Protective effect of metformin on BPA-induced liver toxicity in rats through upregulation of cystathionine ß synthase and cystathionine γ lyase expression.

Human exposure to bisphenol A (BPA) is unavoidable in daily life. Recently, research has showen that BPA could induce oxidative imbalance, thereby causing reproductive toxicity and liver dysfunction. Accumulated evidence has demonstrated that metformin possesses strong anti-oxidative properties. This study aimed to study the mechanism underlying the hepatic-protective effect of metformin on liver injury induced by BPA in rats via the UPLC-MS/MS metabolomics approach. Forty-two male rats were randomly divided into six groups (n = 7), namely the saline group (control), the corn oil group (vehicle), the metformin group (Met), the bisphenol A group (BPA), the bisphenol A and metformin group (BPA + Met), and the bisphenol A and diammonium glycyrrhizinate (positive control) group (BPA + DG). Serum was collected for biochemical analysis and metabolomics, and liver tissue was collected for histopathology and metabolomics in each group. We found that metformin could significantly reduce the levels of liver function enzymes (ALT, AST and GGT) and ameliorate inflammatory cell infiltration and hepatocyte necrosis induced by BPA. On the other hand, metformin could significantly enhance the total antioxidant capacity in BPA rats. Notably, metabolomics data indicated that the principal altered metabolic pathways based on the 26 differential metabolites in liver tissue, and 21 in serum among vehicle, BPA and BPA + Met groups, respectively, including cysteine and methionine metabolism, glutathione metabolism, and arginine biosynthesis and purine metabolism. Additionally, metformin significantly increased cystathionine ß synthase (CBS) and cystathionine γ lyase (CSE), thus reducing serum levels of homocysteine and increasing hepatic levels of cysteine and glutathione in BPA-treated rats. Overall, this study's results provided new insights into the role and mechanism of metformin in BPA-induced liver injury in rats.

Body mass index effects sperm quality: a retrospective study in Northern China.

Excess weight and obesity have become a serious problem in adult men of reproductive age throughout the world. The purpose of this retrospective study was to assess the relationships between body mass index and sperm quality in subfertile couples in a Chinese Han population. Sperm analyses were performed and demographic data collected from 2384 male partners in subfertile couples who visited a reproductive medical center for treatment and preconception counseling. The subjects were classified into four groups according to their body mass index: underweight, normal, overweight, and obese. Of these subjects, 918 (38.3%) had a body mass index of >25.0 kg m-0 2 . No significant differences were found between the four groups with respect to age, occupation, level of education, smoking status, alcohol use, duration of sexual abstinence, or the collection time of year for sperm. The results clearly indicated lower sperm quality (total sperm count, sperm concentration, motile sperm, relative amounts of type A motility, and progressive motility sperm [A + B]) in overweight and obese participants than in those with normal body mass index. Normal sperm morphology and sperm volume showed no clear difference between the four groups. This study indicates that body mass index has a negative effect on sperm quality in men of subfertile couples in a Northern Chinese population. Further study should be performed to investigate the relationship between body mass index and sperm quality in a larger population.

Developmental potential of clinically discarded human embryos and associated chromosomal analysis.

Clinically discarded human embryos, which are generated from both normal and abnormal fertilizations, have the potential of developing into blastocysts. A total of 1,649 discarded human embryos, including zygotes containing normal (2PN) and abnormal (0PN, 1PN, 3PN and ≥4PN) pronuclei and prematurely cleaved embryos (2Cell), were collected for in vitro culture to investigate their developmental potential and chromosomal constitution using an SNP array-based chromosomal analysis. We found that blastocyst formation rates were 63.8% (for 2Cell embryos), 22.6% (2PN), 16.7% (0PN), 11.2% (3PN) and 3.6% (1PN). SNP array-based chromosomal analysis of the resultant blastocysts revealed that the percentages of normal chromosomes were 55.2% (2Cell), 60.7% (2PN), 44.4% (0PN) and 47.4% (0PN). Compared with clinical preimplantation genetic diagnosis (PGD) data generated with clinically acceptable embryos, results of the SNP array-based chromosome analysis on blastocysts from clinically discarded embryos showed similar values for the frequency of abnormal chromosome occurrence, aberrant signal classification and chromosomal distribution. The present study is perhaps the first systematic analysis of the developmental potential of clinically discarded embryos and provides a basis for future studies.

Progesterone elevation on the day of human chorionic gonadotropin administration adversely affects the outcome of IVF with transferred embryos at different developmental stages.

BACKGROUND: The effect of progesterone elevation (PE) on the day of human chorionic gonadotropin (hCG) administration on the pregnancy outcomes of in vitro fertilization/intracytoplasmic sperm injection (IVF/ICSI) cycles is a matter of ongoing debate. The replacement of cleavage-stage embryos with blastocyst-stage embryos for transfer was proposed to avoid the possible impairment of PE in fresh cycles. This study aimed to assess the association between PE on the day of human chorionic gonadotropin (hCG) administration and clinical pregnancy rates (CPRs) in IVF/ICSI cycles with embryos transferred at different developmental stages (cleavage and blastocyst). Moreover, a secondary aim was to determine the thresholds at which PE has a detrimental effect on CPRs. METHODS: This single-center retrospective cohort study included more than 10,000 patients undergoing day 3 cleavage-stage embryo transfer (ET) and 1146 patients undergoing day 5 blastocyst-stage embryo transfer (ET) using gonadotropin and GnRH agonist for controlled ovarian stimulation. RESULTS: Serum PE was inversely associated with CPRs in both cleavage- and blastocyst-stage ET cycles. In the day 3 ET cycles, CPRs (progesterone levels < 0.5 ng/ml, 49.2 %) significantly declined when the progesterone concentration reached 1.0 ng/ml (45.5 %) and decreased further when the progesterone concentration increased to 1.5 ng/ml (36.2 %). In the day 5 blastocyst-stage ET cycles, patients with serum progesterone levels ≥1.75 ng/ml had significantly lower CPRs (31.3 % VS. 41.4 %, p < 0.001) compared to patients with serum progesterone levels <1.75 ng/ml. The negative association of PE with CPRs was noted in both ET groups, even after adjusting for confounders. Furthermore, the developmental stage of the transferred embryos was not linked to the effect of PE on CPRs because the interaction between the developmental stage of the transferred embryos and PE was not significant. CONCLUSIONS: PE on the day of hCG administration is associated with decreased CPRs in GnRH agonist IVF/intracytoplasmic sperm injection (ICSI) cycles regardless of the developmental stage of the transferred embryos (cleavage versus blastocyst stage).

Molecular mechanisms underlying effects of neural stem cells against traumatic axonal injury.

Transplantation of neural stem cells (NSCs) improves functional outcomes following traumatic brain injury (TBI). Previously we demonstrated that human NSCs (hNSCs) via releasing glial cell line-derived neurotrophic factor (GDNF), preserved cognitive function in rats following parasagittal fluid percussion. However, the underlying mechanisms remain elusive. In this study, we report that NSC grafts significantly reduce TBI-induced axonal injury in the fimbria and other brain regions by blocking abnormal accumulation of amyloid precursor protein (APP). A preliminary mass spectrometry proteomics study revealed the opposite effects of TBI and NSCs on many of the cytoskeletal proteins in the CA3 region of the hippocampus, including α-smooth muscle actin (α-SMA), the main stress fiber component. Further, Western blot and immunostaining studies confirmed that TBI significantly increased the expression of α-SMA in hippocampal neurons, whereas NSC grafts counteracted the effect of TBI. In an in vitro model, rapid stretch injury significantly shortened lengths of axons and dendrites, increased the expression of both APP and α-SMA, and induced actin aggregation, effects offset by GDNF treatment. These GDNF protective effects were reversed by a GDNF-neutralizing antibody or a specific calcineurin inhibitor, and were mimicked by a specific Rho inhibitor. In summary, we demonstrate for the first time that hNSC grafts and treatment with GDNF acutely reduce traumatic axonal injury and promote neurite outgrowth. Possible mechanisms underlying GDNF-mediated neurite protection include balancing the activity of calcineurin, whereas GDNF-induced neurite outgrowth may result from the reduction of the abnormal α-SMA expression and actin aggregation via blocking Rho signals. Our study also suggests the necessity of further exploring the roles of α-SMA in the central nervous system (CNS), which may lead to a new avenue to facilitate recovery after TBI and other injuries.

Critical role of PI3K/Akt/GSK3ß in motoneuron specification from human neural stem cells in response to FGF2 and EGF.

Fibroblast growth factor (FGF) and epidermal growth factor (EGF) are critical for the development of the nervous system. We previously discovered that FGF2 and EGF had opposite effects on motor neuron differentiation from human fetal neural stem cells (hNSCs), but the underlying mechanisms remain unclear. Here, we show that FGF2 and EGF differentially affect the temporal patterns of Akt and glycogen synthase kinase 3 beta (GSK3ß) activation. High levels of phosphatidylinositol 3-kinase (PI3K)/Akt activation accompanied with GSK3ß inactivation result in reduction of the motor neuron transcription factor HB9. Inhibition of PI3K/Akt by chemical inhibitors or RNA interference or overexpression of a constitutively active form of GSK3ß enhances HB9 expression. Consequently, PI3K inhibition increases hNSCs differentiation into HB9(+)/microtubule-associated protein 2 (MAP2)(+) motor neurons in vitro. More importantly, blocking PI3K not only enhances motor neuron differentiation from hNSCs grafted into the ventral horn of adult rat spinal cords, but also permits ectopic generation of motor neurons in the dorsal horn by overriding environmental influences. Our data suggest that FGF2 and EGF affect the motor neuron fate decision in hNSCs differently through a fine tuning of the PI3K/AKT/GSK3ß pathway, and that manipulation of this pathway can enhance motor neuron generation.

Blocking epidermal growth factor receptor attenuates reactive astrogliosis through inhibiting cell cycle progression and protects against ischemic brain injury in rats.

Excessive astrogliosis is a major impediment to axonal regeneration in CNS disorders. Overcoming this inhibitory barrier of reactive astrocytes might be crucial for CNS repair. Up-regulation and activation of epidermal growth factor receptor (EGFR) has been shown to trigger quiescent astrocytes into reactive astrocytes in response to several neural injuries. In this study, we investigated the effects of EGFR blockade in cultured astrocytes exposure to oxygen-glucose deprivation/reoxygenation (OGD/R) and in the rat middle cerebral artery occlusion (MCAO) model. Astrocytes in primary culture were used for OGD/R model and adult male Sprague-Dawley rats were used for MCAO model. Cell cycle progression of astrocytes in vitro was studied by flow cytometric analysis. Expression of phosphorylated epidermal growth factor receptor (p-EGFR), glial fibrillary acidic protein (GFAP), and cell proliferation-related molecules in vitro and in vivo were evaluated by immunostaining and western blot analysis. Neuronal apoptosis after MCAO was determined by terminal deoxynucleotidyl transferase dUTP nick end labeling (TUNEL) method. Neurologic scores and infarct volumes post-ischemia were assessed in the rat MCAO model. Astrocytes became activated in the cultured astrocytes exposure to OGD/R and in the rat brain after MCAO, accompanied with phosphorylation of EGFR. EGFR blockade significantly decreased expression of p-EGFR, inhibited cell cycle progression of astrocytes, and reduced reactive astrogliosis in vitro and in vivo. EGFR inhibition also reduced infarct volumes and improved neurologic scores of rats after MCAO. Our findings indicated that blocking EGFR pathway might attenuate reactive astrogliosis through inhibiting cell cycle progression and protect against ischemic brain injury in rats.

Evaluation of four digestive methods for extracting diatoms.

OBJECTIVE: To compare the merit of four digestive methods (nitric acid plus hydrogen peroxide, proteinase K, nitric acid in Disorganization Can and Soluene-350) for extracting diatoms in order to choose the best digestive method for the diagnosis of drowning. METHODS: Liver, kidney and bone marrow of rabbits were minced and then digested by four digestive methods separately with the following indices compared: (1) time demanded for complete digestion; (2) degree of digestion for different tissues; (3) the reclaiming ratio of diatoms; (4) the degree of digestive destruction to diatoms. RESULTS: For sufficiently digesting the same tissue, the demanded times for the different methods ranked from the longest to the shortest were as follows: Soluene-350, proteinase K, nitric acid plus hydrogen peroxide, nitric acid in Disorganization Can. Nitric acid in Disorganization Can method and nitric acid plus hydrogen peroxide method digested the tissues more thoroughly than proteinase K, than Soluene-350 methods. For Cyclotella and Cybella, proteinase K method reclaimed most diatoms and nitric acid plus hydrogen peroxide method reclaimed less, while nitric acid in Disorganization Can and Soluene-350 methods reclaimed the least. For Navicula, the majority of diatoms could be extracted using proteinase K method, but only a few diatoms with other three methods. Under scanning electron microscopy (SEM), the structure of diatoms remained almost perfect after digestion with proteinase K, but destroyed to some extent with other three methods. CONCLUSION: This study demonstrated that different diatoms (in fresh or sea water) have different resistance to different digestive reagents. As far as the reliability and applicability of the diatom test is concerned, proteinase K method is of the best choice, nitric acid plus hydrogen peroxide can be its substitute. Soluene-350 cannot be used for extracting sea water diatoms.