An ELISA-based method for the quantification of incorporated BrdU as a measure of cell proliferation in vivo

Enhancing nucleotide metabolism protects against mitochondrial dysfunction and neurodegeneration in a PINK1 model of Parkinson's disease

Mutations in PINK1 cause early-onset Parkinson's disease (PD). Studies in Drosophila melanogaster have highlighted mitochondrial dysfunction on loss of Pink1 as a central mechanism of PD pathogenesis. Here we show that global analysis of transcriptional changes in Drosophila pink1 mutants reveals an upregulation of genes involved in nucleotide metabolism, critical for neuronal mitochondrial DNA synthesis. These key transcriptional changes were also detected in brains of PD patients harbouring PINK1 mutations. We demonstrate that genetic enhancement of the nucleotide salvage pathway in neurons of pink1 mutant flies rescues mitochondrial impairment. In addition, pharmacological approaches enhancing nucleotide pools reduce mitochondrial dysfunction caused by Pink1 deficiency. We conclude that loss of Pink1 evokes the activation of a previously unidentified metabolic reprogramming pathway to increase nucleotide pools and promote mitochondrial biogenesis. We propose that targeting strategies enhancing nucleotide synthesis pathways may reverse mitochondrial dysfunction and rescue neurodegeneration in PD and, potentially, other diseases linked to mitochondrial impairment.

Neuroendocrine and cardiovascular parameters during simulation of stress-induced rise in circulating oxytocin in the rat

Physiological functions of oxytocin released during stress are not well understood. We have (1) investigated the release of oxytocin during chronic stress using two long-term stress models and (2) simulated stress-induced oxytocin secretion by chronic treatment with oxytocin via osmotic minipumps. Plasma oxytocin levels were significantly elevated in rats subjected to acute immobilization stress for 120 min, to repeated immobilization for 7 days and to combined chronic cold stress exposure for 28 days with 7 days immobilization. To simulate elevation of oxytocin during chronic stress, rats were implanted with osmotic minipumps subcutaneously and treated with oxytocin (3.6 microg/100 g body weight/day) or vehicle for 2 weeks. Chronic subcutaneous oxytocin infusion led to an increase in plasma oxytocin, adrenocorticotropic hormone, corticosterone, adrenal weights and heart/body weight ratio. Oxytocin treatment had no effect on the incorporation of 5-bromo-2-deoxyuridine into DNA in the heart ventricle. Mean arterial pressure response to intravenous phenylephrine was reduced in oxytocin-treated animals. Decrease in adrenal tyrosin hydroxylase mRNA following oxytocin treatment was not statistically significant. Oxytocin treatment failed to modify food intake and slightly increased water consumption. These data provide evidence on increased concentrations of oxytocin during chronic stress. It is possible that the role of oxytocin released during stress is in modulating hypothalamic-pituitary-adrenocortical axis and selected sympathetic functions.

Leukotriene D4 stimulates the migration but not proliferation of endothelial cells mediated by the cysteinyl leukotriene cyslt(1) receptor via the extracellular signal-regulated kinase pathway

The actions of cysteinyl leukotrienes (CysLTs) are mediated by activating CysLT receptors, CysLT(1), and CysLT(2). The CysLT(1) receptor mediates vascular responses to CysLTs; however, its effect on the proliferation and migration of endothelial cells is not clarified. To determine this effect, we observed proliferation and migration in EA.hy926 cells, a human endothelial cell line, and the involvement of activation of mitogen-activated protein kinases (MAPKs). We found that LTD(4) did not affect the proliferation, but significantly stimulated the migration of endothelial cells. LTD(4) also induced the phosphorylation of extracellular signal-regulated kinase (ERK) 1/2, but not those of p38 or JNK. The LTD(4)-induced migration and ERK1/2 phosphorylation were blocked by the CysLT(1)-receptor antagonist montelukast and the dual antagonist Bay u9773, but not by the CysLT(2)-receptor antagonist Bay cysLT2; the migration was also inhibited by the ERK1/2 inhibitor U0126. Our findings indicate that LTD(4) stimulates the CysLT(1) receptor-mediated migration of endothelial cells; this may be regulated by the ERK1/2 pathway.