Melatonin promotes sheep Leydig cell testosterone secretion in a co-culture with Sertoli cells.

Leydig cells synthesize and secrete testosterone, and are regulated by Sertoli cells. These two cell types may work together to regulate testicular androgen production. Studies have shown that Leydig cell androgen synthesis can be dramatically enhanced by Sertoli cells in the presence of melatonin, which can regulate the secretory function of Leydig and Sertoli cells. However, the molecular mechanism of melatonin-regulated Leydig cell androgen production via Sertoli cells remains unclear. Here, we found that 10-7 M melatonin increased testosterone production in co-cultured Leydig and Sertoli cells isolated from sheep. Melatonin increased the expression of stem cell factor and insulin-like growth factor-1 and decreased estrogen synthesis in Sertoli cells. Melatonin promoted insulin-like growth factor-1 and decreased estrogen content via the membrane melatonin receptor 1. It also enhanced stem cell factor expression via the retinoic acid receptor-related orphan receptor alpha. Addition of PD98059, a MEK inhibitor, to Sertoli cell culture demonstrated that the melatonin upregulation of insulin-like growth factor-1 and downregulation of estrogen may be through the MEK/extracellular signal-regulated kinase pathway. Together, these results suggest that melatonin may function through modulating melatonin receptor 1-regulated insulin-like growth factor-1 expression, as well as melatonin receptor 1-induced suppression of estrogen synthesis to increase androgen production in co-cultured Leydig and Sertoli cells.

[Study on Polygonum multi florum Thunb and extracts by DRIFTS and atr-ftir].

The diffuse-reflectance FTIR spectroscopy (DRIFTS) and attenuated total reflection FTIR (ATR-FTIR) were used to study polygonum multi florum Thumb and its extracts. The result shows that when acetone is used as extraction agent, the contents of extracts in polygonum multi florum Thunb's phloem are highest, those in polygonum multi florum Thunb's xylem are the lowest. Compared with DRIFTS and ATR-FTIR, it can be found that there are some differences between polygonum multi florum Thunb and its extracts. There are two gentle absorption peaks at 3 576 and 3 147 cm(-1) respectively for polygonum multi florum Thunb, while there is a strong absorption peak at 3 351 cm(-1) for its extracts, showing that there may be more OH... active ingredients in polygonum multi florum Thunb's extracts. Meanwhile, polygonum multiflorum Thunb has strong absorption peaks at 931, 859, 766 and 709 cm(-1) respectively, while its extracts have no resembling absorption peaks. It also shows that the extracts are active ingredients.

Differences between femoral artery and vein smooth muscle cells in volume-regulated chloride channels.

The purpose of the present study was to compare the differences between the role of volume-regulated Cl⁻ channels (VRCCs) in veins and arteries. We used the whole cell patch clamp and fluorescence imaging techniques to evaluate swelling-induced Cl⁻ current (I(Cl,vol)) and changes in the intracellular concentrations of Cl⁻ ([Cl⁻](i)) induced by hypotonic solutions in rat femoral artery cells (FASMCs) and vein smooth muscle cells (FVSMCs). I(Cl,vol) and [Cl⁻](i) decline induced by hypotonic solution were more prominent in FASMCs than in FVSMCs. I(Cl,vol) and the alterations in [Cl⁻](i) were gradually increased as the number of cell passages increased. However, the regulatory function of tyrosine protein phosphorylation in volume-regulated chloride movement is prominent in veins. The expression of ClC-3 was higher in FASMCs than in FVSMCs. VRCC activity is more pronounced in rat femoral arteries than in veins. VRCC activity and tyrosine protein phosphorylation regulative function increase gradually as vascular cells switch from contractile to proliferative phenotypes.

Involvement of Chk1-Cdc25A-cyclin A/CDK2 pathway in simvastatin induced S-phase cell cycle arrest and apoptosis in multiple myeloma cells.

Statins have been demonstrated to effectively inhibit proliferation and induce apoptosis in cancer cells by inhibition of geranylgeranylation, however its novel molecular mechanism remains to be determined. Recently simvastatin has been found to result in the synergistic induction of apoptosis with 7-hydroxystaurosporine (UCN-01) (a Chk1 inhibitor) in myeloma cells. Therefore we hypothesized that Chk1 plays a role in the anti-myeloma effect of simvastatin. Interestingly, we found that simvastatin caused a dose-dependent increase in S phase cell cycle and induced significant apoptosis. The results of western blot showed that simvastatin-induced S-phase cell cycle arrest was associated with activation of Chk1, downregulation of Cdc25A, cyclin A and CDK2 expression. Additionally, simvastatin-induced apoptosis was accompanied by diminished Bcl-2 protein expression, increased cytosolic cytochrome c level, and activation of caspase 9 and caspase 3. Further investigation revealed that silence of Chk1 expression by Chk1 specific siRNA inhibited simvastatin-induced activation of Chk1, downregulation of Cdc25A, cyclin A and CDK2 expression, and diminished S phase cell cycle arrest. Additionally, inhibition of Chk1 expression enhanced simvastatin-induced downregulation of Bcl-2, caspase 9 cleavage and subsequent apoptosis. These results suggested that the Chk1-Cdc25A-cyclin A/CDk2 pathway was involved in simvastatin-induced S-phase cell cycle arrest and apoptosis in multiple myeloma cell lines.

Associations between 45T/G polymorphism of the adiponectin gene and plasma adiponectin levels with type 2 diabetes.

1. The purpose of the present study was to investigate the association between the single nucleotide polymorphism (SNP) 45T/G and plasma adiponectin levels and the prevalence of Type 2 diabetes mellitus (T2DM) in Uygurs of the Xinjiang region, China. 2. We performed a cross-sectional survey in a representative sample of 151 Uygur adults aged 24-80 years. The polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP) method was used to determine the distribution of allele and genotype frequency of the SNP45 T/G polymorphism (exon 2) in the adiponectin gene. An ELISA was used to determine plasma adiponectin levels. Logistic regression was used to screen risk factors for T2DM. 3. Compared with the normal glucose tolerance (NGT) group, the T2DM group exhibited a higher distribution of the TG + GG genotype, G allele frequency and lower plasma adiponectin concentrations in TG + GG genotype carriers compared with those with the TT genotype. Compared with SNP45 T carriers, in the NGT group, G carriers had higher levels of systolic and diastolic blood pressure, low density lipoprotein (P < 0.05) and total cholesterol (P < 0.005). In the T2DM group, G carriers had lower levels of homeostasis model assessment (HOMA) of insulin sensitivity (P < 0.05) and higher levels of HOMA of insulin resistance (P < 0.05). 4. Adiponectin SNP 45 is positively correlated with the prevalence of T2DM in Uygurs of Xinjiang. The G allele carriers who have reduced plasma concentrations of adiponectin may have associated insulin resistance.