Neurochemical Research

Epilepsy is a common neurological disease. The dysregulated long noncoding RNAs (lncRNAs) are implicated in epileptogenesis. The aim of this research is to explore the role and mechanism of lncRNA zinc finger antisense 1 (ZFAS1) in status epilepticus (SE)-induced hippocampal neurons injury. SE mice model was established and primary hippocampal neurons were isolated. The expression levels of ZFAS1 and microRNA-421 (miR-421) were detected in hippocampus and hippocampal neurons via quantitative reverse transcription polymerase chain reaction. Hippocampal neurons viability, apoptosis and autophagy were analyzed via Cell Counting Kit-8, flow cytometry and western blot. The target relationship between ZFAS1 and miR-421 was analyzed via dual-luciferase reporter assay. The phosphoinositide 3-kinase (PI3K)/protein kinase B (AKT) pathway was blocked by LY294002 and related protein levels were detected via western blot. ZFAS1 expression was elevated in hippocampus and hippocampal neurons from SE mice. Knockdown of ZFAS1 increased SE hippocampal neurons viability and decreased apoptosis and autophagy. ZFAS1 could sponge miR-421. MiR-421 expression was declined in SE mice tissues and cells. Down-regulation of miR-421 abolished the suppressive effect of ZFAS1 knockdown on hippocampal neurons apoptosis and autophagy. Silencing of ZFAS1 induced activation of the PI3K/AKT pathway by up-regulating miR-421. Inhibition of the PI3K/AKT pathway reversed the effect of ZFAS1 knockdown on SE hippocampal neurons apoptosis and autophagy. Interference of ZFAS1 attenuated hippocampal neurons apoptosis and autophagy in SE by increasing miR-421 and activating the PI3K/AKT pathway, indicating a new mechanism for understanding the pathogenesis of SE.

We have demonstrated that the β nerve growth factor will interact with various acidic proteins apparently nonspecifically. When125I-labeled β nerve growth factor at a concentration of 3.8×10−10 M is incubated with an acidic protein at 2 mg/ml (4.5×10−6–4.4×10−5 M), a complex is formed. This complex changes the isoelectric point of the125I-labeled β nerve growth factor sufficiently so that the125I-labeled β nerve growth factor migrates anomalously in polyacrylamide gel electrophoresis. The interaction between β nerve growth factor and bovine serum albumin, which appears to be complex, may be the cause of the previously reported activation of the β nerve growth factor when bovine serum albumin is present in a typical bioassay.

In a previous paper, δ and κ opiate receptors were shown to be co-localized on the same cell in enriched primary cultures of astroglia from neonatal rat cerebral cortex. Activation of the receptors inhibited adenylate cyclase. In this work, the presence of opiate receptors was investigated in astroglial primary cultures from neonatal rat striatum and brain stem. Cyclic adenosine 3′, 5′-monophosphate accumulation was quantified in the presence of different opioid receptor ligands after stimulation of the cyclic adenosine 3′,5′-monophosphate system with forskolin. Morphine was used as a μ receptor agonist. [d-Ala2, D-Leu5]-enkephalin or[d-Pen2,d-Pen5]-enkephalin were used as δ receptor agonists and dynorphin 1–13 or U-50,488H were used as κ receptor agonists. Specific antagonists for the respective receptors were used. After striatum or brain stem cultures had been incubated in 10−9–10−5M of each [d-Ala2,d-Leu5]-enkephalin, [d-Pen2, D-Pen5]-enkephalin and Dynorphin 1–13 or U-50,488H, dose related inhibitions of the 10−5M rorskolin stimulated cyclic adenosine 3′,5′-monophosphate accumulation were observed. The changes were reversed to the forskolin-induced control level in the presence of the respective antagonists. 10−9–10−5M morphine did not significantly change the forskolin-induced accumulation of cyclic adenosine 3′,5′-monophosphate in the cultures studied. Furthermore, cultures from cerebral cortex, striatum or brain stem were incubated with isoproterenol alone or together with morphine or [d-Ala2,d-Leu5]-enkephalin. Isoproterenol stimulated cyclic adenosine 3′,5′-monophosphate accumulation more prominently in the cerebral cortex and striatum cultures than in the brain stem cultures. Morphine did not influence isoproterenol-induced cyclic adenosine 3′,5′-monophosphate accumulation, while [d-Ala2,d-Leu5]-enkephalin inhibited the accumulation. The results indicate that astroglial cells in primary cultures from striatum, brain stem and cerebral cortex express δ andk opioid receptors linked to the adenylate cyclase/cyclic adenosine 3′,5′-monophosphate system. No μ receptors were detected, however, in the present model. Aspects of the relation between the expression of opioid peptides and opioid receptors are discussed, while speculations are also made on the functional aspects of opioid receptors on astroglia.

Decursin, purified from Angelica gigas Nakai, has been proven to exert neuroprotective property. Previous study revealed decursin protected the PC12 cells from Aβ25–35-induced oxidative cytotoxicity. The present study aimed to investigate whether decursin could protect PC12 cells from apoptosis caused by Aβ. Our results indicated that pretreatment of PC12 cells with decursin significantly inhibited Aβ25–35-induced cytotoxicity and apoptosis. The mechanism of action is likely to reverse Aβ25–35-induced mitochondrial dysfunction, including the reduction of mitochondrial membrane potential, the inhibition of reactive oxygen species production, and the decrease of mitochondrial release of cytochrome c in PC12 cells. In addition, decursin significantly suppressed the activity of caspase-3 and moderated the ratio of Bcl-2/Bax induced by Aβ25–35. These findings indicate that decursin exerts a neuroprotective effect against Aβ25–35-induced neurotoxicity in PC12 cells, at least in part, via suppressing the mitochondrial pathway of cellular apoptosis.

DNA, RNA, and protein synthesis in mitochondria isolated from cerebral hemispheres, brain stem, and cerebellum of 10- and 30-day-old rats was measured. Synthesis of different macromolecules was affected by the respective mitochondrial specific inhibitors, showing a good level of purity of mitochondrial preparations. DNA and protein synthesis in 10-day-old rats was about 70% higher than in 30-day-old animals. In contrast, RNA synthesis did not decrease with age in all the regions examined.

Xenopus laevis tadpoles undergoing metamorphosis were used to study the turnover of cerebrosides and sulfatides in the nervous system of the frog. Tadpoles at the beginning of metamorphosis were treated by intraperitoneal injection with [U-14C]glucose and radioactivity incorporated into galactosphingolipids of brain and tail was measured after various times. The specific activity of brain cerebrosides increased rapidly for the first 24 hr after injection, reached a plateau after 48hr, and then declined 40% by 7 days. The specific activity of sulfatides changed somewhat more slowly. Hydroxy fatty acid-containing galactosphingolipids had nearly twice the specific activity compared with their nonhydroxy counterparts in brain. Despite the complete regression of tail nerve cord, metabolism of glycosphingolipids in this tissue also indicated active synthesis as well as degradation during this period. The specific activities of these lipids were similar and all reached a peak 24 hr after injection. Examination of the components of these galactosphingolipids disclosed that only a small fraction (7–25%) of the radioactivity was in the galactose moiety in both brain and tail. The ratios of the radioactivity in fatty acid to that in the sphingoid base were much higher for hydroxycerebroside and hydroxysulfatide than for the nonhydroxy isomers.

Repeated audiogenic seizures (4 times a day for 14 days), in genetically selected sensitive mice, induce a significant decrease in GABA level in the following brain areas: nucleus caudatus, posterior colliculus, occipital and frontal cortex, cerebellum, substantia nigra, hippocampus, amygdala, and temporal cortex. No variations were observed in olfactory bulbs, pons medulla, hypothalamus, thalamus, or cochlear area.

We aimed to observe the therapeutic effects of lithium on inhalational anesthetic sevoflurane-induced apoptosis in immature brain hippocampus. From postnatal day 5 (P5) to P28, male Sprague–Dawley pups were intraperitoneally injected with lithium chloride or 0.9 % sodium chloride. On P7 after the injection, pups were exposed to 2.3 % sevoflurane or air for 6 h. Brain tissues were harvested 12 h and 3 weeks after exposure. Cleaved caspase-3, nNOS protein, GSK-3β,p-GSK-3β were assessed by Western blot, and histopathological changes were assessed using Nissl stain and TUNEL stain. From P28, we used the eight-arm radial maze test and step-through test to evaluate the influence of sevoflurane exposure on the learning and memory of juvenile rats. The results showed that neonatal sevoflurane exposure induced caspase-3 activation and histopathological changes in hippocampus can be attenuated by lithium chloride. Sevoflurane increased GSK-3β activity while pretreatment of lithium decreased GSK-3β activity. Moreover, sevoflurane showed possibly slight but temporal influence on the spatial learning and the memory of juvenile rats, and chronic use of lithium chloride might have the therapeutic effect. Our current study suggests that lithium attenuates sevoflurane induced neonatal hippocampual damage by GSK-3β pathway and might improve learning and memory deficits in rats after neonatal exposure.

Developmental changes in three enzymes associated with myelin lipids were studied in the shiverer mouse, a murine mutant showing a severe deficiency of CNS myelin. Age-related changes in cerebroside sulfotransferase (measured in brain) and arylsulfatase A and cerebroside B-galactosidase (measured in brain and liver) were the same for shiverer and control mice. The shiverer mouse, therefore, demonstrates a dissociation between the genetic mechanisms regulating myelination in the CNS and developmental changes in enzyme activities thought to be closely related to the synthesis of myelin. In addition, we found no defect in the shiverer mouse in the incorporation of glycine-labeled basic protein into CNS myelin, indicating an important metabolic difference between the morphologically similar shiverer and quaking mutants.