that histopathological analysis and immunohistochemistry for T4 and TSH might be useful and sensitive methods of detecting thyroid dysfunction, and that combining organ weight measurements is a reliable parameter of detecting endocrine disruptors.

Multicomponent Materials to Improve Solubility: Eutectics of Drug Aminoglutethimide

Here, we report the synthesis and experimental characterization of three drug-drug eutectic mixtures of drug aminoglutethimide (AMG) with caffeine (CAF), nicotinamide (NIC) and ethenzamide (ZMD). The eutectic mixtures i.e., AMG-CAF (1:0.4, molar ratio), AMG-NIC (1:1.9, molar ratio) and AMG-ZMD (1:1.4, molar ratio) demonstrate significant melting point depressions ranging from 99.2 to 127.2 °C compared to the melting point of the drug AMG (151 °C) and also show moderately higher aqueous solubilities than that of the AMG. The results presented include the determination of the binary melt phase diagrams and accompanying analytical characterization via X-ray powder diffraction, FT-IR spectroscopy and scanning electron microscopy.

Molecularly Imprinted Polymers Doped with Carbon Nanotube with Aid of Metal-Organic Gel for Drug Delivery Systems.

The incidence of breast cancer worldwide has been on the rise since the late 1970s, and it has become a common tumor that threatens women's health. Aminoglutethimide (AG) is a common treatment of breast cancer. However, current treatments require frequent dosing that results in unstable plasma concentration and low bioavailability, risking serious adverse reactions. Our goal was to develop a molecularly imprinted polymer (MIP) based delivery system to control the release of AG and demonstrate the availability of this drug delivery system (DDS), which was doped with carbon nanotube with aid of metal-organic gel. Preparation of MIP was optimized by key factors including composition of formula, ratio of monomers and drug loading concentration. By using multi-walled carbon nanotubes (MWCNT) and metal-organic gels (MOGs), MIP doubled the specific surface area, pore volume tripled and the IF was 1.6 times than the reference. Compared with commercial tablets, the relative bioavailability was 143.3% and a more stable release appeared. The results highlight the influence of MWCNT and MOGs on MIP, which has great potential as a DDS.

Tumor microenvironment-targeted poly-L-glutamic acid-based combination conjugate for enhanced triple negative breast cancer treatment

The intrinsic characteristics of the tumor microenvironment (TME), including acidic pH and overexpression of hydrolytic enzymes, offer an exciting opportunity for the rational design of TME-drug delivery systems (DDS). We developed and characterized a pH-responsive biodegradable poly-L-glutamic acid (PGA)-based combination conjugate family with the aim of optimizing anticancer effects. We obtained combination conjugates bearing Doxorubicin (Dox) and aminoglutethimide (AGM) with two Dox loadings and two different hydrazone pH-sensitive linkers that promote the specific release of Dox from the polymeric backbone within the TME. Low Dox loading coupled with a short hydrazone linker yielded optimal effects on primary tumor growth, lung metastasis (∼90% reduction), and toxicological profile in a preclinical metastatic triple-negative breast cancer (TNBC) murine model. The use of transcriptomic analysis helped us to identify the molecular mechanisms responsible for such results including a differential immunomodulation and cell death pathways among the conjugates. This data highlights the advantages of targeting the TME, the therapeutic value of polymer-based combination approaches, and the utility of –omics-based analysis to accelerate anticancer DDS.

Electrochemically Modulated Surface-Enhanced Raman Spectra of Aminoglutethimide (AGI) on a Ag-Sputtered Electrode

Abstract We have investigated the quantitative detection of aminoglutethimide (AGI) based on its adsorption on a SERS-active screen-printed electrode employing Electrochemical Surface-Enhanced Raman Spectroscopy (EC-SERS) technology. EC-SERS spectra of AGI molecules exhibited different adsorption mode onto the substrate with different potentials applied. When the applied potential reaches −400 mV, the intensities of the EC-SERS peaks provided by both aniline moiety and glutarimide moiety were significantly enhanced, which suggests the bidentate interaction of AGI molecule with the substrate. The peak of 1147 cm−1 showed the strongest intensity among the wavenumbers, with peak intensity over 30 times stronger than that of the standard SERS signal. A linear dependence occurred in the range of 1 × 10−5 M to 2 × 10−7 M. The limit of detection (LOD) is 40 ng/mL and the R squared of the linear curve was 0.98. This work was completed on a coin-sized chip using low sample volume (30 µL) only. Trace detection of this drug using this technique would be useful for the deterrence and prevention of dopant usage and other point-of-care diagnostics (POCD).

TSPO-ligands prevent oxidative damage and inflammatory response in C6 glioma cells by neurosteroid synthesis

Translocator protein 18kDa (TSPO) is predominantly located in the mitochondrial outer membrane, playing an important role in steroidogenesis, inflammation, cell survival and proliferation. Its expression in central nervous system, mainly in glial cells, has been found to be upregulated in neuropathology, and brain injury.In this study, we investigated the anti-oxidative and anti-inflammatory effects of a group of TSPO ligands from the N,N-dialkyl-2-phenylindol-3-ylglyoxylamide class (PIGAs), highlighting the involvement of neurosteroids in their pharmacological effects. To this aim we used a well-known in vitro model of neurosteroidogenesis: the astrocytic C6 glioma cell line, where TSPO expression and localization, as well as cell response to TSPO ligand treatment, have been established. All PIGAs reduced l-buthionine-(S,R)-sulfoximine (BSO)-driven cell cytotoxicity and lipid peroxidation. Moreover, an anti-inflammatory effect was observed due to the reduction of inducible nitric oxide synthase and cyclooxygenase-2 induction in LPS/IFNγ challenged cells. Both effects were blunted by aminoglutethimide (AMG), an inhibitor of pregnenolone synthesis, suggesting neurosteroids' involvement in PIGA protective mechanism. Finally, pregnenolone evaluation in PIGA exposed cells revealed an increase in its synthesis, which was prevented by AMG pre-treatment.These findings indicate that these TSPO ligands reduce oxidative stress and pro-inflammatory enzymes in glial cells through the de novo synthesis of neurosteroids, suggesting that these compounds could be potential new therapeutic tools for the treatment of inflammatory-based neuropathologies with beneficial effects possibly comparable to steroids, but potentially avoiding the negative side effects of long-term therapies with steroid hormones.

Inhibition of Neuropathic Pain by a Single Intraperitoneal Injection of Diazepam in the Rat: Possible Role of Neurosteroids.

Diazepam binds with the same high affinity to the central benzodiazepine receptor (CBR) and the peripheral benzodiazepine receptor, which has been renamed translocator protein (TSPO). Both receptors could promote neurosteroid synthesis. In the present study, we investigated whether a single dose of diazepam could inhibit neuropathic pain induced by L5 spinal nerve ligation (L5 SNL), and whether CBR and TSPO mediated this effect. We found that a single intraperitoneal injection of diazepam 9 d after L5 SNL significantly depressed the established mechanical allodynia and thermal hyperalgesia, which persisted until the end of the experiments. Furthermore, the effects were mimicked by a single intraperitoneal injection of Ro5-4864, a specific TSPO agonist and pregnenolone, a neurosteroid precursor. In addition, we found that the inhibitory effect of diazepam was also completely blocked by pretreatment with a specific CBR antagonist, flumazenil. The effects of diazepam or Ro5-4864 on neuropathic pain were completely blocked by pretreatment with a neurosteroid synthesis inhibitor, aminoglutethimide (AMG). Finally, any one of the three drugs, diazepam, Ro5-4864 and pregnenolone, could reduce the activation of astrocytes and the production of interleukin-1beta (IL-1β) in the L5 spinal dorsal horn 14 d after L5 SNL. These results suggest that in addition to exerting effects on CBR, diazepam may inhibit neuropathic pain via TSPO, which promotes neurosteroid formation, subsequently reducing the activation of astrocytes and production of cytokines.

Aminoglutethimide-imprinted xerogels in bulk and spherical formats, based on a multifunctional organo-alkoxysilane precursor

The multifunctional alkoxysilane precursor, 2,6-bis(propyl-trimethoxysilylurelene)pyridine (DPS) was designed and synthesized, envisaging a multiple hydrogen-bond interaction in the molecular imprinting of the drug aminoglutethimide (AGT). Imprinted xerogels were obtained in bulk and spherical formats. The spherical format was achieved by pore-filling onto spherical mesoporous silica, as a straightforward technique to generate the spherical format. The bulk gels presented better selectivity for the template against its glutarimide (GLU) analogue (selectivity factor: bulk 13.4; spherical 4.6), and good capacity (bulk 5521μmol/L; spherical 2679μmol/L) and imprinting factor parameters (bulk 11.3; spherical 1.4). On the other hand, the microspherical format exhibited better dynamic properties associated to chromatographic efficiency (theoretical plates: bulk 6.8; spherical 75) and mass transfer, due mainly to the existence of a mesoporous network, lacking in the bulk material. The performance of the imprinted xerogels was not as remarkable as that of their acrylic counterparts, previously described. Overall it was demonstrated that the use of designed new “breeds” of organo-alkoxysilanes may be a strategy to achieve satisfactory imprints by the sol–gel processes. DPS may in principle be applied even more effectively to other templates bearing better-matching spatially compatible acceptor–donor–acceptor arrays.

Macromolecular crowding of molecular imprinting: A facile pathway to produce drug delivery devices for zero-order sustained release

This paper reported the facile fabrication of drug delivery devices for zero-order sustained release by molecular crowding strategy of molecularly imprinting technology. Crowding-assisted molecularly imprinting polymers (MIPs) matrices were prepared by free-radical precipitation polymerization using aminoglutethimide (AG) as a model drug. The crowding effect was achieved by adding polystyrene as a macromolecular co-solute in pre-polymerization mixture. The MIP prepared under the non-MMC condition and the two corresponding non-imprinted particles were tested as controlled vehicles. The release profiles presented zero-order behaviors from two crowding-assisted polymers, the duration of approximately 18h for the crowding-assisted MIP and 10h for the crowding-assisted NIP, respectively while AG were all very rapid released from the other two controlled particles (85% occurring in the first hour). The BET surface area and pore volume of the crowding-assisted MIP were about ten times than those of the controlled MIP. The value of imprinting factor is 6.02 for the crowding-assisted MIP and 1.19 for the controlled MIP evaluated by the equilibrium adsorption experiment. Furthermore, the values of effective diffusivity (Deff) obtained from crowding-assisted MIP (10−17cm2/s) was about two orders of magnitude smaller than those from the controlled MIP, although the values of free drug diffusivity (D) were all found in the order of 10−13cm2/s. Compared with the commercial AG tablet, the MMC-assisted MIP gave a markedly high relative bioavailability of 266.3%, whereas the MMC-assisted NIP gave only 57.7%. The results indicated that the MMC condition can modulate the polymer networks approaciate to zero-order release of the drug and maintain the molecular memory pockets, even if under the poor polymerization conditions of MIPs preparation.

Proteomic profile of aminoglutethimide-induced apoptosis in HL-60 cells: Role of myeloperoxidase and arylamine free radicals

In this study, the cellular effects resulting from the metabolism of aminoglutethimide by myeloperoxidase were investigated. Human promyelocytic leukemia (HL-60) cells were treated with aminoglutethimide (AG), an arylamine drug that has a risk of adverse drug reactions, including drug-induced agranulocytosis. HL-60 cells contain abundant amounts of myeloperoxidase (MPO), a hemoprotein, which catalyzes one-electron oxidation of arylamines using H2O2 as a cofactor. Previous studies have shown that arylamine metabolism by MPO results in protein radical formation. The purpose of this study was to determine if pathways associated with a toxic response could be determined from conditions that produced protein radicals. Conditions for AG-induced protein radical formation (with minimal cytotoxicity) were optimized, and these conditions were used to carry out proteomic studies. We identified 43 proteins that were changed significantly upon AG treatment among which 18 were up-regulated and 25 were down-regulated. The quantitative proteomic data showed that AG peroxidative metabolism led to the down-regulation of critical anti-apoptotic proteins responsible for inhibiting the release of pro-apoptotic factors from the mitochondria as well as cytoskeletal proteins such as nuclear lamina. This overall pro-apoptotic response was confirmed with flow cytometry which demonstrated apoptosis to be the main mode of cell death, and this was attenuated by MPO inhibition. This response correlated with the intensity of AG-induced protein radical formation in HL-60 cells, which may play a role in cell death signaling mechanisms.

Molecularly imprinted microspheres for the anticancer drug aminoglutethimide: Synthesis, characterization, and solid-phase extraction applications in human urine samples

Molecularly imprinted microspheres (MIMs) for the anticancer drug aminoglutethimide (AG) were synthesized by aqueous suspension polymerization. The expected size and diameter of MIMs are controlled easily by changing one of the surfactant types, ratio of organic-to-water phase or stirring rate during polymerization. The obtained MIMs exhibit specific affinity toward AG with imprinting factor of 3.11 evaluated with a chromatographic model. The resultant MIMs were used as the SPE materials for the extraction of AG from human urine. A molecularly imprinted SPE (MISPE) method coupled with HPLC has been developed for the extraction and detection of AG in urine. Our results showed that most impurities from urine can be removed effectively after a washing step and the AG has been enriched effectively after MISPE operation with the recovery of >90% (n = 3). The developed MISPE-HPLC method could be used for enrichment and detection of AG in human urine.

Hepatic effects of aminoglutethimide: A model aromatic amine

Primary aromatic amine drugs are structural alerts in drug development because of their association with a high incidence of idiosyncratic drug reactions (IDRs). If biomarkers could be found that predict IDR risk, it would have a major impact on drug development. Previous attempts to do this through screening of hepatic gene expression profiles in rodents treated with aromatic amine drugs found limited changes. Of the drugs studied, aminoglutethimide (AMG) induced the most changes, and this led to a more comprehensive study of its effects on the liver. Brown Norway rats treated with AMG for up to 14 days showed only a transient elevation of glutamate dehydrogenase. Pathway-specific PCR arrays found few AMG-induced gene changes associated with an immune response and, of these changes, the majority were involved with innate immunity such as Tlr2, Ticam2, CD14, and C3. AMG treatment also led to significant changes in the apoptosis and mitochondrial panel of genes. It was recently found that AMG does induce significant changes in the bone marrow of rats, and agranulocytosis is a common IDR caused by AMG. In contrast, liver injury is not a common IDR associated with AMG. Therefore, the liver may be able to effectively deal with AMG reactive metabolites, and changes observed in this study may be involved in adaptation. Myeloperoxidase is also known to be able to oxidize aromatic amines to reactive metabolites, and these observations suggest that metabolism outside of the liver may be important for the mechanism of aromatic amine-induced IDRs.

Effect of Aminoglutethimide on Neutrophils in Rats: Implications for Idiosyncratic Drug-Induced Blood Dyscrasias

Aminoglutethimide (AMG) is an aromatic amine aromatase inhibitor associated with a high incidence of idiosyncratic blood dyscrasias, especially agranulocytosis. Animal models of idiosyncratic drug reactions (IDRs) represent essential tools to study these reactions; however, there is currently no valid model of idiosyncratic drug-induced agranulocytosis. Although AMG does not cause agranulocytosis in most animals or humans, drugs associated with serious IDRs generally cause a higher incidence of mild reactions that resolve despite continued treatment. Therefore, the effects of AMG on neutrophils and bone marrow in rats were studied to understand the mechanisms of more serious IDRs. An increase in peripheral blood neutrophils occurred as early as 24 h after AMG treatment with minimal changes to the total leukocyte count. Further investigation using 5-bromo-2'-deoxyuridine (BrdU) found an increased release of neutrophils from the bone marrow. Histologically, this corresponded to an increase in myeloid cells in the bone marrow, which was confirmed by differential staining with CD45 and CD71. AMG treatment stimulated an increase in colony forming unit granulocyte-macrophage and colony forming unit granulocyte ex vivo. There was also a marked increase in the number of activated neutrophils in the circulation expressing the extravasation marker CD62L. These findings indicate that AMG affects neutrophil production, release, and function. Similar effects on neutrophil kinetics in clozapine-treated rats have previously been found, and transient neutrophilia has been observed in patients taking other drugs associated with idiosyncratic agranulocytosis; therefore, the changes observed with AMG may be biomarkers to predict the risk that a drug will cause agranulocytosis.

The steroidogenic enzyme Cyp11a1 is essential for development of peanut-induced intestinal anaphylaxis

Cytochrome P450, family 11, subfamily A, polypeptide 1 (Cyp11a1), a cytochrome P450 enzyme, is the first and rate-limiting enzyme in the steroidogenic pathway, converting cholesterol to pregnenolone. Cyp11a1 expression is increased in activated T cells. We sought to determine the role of Cyp11a1 activation in the development of peanut allergy and TH cell functional differentiation. A Cyp11a1 inhibitor, aminoglutethimide (AMG), was administered to peanut-sensitized and challenged mice. Clinical symptoms, intestinal inflammation, and Cyp11a1 levels were assessed. The effects of Cyp11a1 inhibition on T(H)1, T(H)2, and T(H)17 differentiation were determined. Cyp11a1 gene silencing was performed with Cyp11a1-targeted short hairpin RNA. Peanut sensitization and challenge resulted in diarrhea, inflammation, and increased levels of Cyp11a1, IL13, and IL17A mRNA in the small intestine. Inhibition of Cyp11a1 with AMG prevented allergic diarrhea and inflammation. Levels of pregnenolone in serum were reduced in parallel. AMG treatment decreased IL13 and IL17A mRNA expression in the small intestine without affecting Cyp11a1 mRNA or protein levels. In vitro the inhibitor decreased IL13 and IL17A mRNA and protein levels in differentiated T(H)2 and T(H)17 CD4 T cells, respectively, without affecting GATA3, retinoic acid-related orphan receptor γt (RORγt), or T(H)1 cells and IFNG and T-bet expression. Short hairpin RNA-mediated silencing of Cyp11a1 in polarized T(H)2 CD4 T cells significantly decreased pregnenolone and IL13 mRNA and protein levels. Cyp11a1 plays an important role in the development of peanut allergy, regulating peanut-induced allergic responses through effects on steroidogenesis, an essential pathway in T(H)2 differentiation. Cyp11a1 thus serves as a novel target in the regulation and treatment of peanut allergy.

Changes in gene expression induced by aromatic amine drugs: Testing the danger hypothesis

Virtually all drugs that contain a primary aromatic amine are associated with a high incidence of idiosyncratic drug reactions (IDRs), suggesting that this functional group has biological effects that may be used as biomarkers to predict IDR risk. Most IDRs exhibit evidence of immune involvement and the ability of aromatic amines to form reactive metabolites and redox cycle may be responsible for initiation of an immune response through induction of cell stress, as postulated by the Danger Hypothesis. If true, danger signals could be biomarkers of IDR risk. A previous attempt to test the Danger Hypothesis found that sulfamethoxazole (SMX), the only aromatic amine tested, was also the only drug not associated with an increase of cell stress genes in mice. To ensure that these observations were not species-specific, and to determine biomarkers of IDR risk common to aromatic amines, rats were treated with SMX and two other aromatic amine drugs, dapsone (DDS) and aminoglutethimide (AMG), and hepatic gene expression was determined using microarrays. As in mice, SMX induced minimal gene changes in the rat, and none indicated cell stress, whereas DDS and AMG induced several changes including up-regulation of enzymes such as aldo-keto reductase, glutathione-S-transferase, and aldehyde dehydrogenase, which may represent danger signals. Early insulin-induced hepatic gene (Eiih) was up-regulated by all three drugs. Some mRNA changes were observed in the Keap-1-Nrf2-ARE pathway; however, the pattern was significantly different for each drug. Overall, the most salient finding was that the changes in the liver were minimal, even though aromatic amines cause a high incidence of IDRs. The liver generates a large number of reactive species; however, the ability of aromatic amines to be bioactivated by cells of the immune system may be why they cause a high incidence of IDRs.

Adsorption and Detection of Sport Doping Drugs on Metallic Plasmonic Nanoparticles of Different Morphology

A comparative study of different plasmonic nanoparticles with different morphologies (nanospheres and triangular nanoprisms) and metals (Ag and Au) was done in this work and applied to the ultrasensitive detection of aminoglutethimide (AGI) drug by surface enhanced Raman spectroscopy (SERS) and plasmon resonance. AGI is an aromatase inhibitor used as an antitumoral drug with remarkable pharmacological interest and also in illegal sport doping. The application of very sensitive spectroscopic techniques based on the localization of an electromagnetic field on plasmonic nanoparticles confirms the previous study of the adsorption of drugs onto a metal surface due to the near field character of these techniques. The adsorption of AGI on the above substrates was investigated at different pH values and surface coverages, and the results were analyzed on the basis of AGI/metal affinity, considering the interaction mechanism, the existence of two binding sites in AGI, and the influence of the interface on the adsorption in terms of surface charge due to the presence of other ions linked to the surface. Finally, a comparative quantitative detection of AGI was performed on both spherical and triangular nanoprism nanoparticles, and a limit of detection lower than those reported so far was deduced on the latter nanoparticles.

Continuous de novo synthesis of neurosteroids is required for normal synaptic transmission and plasticity in the dentate gyrus of the rat hippocampus

Both in vivo and in vitro studies have shown that neurosteroids promote learning and memory by modulating synaptic functions in the hippocampus. However, we do not know to what degree endogenously synthesized neurosteroids contribute to the hippocampal synaptic functions. Cytochrome P450scc is the enzyme that converts cholesterol to pregnenolone (PREG), which is required for the biosynthesis of all other neurosteroids. To investigate the physiological roles of endogenous neurosteroids in synaptic functions, we electrophysiologically examined the effects of aminoglutethimide (AG), a selective inhibitor of P450scc, on the synaptic transmission and plasticity in the dentate gyrus of rat hippocampal slices. The application of AG (100 μM) decreased the slope of the field excitatory postsynaptic potentials (fEPSPs) in granule cells by 20–30% in 20 min through the modulation of postsynaptic AMPA receptors, while it did not affect the presynaptic properties, including the paired-pulse ratio and the probability of glutamate release from presynaptic terminals. The AG-induced depression was nearly completely rescued by exogenously applied 500 nM PREG or by 1 nM dehydroepiandrosterone sulfate (DHEAS), one of the neurosteroids synthesized from PREG, suggesting that the AG-induced depression was caused by the loss of DHEAS. AG also reduced NMDA receptor activity, and suppressed high-frequency stimulation (HFS)-induced long-term potentiation (LTP). These findings provide novel evidence that the endogenous neurosteroids locally synthesized in the brain are required to maintain the normal excitatory synaptic transmission and plasticity in the dentate gyrus of the rat hippocampus.

Expression of ghrelin and the ghrelin receptor in different stages of porcine corpus luteum development and the inhibitory effects of ghrelin on progesterone secretion, 3β-hydroxysteroid dehydrogenase (3β-honestly significant difference (HSD)) activity and protein expression

Recent studies have suggested that ghrelin plays a direct role in controlling female reproduction. The aim of the present study was to investigate the mRNA and protein expression of ghrelin and its receptor (via real time PCR, Western blot and immunohistochemistry analysis, respectively) in porcine corpora lutea (CL) collected during early (CL1: 1–2 days after ovulation), middle (CL2: 7–10 after ovulation), and late luteal phase (CL3: 13–15 after ovulation). Ghrelin expression and concentration of both acylated and unacylated forms of ghrelin significantly increased during CL development. Immunohistochemistry analysis shown localization of ghrelin protein in the cytoplasm of large luteal cells. No changes in the expression of the ghrelin receptor were observed. Direct in vitro effects of ghrelin on progesterone (P4) secretion and 3-beta-hydroxysteroid dehydrogenase (3β-honestly significant difference (HSD)) activity, which were measured by the conversion of pregnenolone (P5) to P4, and 3β-HSD protein expression were then analyzed. To assess 3β-HSD activities, mature luteal cells were first cultured for 24 h with ghrelin at 100, 250, 500 and 1000 pg/mL with P5, or with aminoglutethimide (AMG). AMG is an inhibitor of CYP11A1-mediated hydroxylation; an addition of AMG and P5 enabled P4 production to serve as an index of 3β-HSD activity. Inhibitory effects of ghrelin on P4 secretion, 3β-HSD activity and protein expression were observed. In conclusion, the presence of ghrelin and its receptor in porcine corpora lutea and the direct inhibitory effects of ghrelin on luteal P4 secretion and 3β-HSD suggest potential auto/paracrine regulation by ghrelin in the luteal phase of ovary function.

Endocrine Cocktails for Advanced Breast Cancer

Prior studies have provided little evidence that combination endocrine therapy — for example, with tamoxifen plus older-generation aromatase inhibitors such as aminoglutethimide — improves outcomes over more common sequential endocrine therapy for patients with metastatic, hormone receptor–positive breast cancer. However, with the introduction of more-selective aromatase inhibitors (anastrozole, letrozole, and exemestane) and the novel estrogen-receptor agonist fulvestrant, the concept of combination endocrine therapy has been revisited. Investigators have now compared the efficacy of …