Involvement of PPARs in the regulation of brain CYP2D by growth hormone / 中国药理学与毒理学杂志

OBJECTIVE CYP2D is one of the most abundant subfamily of CYPs in the brain, especially in the cerebellum. Brain CYP2D is responsible for the metabolism of endogenous neurotransmitters such as tyramine and serotonin. Our previous studies have shown brain CYP2D can be regulated by exogenous and endogenous substances with tissue- specificity. The purpose of this study is to examine the effects of cerebral CYP2D on the mice behavior and the regulatory mechanism of brain CYP2D by growth hormone. METHODS Mice received the stereotaxic injection with CYP2D inhibitor quinine in deep cerebellar nuclei of cerebellum. The animals were tested with rotarod apparatus, balance beam, water maze, elevated plus maze and open field. The changes in CYP2D22, PPARαand PPARγ in brain regions and liver were assayed in male growth hormone receptor knockout mice, SH-SY5Y cells and HepG2 cells. RESULTS The inhibition of cerebellum CYP2D significantly affected the spatial learning and exploring ability of mice. Compared with WT mice, CYP2D expression was lower in brain regions from GHR(-/- ) male mice; however, hepatic CYP2D level was similar. Pulsatile GH decreased PPARα mRNA level, and increased mRNA levels of CYP2D6 and PPARα in SH- SY5Y cells. In HepG2 cells, pulsatile GH resulted in decreases in PPARα and PPARγ mRNA levels, but not CYP2D6. PPARα inhibitor induced CYP2D6 mRNA and protein by 1.32-fold and 1.43-fold in SH-SY5Y cells. PPARγ inhibitor decreased CYP2D6 mRNA and protein by 74.76% and 40.93%. PPARα agonist decreased the level of CYP2D22 mRNA in liver and cerebellum, while PPARγ agonist rosiglitazone resulted in diametrically increases. The luciferase assay showed that PPARγ actived the CYP2D6 gene promoter while PPARα inhibited its function. Pulsatile GH declined the binding of PPARα with CYP2D6 promoter by 40%, promoted the binding of PPARγ with CYP2D6 promoter by approximate 60%. The levels of brain and liver PPARα expression in male GHR(-/- ) mice is obviously higher than those in WT mice. The level of PPARγ in male GHR(-/- ) mice was decreased in the frontal cortex and hippocampus, while remained stable in the cerebellum and striatum; meanwhile, PPARγ was increased in the liver. CONCLUSION Brain CYP2D may be involved in learning and memory functions of central system. Masculine GH secretion altered the PPARs expression and the binding of PPARs to CYP2D promoter, leading to the elevated brain CYP2D in a tissue- specific manner. Growth hormone may specifically alter the metabolic and synthetic of important endogenous substances in the central nervous system (such as serotonin) through the specific regulation of brain CYP2D expression.

Inhibition of miR-873 provides therapeutic benefit in lipopolysaccharide-induced Parkinson disease animal model / 中国药理学与毒理学杂志

OBJECTIVE Neuroinflammation plays a critical role in neurodegenerative disorders, although the inflammation may not the initiating factor. Parkinson disease (PD) is characterized patho?logically by the accumulation of alpha synuclein (α-syn) and the loss of the dopamine (DA) neurons in the substantia nigra (SN), which has been reported to be induced by the stereotaxic injection of lipopolysaccharide (LPS) to the SN region in rodents. This study is to investigate the therapeutic benefit of the inhibition of miR-873 in PD. METHODS Rats received the right-unilaterally injection with concentrated LV-sponge or LV-EGFP 3 d before LPS treatment, 7 or 14 d after LPS treatment. The animals were tested for rotational behavior with the dopaminergic agonist apomorphine dissolved in sterile saline at 21 d after LPS injection. The regulation of miR-873 on the genes related with cholesterol transport and inflammation was assayed in SH-SY5Y cells and U251 cells. RESULTS TLR4-MyD88 signaling pathway was involved the regulation of miR-873 by LPS. The luciferase assay showed that HMGCR, ABCA1 and A20 were down- stream genes of miR- 873. The transfection of miR- 873 decreased the cholesterol levels in cell membrane, but increased in lysosome in SH-SY5Y cells. Compared with the control SH-SY5Y cells, cholesterol levels were higher in lysosome with α-synuclein overexpression or LPS treatment. The transfection of miR-873 increased the α-syn levels in lysosome in cells with α-synuclein overexpression. The loss of dopaminergic neuorns induced by LPS was significantly respectively decreased by 22.8%, 35.6% and 57% after the inhibition of miR-873 at 3 d before LPS treatment, 7 or 14 d after LPS treatment. Compared with LPS-treated group, the number of the rotation of rats was decreased by 60.4%, 33.5% and 13.2% after the inhibition of miR-873 at 3 d before LPS treatment, 7 or 14 d after LPS treatment. The inhibition of miR-873 significantly decreased accumulation of α-syn. The mRNA levels of HMGCR, ABCA1 and A20 in SN were decreased by LPS treatment, which was attenuated by the injection of LV- sponge. CONCLUSION The selective regulation of miR- 873 can protect the dopaminergic neurons from the LPS-induced damage. The inhibition of miR-873 can attenuate the relocation of cholesterol in lysosome and the accumulation of α-syn in neurons induced by LPS via the regulation of HMGCR, ABCA1 and A20.

Chemical composition, antimicrobial and antioxidant activities of essential oil from Ampelopsis megalophylla.

Chemical composition, antimicrobial and antioxidant activities of the essential oil of Ampelopsis megalophylla were evaluated in this research. GC-MS analysis of the essential oil revealed 42 compounds, representing 88.54% of the oil. The major compounds were borneol (10.81%), α-pinene (6.74%) and ß-elemene (6.23%). The antimicrobial activity of the essential oil was evaluated against 13 micro-organisms using the disc diffusion and broth microdilution methods. Results demonstrated higher effects of this oil against Gram-positive bacteria than the other reference strains tested. The antioxidant effect of the essential oil was evaluated by using 1,1-Diphenyl-2-picrylhydrazyl (DPPH) and 2,20-azinobis-3-ethylbenzthiazoline-6-sulfonate scavenging assays. The essential oil exhibited moderate antioxidant activity.

Protective effect of 20-hydroxyeicosatetraenoic acid (20-HETE) on adriamycin-induced toxicity of human renal tubular epithelial cell (HK-2).

20-Hydroxyeicosatetraenoic acid is a cytochrome P4504A11 metabolite of arachidonic acid that plays an important role in the regulation of human renal functions. In the present study, we investigated the role of 20-hydroxyeicosatetraenoic acid on adriamycin induced toxicity in human renal tubular epithelial cells. Results showed that cell viability was decreased significantly and lactate dehydrogenase activity was increased significantly in a concentration-dependent manner when human renal tubular epithelial cells were incubated with adriamycin (10⁻7-10⁻³ mol/l) for 24h. In contrast, 20-hydroxyeicosatetraenoic acid (0.1, 1, 10, 50 µmol/l) increased cell survival and decreased lactate dehydrogenase activity concentration dependently in human renal tubular epithelial cells. When 20-hydroxyeicosatetraenoic acid (10, 50 µmol/l) was co-administered with adriamycin (10⁻³ mol/l), it significantly increased cell viability and decreased lactate dehydrogenase activity. On the other hand, N-hydroxy-N'-(4-butyl-2-methylphenyl)formamidine (HET-0016) (1 µM), a selective inhibitor of 20-hydroxyeicosatetraenoic acid synthesizing enzyme exaggerated cell viability reduction and lactate dehydrogenase activity augmentation induced by adriamycin. Adriamycin suppressed the expression of cytochrome P4504A11 gene and its protein production in human renal tubular epithelial cells. Furthermore, adriamycin was more effective than N-hydroxy-N'-(4-butyl-2-methylphenyl)formamidine at lowering the expression of cytochrome P4504A11 gene and its protein. These results suggest that 20-hydroxyeicosatetraenoic acid may protect adriamycin-induced toxicity of human renal tubular epithelial cells, meanwhile, adriamycin-induced toxicity of human renal tubular epithelial cells possibly involves inhibiting cytochrome P4504A11 expression.

Effects of amlodipine on TGF-ß-induced Smad2, 4 expressions in adriamycin toxicity of rat mesangial cells.

Transforming growth factor-ß (TGF-ß) is closely associated with progressive renal fibrosis. A central component of TGF-ß-stimulated mesangial cell fibrogenesis is the TGF-ß family-specific Smad signal transduction pathway. This study investigated the expression of TGF-ß-receptor--activated Smad2, its common partner Smad4, and the phosphorylated Smad2 (p-Smad2) in adriamycin-induced toxicity of cultured rat mesangial cells. This in vitro study showed that amlodipine (10(-9) to 10(-5) mol/l) had no effect on the toxicity of rat mesangial cells induced by adriamycin in the absence of TGF-ß1. However, amlodipine (10(-7) to 10(-5) mol/l) reduced the toxicity of rat mesangial cells induced by TGF-ß1 in the absence of adriamycin; moreover, amlodipine (10(-8) to 10(-5) mol/l) significantly reduced adriamycin-induced cytotoxicity when it was given in combination with TGF-ß1; amlodipine (10(-6), 10(-5) mol/l) had no effect on Smad2 mRNA and protein expression induced by adriamycin + TGF-ß1, but it (10(-6), 10(-5) mol/l) dramatically inhibited the down-regulation of p-Smad2 protein expression as well as Smad4 mRNA and protein expression induced by adriamycin + TGF-ß1 in rat mesangial cells. Present study shows that amlodipine exerts a significant inhibition on adriamycin-induced toxicity in rat mesangial cells by affecting the expression of TGF-ß/Smad signaling intermediates p-Smad2 and Smad4.

Differential roles of dihydropyridine calcium antagonist nifedipine, nitrendipine and amlodipine on gentamicin-induced renal tubular toxicity in rats.

In the present study, we investigated the antioxidative potencies of dihydropyridine calcium antagonists prototype nifedipine, the second generation drug nitrendipine, and the long acting, third generation drug amlodipine on gentamicin-induced renal tubular toxicity in Sprague-Dawley rats. In addition, we analyzed the relationship between renal tubular cell apoptosis and the antioxidative properties of these dihydropyridine calcium antagonists. Results showed that treatment with gentamicin alone caused significant changes in the levels of urinary protein, urinary N-acetyl-beta-d-glucosaminidase, serum creatinine, and blood urea nitrogen. Nifedipine and amlodipine effectively reversed the effect of gentamicin on these parameters. In contrast, nitrendipine either had no effect or worsened gentamicin-induced changes in the levels of urinary protein, urinary N-acetyl-beta-d-glucosaminidase, serum creatinine, and blood urea nitrogen. Furthermore, gentamicin treatment caused significant increases in the levels of malondialdehyde, nitric oxide, nitric oxide synthase and significant decreases in the levels of reduced glutathione, glutathione-S-transferase, and superoxide dismutase in kidney tissues. These effects were dramatically reduced by nifedipine and amlodipine but not affected by nitrendipine. In addition to the biochemical changes, histopathological studies showed that gentamicin caused structural damages in the kidneys; renal tubular cell apoptosis, a decrease in Bcl-2 expression and an increase in Bax expression were observed in all rats treated with gentamicin, nifedipine and amlodipine effectively reversed the effect of gentamicin while nitrendipine worsened them. In conclusion, this study clearly indicated that nifedipine and amlodipine protected against gentamicin-induced nephrotoxicity while nitrendipine had little effect, or even worsened.

Hepatotoxicity and gene expression down-regulation of CYP isozymes caused by renal ischemia/reperfusion in the rat.

Renal ischemia/reperfusion (I/R) occurs in many clinical scenarios, including trauma, elective surgery, and transplantation. Events initiated by this process can lead to inflammation in the kidneys, culminating in local injury as well as distant organ dysfunction. The objectives of this study were to investigate the changes in the functions of the liver and the regulation of gene expression of cytochrome P450 (CYP) isozymes after renal I/R. Hepatoxocity was assessed by serum alanine aminotransferase (sALT), serum aspartate aminotransferase (sAST) and liver glutathione-S-transferase (GST) activities, liver glutathione (GSH) level, and histopathological examination. Hepatic cytochrome P4503A1 (CYP3A1) and cytochrome P4502E1 (CYP2E1) activities were measured by erythromycin N-demethylase (ERD) and aniline hydroxylase (ANH) activities, respectively. CYP3A1 and CYP2E1 mRNA expression was determined by RT-PCR. Results showed that activities of sALT and sAST were significantly increased, while hepatic CYP3A1and CYP2E1 activities as well as their respective mRNA levels were significantly decreased after renal I/R. Moreover, hepatic tissue congestion, degeneration, and local necrosis were observed in rats after 1, 4, and 8h renal reperfusion following 2h renal ischemia. In conclusion, the present study suggests that renal I/R can cause hepatotoxicity and gene expression down-regulation of CYP isozymes in rats.