Subclinical Cushing's syndrome associated with an adrenocortical oncocytoma

Oncocytoma is a neoplasm that can arise in several organs, and it has been more commonly described in the kidney, salivary gland and thyroid. Oncocytoma arising in the adrenal gland is a rare finding. Moreover, functioning adrenocortical oncocytoma is exceptionally rare. A 47-yr-old man was incidentally discovered to have a right adrenal mass. The patient had no clinical features suggestive of increased adrenal function. However, hormonal evaluation showed a disturbed cortisol circadian rhythm, supranormal urinary cortisol excretion, a low level of ACTH, and a lack of suppressibility of cortisol secretion after dexamethasone. Right adrenalectomy was performed, and this revealed a well-circumscribed dark-brown tumor that measured 2.4x2.2 cm. The tumor consisted almost exclusively of large eosinophilic and epitheloid cells whose cytoplasm was packed with eosinophilic granulations, which corresponded to the numerous mitochondria confirmed on electron microscopy. This is a rare case of subclinical Cushing's syndrome that was caused by adrenocortical oncocytoma.

Interleukin-6 induces proliferation in adult spinal cord-derived neural progenitors via the JAK2/STAT3 pathway with EGF-induced MAPK phosphorylation

INTRODUCTION

In a previous study, we observed cell proliferation 3 days after spinal cord injury, and levels of interleukin-6 (IL-6) and epidermal growth factor (EGF) had significantly increased in the region of the injury.

OBJECTIVES

The purpose of the new study described here was to evaluate the roles of IL-6 and EGF after traumatic damage to the spinal cord having isolated neural progenitor cells (NPC) from adult mice.

METHODS AND RESULTS

Evidence provided by the trypan blue dye exclusion assay, 5-bromodeoxyuridine immunoreactivity and Western blot analysis indicated that IL-6 and EGF induced proliferation of these spinal cord-derived NPCs via phosphorylation of Janus-activated kinase 2 (JAK2)/signal transducer and activator of transcription 3 (STAT3) and mitogen-activated protein kinases (MAPK), respectively. Combined treatment with IL-6 and EGF accelerated proliferation of cells synergistically and phosphorylation of STAT3 and extracellular signal-regulated kinase 1/2 (Erk1/2). Furthermore, AG490 and AG1478, JAK2 inhibitor and EGFR inhibitor, respectively, prevented the IL-6- and EGF-induced proliferation of the cells. Interestingly, IL-6-activated MAPKs but EGF did not influence JAK2/STAT3 activation; AG490 specifically inhibited IL-6-induced Erk1/2 phosphorylation without affecting IL-6-induced phosphorylation of Raf and MEK1/2. These results indicate that IL-6 is directly involved in Erk1/2 activation via JAK2 and that Erk1/2 provides a signal bridge between the IL-6-induced JAK2/STAT3 pathway and EGF-induced MAPK pathway.

CONCLUSIONS

Our study is the first demonstration of IL-6- and EGF-stimulated proliferation of spinal cord progenitor cells via JAK2/STAT3 and MAPK signalling pathways. These pathways play key roles in repopulation and regeneration of spinal cord tissue after injury. It may represent novel therapeutic targets for pharmacological intervention in central nervous system disease, including spinal cord injury.

Improvement of canine somatic cell nuclear transfer procedure

The purpose of the present study on canine somatic cell nuclear transfer (SCNT) was to evaluate the effects of fusion strength, type of activation, culture media and site of transfer on developmental potential of SCNT embryos. We also examined the potential of enucleated bovine oocytes to serve as cytoplast recipients of canine somatic cells. Firstly, we evaluated the morphological characteristics of in vivo-matured canine oocytes collected by retrograde flushing of the oviducts 72 h after ovulation. Secondly, the effectiveness of three electrical strengths (1.8, 2.3 and 3.3 kV/cm), used twice for 20 micros, on fusion of canine cytoplasts with somatic cells were compared. Then, we compared: (1) chemical versus electrical activation (a) after parthenogenetic activation or (b) after reconstruction of canine oocytes with somatic cells; (2) culture of resulting intergeneric (IG) embryos in either (a) mSOF or (b) TCM-199. The exposure time to 6-DMAP was standardized by using bovine oocytes reconstructed with canine somatic cells. Bovine oocytes were used for SCNT after a 22 h in vitro maturation interval. The fusion rate was significantly higher in the 3.3 kV/cm group than in the 1.8 and 2.3 kV/cm treatment groups. After parthenogenesis or SCNT with chemical activation, 3.4 and 5.8%, respectively, of the embryos developed to the morula stage, as compared to none of the embryos produced using electrical activation. Later developmental stages (8-16 cells) were transferred to the uterine horn of eight recipients, but no pregnancy was detected. However, IG cloned embryos (bovine cytoplast/canine somatic cell) were capable of in vitro blastocyst development. In vitro developmental competence of IG cloned embryos was improved after exposure to 6-DMAP for 4 h as compared to 0, 2 or 6h exposure, although the increase was not significantly different among culture media. In summary, for production of canine SCNT embryos, we recommend fusion at 3.3 kV/cm, chemical activation, culture in mSOF medium and transfer of presumptive zygotes to the oviduct of recipient animals. The feasibility of IG production of cloned canine embryos using bovine cytoplasts as recipient of canine somatic cells was demonstrated.

Effects of fructose supplementation in chemically defined protein-free medium on development of bovine in vitro fertilized embryos

The present study evaluated the possible embryotrophic role of fructose supplementation in potassium simplex optimization medium (KSOM) on preimplantation development of bovine in vitro matured and fertilized (IVF) embryos under chemically defined conditions. In Experiment 1, the rates of cleavage (74.0-75.5%) and blastocyst formation (21.0-24.5%) were not affected by the supplementation of fructose in KSOM in absence or presence of glucose. In Experiment 2, the rates of cleavage (71.7-77.3%) and blastocyst formation (19.9-26.3%) did not differ significantly among the concentrations (0.0, 0.2, 1.5, 3.0, 5.6mM) of fructose supplementations in KSOM in presence of glucose. Moreover, the number of total ICM and TE cells, and percentage of ICM to total cell in blastocysts did not differ significantly among the concentrations of fructose supplementations in presence of glucose. In Experiment 3, the rates of cleavage (67.3-74.7%) and blastocyst formation (14.4-19.3%) did not differ significantly among the concentrations (0.0, 0.2, 1.5, 3.0, 5.6mM) of fructose supplementations in KSOM in absence of glucose. Although the number of total and ICM cells, and percentage of ICM to total cells in blastocysts did not differ significantly among the concentrations of fructose supplementations, 1.5mM fructose supplementation in absence of glucose had significantly (P<0.05) higher number of TE cells (106.2) than that of 5.6mM (84.0) supplementation. The study indicates that, fructose up to 5.6mM concentration can be used as an alternative for energy substrate in culture media without any detrimental effect on pre-implantation development in bovine IVF embryos.

Birth of viable female dogs produced by somatic cell nuclear transfer

Since the only viable cloned offspring born in dogs was a male, the purpose of the present study was to produce female puppies by somatic cell nuclear transfer (SCNT). Adult ear fibroblasts from a 2-month-old female Afghan hound were isolated and used as donor cells. In vivo-matured canine oocytes surgically collected (approximately 72h after ovulation) from the oviducts of 23 donors were used for SCNT. After removal of the cumulus cells, oocytes were enucleated, microinjected, fused with a donor cell, and activated. A total of 167 reconstructed SCNT embryos were surgically transferred (Day 0) into the oviducts of 12 recipient bitches (average 13.9 embryos/recipient, range 6-22) with spontaneous, synchronous estrous cycles. Three pregnancies were detected by ultrasonography on Day 23, maintained to term, and three healthy female puppies (520, 460, and 520g), were delivered by Caesarean section on Day 60. These puppies were phenotypically and genotypically identical to the cell donor. In conclusion, we have provided the first demonstration that female dogs can be produced by nuclear transfer of ear fibroblasts into enucleated canine oocytes.

15-Deoxy-Δ12,14-prostaglandin J2 (15d-PGJ2) Induces Cell Death Through Caspase-independent Mechanism in A172 Human Glioma Cells

15-Deoxy-(Delta12,14)-prostaglandin J(2) (15d-PGJ(2)) is a naturally occurring cyclopentenone metabolite of prostaglandin D(2) (PGD(2)) and is known as a specific potent ligand for the peroxisome proliferators activator receptor-gamma (PPARgamma). 15d-PGJ(2) inhibits cell growth and induces apoptosis in a number of different cancer cells. However, the underlying mechanism by which 15d-PGJ(2) induces cell death remains to be defined. The present study was undertaken to determine the effect of 15d-PGJ(2) on cell death in A172 human glioma cells. 15d-PGJ(2) caused reactive oxygen species (ROS) generation. 15d-PGJ(2)-induced ROS production and cell death were prevented by the antioxidant N-acetylcysteine. Activation of mitogen-activated protein kinases (MAPK) was not observed in cells treated with 15d-PGJ(2 )and inhibitors of MAPK subfamilies also were not effective in preventing 15d-PGJ(2)-induced cell death. 15d-PGJ(2) treatment caused mitochondrial dysfunction, as evidenced by depolarization of mitochondrial membrane potential. 15d-PGJ(2) induced caspase activation at 24 h of treatment, but the 15d-PGJ(2)-induced cell death was not prevented by caspase inhibitors. The antiapoptotic protein XIAP levels and release of apoptosis inducing factor (AIF) into the cytosol were not altered by 15d-PGJ(2) treatment. Taken together, these findings indicate that 15d-PGJ(2) triggers cell death through a caspase-independent mechanism and ROS production and disruption of mitochondrial membrane potential play an important role in the 15d-PGJ(2)-induced cell death in A172 human glioma cells.

The analysis of telomere length and telomerase activity in cloned pigs and cows

Inefficiency in the production of cloned animals is most likely due to epigenetic reprogramming errors after somatic cell nuclear transfer (SCNT). In order to investigate whether nuclear reprogramming restores cellular age of donor cells after SCNT, we measured telomere length and telomerase activity in cloned pigs and cattle. In normal pigs and cattle, the mean telomere length was decreased with biological aging. In cloned or transgenic cloned piglets, the mean telomere length was elongated compared to nuclear donor fetal fibroblasts and age-matched normal piglets. In cloned cattle, no increases in mean telomere length were observed compared to nuclear donor adult fibroblasts. In terms of telomerase activity, significant activity was observed in nuclear donor cells and normal tissues from adult or new-born pigs and cattle, with relatively higher activity in the porcine tissues compared to the bovine tissues. Cloned calves and piglets showed the same level of telomerase activity as their respective donor cells. In addition, no difference in telomerase activity was observed between normal and transgenic cloned piglets. However, increased telomerase activity was observed in porcine SCNT blastocysts compared to nuclear donor cells and in vitro fertilization (IVF)-derived blastocysts, suggesting that the elongation of telomere lengths observed in cloned piglets could be due to the presence of higher telomerase activity in SCNT blastocysts. In conclusion, gathering from the comparative studies with cattle, we were able to demonstrate that telomere length in cloned piglets was rebuilt or elongated with the use of cultured donor fetal fibroblasts.

Cats cloned from fetal and adult somatic cells by nuclear transfer

This work was undertaken in order to study the developmental competence of nuclear transfer (NT) into cat embryos using fetal fibroblast and adult skin fibroblast cells as donor nuclei. Oocytes were recovered by mincing the ovaries in Hepes-buffered TCM199 and selecting the cumulus oocyte complexes (COCs) with compact cumulus cell mass and dark color. Homogenous ooplasm was cultured for maturation in TCM199+10% fetal bovine serum (FBS) for 12 h and used as a source of recipient cytoplast for exogenous somatic nuclei. In experiment 1, we evaluated the effect of donor cell type on the reconstruction and development of cloned embryos. Fusion, first cleavage and blastocyst developmental rate were not different between fetal fibroblasts and adult skin cells (71.2 vs 66.8; 71.0 vs 57.6; 4.0 vs 6.1% respectively; P < 0.05). In experiment 2, cloned embryos were surgically transferred into the oviducts of recipient queens. One of the seven recipient queens was delivered naturally of 2 healthy cloned cats and 1 stillborn from fetal fibroblast cells of male origin 65 days after embryo transfer. One of three recipient queens was delivered naturally of 1 healthy cloned cat from adult skin cells of female origin 65 days after embryo transfer. The cloned cats showed genotypes identical to the donor cell lines, indicating that adult somatic cells can be used for feline cloning.

The effect of PDE5 inhibition on the erectile function in streptozotocin-induced diabetic rats

The aim of this study was to assess the effect of phosphodiesterase 5 inhibitor, DA-8159, on erectile function throughout the quantitative analysis of vascular endothelial cell, smooth muscle (SM), TGF-beta1 expression in rat corpus cavernosum and measurement of intracavernous pressure (ICP) in diabetic rats. DA-8159 (0, 5, 10, 20 mg/kg) was administered orally once a day to diabetic rats. After 8 weeks, immunohistochemistry and computerized image analysis were performed to quantify the percent area within the Corpora Cavernosa occupied by the endothelial cells, SM cells and fibrotic tissues. ICP/mean arterial pressure (MAP) was also measured by electrostimulation of the cavernous nerve. Diabetic rats showed a significant decrease in the SM and endothelial cell content, and an increase in the TGF-beta1 expression level within the cavernosa areas compared to the normal rats. The mean cavernous SM, endothelial cell content and TGF-beta1 expression level were 9.7+/-0.7, 4.5+/-0.7 and 17.9+/-2.1%, respectively. DA-8159 prevented reduction of SM (12.3+/-0.4% (5 mg/kg), 13.8+/-0.4% (20 mg/kg)) and endothelial cell content (5.6+/-0.5% (5 mg/kg), 6.3+/-0.6% (20 mg/kg)). Immunoreactivity of TGF-beta1 and intracorporal fibrosis were also significantly lower in DA-8159-treated groups (11.8+/-1.2% (5 mg/kg), 9.5+/-1.1% (20 mg/kg)). Electrostimulation of the cavernous nerve induced significant increase in maximum ICP (62.2+/-13.6 mmHg in 10 mg/kg vs 37.5+/-17.5 mmHg in diabetic group) and area under the curve of the ratio of ICP/MAP (8891.09+/-1957 in 10 mg/kg vs 6315.87+/-2272 in diabetic group). These results suggest that subchronic treatment of DA-8159 can prevent the development of erectile dysfunction (ED), and provides a rationale for the use of DA-8159 as treatment of diabetic ED.

Comparison of one-step RT-PCR and a nested PCR for the detection of canine distemper virus in clinical samples

OBJECTIVE

To develop a rapid and sensitive method for the detection of canine distemper virus (CDV) by nested PCR using clinical specimens.

DESIGN

A nested PCR was developed, compared to a one-step RT-PCR and validated.

PROCEDURE

Two sets of specific primers for a one-step RT-PCR and a nested PCR, targeting a 640 bp fragment and a 297 bp fragment, respectively, were selected from the highly conserved region of the nucleocapsid protein (NP) gene of CDV. The nested PCR and the one-step RT-PCR were used to amplify a part of the CDV NP gene of a CDV vaccinal strain and samples of urine, blood, nasal discharge and saliva from 29 dogs suspected of suffering CD.

RESULTS

Both the one-step RT-PCR and the nested PCR reacted with the CDV vaccinal strain, but not with canine parvovirus. The expected 640 bp fragment of the NP gene was detected in 11/22 (50.0%) blood, 10/20 (50.0%) urine, 5/25 (20.0%) saliva and 6/27 (22.2%) nasal swab samples by one-step RT-PCR, whereas the nested PCR amplified an expected 297 bp fragment of the NP gene in 18/22 (81.8%) blood, 15/20 (75.0%) urine, 14/25 (56%) saliva and 19/27 (70.3%) nasal swab samples.

CONCLUSION

The nested PCR detected CDV in blood, urine, nasal swab and saliva more frequently than did the one-step RT-PCR. Therefore, this assay should be a useful aid to antemortem diagnosis of CDV infections in dogs.

Expression of the intermediate filament vimentin in proliferating duct cells as a marker of pancreatic precursor cells

OBJECTIVES

The expression of the intermediate filament (IF) vimentin, usually considered a marker of mesenchymal cells, has been observed in the epithelial cells during embryogenesis, carcinogenesis, and dedifferentiation, suggesting that it might be useful as a marker of proliferating precursor cells in the pancreas.

METHODS

Rat pancreata at E18 and at different time points after partial pancreatectomy (Px) and human and neonatal pig pancreatic tissue sections and monolayer cultured pancreatic duct cells were observed. All tissues were simultaneously immunostained with pancytokeratin and vimentin antibodies. In costained duct cells, PDX-1 or PCNA expression was also analyzed using confocal microscope images.

RESULTS

In the rat embryonic pancreas at E18, all epithelial cells that formed ductlike structures expressed both cytokeratin and vimentin IF, whereas no duct cells costained for IF in the adult rat or neonatal pig pancreas. Such costaining reappeared in the following order: common pancreatic duct, main ducts, foci of regeneration and then disappeared completely at 30 days after Px. In humans, costaining was found in only 1 diabetic patient's pancreatic section, which was accompanied by massive duct cell proliferation. In monolayer culture, most of the duct cells of human and neonatal pigs coexpressed both IF proteins. Only a few costained duct cells also expressed PDX-1, and most of those cells were also stained with PCNA in rat embryonic pancreas and regenerating foci after partial Px.

CONCLUSIONS

Vimentin IF expression might be a useful marker for pancreatic precursor cells and could be used to investigate the concept of the dedifferentiation of fully matured duct cells during the process of the beta-cell neogenesis.

Incidence of apoptosis in clone embryos and improved development by the treatment of donor somatic cells with putative apoptosis inhibitors

This study was conducted to promote in vitro-development of clone embryos by the treatment of donor somatic cells with hemoglobin (Hb) and/or beta-mercaptoethanol (ME), based on the analysis of apoptosis after somatic cell nuclear transfer (SCNT). Prospective, randomized study was conducted and, in vitro-matured bovine oocytes and fetal fibroblasts were provided for SCNT. In the first series of experiment, embryo apoptosis after SCNT was monitored by a terminal deoxynucleotidyl transferase-mediated d-UTP nick end-labeling assay. As results, apoptosis occurred more (P < 0.05) frequently after SCNT than after in vitro-fertilization (IVF) of control treatment. Subsequently, donor somatic cells treated with Hb (1 microg/ml) and/or ME (10 microM) were provided for SCNT. Either Hb or ME greatly reduced apoptosis (0.083 +/- 0.006 vs. 0.058-0.068 +/- 0.005), while combined treatment did not. ME was more promotive than Hb; significant increases were found in morula compaction (86%), cell numbers of blastocyst (131.3 +/- 1.3 cells/blastocyst), and inner cell mass (31.9 +/- 0.8 cells/blastocyst) cell, and the ratio of inner cell mass to trophectodermal cell numbers (0.24 +/- 0.01). In conclusion, the treatment of donor somatic cells with ME or Hb could reduce apoptosis after SCNT, resulting improved preimplantation development.

Potential role of gonadotrophin-releasing hormone (GnRH)-I and GnRH-II in the ovary and ovarian cancer

Gonadotrophin-releasing hormone (GnRH) functions as a key neuroendocrine regulator of the hypothalamic-pituitary-gonadal axis. In addition to the hypothalamus and pituitary gland, GnRH and its receptor have been detected in other reproductive tissues including the gonads, placenta and tumours arising from these tissues. Recently, a second form of GnRH (GnRH-II) and type II GnRH receptor have been found in normal ovarian surface epithelium and neoplastic counterparts. The two types of GnRH may play an important role as an autocrine/paracrine regulator of reproductive functions and ovarian tumour growth. In this review, the distribution and potential roles of GnRH-I/-II and their GnRH receptors in the ovarian cells and ovarian cancer will be discussed.

Effect of maturation media and oocytes derived from sows or gilts on the development of cloned pig embryos

In order to develop a culture system and recipient cytoplasm that could improve the developmental competence of somatic cell nuclear transfer (SCNT) embryos for successful cloning of pigs, we evaluated the effect of donor oocytes and in vitro maturation (IVM) media on maturation of oocytes and developmental competence of SCNT embryos. In Experiment 1, oocytes derived from sows or gilts were matured in two IVM media (TCM-199 versus NCSU-23) and maturation of oocytes was evaluated by the status of chromatin configuration, the diameter of matured oocytes, the thickness of the zona pellucida, and the size of the perivitelline space (PVS). Sow oocytes matured in TCM-199 (S-TCM group) and NCSU-23 (S-NCSU group) showed significantly higher (P<0.05) maturation rates (S-TCM and S-NSCU, 86+/-4 and 82+/-4%, respectively) when evaluated by metaphase-II status than the gilt oocytes matured in TCM-199 (G-TCM group, 71+/-3%) and in NCSU-23 (G-NCSU-23 group, 71+/-3%). Oocyte diameter, the thickness of the zona pellucida, and the perivitelline space of sow oocytes (S-TCM and S-NCSU) were larger than those of gilt oocytes (G-TCM and G-NCSU) after IVM (P<0.05). In Experiment 2, SCNT was performed, using in vitro-matured oocytes from each group as recipient cytoplasm and porcine fetal fibroblasts as karyoplasts. The reconstructed embryos were electrically fused and activated, and cleavage and blastocyst formation were monitored under a stereomicroscope. The total cell number of flattened blastocysts stained with 5 microM bisbenzimide on day 7 were counted. In addition, in vitro matured non-enucleated oocytes were also electrically activated (parthenogenetic activation) and pronuclear formation was monitored. No difference in pronuclear formation rate after parthenogenetic activation and fusion rate after SCNT was observed among experimental groups. A significantly higher cleavage rate (P<0.05) was observed in S-TCM (69+/-4%) when compared with only G-NCSU (58+/-4%), but not with G-TCM (60+/-4%) or S-NCSU (68+/-4%). The rate of blastocyst formation was significantly higher (P<0.05) in sow oocytes (24% in S-TCM and S-NCSU), when compared to that observed in G-TCM (15%), and G-NCSU (14%). When the same source of oocytes was used, there was no significant difference in rate of blastocyst formation in the two culture media. Total cell number of blastocysts were not significantly different among experimental groups. In conclusion, the present study clearly demonstrated that sow oocytes have a greater developmental competence than gilt oocytes, regardless of the maturation medium examined.

A comparative study of the optical characteristics of commonly used sinoscopes: do you know where you are looking?

Endoscopic ethmoidectomy is a delicate operation on the thin, honey-comb-like laminae of the ethmoidal sinuses. A high degree of precision is required to minimize disruption of the natural sinus mucociliary clearance system and to reduce the risk of orbital and skull base complications. It is therefore important that surgeons are aware of variation in the optical characteristics of the rod-lens telescopes produced by different manufacturers. A simple but precision endoscope goniometer was designed and manufactured. This was used to carry out a comparative study of the sinus telescopes in common use. The results showed significant variation in the view angle of the four brands of telescopes (Karl Storz, Olympus, Richards Smith & Nephew, and Richard Wolf) tested. Differences in the position of the horizon in the visual field, and different degrees of visuospatial distortion were evident. We also noted and measured the blind angle of telescopes, which, by virtue of a high degree of angulation, cannot view the horizon.

Baculovirus expression vectors that incorporate the foreign protein into viral occlusion bodies

Current baculovirus expression systems typically produce soluble proteins that accumulate within the infected insect cell or are secreted into the growth medium. A system has now been developed for the incorporation of foreign proteins, along with the matrix protein, polyhedrin, into baculovirus occlusion bodies. Initial studies showed that a recombinant virus expressing a translational fusion between polyhedrin and GFP did not form occlusion bodies. However, a baculovirus coexpressing native polyhedrin and the polyhedrin-GFP fusion protein formed occlusion bodies that fluoresced under UV light, demonstrating that they included the polyhedrin-GFP fusion protein. This was confirmed by immunoblot analysis. Thus, incorporation of a foreign protein into occlusion bodies depends on an interaction between native polyhedrin and the polyhedrin fusion protein. Electron microscopy demonstrated that the occlusion bodies containing GFP also incorporated virions as expected. These ColorPol occlusion bodies were as infectious to insect larvae as occlusion bodies produced by wild-type virus. This new system expands the capabilities for foreign gene expression by baculoviruses, which has implications for biopesticide design, novel vaccine delivery systems, and fusion protein purification applications.

Effects of peripheral benzodiazepine receptor ligands on proliferation and differentiation of human mesenchymal stem cells

The peripheral benzodiazepine receptor (PBR) has been known to have many functions such as a role in cell proliferation, cell differentiation, steroidogenesis, calcium flow, cellular respiration, cellular immunity, malignancy, and apoptosis. However, the presence of PBR has not been examined in mesenchymal stem cells. In this study, we demonstrated the expression of PBR in human bone marrow stromal cells (hBMSCs) and human adipose stromal cells (hATSCs) by RT-PCR and immunocytochemistry. To determine the roles of PBR in cellular functions of human mesenchymal stem cells (hMSCs), effects of diazepam, PK11195, and Ro5-4864 were examined. Adipose differentiation of hMSCs was decreased by high concentration of PBR ligands (50 microM), whereas it was increased by low concentrations of PBR ligands (<10 microM). PBR ligands showed a biphasic effect on glycerol-3-phosphate dehydrogenase (GPDH) activity. High concentration of PBR ligands (from 25 to 75 microM) inhibited proliferation of hMSCs. However, clonazepam, which does not have an affinity to PBR, did not affect adipose differentiation and proliferation of hMSCs. The PBR ligands did not induce cell death in hMSCs. PK11195 (50 microM) and Ro5-5864 (50 microM) induced cell cycle arrest in the G(2)/M phase. These results indicate that PBR ligands play roles in adipose differentiation and proliferation of hMSCs.