| Biofizika. 2014 Sep-Oct;59(5):941-5. |
| The effect of uridine on the endurance of animals with different resistance to physical stress: the role of mitochondrial ATP-dependent potassium channel.[Pubmed: 25730977] |
The effect of a metabolic precursor of natural activator of mitochondrial ATP-dependent potassium channel (mitochondrial K+(ATP))--uridine on animal's endurance to physical stress was studied.
METHODS AND RESULTS:
The endurance was determined by recording the time period during which the rat loaded with a plummet of 20% of body weight can swim until physical exhaustion at 32 degrees C. It was found that highly resistant animals swam until exhaustion for 7.40 ± 0.35 min, whereas low resistant rats hold out 2.07 ± 0.10 min only. The injection of uridine influenced the swimming time of the animals, increasing it twofold in low-resistant rats. The effect of uridine was decreased by injection of inhibitors of mitochondrial K+(ATP) channel.
CONCLUSIONS:
It was found that the injection of uridine into low resistant rats increased the rate of potassium transport in mitochondria isolated from liver of these rats, and inhibitors of the channel prevent the channel activating effect of uridine. The role of mitochondrial K+(ATP) cannel in the formation of animal's resistance to physical stress and protection of tissues from hypoxia is discussed. |
| BMC Pharmacol Toxicol. 2014 May 23;15:27. |
| Uridine prevents tamoxifen-induced liver lipid droplet accumulation.[Pubmed: 24887406 ] |
Tamoxifen, an agonist of estrogen receptor, is widely prescribed for the prevention and long-term treatment of breast cancer. A side effect of tamoxifen is fatty liver, which increases the risk for non-alcoholic fatty liver disease. Prevention of tamoxifen-induced fatty liver has the potential to improve the safety of long-term tamoxifen usage.
METHODS AND RESULTS:
Uridine, a pyrimidine nucleoside with reported protective effects against drug-induced fatty liver, was co-administered with tamoxifen in C57BL/6J mice. Liver lipid levels were evaluated with lipid visualization using coherent anti-Stokes Raman scatting (CARS) microscopy, biochemical assay measurement of triacylglyceride (TAG), and liquid chromatography coupled with mass spectrometry (LC-MS) measurement of membrane phospholipid. Blood TAG and cholesterol levels were measured. Mitochondrial respiration of primary hepatocytes in the presence of tamoxifen and/or uridine was evaluated by measuring oxygen consumption rate with an extracellular flux analyzer. Liver protein lysine acetylation profiles were evaluated with 1D and 2D Western blots. In addition, the relationship between endogenous uridine levels, fatty liver, and tamoxifen administration was evaluated in transgenic mice UPase1-/-and UPase1-TG.
Uridine co-administration prevented tamoxifen-induced liver lipid droplet accumulation in mice. The most prominent effect of uridine co-administration with tamoxifen was the stimulation of liver membrane phospholipid biosynthesis. Uridine had no protective effect against tamoxifen-induced impairment to mitochondrial respiration of primary hepatocytes or liver TAG and cholesterol export. Uridine had no effect on tamoxifen-induced changes to liver protein acetylation profile. Transgenic mice UPase1-/-with increased pyrimidine salvage activity were protected against tamoxifen-induced liver lipid droplet accumulation. In contrast, UPase1-TG mice with increased pyrimidine catabolism activity had intrinsic liver lipid droplet accumulation, which was aggravated following tamoxifen administration.
CONCLUSIONS:
Uridine co-administration was effective at preventing tamoxifen-induced liver lipid droplet accumulation. The ability of uridine to prevent tamoxifen-induced fatty liver appeared to depend on the pyrimidine salvage pathway, which promotes biosynthesis of membrane phospholipid. |
| Proc Natl Acad Sci U S A. 1997 Mar 4; 94(5): 1795–1799. |
| Inhibition by uridine but not thymidine of p53-dependent intestinal apoptosis initiated by 5-fluorouracil: Evidence for the involvement of RNA perturbation.[Reference: WebLink] |
The epithelia from the crypts of the intestine are exquisitely sensitive to metabolic perturbation and undergo cell death with the classical morphology of apoptosis.
METHODS AND RESULTS:
Administration of 40 mg/kg 5-fluorouracil (5-FU) to BDF-1 p53+/+ mice resulted in an increase in p53 protein at cell positions in the crypts that were also those subjected to an apoptotic cell death. In p53−/− mice apoptosis was almost completely absent, even after 24 hr. 5-FU is a pyrimidine antimetabolite cytotoxin with multiple mechanisms of action, including inhibition of thymidylate synthase (TS), which gives rise to DNA damage, and incorporation into RNA. The inhibition of TS can be increased by coadministration of folinic acid and can be abrogated by administration of thymidine. The incorporation of 5-FU into RNA is inhibited by administration of Uridine. p53-Dependent cell death induced by 5-FU was only inhibited by administration of Uridine. Uridine had no effect on the apoptosis initiated by 1 Gy of γ-radiation. Although thymidine abrogated apoptosis induced by the pure TS inhibitor Tomudex, it had no effect on 5-FU-induced apoptosis, and coadministration of folinic acid did not increase apoptosis.
CONCLUSIONS:
The data show that 5-FU-induced cell death of intestinal epithelial cells is p53-dependent and suggests that changes in RNA metabolism initiate events culminating in the expression of p53. |
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