N,N-dimethylacetamide targets neuroinflammation in Alzheimer's disease in in-vitro and ex-vivo models.

Alzheimer's disease (AD) is a chronic degenerative brain disorder with no clear pathogenesis or effective cure, accounting for 60-80% of cases of dementia. In recent years, the importance of neuroinflammation in the pathogenesis of AD and other neurodegenerative disorders has come into focus. Previously, we made the serendipitous discovery that the widely used drug excipient N,N-dimethylacetamide (DMA) attenuates endotoxin-induced inflammatory responses in vivo. In the current work, we investigate the effect of DMA on neuroinflammation and its mechanism of action in in-vitro and ex-vivo models of AD. We show that DMA significantly suppresses the production of inflammatory mediators, such as reactive oxygen species (ROS), nitric oxide (NO) and various cytokines and chemokines, as well as amyloid-ß (Aß), in cultured microglia and organotypic hippocampal slices induced by lipopolysaccharide (LPS). We also demonstrate that DMA inhibits Aß-induced inflammation. Finally, we show that the mechanism of DMA's effect on neuroinflammation is inhibition of the nuclear factor kappa-B (NF-κB) signaling pathway and we show how DMA dismantles the positive feedback loop between NF-κB and Aß synthesis. Taken together, our findings suggest that DMA, a generally regarded as safe compound that crosses the blood brain barrier, should be further investigated as a potential therapy for Alzheimer's disease and neuroinflammatory disorders.

Synthesis of N-1', N-3'-disubstituted spirohydantoins and their anticonvulsant activities in pilocarpine model of temporal lobe epilepsy.

Herein we report the synthesis and anticonvulsant activity of a library of eighteen new compounds that are structural mimics of phenytoin. These class of compounds contain a N-1', N-3'-disubstituted spirohydantoin scaffold, where the N-1' and N-3' positions are modified with an alkyl group or aryl group. Of the eighteen compounds synthesized and tested, compound 5c showed the best anticonvulsant activity. It completely prevented the precursor events of motor seizure in the pilocarpine model of temporal lobe epilepsy. Additionally, ten of the analogs were more effective than phenytoin when compared using the Racine's score in the pilocarpine model. Based on the structure activity relationship (SAR), we concluded that alkyl groups (ethyl, propyl or cyclopropyl) at N-3' position and 4-nitro phenyl group at N-1' position are desirable.

Pairing elevation of [cyclic GMP] with inhibition of PKA produces long-term depression of glutamate release from isolated rat hippocampal presynaptic terminals.

Data suggest both presynaptic and postsynaptic changes contribute to activity-dependent long-term synaptic plasticity. We have shown that pairing elevation of intracellular [cyclic GMP], using the type V phosphodiesterase inhibitor zaprinast, with inhibition of cyclic AMP-dependent protein kinase (PKA), is sufficient to elicit chemical long-term depression (CLTD) of synaptic transmission at Schaffer collateral-CA1 and mossy fibre-CA3 synapses in rat hippocampus. CLTD does not require synaptic activity, and selective postsynaptic drug injections do not affect it, suggesting it is presynaptically induced and expressed. To directly evaluate this hypothesis, we tested whether CLTD of transmitter release can be expressed in isolated presynaptic nerve terminals. Presynaptic nerve terminals (synaptosomes) were isolated from rat hippocampi by Percoll density gradient centrifugation. Synaptosomes were loaded with [3H]glutamate, and basal and depolarisation-induced release of [3H]glutamate measured in control medium versus medium containing zaprinast (20 microm) plus or minus the PKA inhibitor H-89 (10 microm). Zaprinast produced a significant decrease in basal [3H]glutamate release. However, only combining zaprinast with H-89 significantly depressed K+-evoked [3H]glutamate release. After a 20-min drug washout, basal release returned to normal in all conditions, but K+-evoked [3H]glutamate release was persistently reduced only by the combination of zaprinast plus H-89. Long-term reduction of [3H]glutamate release from synaptosomes was completely prevented by the PKG inhibitor KT5823 (5 microm). These data demonstrate the existence of a presynaptic, cyclic GMP-PKG dependent cascade capable of expressing LTD of glutamate release from isolated hippocampal nerve terminals.

Oxidative stress-induced calcium signalling in Aspergillus nidulans.

The effects of oxidative stress on levels of calcium ion (Ca(2+)) in Aspergillus nidulans were measured using strains expressing aequorin in the cytoplasm (Aeq(cyt)) and mitochondria (Aeq(mt)). When oxidative stress was induced by exposure to 10-mM H(2)O(2), the mitochondrial calcium response (Ca(mt)(2+)) was greater than the change in cytoplasmic calcium (Ca(c)(2+)). The Ca(mt)(2+) response to H(2)O(2) was dose dependent, while the increase in [Ca(c)(2+)] did not change with increasing H(2)O(2). The increase in both [Ca(c)(2+)] and [Ca(mt)(2+)] in response to oxidative stress was enhanced by exposure of cells to Ca(2+). The presence of chelator in the external medium only partially inhibited the Ca(mt)(2+) and Ca(c)(2+) responses to oxidative stress. Reagents that alter calcium fluxes had varied effects on the Ca(mt)(2+) response to peroxide. Ruthenium red blocked the increase in [Ca(mt)(2+)], while neomycin caused an even greater increase in [Ca(mt)(2+)]. Treatment with ruthenium red and neomycin had no effect on the Ca(c)(2+) response. Bafilomycin A and oligomycin had no effect on either the mitochondrial or cytoplasmic response. Inhibitors of both voltage-regulated calcium channels and intracellular calcium release channels inhibited the Ca(2+)-dependent component of the Ca(mt)(2+) response to oxidative stress. We conclude that the more significant Ca(2+) response to oxidative stress occurs in the mitochondria and that both intracellular and extracellular calcium pools can contribute to the increases in [Ca(c)(2+)] and [Ca(mt)(2+)] induced by oxidative stress.