Synergistic neuroprotective effects of lithium and valproic acid or other histone deacetylase inhibitors in neurons: Roles of glycogen synthase kinase-3 inhibition
ABSTRACT Lithium and valproic acid (VPA) are two primary drugs used to treat bipolar mood disorder and have frequently been used in combination to treat bipolar patients resistant to monotherapy with either drug. Lithium, a glycogen synthase kinase-3 (GSK-3) inhibitor, and VPA, a histone deacetylase (HDAC) inhibitor, have neuroprotective effects. The present study was undertaken to demonstrate synergistic neuroprotective effects when both drugs were coadministered. Pretreatment of aging cerebellar granule cells with lithium or VPA alone provided little or no neuroprotection against glutamate-induced cell death. However, copresence of both drugs resulted in complete blockade of glutamate excitotoxicity. Combined treatment with lithium and VPA potentiated serine phosphorylation of GSK-3 alpha and beta isoforms and inhibition of GSK-3 enzyme activity. Transfection with GSK-3alpha small interfering RNA (siRNA) and/or GSK-3beta siRNA mimicked the ability of lithium to induce synergistic protection with VPA. HDAC1 siRNA or other HDAC inhibitors (phenylbutyrate, sodium butyrate or trichostatin A) also caused synergistic neuroprotection together with lithium. Moreover, combination of lithium and HDAC inhibitors potentiated beta-catenin-dependent, Lef/Tcf-mediated transcriptional activity. An additive increase in GSK-3 serine phosphorylation was also observed in mice chronically treated with lithium and VPA. Together, for the first time, our results demonstrate synergistic neuroprotective effects of lithium and HDAC inhibitors and suggest that GSK-3 inhibition is a likely molecular target for the synergistic neuroprotection. Our results may have implications for the combined use of lithium and VPA in treating bipolar disorder. Additionally, combined use of both drugs may be warranted for clinical trials to treat glutamate-related neurodegenerative diseases.
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ABSTRACT: Bipolar disorder is a severe mood disorder with high morbidity and mortality. Despite adequate treatment, patients continue to have recurrent mood episodes, residual symptoms, and functional impairment. Some preclinical studies have shown that histone deacetylase inhibitors may act on depressive-like and manic-like behaviors. Therefore, the aim of the present study was to evaluate the effects of sodium butyrate (SB) on behavioral changes in animal models of depression and mania. The animals were submitted to protocols of chronic mild stress or maternal deprivation for induction of depressive-like behaviors and subjected to amphetamine, or ouabain administration for induction of manic-like behaviors. SB reversed the depressive-like and manic-like behaviors evaluated in the animal models. From these results we can suggest that SB may be a potential mood stabilizer.Behavioural pharmacology 08/2013; 24(7). DOI:10.1097/FBP.0b013e32836546fc · 2.19 Impact Factor
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ABSTRACT: Evidence from basic molecular biology has noted a critical role of GSK-3 in Alzheimer's disease (AD) pathogenesis such as beta-amyloid (Aβ) production and accumulation, the formation of neurofibrillary tangle (NFT), and neuronal degeneration. Aβ generation and deposition represents a key feature and is generated from APP by the sequential actions of two proteolytic enzymes: β-secretase and γ-secretase. GSK-3 could play a critical role in Aβ production via enhancing β-secretase activity. GSK-3 not only modulates APP processing in the process of Aβ generation, but regulates Aβ production by interfering with APP cleavage at the γ-secretase complex step since the APP and PS1 (a component of γ- secretase complex) are substrates of GSK-3 as well. GSK-3 may downregulate α-secretase through inhibiting PKC and ADAMs activity which are the substrates of GSK-3 contributing to Aβ production. Meanwhile, Aβ accumulation can induce GSK-3 activation through Aβ-mediated neuroinflammation and oxidative stress. Considering that active GSK-3 and some common GSK-3-shared factors induce the hyperphosphorylation of tau and neurofibrillary lesions, GSK-3 is a possible linking between amyloid plaques and NFT pathology. Additionally, GSK-3 could disrupt acetylcholine activity, and accelerate axon degeneration and failures in axonal transport, and lead to cognitive impairment in AD. Preclinical and clinical studies have supported that GSK-3β inhibitors could be useful in the treatment of AD. Consequently, an effective measure to inhibit GSK-3 activity may be a very attractive drug target in AD.Current Alzheimer research 01/2012; 9(7):864-79. DOI:10.2174/156720512802455386 · 3.80 Impact Factor
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ABSTRACT: Histone deacetylase (HDAC) inhibitors have promising neuroprotective and anti-inflammatory properties although the exact mechanisms are unclear. We have earlier showed that factors from lipopolysaccharide (LPS)-activated microglia can down-regulate the astroglial nuclear factor-erythroid 2-related factor 2 (Nrf2)-inducible anti-oxidant defence. Here we have evaluated whether histone modification and activation of GSK3β are involved in these negative effects of microglia. Microglia were cultured for 24 h in serum-free culture medium to achieve microglia-conditioned medium from non-activated cells (MCM(0)) or activated with 10 ng/mL of LPS to produce MCM(10). Astrocyte-rich cultures treated with MCM(10) showed a time-dependent (0-72 h) increase in astroglial HDAC activity that correlated with lower levels of acetylation of histones H3 and H4 and decreased levels of the transcription factor Nrf2 and γ-glutamyl cysteine ligase modulatory subunit (γGCL-M) protein levels. The HDAC inhibitors valproic acid (VPA) and trichostatin-A (TSA) elevated the histone acetylation levels, restored the Nrf2-inducible anti-oxidant defence and conferred protection from oxidative stress-induced (H(2)O(2)) death in astrocyte-rich cultures exposed to MCM(10). Inhibitors of GSK3β (lithium) and p38 MAPK (SB203580) signaling pathways restored the depressed histone acetylation and Nrf2-related transcription whereas an inhibitor of Akt (Ly294002) caused a further decrease in Nrf2-related transcription. In conclusion, the study shows that well tolerated drugs such as VPA and lithium can restore an inflammatory induced depression in the Nrf2-inducible antioxidant defence, possibly via normalised histone acetylation levels.Neurobiology of Disease 10/2011; 44(1):142-51. DOI:10.1016/j.nbd.2011.06.016 · 5.20 Impact Factor