Neuroprotective effects of Paeonia Lactiflora extract against cell death of dopaminergic SH-SY5Y cells is mediated by epigenetic modulation

Mechanism by which HDAC3 regulates manganese induced H3K27ac in SH-SY5Y cells and intervention by curcumin

Long-term excessive exposure to manganese can impair neuronal function in the brain, but the underlying pathological mechanism remains unclear. Oxidative stress plays a central role in manganese-induced neurotoxicity. Numerous studies have established a strong link between abnormal histone acetylation levels and the onset of various diseases. Histone deacetylase inhibitors and activators, such as TSA and ITSA-1, are often used to investigate the intricate mechanisms of histone acetylation in disease. In addition, recent experiments have provided substantial evidence demonstrating that curcumin (Cur) can act as an epigenetic regulator. Given these findings, this study aims to investigate the mechanisms underlying oxidative damage in SH-SY5Y cells exposed to MnCl2·4H2O, with a particular focus on histone acetylation, and to assess the potential therapeutic efficacy of Cur. In this study, SH-SY5Y cells were exposed to manganese for 24 h, were treated with TSA or ITSA-1, and were treated with or without Cur. The results suggested that manganese exposure, which leads to increased expression of HDAC3, induced H3K27 hypoacetylation, inhibited the transcription of antioxidant genes, decreased antioxidant enzyme activities, and induced oxidative damage in cells. Pretreatment with an HDAC3 inhibitor (TSA) increased the acetylation of H3K27 and the transcription of antioxidant genes and thus slowed manganese exposure-induced cellular oxidative damage. In contrast, an HDAC3 activator (ITSA-1) partially increased manganese-induced cellular oxidative damage, while Cur prevented manganese-induced oxidative damage. In summary, these findings suggest that inhibiting H3K27ac is a possible mechanism for ameliorating manganese-induced damage to dopaminergic neurons and that Cur exerts a certain protective effect against manganese-induced damage to dopaminergic neurons.

Effects of Histone Modification in Major Depressive Disorder

Major depressive disorder (MDD) is a disease associated with many factors; specifically, environmental, genetic, psychological, and biological factors play critical roles. Recent studies have demonstrated that histone modification may occur in the human brain in response to severely stressful events, resulting in transcriptional changes and the development of MDD. In this review, we discuss five different histone modifications, histone methylation, histone acetylation, histone phosphorylation, histone crotonylation and histone β-hydroxybutyrylation, and their relationships with MDD. The utility of histone deacetylase (HDAC) inhibitors (HDACis) for MDD treatment is also discussed. As a large number of MDD patients in China have been treated with traditional Chineses medicine (TCM), we also discuss some TCM therapies, such as Xiaoyaosan (XYS), and their effects on histone modification. In summary, targeting histone modification may be a new strategy for elucidating the mechanism of MDD and a new direction for MDD treatment.

Pharmacological Modulation of Nrf2/HO-1 Signaling Pathway as a Therapeutic Target of Parkinson's Disease

Parkinson’s disease (PD) is a complex neurodegenerative disorder featuring both motor and nonmotor symptoms associated with a progressive loss of dopaminergic neurons in the substantia nigra pars compacta. Oxidative stress (OS) has been implicated in the pathogenesis of PD. Genetic and environmental factors can produce OS, which has been implicated as a core contributor to the initiation and progression of PD through the degeneration of dopaminergic neurons. The transcription factor nuclear factor erythroid 2-related factor 2 (Nrf2) orchestrates activation of multiple protective genes, including heme oxygenase-1 (HO-1), which protects cells from OS. Nrf2 has also been shown to exert anti-inflammatory effects and modulate both mitochondrial function and biogenesis. Recently, a series of studies have reported that different bioactive compounds were shown to be able to activate Nrf2/antioxidant response element (ARE) and can ameliorate PD-associated neurotoxin, both in animal models and in tissue culture. In this review, we briefly overview the sources of OS and the association between OS and the pathogenesis of PD. Then, we provided a concise overview of Nrf2/ARE pathway and delineated the role played by activation of Nrf2/HO-1 in PD. At last, we expand our discussion to the neuroprotective effects of pharmacological modulation of Nrf2/HO-1 by bioactive compounds and the potential application of Nrf2 activators for the treatment of PD. This review suggests that pharmacological modulation of Nrf2/HO-1 signaling pathway by bioactive compounds is a therapeutic target of PD.

Prophylactic Neuroprotection of Total Glucosides of Paeoniae Radix Alba against Semen Strychni-Induced Neurotoxicity in Rats: Suppressing Oxidative Stress and Reducing the Absorption of Toxic Components

Strychnos alkaloids (SAs) are the main toxic constituents in Semen Strychni, a traditional Chinese medicine, which is known for its fatal neurotoxicity. Hence, the present study was carried out to evaluate the neurotoxicity induced by SAs and the pre-protective effects of the total glucosides of Paeoniae Radix Alba (TGP). An SA brain damage model was firstly established. The neurotoxicity induced by SAs and the pre-protective effects of TGP were confirmed by physical and behavioral testing, biochemical assay, and histological examination. Then, a liquid chromatography-tandem mass spectrometry method was developed and validated to investigate the time-course change and distribution of strychnine and brucine (two main SAs) in the brain after oral SA administration with or without TGP pretreatment. Biochemical analysis results indicated that TGP could ameliorate the oxidative stress status caused by SAs. Time-course change and distribution studies demonstrated that strychnine and brucine were rapidly absorbed into the brain, peaked early at 0.5 h, and were mainly located in the hippocampus and cerebellum. TGP showed a pre-protective effect against neurotoxicity by reducing the absorption of toxic alkaloids into the brain. These findings could provide beneficial information in facilitating future studies of Semen Strychni neurotoxicity and developing herbal medicines to alleviate neurotoxicity in the clinic.