Promote lipolysis in white adipocytes by magnetic hyperthermia therapy with Fe3O4microsphere-doped hydrogel.

Obesity has become an ongoing global crisis, since it increases the risks of cardiovascular disease, type 2 diabetes, fatty liver, cognitive decline, and some cancers. Adipose tissue is closely associated with the disorder of lipid metabolism. Several efforts have been made toward the modulation of lipid accumulation, but have been hindered by poor efficiency of cellular uptake, low safety, and uncertain effective dosage. Herein, we design an Fe3O4microsphere-doped composite hydrogel (Fe3O4microspheres @chitosan/ß-glycerophosphate/collagen), termed as Fe3O4@Gel, as the magnetocaloric agent for magnetic hyperthermia therapy (MHT), aiming to promote lipolysis in white adipocytes. The experimental results show that the obtained Fe3O4@Gel displays a series of advantages, such as fast sol-gel transition, high biocompatibility, and excellent magneto-thermal performance. MHT, which is realized by Fe3O4@Gel subjected to an alternating magnetic field, leads to reduced lipid accumulation, lower triglyceride content, and increased mitochondrial activity in white adipocytes. This work shows that Fe3O4@Gel-mediated MHT can effectively promote lipolysis in white adipocytesin vitro, which provides a potential approach to treat obesity and associated metabolic disorders.

Aptamer-modified atomically precise gold nanoclusters as targeted nanozymes to scavenge reactive oxygen species in white adipocytes.

Oxidative stress caused by excessive reactive oxygen species (ROS) leads to the dysfunction of white adipocytes and white fat, and also promotes triglyceride storage by inhibiting the respiration of adipocytes directly. Nanozymes, as a new generation of artificial enzymes, have exhibited attractive potential in scavenging ROS and treatment of ROS-related diseases. Herein, aptamer-modified atomically precise gold Au25nanoclusters (Apt-Au25NCs), are employed as targeted nanozymes to scavenge ROS in white adipocytes. Our results show that Apt-Au25NCs have high targeting capability toward white adipocytes with low cytotoxicity. Furthermore, Apt-Au25NCs show high superoxide dismutase (SOD)-like and catalase (CAT)-like activity in a concentration-dependent manner, and also good thermal and pH stability compared with natural SOD and CAT. Finally, the efficiency of ROS scavenging by Apt-Au25NCs in white adipocytes is evaluated. This work demonstrates that Apt-Au25NCs, as targeted nanozymes, are efficient in scavenging ROS in white adipocytes, exhibiting promising potential for the treatment of obesity and related diseases.

Label-free detection of biomarker alpha fetoprotein in serum by ssDNA aptamer functionalized magnetic nanoparticles.

Hepatocellular carcinoma (HCC) is one of the most common malignant tumors in the clinic, with the characteristics of occult onset, rapid progression, and high degree of malignancy. Alpha fetoprotein (AFP) is the most important biomarker of HCC, which is widely used in early screening, diagnosis, and prognosis observation. A series of immunoassays have been developed and frequently used in the detection of AFP based on antibodies. Unfortunately, the shortcomings of antibodies, such as thermal unstable and fluctuant activity by batches, lead to the inaccuracy in the detection of AFP. In this study, aptamers instead of antibodies were adopted as the specific recognition element for AFP, aiming to seek an alternative strategy to immunoassays. An AFP-specific ssDNA aptamer was grafted to magnetic nanoparticles (Fe3O4@SiO2) via avidin-biotin interaction, and the resultant aptamer functionalized magnetic nanoparticles (Ap-MNPs) were adequately characterized and tested. The Ap-MNPs in solution exhibited a fast response to the outer magnetic field, and can be completely separated in several minutes. It was found that Ap-MNPs have good specificity to the target AFP, as the recovery of AFP (87.0%) was much higher than the competitive proteins IgG (38.9%), HSA (18.5%), and FIB (11.4%). A convenient and efficient label-free detection method of AFP in serum was developed based on Ap-MNPs in combination with high-performance liquid chromatography. The linearity of this method was over a range of 1-50 µg ml-1 with a correlation coefficient of 0.9999, and the limit of detection was 0.27 µg ml-1. This study indicated that aptamers are an ideal tool for the recognition and detection of biomarkers, and thus will find wide applications in clinical practice.

Graphene oxide-based magnetic nanocomposites for the delivery of melittin to cervical cancer HeLa cells.

Melittin (MEL), the primary active component of bee venom, has recently emerged as a promising cancer chemotherapeutic agent. However, the instability and rapid degradation of MEL is a significant challenge in practical therapeutic applications. In the present study, graphene oxide (GO)-based magnetic nanocomposites (PEG-GO-Fe3O4) were prepared and adopted as the drug delivery vehicles of MEL, and the anticancer effects of PEG-GO-Fe3O4/MEL complexes on human cervical cancer HeLa cells were studied. PEG-GO-Fe3O4 exhibited a series of unique physical and chemical properties resulting in multiple interactions with MEL, and ultimately the release of MEL. In vitro experiments showed that PEG-GO-Fe3O4/MEL not only distinctly enhanced the inhibition effect on HeLa cells, but also induced pore formation in the cell membrane that ultimately led to cell lysis. In this newly developed drug delivery system, PEGylated GO plays the role of a MEL protector while Fe3O4 nanoparticles act as magnetic responders; therefore active MEL can be released over a long period of time (up to 72 h) and maintain its inhibition effect on HeLa cells.

Imaging of Polar and Nonpolar Species Using Compact Desorption Electrospray Ionization/Postphotoionization Mass Spectrometry.

Desorption electrospray ionization (DESI) mass spectrometry imaging (MSI) can simultaneously record the 2D distribution of polar biomolecules in tissue slices at ambient conditions. However, sensitivity of DESI-MSI for nonpolar compounds is restricted by low ionization efficiency and strong ion suppression. In this study, a compact postphotoionization assembly combined with DESI (DESI/PI) was developed for imaging polar and nonpolar molecules in tissue sections by switching off/on a portable krypton lamp. Compared with DESI, higher signal intensities of nonpolar compounds could be detected with DESI/PI. To further increase the ionization efficiency and transport of charged ions of DESI/PI, the desorption solvent composition and gas flow in the ionization tube were optimized. In mouse brain tissue, more than 2 orders of magnitude higher signal intensities for certain neutral biomolecules like creatine, cholesterol, and GalCer lipids were obtained by DESI/PI in the positive ion mode, compared with that of DESI. In the negative ion mode, ion yields of DESI/PI for glutamine and some lipids (HexCer, PE, and PE-O) were also increased by several-fold. Moreover, nonpolar constituents in plant tissue, such as catechins in leaf shoots of tea, could also be visualized by DESI/PI. Our results indicate that DESI/PI can expand the application field of DESI to nonpolar molecules, which is important for comprehensive imaging of biomolecules in biological tissues with moderate spatial resolution at ambient conditions.

Extraction and detection of bisphenol A in human serum and urine by aptamer-functionalized magnetic nanoparticles.

A new type of magnetic nanoparticles (MNPs), as the absorbents of bisphenol A (BPA), was prepared by functionalization of Fe3O4@SiO2 with BPA-specific aptamer in this work. ssDNA aptamer was immobilized on the Fe3O4@SiO2 surface through biotin-avidin interactions, playing a role of the specific probe for BPA. The resultant materials (Apt-MNPs) exhibited outstanding magnetic responsibility and can be separated efficiently by the magnetic field. Experimental results also showed that Apt-MNPs had large adsorption capacity and high competitive selectivity for the targeted compound BPA. Furthermore, Apt-MNPs were adopted as the specific absorbents to extract and enrich BPA from human serum and urine samples. Therefore, an efficient detection method of BPA was developed in combination with high-performance liquid chromatography (HPLC). The linearity of the method was over a range of 5-10,000 ng mL-1 with a correlation coefficient of 0.99997, and the limit of detections (LODs) for serum and urine were 2.0 and 1.0 ng mL-1, respectively. The recoveries of BPA in the spiked human serum and urine samples were 90.8 ± 7.3% (RSD) and 92.3 ± 1.5%, respectively. Our results demonstrated that Apt-MNPs were high-performance adsorbents for extracting and enriching BPA, resulting in fast and efficient detection of BPA in serum and urine samples. Graphical abstract Aptamer-MNPs were effective for BPA separation from serum and urine.

Selective extraction of bisphenol A from water by one-monomer molecularly imprinted magnetic nanoparticles.

One-monomer molecularly imprinted magnetic nanoparticles were prepared as adsorbents for selective extraction of bisphenol A from water in this study. A single bi-functional monomer was adopted for preparation of the molecularly imprinted polymer, avoiding the tedious trial-and-error optimizations as traditional strategy. Moreover, bisphenol F was used as the dummy template for bisphenol A to avoid the interference from residual template molecules. These nanoparticles showed not only large adsorption capacity and good selectivity to the bisphenol A but also outstanding magnetic response performance. Furthermore, they were successfully used as magnetic solid-phase extraction adsorbents of bisphenol A from various water samples, including tap water, river water, and seawater. The developed method was found to be much more efficient, convenient, and economical for selective extraction of bisphenol A compared with the traditional solid-phase extraction. Separation of these nanoparticles can be easily achieved with an external magnetic field, and the optimized adsorption time was only 15 min. The recoveries of bisphenol A in different water samples ranged from 85.38 to 93.75%, with relative standard deviation lower than 7.47%. These results showed that one-monomer molecularly imprinted magnetic nanoparticles had the potential to be popular adsorbents for selective extraction of pollutants from water.

Novel Beta-Functionalized Porphyrins Approaching 11% Efficiency for Organic Solar Cells.

Porphyrins and their derivatives possess high molar extinction coefficients and strong electron-donating abilities and have been widely used in organic solar cells (OSCs). Though porphyrins can be easily functionalized at the four meso-positions and the eight ß-positions, nearly all porphyrin photovoltaic materials are reported to be functionalized at the meso-positions, and the porphyrin photovoltaic materials functionalized at the ß-positions are to be explored. Herein, the regioselective ß-positions of a porphyrin are first brominated without using rare metal iridium catalysts, and then, after two more reactions, two antipodal ß-substituted porphyrin donors EHDPP-Por and BODPP-Por are synthesized, in which four DPP (diketopyrrolopyrrole) units are connected symmetrically with acetylene at four of the ß-positions, for OSCs. The all-small-molecule organic solar cells based on EHDPP-Por:Y6 and BODPP-Por:Y6 active layers achieved power conversion efficiencies of 10.19 and 10.99%, respectively, which are higher than most of the binary OSCs based on the porphyrins functionalized at the meso-positions, demonstrating that ß-functionalized porphyrins are very promising for OSCs.

Aptamer-functionalized AuNCs nanogel for targeted delivery of docosahexaenoic acid to induce browning of white adipocytes.

Obesity, as a global public health concern, causes a series of metabolic disorders and other diseases. Browning of white fat (white adipocytes transforming to beige adipocytes) offers an attractive approach for obesity treatment. In the present study, aptamer-functionalized nanogel of gold nanoclusters (AuNCs), termed Apt-NG, was developed as the targeted delivery vehicle of browning agent docosahexaenoic acid (DHA). Apt-NG has multiple advantages, including nanoscale size, strong autofluorescence, low toxicity, and excellent targeting capability to white adipocytes. After treatment with DHA@Apt-NG, the morphology of lipid droplets changed evidently; meanwhile the triglyceride level decreased while the mitochondrial activity increased. The DHA@Apt-NG treatment effectively up-regulated the mRNA expression levels of Ucp1, Pgc-1α, Pparg, and Prdm16, which play important roles in browning of white adipocytes. This study provides a feasible strategy to achieve efficient browning of white adipocytes based on targeted delivery nanosystems, inspiring a new idea for obesity treatment.

Polybrominated diphenyl ethers (PBDEs) in human serum from Southeast China.

Polybrominated diphenyl ethers (PBDEs) have been used extensively in electrical and electronic products, but little is known about the exposure level in the electrical appliance factories workers and nearby local residents. In this study, we assessed body burdens of PBDEs in 194 Chinese injection workers from electrical appliance factories and also measured 205 blood samples from catering workers, leather factory workers, umbilical cord and infertile men for comparison. Twelve PBDE congeners in serum samples were measured by GC-MS. The highest concentration for total PBDEs was found in injection workers, which is positively correlated to employment duration. BDE-209 was the most dominant congener followed by BDE-47, 28 and 99. We also found the presence of all twelve PBDEs in cord blood, suggesting an evidence of fetal exposure. Concentration of BDE-47 was particularly higher in serum samples from infertile men in comparison with that of catering workers and leather factory workers.

Glucose and Its Derivatives as Interfacial Materials for Inverted Organic Solar Cells.

Glucose, a widely distributed biomaterial in nature, is presented as a new cathode interfacial material for highly efficient inverted organic solar cells. The interactions between glucose and the indium tin oxide (ITO) substrate as well as the formation mechanisms of the glucose interlayer were investigated by molecular dynamics simulation and relevant experimental tests. The results revealed that the In-OH coordination between the oxygen atom of glucose and the indium of ITO is the key factor for the formation of interfacial dipoles, thereby reducing the work function of the ITO cathode for efficient charge transfer. With PM6:Y6 as the active layer, the power conversion efficiency (PCE) of the organic solar cells was significantly increased from 1.99 to 15.42% after ITO was modified by a glucose interlayer through the traditional spin-coating method. More importantly, glucose can be adsorbed on the ITO surface by a simple immersion process, and the devices based on the modified ITO by immersed glucose achieved a PCE of 14.48%, which is comparable to that of the traditional spin-coating method. Furthermore, we found that the OSCs with the ITO cathodes modified with glucose derivatives including sorbitol and sodium gluconate by different preparation methods also exhibited high performance. The overall performance of the devices with ITO modified by a simple and low-cost immersion method can be maintained at more than 93% of that prepared with the traditional spin-coating method. The results demonstrated that low-price glucose and its derivatives are good candidates as ITO interlayer materials for OSCs, and the effectiveness of the immersion process paves a way for simplifying the manufacture of low-cost and large-area organic solar cells.

Browning of white adipocytes by gold nanocluster mediated electromagnetic induction heating hyperthermia.

Browning of white adipose tissue (WAT) is becoming an attractive therapeutic target for obesity. Great efforts have been made to develop effective approaches to induce browning. Unfortunately, the current methods suffer from a series of disadvantages, such as low efficiency, unsatisfactory stability, and side effects. Herein, we report a new approach to induce browning of 3T3-L1 white adipocytes based on electromagnetic induction heating (EIH) hyperthermia. In particular, adipocyte-targeting aptamer modified gold nanoclusters (Apt-AuNCs) were employed as the mediators of EIH. Apt-AuNCs had good biocompatibility and excellent targeting performance with white adipocytes. After Apt-AuNCs/EIH treatment, adipocytes with characteristic multilocular and small lipid droplets increased, and the content of triglycerides reduced effectively. Apt-AuNCs/EIH treatment also significantly increased the mitochondrial activity in adipocytes. Meanwhile, the mRNA levels of key genes that are involved in browning, for example UCP1, PRDM16, PPARγ, and PGC-1α, were upregulated. Finally, the induction mechanism of Apt-AuNCs/EIH on browning of white adipocytes was explained by the synergistic effects of EIH hyperthermia and pharmacological action of AuNCs. To the best of our knowledge, this is the first attempt on induction of browning by metal nanocluster-mediated EIH hyperthermia, thus providing an interesting and efficient channel for obesity treatment.

Effects of room temperature ionic liquids on fluorescence characteristics of 17ß-estradiol and its derivative.

Previous reports have seldom concerned about the RTILs (Room temperature ionic liquids), and their effects on derivatization reaction or derivatives. In this study, we reported that the effects of four different RTILs, i.e., [EMIM]PF(6), [BMIM]PF(6), [HMIM]PF(6) and [OMIM]PF(6), on fluorescence spectra of 17 ß-estradiol (E2), and its derivatization solvent dansyl chloride (DNSCl) and the derivative. [BMIM]PF(6) had a significant quenching effect on the fluorescence intensity of E2, suggesting the formation of [BMIM]PF(6)/E2 complexes and possible buried E2 molecular in a more hydrophobic microenvironment. The estimated Stern-Volmer quenching constant (Ksv=0.3519) proved that E2 quenching caused by [BMIM]PF(6) was a dynamic quenching process. Four RTILs, with different alkyl chain-length in imidazolium cation, resulted in different quenching intensities to E2 as follows: [EMIM]PF(6) > [BMIM]PF(6) > [HMIM]PF(6) > [OMIM]PF(6). At 5 mg L(-1) of DNSCl, [BMIM]PF(6), [HMIM]PF(6) and [OMIM]PF(6) increased the fluorescence intensities of E2 in water by 8.5, 7.6 and 6.1 times, respectively, and a 37-nm hypsochromic shift occurred. The fluorescence intensity for [BMIM]PF(6)-extracted derivative of E2 increased more than two times compared with that for the control. In conclusion, this study demonstrated that above four hexafluorophosphate salt ionic liquids could be used in derivatization reaction to enhance fluorescent sensitivity in E2 trace residual analysis.

Perfluorinated chemicals in blood of residents in Wenzhou, China.

Perfluorinated compounds (PFCs) are persistent organic pollutants ubiquitously distributed in the environment and human populations. Here we report PFC concentrations in the residents of Wenzhou City, which is characterized as the 'Footwear Capital' of China. Specifically, fifty serum samples collected from workers in a leather factory, fifty-five umbilical cord serum samples and fifteen serum samples from infertile men were analyzed. PFOS was one of the most frequently detected PFCs and showed the highest level. The mean serum levels of PFOS and PFOA of workers and infertile males were higher than the cord serum. PFOS concentration in cord serum increased with increase in age of the mother. Gender differences were significant both in worker serum samples and umbilical cord samples with higher levels found in males/male fetuses. Our findings suggested that PFOS, PFOA and PFHxS were widely distributed in Wenzhou residents, but occupational exposure was not the main source for workers.

Analysis and control of biped robot with variable stiffness ankle joints.

BACKGROUND: Biped robot locomotion is an active topic of research, and the walking stability is one of the research objectives. OBJECTIVE: This paper discusses the variable stiffness ankle joint and the walking control of a biped robot. METHODS: A design is introduced that achieves the ankle joint variable stiffness by using a pneumatic unit. The actuation system of the biped robot is based on the hybrid use of electric and pneumatic. The locomotion control architecture has been proposed to exploit natural leg dynamics in order to improve the biped robot walking stability. We also present a dynamic simulation which matches the biped robot and experiments with the real biped robot. RESULTS: The simulation and experiments result that introducing the variable stiffness ankle joint and the controller achieve a significant improvement in foot-ground impact and walking stability of the biped robot. CONCLUSION: The biped robot with variable stiffness ankle joints has a better walking performance under the control method.

In utero cadmium and dibutyl phthalate combination exposure worsens the defects of fetal testis in rats.

Testicular dysgenesis syndrome might be due to the fetal testis defects caused by endocrine disruptors. Here, we report the combined effects of in utero exposure to cadmium (CdCl2, Cd) and di-n-butyl phthalate (DBP) on fetal testis development in rats. Pregnant Sprague-Dawley rats were randomly divided into four groups: control, Cd, DBP (250 mg/kg/day), and Cd + DBP. Cd (0.25 mg/kg/once) was intraperitoneally injected to the dam on gestational day 12 and DBP (250 mg/kg) was daily gavaged to the dam on gestational day 12 for 10 days. Cd, DBP, and Cd + DBP lowered serum testosterone levels in male fetuses. Cd and DBP did not alter fetal Leydig cell (FLC) number, but the combined exposure led to decreased FLC number. Cd did not affect FLC aggregation while DBP caused FLC aggregation and the combined exposure worsened FLC aggregation. Cd lowered FLC mRNA (Lhcgr, Star, Cyp11a1, and Insl3) levels and DBP lowered Lhcgr, Star, Insl3, and Nr5a1 levels. DBP up-regulated Scarb1 expression without affecting Cyp11a1 while the combined exposure antagonized DBP. These two chemicals and its combination did not affect Sertoli cell number and gene (Amh, Fshr, and Sox9) expression at current doses. In conclusion, the combined exposure of Cd and DBP exerts synergically antiandrogenic effects via targeting FLC development.

Combustion intermediates in fuel-rich 1,4-dioxane flame studied by tunable synchrotron vacuum ultraviolet photoionization.

Combustion intermediates of a cyclic oxygenated hydrocarbon, 1,4-dioxane, were studied with the tunable synchrotron vacuum ultraviolet photoionization and molecular-beam mass spectrometry (MBMS) technique. A fuel-rich premixed laminar 1,4-dioxane/O(2)/Ar flame at low pressure with an equivalence ratio of 1.80 was investigated in the present work. A total of 20 intermediates were observed, and their mole fraction profiles are calculated. Aromatic intermediates were not observed, and this was a prominent difference between the fuel-rich flames of 1,4-dioxane and previously studied noncyclic oxygenated hydrocarbons. The fuel-rich 1,4-dioxane flame could be divided into four zones, and formation routes of the intermediates were proposed. The discussion on the pollutant emissions showed that some light toxic molecules were produced from 1,4-dioxane combustion; however, toxic aromatics and soot emissions were possibly avoided.

Synthesis of Bithiophene-Based D-A1-D-A2 Terpolymers with Different A2 Moieties for Polymer Solar Cells via Direct Arylation.

A series of bithiophene (2T)-based D-A1-D-A2 terpolymers with different A2 moieties were prepared via direct arylation reaction. In these terpolymers, pyrrolo[3,4-c]pyrrole-1,4-dione (DPP) was selected as the first electron-accepting (A1) moiety, 2,1,3-benzothiadiazole (BT) or fluorinated benzothiadiazole (FBT) or octyl-thieno[3,4-c]pyrrole-4,6-dione (TPD) or 2,1,3-benzoselendiazole (SeT) was selected as the second electron-accepting (A2) moiety, while bithiophene with hexyl side chain was used as the electron-donating moiety. The UV-vis absorption, electrochemical properties, blend film morphology, and photovoltaic properties were studied to explore the effects of the A2 moiety. It is shown that these terpolymer films exhibit broad absorption (350⁻1000 nm), full width at half-maximum of more than 265 nm and ordered molecular packing. Varying the A2 moiety could affect the energy levels and blend film morphology leading to different polymer solar cell (PSC) performances of these (2T)-based D-A1-D-A2 terpolymers. As a result, the highest Jsc of 10.70 mA/cm² is achieved for Polymer 1 (P1) with BT as A2 moiety, while the higher highest occupied molecular orbital (HOMO) level limits the open circuit voltage (Voc) and leads to a power conversion efficiency (PCE) of 3.46%.

Bicomponent Random Approach for the Synthesis of Donor Polymers for Efficient All-Polymer Solar Cells Processed from A Green Solvent.

All-polymer solar cells (all-PSCs) can offer unique merits of high morphological stability to thermal and mechanical stress. To realize their full potential as flexible or wearable devices, it is highly desirable that the all-PSCs can be fabricated from a green solvent with simple post-treatment to avoid thermal annealing on the flexible substrate. This posed a severe challenge on material design to tune their properties with suitable solubility, aggregation, and morphology. To address this challenge, here, a simple bicomponent random approach on a D-A-type polymer donor was developed by just varying the D-A molar ratio. Under this approach, a series of new random polymers PBDTa-TPDb with different molar ratios of the D component of 2D-benzo[1,2-b:4,5-b']dithiophene (BDT) and A component of thieno[3,4-c]pyrrole-4,6-dione (TPD) were designed and synthesized. The energy levels, light absorption, solubility, and packing structure of random donors PBDTa-TPDb were found to vary substantially with the various D-A molar ratios. The devices based on PBDTa-TPDb/P(NDI2HD-T) were fabricated to explore the synergistic effects of the processing solvent and composition of D-A-type random polymers. The results show that nanoscale morphology, balanced miscibility/crystallinity of blend, and photovoltaic properties could be rationally optimized by tuning the composition of random donors. As a result, as-cast all-PSC-based optimal donor PBDT5-TPD4 achieves the best power conversion efficiency (PCE) of 8.20% processed from a green solvent, which performs better than that the reference polymer (PCE: 6.41%). This efficiency is the highest value for all-PSCs from BDT-TPD-based donors. Moreover, the optimized devices were relatively insensitive to the thickness of the active layer and exhibited good stability.

The cross talk of adrenal and Leydig cell steroids in Leydig cells.

Glucocorticoid is secreted by adrenal cortex, which binds to intracellular glucocorticoid and mineralocorticoid receptors to regulate steroidogenesis-related gene expression and testosterone production in Leydig cells. Glucocorticoid receptor activity shows inhibitory action on Leydig cell steroidogenesis, while mineralocorticoid receptor activity shows the stimulatory action. Leydig cells contain two important glucocorticoid-metabolizing enzymes, 11ß-hydroxysteroid dehydrogenase type 1 and type 2, regulating the intracellular levels of glucocorticoids by a pre-receptor mechanism. 11ß-Hydroxysteroid dehydrogenase type 1 is a bidirectional enzyme, and its direction is regulated by intracellular NADP+/NADPH redox potential. Leydig cells contain many steroidogenic enzymes, possibly regulating NADP+/NADPH redox potential by coupling with 11ß-hydroxysteroid dehydrogenase type 1. Here, we review the 11ß-hydroxysteroid dehydrogenase regulation and possible consequences in Leydig cell biology and pathology.