ABSTRACT
OBJECTIVE: To investigate the effects of high-altitude hypoxic environment on the expression of pregnane X receptor (PXR) in rat liver and related mechanism. METHODS: Wistar rats were randomly divided into five groups with 8 rats in each group, the rats were exposed to high-plateau hypoxia for 0 (control group), 12, 24, 36 and 48 h, respectively. Abdominal aortic blood samples were collected for blood gas analysis. HE staining was used to observe the pathological changes of liver tissue. The expression levels of PXR mRNA in liver tissues were determined by RT-PCR. Western blot analysis was performed to determine the protein expression of PXR and protease SUG1 in liver tissues of rats. RESULTS Compared with the control group, the blood pH of the rats decreased after 12 h of acute hypoxia. After 24 h exposed to hypoxia, SaO2 was lower than 80%, PaO2 was lower than 60 mmHg (1 mmHg=0.133 kPa); and PaCO2 increased after 48 h exposed to hypoxia (P<0.05). There was obvious edema in the central vein of the liver tissue at 12 h and 24 h after exposure to hypoxia. The liver tissue of the rats exposed to hypoxia for 36 h and 48 h showed inflammatory infiltration. The expression of PXR mRNA was significantly decreased by 63%, 96%, 86%, and 85%at 12, 24, 36 h, and 48 h after exposure to hypoxia (all P<0.05), respectively. The protein expression of PXR was significantly up-regulated by 93%and 99%after 36 h and 48 h exposure to hypoxia (all P<0.05), respectively. The protein expression of proteinase SUG1 decreased by 14%, 34%and 46%after 24, 36 and 48 h after hypoxia (all P<0.01). CONCLUSIONS Acute hypoxia at high altitude can affect the expression of nuclear receptor PXR in rat liver, and protease SUG1 may be a regulatory factor for PXR expression in hypoxia.
ABSTRACT
Drug metabolism is significantly affected under hypoxia environment with changes of pharmacokinetics, expression and function of drug-metabolizing enzymes and transporters. Studies have shown that hypoxia increases the release of a series of inflammatory cytokines which can modulate drug metabolism. Besides, both hypoxia inducible factor 1α (HIF-1α) and microRNA-mediated pathways play a role in regulating drug metabolism. This article reviewed the impact and single-factor modulating mechanisms of drug metabolism under hypoxia, and put forward the speculation and prospects of multi-factor modulating mechanisms.
Subject(s)
Humans , Cell Hypoxia , Hypoxia , Hypoxia-Inducible Factor 1, alpha Subunit , Physiology , Membrane Transport Proteins , Physiology , MicroRNAs , Physiology , Pharmaceutical Preparations , MetabolismABSTRACT
In this study, the change of intestinal microflora in rat fecal samples after amoxicillin administration was observed. In vitro incubation experiments combined with LC-MS/MS assay were used to test the role of intestinal flora in the metabolism of nifedipine. The effect of changes of intestinal flora was determined after amoxicillin administration on the metabolism of nifedipine. We found that the number and types of intestinal flora decreased after taking amoxicillin. After incubation for 12 h, the results showed that the remaining amounts of nifedipine in the N1 group (nifedipine) and N2 group (amoxicillin + nifedipine) were 0.057 6 and 0.064 8 μmol·L-1, respectively, while the remaining amounts of nifedipine after 24 h of incubation were 0.039 6 and 0.050 4 μmol·L-1, respectively. These results show that the intestinal flora is involved in the metabolism of nifedipine. After administration of amoxicillin, the metabolism of nifedipine was slowed down, the AUC0-t was increased by 39.10%, tmax was advanced by 0.45 h, and the CL was reduced 34.71%. The data suggest that the combination may enhance the therapeutic effect of nifedipine. Therefore, drug-drug interactions mediated by gut microbiota cannot be ignored when combined with antibiotics and nifedipine, one of the important factors affecting drug efficacy.
ABSTRACT
<p><b>OBJECTIVE</b>To investigate mutational spectrum and frequency of the mitochondrial 12S rRNA gene in Chinese subjects with aminoglycoside-induced and non-syndromic hearing loss.</p><p><b>METHODS</b>Total of 456 subjects with non-syndromic hearing loss were recruited from seven schools for deaf-mutes in Zhejiang province. Genomic DNA was extracted from the whole blood, and then the DNA fragment was amplified spanning the 12S rRNA gene, followed by sequencing and analyzed.</p><p><b>RESULTS</b>Thirty-one variants were identified by mutation analysis of 12S rRNA gene in these subjects. The frequency of the known 1555A > G mutation was 4.4% (20/456). Prevalence of other putative deafness-associated mutation at positions 961 and 1095 were 2.0% (9/456) and 0.7% (3/456) respectively. Furthermore, the 1027A > G, 1109T > C and 1431G > A variants conferred increased sensitivity to ototoxic drugs or non-syndromic deafness as they were absent in 449 Chinese controls and localized at highly conserved nucleotides of this 12S rRNA gene. Moreover, clinical data showed a wide range of age-of-onset, variety of severity and various audiometric configurations in subjects carrying the 1555A > G mutation.</p><p><b>CONCLUSIONS</b>Our data demonstrated that the mitochondrial 12S rRNA gene is the hot spot for mutations associated with aminoglycoside ototoxicity and non-syndromic hearing loss. Nuclear modifier genes, mitochondrial haplotypes and environmental factors might play a role in the phenotypic manifestation of these mutations.</p>