[Regulatory mechanism of MS275 on the p38 MAPK signaling pathway in rats with convulsion in the developmental stage].

OBJECTIVE: To study the regulatory mechanism of MS275, a histone deacetylase inhibitor, on the p38 MAPK signaling pathway in rats with convulsion in the developmental stage. METHODS: Thirty-two male rats were randomly divided into four groups: control, pentylenetetrazol (PTZ), PTZ+3 mg/kg MS275, and PTZ+6 mg/kg MS275 (n=8 each). A rat model of convulsion in the developmental stage was prepared by an intraperitoneal injection of PTZ. The rats in the control group were given an injection of normal saline alone. MS275 was given by an intraperitoneal injection at 2 hours before PTZ injection. At 24 hours after successful modeling, 6 rats were taken from each group. Western blot and qRT-PCR were used to measure the protein and mRNA expression of p38, MK2, cAMP response element-binding protein (CREB), and interleukin-6 (IL-6) in the hippocampus. Hematoxylin-eosin (HE) staining was used to observe brain pathological changes. Western blot was used to measure the expression of CD11b as a marker for the activation of microglial cells. RESULTS: Compared with the control group, the PTZ group had significant increases in the mRNA and protein expression of p38, MK2, CREB, and IL-6 (P<0.05). MS275 significantly inhibited the mRNA and protein expression of the above markers in the rats with convulsion in the developmental stage (P<0.05), and 6 mg/kg MS275 had a significantly better inhibitory effect on the mRNA and protein expression of IL-6 and CREB than 3 mg/kg MS275 (P<0.05). HE staining showed that the PTZ group had marked neuron apoptosis, cellular edema, and inflammatory cell infiltration, while MS275 intervention alleviated neuron apoptosis and cellular edema and reduced inflammatory cell infiltration in the rats with convulsion. The PTZ group had a significant increase in the activation of microglial cells, while MS275 significantly inhibited the activation of microglial cells in the rats with convulsion (P<0.05); 6 mg/kg MS275 had a significantly better inhibitory effect than 3 mg/kg MS275 (P<0.05). CONCLUSIONS: In rats with convulsion in the developmental stage, the histone deacetylase inhibitor MS275 can inhibit the p38 MAPK signaling pathway, the apoptosis of hippocampal neurons, and the activation of microglial cells and thus reduce inflammatory response and convulsion-induced brain injury in a dose-dependent manner.

Histone deacetylase inhibitor SAHA attenuates post-seizure hippocampal microglia TLR4/MYD88 signaling and inhibits TLR4 gene expression via histone acetylation.

BACKGROUND: Epilepsy is a common neurological disorder characterized by recurrent unprovoked seizures. Seizure-induced TLR4/MYD88 signaling plays a critical role in activating microglia and triggering neuron apoptosis. SAHA is a histone deacetylase inhibitor that regulates gene expression by increasing chromatin histone acetylation. In this study, we investigated the role of SAHA in TLR4/MYD88 signaling in a rat seizure model. RESULTS: Sprague-Dawley rats with kainic acid (KA)-induced seizures were treated with SAHA. The expression of TLR4, MYD88, NF-κB P65 and IL-1ß in hippocampus was detected at hour 2 and 6 and day 1, 2, and 3 post seizure. SAHA pretreatment increased seizure latency and decreased seizure scores. The expression levels of TLR4, MYD88, NF-κB and IL-1ß increased significantly in both activated microglia and apoptotic neurons after KA treatment. The effects were attenuated by SAHA. Chromatin immunoprecipitation assays indicated that the H3 histone acetylation levels significantly decreased while H3K9 levels significantly increased in the KA treatment group. The H3 and H3K9 acetylation levels returned to control levels after SAHA (50 mg/kg) pretreatment. There was a positive correlation between the expression of TLR4 and the acetylation levels of H3K9. CONCLUSIONS: Histone deacetylase inhibitor SAHA can suppress seizure-induced TLR4/MYD88 signaling and inhibit TLR4 gene expression through histone acetylation regulation. This suggests that SAHA may protect against seizure-induced brain damage.

Everolimus inhibits PI3K/Akt/mTOR and NF-kB/IL-6 signaling and protects seizure-induced brain injury in rats.

BACKGROUND: Epilepsy is a common chronic neurological disease caused by the over-synchronization of neurons leading to brain dysfunction. Recurrent seizures can lead to cognitive and behavioral deficits, and irreversible brain damage. While the PI3K/Akt/mTOR pathway regulates various physiological processes of neurons and glia, it may also lead to abnormal neuronal signal transduction under pathological conditions, including that of epilepsy. Everolimus (Eve), an mTOR inhibitor, may modulate neuronal excitability and therefore exert protection against epilepsy. Therefore, this study aimed to investigate the neuroprotective effect of Everolimus on seizure-induced brain injury and its regulation of the PI3K/Akt/mTOR and NF-kB/IL-6 signaling pathway. Kainic acid (KA) 15 mg/kg was used to induce seizures and Everolimus (1, 2, 5 mg/kg) was administered as a pretreatment. Hippocampal tissue was extracted 24 h post-seizure. RESULTS: The protein and mRNA expression levels of PI3K、p-AKt、p-mTOR、NF-kB and IL-6 as well as neuronal apoptosis and microglia activation, significantly increased after KA-induced seizures, however, these effects were inhibited by Everolimus treatment. Furthermore, pretreatment with Everolimus decreased seizure scores and increased seizure latency. CONCLUSIONS: Everolimus can decrease the PI3K/Akt/mTOR and NF-kB/IL-6 signaling pathway, reduce neuronal apoptosis and microglia activation, and attenuate seizure susceptibility and intensity, thus having a protective effect on seizure-induced brain damage.

Genistein protects epilepsy-induced brain injury through regulating the JAK2/STAT3 and Keap1/Nrf2 signaling pathways in the developing rats.

BACKGROUND: Epilepsy is a common chronic neurological disease. Recurrent seizures can cause irreversible brain damage. This study aimed to explore the regulation of Genistein on JAK2/STAT3 and Keap1/Nrf2 signaling pathway and the protective effects on brain injury after epilepsy. METHODS: Pentylenetetrazole (PTZ) was used to induce epilepsy in developing rats and Genistein was used for pretreatment of epilepsy. The seizure latency, grade scores and duration of the first generalized tonic-clonic seizure (GTCs) were recorded. Hippocampus tissue was sampled at 24 h post-epilepsy. Immunofluorescence staining was used to observe mature neurons, activated microglia and astrocytes in the hippocampal CA1 region. Western blot and qRT-PCR were used to determine the protein and mRNA levels of JAK2, STAT3, TNF-α, IL-1ß, Keap1, Nrf2, HO-1, NQO1, caspase3, Bax and Bcl2 in the hippocampus. RESULTS: Immunofluorescence showed that the number of neurons significantly decreased, and activated microglia and astrocytes significantly increased after epilepsy; Western blot and q-PCR showed that the expressions of JAK2, STAT3, TNF-α, IL-1ß, Keap1, caspase3 and Bax significantly increased, while Nrf2, HO-1, NQO1 and Bcl-2 were significantly reduced after epilepsy. These effects were reversed by Genistein treatment. Moreover, Genistein was found to prolong seizure latency and reduce seizure intensity score and duration of generalized tonic-clonic seizures(GTCs) CONCLUSIONS: Genistein can activate the Keap1/Nrf2 antioxidant stress pathway and attenuate the activation of microglia and astrocytes. Genistein also inhibits the JAK2-STAT3 inflammation pathway and expression of apoptotic proteins, and increases the number of surviving neurons, thus having a protective effect on epilepsy-induced brain damage.

MS275 reduces seizure-induced brain damage in developing rats by regulating p38 MAPK signaling pathways and epigenetic modification.

Seizure is a common acute and severe disease in infants and children. Recurrent seizures or persistent seizures may cause irreversible brain damage. Mitogen activated protein kinase (MAPK) signaling pathway is associated with an inflammatory response, however it's involvement in the pathological process of seizures is not clear. Histone deacetylase inhibitors (HDACi) have promising neuroprotective effects through epigenetic regulation. Therefore, this study aimed to investigate the mechanism of HDACi MS275 on p38 MAPK signaling pathway and p38 histone modifications in developing rats post-seizure. Intraperitoneal administration of Pentylenetetrazole (PTZ) was used to induce developing rat seizures, and MS275 (5 or 10 mg/kg) was injected intraperitoneally 2 h before PTZ injection. Hippocampal tissues were sampled at 24 h post-seizures for protein and mRNA levels of p38、MK2、CREB and IL-6. Neuronal apoptosis and microglia activation significantly increased after PTZ treatment. However, pretreatment with MS275 attenuated these effects as well as increased seizure latency and decreased seizure scores. Furthermore, MS275 was found to inhibit the expression of p38 by increasing histone H3 and H4 acetylation and decreasing histone H3 and H4 methylation. This study thereby demonstrates that HDACi MS275 can reduce the inflammatory response associated with seizure-induced brain injury through inhibiting the p38 MAPK signaling pathway and p38 gene expression.