AbstractAntagonists at α-amino-3-hydroxy-5-methyl-4-isoxazolepropionate (AMPA) - type glutamate receptors limit growth of human cancers in vitro. However, the mechanism of anticancer action of AMPA antagonists is not known. Here we report that the AMPA antagonists GYKI 52466 and CFM-2 inhibit the extracellular signal regulated kinase (ERK1/2) pathway, an intracellular signaling cascade which is activated by growth factors and controls proliferation of lung adenocarcinoma cells. AMPA antagonists reduced phosphorylation of cAMP-responsive element binding protein (CREB), suppressed expression of cyclin D1, upregulated the cell cycle regulators and tumor suppressor proteins p21 and p53 and decreased number of lung adenocarcinoma cells in G2 and S phases of the cell cycle. These findings reveal potential mechanism of antiproliferative action of AMPA antagonists and indicate that this class of compounds may be useful in the therapy of human cancers.
Cerebral white matter injury is a leading cause of adverse neurodevelopmental outcome in prematurely born infants involving cognitive deficits in later life. Despite increasing knowledge about the pathophysiology of perinatal brain injury, therapeutic options are limited. In the adult demyelinating disease multiple sclerosis the sphingosine-1-phosphate (S1P) receptor modulating substance fingolimod (FTY720) has beneficial effects. Herein, we evaluated the neuroprotective potential of FTY720 in a neonatal model of oxygen-toxicity, which is associated with hypomyelination and impaired neuro-cognitive outcome. A single dose of FTY720 (1mg/kg) at the onset of neonatal hyperoxia (24h 80% oxygen on postnatal day 6) resulted in improvement of neuro-cognitive development persisting into adulthood. This was associated with reduced microstructural white matter abnormalities 4 months after the insult. In search of the underlying mechanisms potential non-classical (i.e. lymphocyte-independent) pathways were analysed shortly after the insult, comprising modulation of oxidative stress and local inflammatory responses as well as myelination, oligodendrocyte degeneration and maturation. Treatment with FTY720 reduced hyperoxia-induced oxidative stress, microglia activation and associated pro-inflammatory cytokine expression. In vivo and in vitro analyses further revealed that oxygen-induced hypomyelination is restored to control levels, which was accompanied by reduced oligodendrocyte degeneration and enhanced maturation. Furthermore, hyperoxia-induced elevation of S1P receptor 1 (S1P1) protein expression on in vitro cultured oligodendrocyte precursor cells was reduced by activated FTY720 and protection from degeneration is abrogated after selective S1P1 blockade. Finally, FTY720s' classical mode of action (i.e. retention of immune cells within peripheral lymphoid organs) was analysed demonstrating that FTY720 diminished circulating lymphocyte counts independent from hyperoxia. Cerebral immune cell counts remained unchanged by hyperoxia and by FTY720 treatment. Taken together, these results suggest that beneficial effects of FTY720 in neonatal oxygen-induced brain injury may be rather attributed to its anti-oxidative and anti-inflammatory capacity acting in concert with a direct protection of developing oligodendrocytes than to a modulation of peripheral lymphocyte trafficking. Thus, FTY720 might be a potential new therapeutic option for the treatment of neonatal brain injury through reduction of white matter damage.
Oxygen toxicity appears to contribute to the pathogenesis of adverse neurological outcome in survivors of preterm birth. In infant rodent brains, hyperoxia triggers widespread apoptotic neurodegeneration, induces proinflammatory cytokines and inhibits growth factor signaling cascades. Since a tissue-protective effect has been observed for recombinant erythropoietin (rEpo), we hypothesized that rEpo would influence the expression of proinflammatory cytokines and matrix metalloproteinase (MMP)-2 and MMP-9. Six-day-old Wistar rats were exposed to 80% oxygen for 2–48 h and received 20,000 IU rEpo i.p. Sex-matched littermates kept in room air and injected with normal saline or rEpo served as controls. Treatment with rEpo significantly reduced hyperoxia-induced upregulation of the proinflammatory cytokines IL-1β and IL-18 in infant rodent brains on the mRNA and protein levels. In parallel, gelatin zymography in hyperoxia-treated immature rat brains revealed an upregulation of active MMP-2 which was reduced by concomitant rEpo treatment. Furthermore, hyperoxia induced upregulation of MMP-9 following 12 h of oxygen exposure and this was attenuated by rEpo treatment. Our results suggest that rEpo generates its protective effect against oxygen toxicity through a reduction of proinflammatory mediator levels.
Untreated exposure to pain in preterm neonates might damage the vulnerable premature brain and alter development. Pain treatment is limited because analgesic agents may also have adverse neurodevelopmental consequences in newborns.To study the effects of neonatal pain and morphine treatment on the developing brain in a neonatal rat model.Newborn rats were randomly assigned to: treatment with formalin injections (group 1), saline injections (group 2) and controls receiving no injections (group 3). Treatment was given on postnatal days 1-3 (model A), 1-5 (model B) and 10-12 (model C). Brains were studied histologically and protein expression was evaluated (protein kinase C epsilon and doublecortin). Effects of preemptive morphine treatment were studied in the same models (models A+M and B+M).Formalin injections resulted in increased apoptotic scores in models A and B. Saline injections increased the number of degenerative cells only in model B. Morphine showed protective effects in formalin-treated animals of model A+M and saline-treated animals of model B+M only. In model C, no neurodegenerative effects were detected. The protein expression of doublecortin showed a pain-related upregulation in the thalamus region, whereas protein kinase C epsilon expression was upregulated in the cortex.Severe inflammatory pain and pain caused by repetitive injections in neonatal rats may cause major changes in the developing brain during the first week of life. Morphine may only protect the newborn brain against these changes in specific situations.
Abstract Infections and perioperative stress can lead to neuroinflammation, which in turn is linked to cognitive impairments such as postoperative delirium or postoperative cognitive dysfunctions. The α2-adrenoceptor agonist dexmedetomidine (DEX) prevents cognitive impairments and has organo-protective and anti-inflammatory properties. Macroautophagy (autophagy) regulates many biological processes, but its role in DEX-mediated anti-inflammation and the underlying mechanism of DEX remains largely unclear. We were interested how a pretreatment with DEX protects against lipopolysaccharide (LPS)-induced inflammation in adult male Wistar rats. We used Western blot and activity assays to study how DEX modulated autophagy- and apoptosis-associated proteins as well as molecules of the cholinergic anti-inflammatory pathway, and qPCR to analyse the expression of autophagy and inflammation-associated microRNAs (miRNA) in the spleen, cortex and hippocampus at different time points (6 h, 24 h, 7 d). We showed that a DEX pretreatment prevents LPS-induced impairments in autophagic flux and attenuates the LPS-induced increase in the apoptosis-associated protein cleaved poly(ADP-ribose)-polymerase (PARP) in the spleen. Both, DEX and LPS altered miRNA expression and molecules of the cholinergic anti-inflammatory pathway in the spleen and brain. While only a certain set of miRNAs was up- and/or downregulated by LPS in each tissue, which was prevented or attenuated by a DEX pretreatment in the spleen and hippocampus, all miRNAs were up- and/or downregulated by DEX itself – independent of whether or not they were altered by LPS. Our results indicate that the organo-protective effect of DEX may be mediated by autophagy, possibly by acting on associated miRNAs, and the cholinergic anti-inflammatory pathway. Graphical abstract Preventive effects of DEX on LPS-induced inflammation . DEX restores the LPS-induced impairments in autophagic flux, attenuates PARP cleavage and alters molecules of the cholinergic system in the spleen. Furthermore, DEX alters and prevents LPS-induced miRNA expression changes in the spleen and brain along with LPS.
Marijuana and alcohol are the most widely abused drugs among women of reproductive age. This study was designed to explore how cannabinoids modulate neurotoxicity of ethanol in the developing rodent brain.
