Maternal separation early in life induces excessive activity of the central amygdala related to abnormal aggression.

Epidemiological studies have indicated that child maltreatment, such as neglect, is a risk factor of escalated aggression, potentially leading to delinquency and violent crime in the future. However, little is known about the mechanisms by which an early adverse environment may later cause violent behavior. In this study, we aimed to thoroughly examine the association between aggression against conspecific animals and the activity of amygdala subnuclei using the maternal separation (MS) model, which is a common model of early life stress. In the MS group, pups of Sprague-Dawley rats were separated from their dam during postnatal days 2-20 (twice a day, 3 h each). We only included 9-week-old male offspring for each analysis and compared the MS group with the mother-reared control group; both groups were raised by the same dam during postnatal days 2-20. The results revealed that the MS group exhibited higher aggression and excessive activity of only the central amygdala (CeA) among the amygdala subnuclei during the aggressive behavior test. Moreover, a significant positive correlation was observed between higher aggression and CeA activation. While CeA activity is known to be involved in hunting behavior for prey, some previous studies have also indicated a relationship between CeA and intraspecific aggression. It remains unclear, however, whether excessive CeA activity directly induces intraspecific aggression. Therefore, we stimulated the CeA using optogenetics with 8-week-old rats to clarify the relationship between intraspecific aggression and CeA activity. Notably, CeA activation resulted in higher aggression, even when the opponent was a conspecific animal. In particular, bilateral CeA activation resulted in more severe displays of aggressive behavior than necessary, such as biting a surrendered opponent. These findings suggest that an adverse environment during early development intensifies aggression through excessive CeA activation, which can increase the risk of escalating to violent behavior in the future.

PLAAT1 deficiency alleviates high-fat diet-induced hepatic lipid accumulation in mice.

The phospholipase A and acyltransferase (PLAAT) family is composed of three isoforms in mice (PLAAT1, 3, and 5), all of which function as phospholipid-metabolizing enzymes exhibiting phospholipase A1 /A2 and acyltransferase activities. Plaat3-deficient (Plaat3-/- ) mice were previously reported to show lean phenotype and remarkable hepatic fat accumulation under high-fat diet (HFD) feeding, while Plaat1-/- mice have not been analyzed. In the present study, we generated Plaat1-/- mice and investigated the effects of PLAAT1 deficiency on HFD-induced obesity, hepatic lipid accumulation, and insulin resistance. After HFD treatment, PLAAT1 deficiency caused a lower body weight gain compared to wild-type mice. Plaat1-/- mice also showed reduced liver weight with negligible hepatic lipid accumulation. In accordance with these findings, PLAAT1 deficiency improved HFD-induced hepatic dysfunction and lipid metabolism disorders. Lipidomics analysis in the liver revealed that in Plaat1-/- mice, the levels of various glycerophospholipids tended to increase, while all classes of lysophospholipids examined tended to decrease, suggesting that PLAAT1 functions as phospholipase A1 /A2 in the liver. Interestingly, the HFD treatment of wild-type mice significantly increased the mRNA level of PLAAT1 in the liver. Furthermore, the deficiency did not appear to elevate the risk of insulin resistance in contrast to PLAAT3 deficiency. These results suggested that the suppression of PLAAT1 improves HFD-induced overweight and concomitant hepatic lipid accumulation.

Genetic and histopathological analysis of spermatogenesis after short-term testicular torsion in rats.

BACKGROUND: Patients with testicular torsion (TT) may exhibit impaired spermatogenesis from reperfusion injury after detorsion surgery. Alteration in the expressions of spermatogenesis-related genes induced by TT have not been fully elucidated. METHODS: Eight-week-old Sprague-Dawley rats were grouped as follows: group 1 (sham-operated), group 2 (TT without reperfusion) and group 3 (TT with reperfusion). TT was induced by rotating the left testis 720° for 1 h. Testicular reperfusion proceeded for 24 h. Histopathological examination, oxidative stress biomarker measurements, RNA sequencing and RT-PCR were performed. RESULTS: Testicular ischemia/reperfusion injury induced marked histopathological changes. Germ cell apoptosis was significantly increased in group 3 compared with group 1 and 2 (mean apoptotic index: 26.22 vs. 0.64 and 0.56; p = 0.024, and p = 0.024, respectively). Johnsen score in group 3 was smaller than that in group 1 and 2 (mean: 8.81 vs 9.45 and 9.47 points/tubule; p = 0.001, p < 0.001, respectively). Testicular ischemia/reperfusion injury significantly upregulated the expression of genes associated with apoptosis and antioxidant enzymes and significantly downregulated the expression of genes associated with spermatogenesis. CONCLUSION: One hour of TT followed by reperfusion injury caused histopathological testicular damage. The relatively high Johnsen score indicated spermatogenesis was maintained. Genes associated with spermatogenesis were downregulated in the TT rat model. IMPACT: How ischemia/reperfusion injury in testicular torsion (TT) affects the expressions of genes associated with spermatogenesis has not been fully elucidated. This is the first study to report comprehensive gene expression profiles using next generation sequencing for an animal model of TT. Our results revealed that ischemia/reperfusion injury downregulated the expression of genes associated with spermatogenesis and sperm function in addition to histopathological damage, even though the duration of ischemia was short.

Impact of hydrogen gas inhalation during therapeutic hypothermia on cerebral hemodynamics and oxygenation in the asphyxiated piglet.

We previously reported the neuroprotective potential of combined hydrogen (H2) gas ventilation therapy and therapeutic hypothermia (TH) by assessing the short-term neurological outcomes and histological findings of 5-day neonatal hypoxic-ischemic (HI) encephalopathy piglets. However, the effects of H2 gas on cerebral circulation and oxygen metabolism and on prognosis were unknown. Here, we used near-infrared time-resolved spectroscopy to compare combined H2 gas ventilation and TH with TH alone. Piglets were divided into three groups: HI insult with normothermia (NT, n = 10), HI insult with hypothermia (TH, 33.5 ± 0.5 °C, n = 8), and HI insult with hypothermia plus H2 ventilation (TH + H2, 2.1-2.7%, n = 8). H2 ventilation and TH were administered and the cerebral blood volume (CBV) and cerebral hemoglobin oxygen saturation (ScO2) were recorded for 24 h after the insult. CBV was significantly higher at 24 h after the insult in the TH + H2 group than in the other groups. ScO2 was significantly lower throughout the 24 h after the insult in the TH + H2 group than in the NT group. In conclusion, combined H2 gas ventilation and TH increased CBV and decreased ScO2, which may reflect elevated cerebral blood flow to meet greater oxygen demand for the surviving neurons, compared with TH alone.

An enriched environment ameliorates the reduction of parvalbumin-positive interneurons in the medial prefrontal cortex caused by maternal separation early in life.

Early child maltreatment, such as child abuse and neglect, is well known to affect the development of social skills. However, the mechanisms by which such an adverse environment interrupts the development of social skills remain unelucidated. Identifying the period and brain regions that are susceptible to adverse environments can lead to appropriate developmental care later in life. We recently reported an excitatory/inhibitory imbalance and low activity during social behavior in the medial prefrontal cortex (mPFC) of the maternal separation (MS) animal model of early life neglect after maturation. Based on these results, in the present study, we investigated how MS disturbs factors related to excitatory and inhibitory neurons in the mPFC until the critical period of mPFC development. Additionally, we evaluated whether the effects of MS could be recovered in an enriched environment after MS exposure. Rat pups were separated from their dams on postnatal days (PDs) 2-20 (twice daily, 3 h each) and compared with the mother-reared control (MRC) group. Gene expression analysis revealed that various factors related to excitatory and inhibitory neurons were transiently disturbed in the mPFC during MS. A similar tendency was found in the sensory cortex; however, decreased parvalbumin (PV) expression persisted until PD 35 only in the mPFC. Moreover, the number of PV+ interneurons decreased in the ventromedial prefrontal cortex (vmPFC) on PD 35 in the MS group. Additionally, perineural net formation surrounding PV+ interneurons, which is an indicator of maturity and critical period closure, was unchanged, indicating that the decreased PV+ interneurons were not simply attributable to developmental delay. This reduction of PV+ interneurons improved to the level observed in the MRC group by the enriched environment from PD 21 after the MS period. These results suggest that an early adverse environment disturbs the development of the mPFC but that these abnormalities allow room for recovery depending on the subsequent environment. Considering that PV+ interneurons in the mPFC play an important role in social skills such as empathy, an early rearing environment is likely a very important factor in the subsequent acquisition of social skills.

Formation of N-acyl-phosphatidylethanolamines by cytosolic phospholipase A2ε in an ex vivo murine model of brain ischemia.

N-Acyl-phosphatidylethanolamines (NAPEs), a minor class of membrane glycerophospholipids, accumulate along with their bioactive metabolites, N-acylethanolamines (NAEs) during ischemia. NAPEs can be formed through N-acylation of phosphatidylethanolamine by cytosolic phospholipase A2ε (cPLA2ε, also known as PLA2G4E) or members of the phospholipase A and acyltransferase (PLAAT) family. However, the enzyme responsible for the NAPE production in brain ischemia has not yet been clarified. Here, we investigated a possible role of cPLA2ε using cPLA2ε-deficient (Pla2g4e-/-) mice. As analyzed with brain homogenates of wild-type mice, the age dependency of Ca2+-dependent NAPE-forming activity showed a bell-shape pattern being the highest at the first week of postnatal life, and the activity was completely abolished in Pla2g4e-/- mice. However, liquid chromatography-tandem mass spectrometry revealed that the NAPE levels of normal brain were similar between wild-type and Pla2g4e-/- mice. In contrast, post-mortal accumulations of NAPEs and most species of NAEs were only observed in decapitated brains of wild-type mice. These results suggested that cPLA2ε is responsible for Ca2+-dependent formation of NAPEs in the brain as well as the accumulation of NAPEs and NAEs during ischemia, while other enzyme(s) appeared to be involved in the maintenance of basal NAPE levels.

Ethanol concentration induces production of 3,4-dihydroxyphenylacetic acid and homovanillic acid in mouse brain through activation of monoamine oxidase pathway.

First, we aimed to investigate ex vivo the effects of ethanol (EtOH) on levels of norepinephrine (NE), dopamine (DA), serotonin (5-HT), and their metabolites in the frontal cortex, hippocampus, and striatum of Aldh2-knockout (Aldh2-KO) and wild-type (WT) mice. Animals were treated intraperitoneally with saline (control) or EtOH (1.0, 2.0, or 3.0 g/kg). Brain samples were collected 60 and 120 min after EtOH injection, and monoamines and their metabolites were measured by HPLC-ECD. We found in both WT and Aldh2-KO mice that 3.0 g/kg EtOH increased the levels of 3,4-dihydroxyphenylacetic acid (DOPAC) and homovanillic acid (HVA) and decreased the level of 3-methoxytyramine (3-MT). A 2.0 g/kg dose of EtOH also increased HVA, but there was not a consistent effect within the brain regions of Aldh2-KO and WT mice. There were inconsistent findings of genotype differences in the levels of DA, 5-HT, and their metabolites in the brain regions tested. None of the EtOH doses altered NE, DA, 5-HT, or 5-hydroxyindoleacetic acid contents in any of the brain regions studied. Second, we tested whether EtOH-induced increases in DOPAC and HVA are mediated by increased monoamine oxidase (MAO) or catechol-O-methyltransferase (COMT) activity. To test this, we used the MAO blocker clorgyline (2.0 and 4.0 mg/kg) and the COMT blocker tolcapone (15 and 30 mg/kg) alone or in combination with EtOH (3.0 g/kg). Clorgyline alone increased 3-MT and decreased DOPAC and HVA levels, whereas tolcapone alone increased DOPAC and decreased 3-MT and HVA levels. Surprisingly, the combination of EtOH with clorgyline (4.0 mg/kg) or tolcapone (30 mg/kg) further decreased 3-MT and increased DOPAC and HVA levels, an effect that reversed the inhibitor-induced decreases in HVA. These results suggest that a high concentration of EtOH can accelerate DA metabolism, as evidenced by the increase in DOPAC and HVA, and this effect is likely a consequence of increased degradation of DA by MAO.

Brain-derived neurotrophic factor predominantly regulates the expression of synapse-related genes in the striatum: Insights from in vitro transcriptomics.

AIM: The striatum, a main component of the basal ganglia, is a critical part of the motor and reward systems of the brain. It consists of GABAergic and cholinergic neurons and receives projections of dopaminergic, glutamatergic, and serotonergic neurons from other brain regions. Brain-derived neurotrophic factor (BDNF) plays multiple roles in the central nervous system, and striatal BDNF has been suggested to be involved in psychiatric and neurodegenerative disorders. However, the transcriptomic impact of BDNF on the striatum remains largely unknown. In the present study, we performed transcriptomic profiling of striatal cells stimulated with BDNF to identify enriched gene sets (GSs) and their novel target genes in vitro. METHODS: We carried out RNA sequencing (RNA-Seq) of messenger RNA extracted from primary dissociated cultures of rat striatum stimulated with BDNF and conducted Generally Applicable Gene-set Enrichment (GAGE) analysis on 10599 genes. Significant differentially expressed genes (DEGs) were determined by differential expression analysis for sequence count data 2 (DESeq2). RESULTS: GAGE analysis identified significantly enriched GSs that included GSs related to regulation and dysregulation of synaptic functions, such as synaptic vesicle cycle and addiction to nicotine and morphine, respectively. It also detected GSs related to various types of synapses, including not only GABAergic and cholinergic synapses but also dopaminergic and glutamatergic synapses. DESeq2 revealed 72 significant DEGs, among which the highest significance was observed in the apolipoprotein L domain containing 1 (Apold1). CONCLUSIONS: The present study indicates that BDNF predominantly regulates the expression of synaptic-function-related genes and that BDNF promotes synaptogenesis in various subtypes of neurons in the developing striatum. Apold1 may represent a unique target gene of BDNF in the striatum.

Concomitant attenuation of HMGCR expression and activity enhances the growth inhibitory effect of atorvastatin on TGF-ß-treated epithelial cancer cells.

Epithelial-mesenchymal transition (EMT) in primary tumor cells is a key prerequisite for metastasis initiation. Statins, cholesterol-lowering drugs, can delay metastasis formation in vivo and attenuate the growth and proliferation of tumor cells in vitro. The latter effect is stronger in tumor cells with a mesenchymal-like phenotype than in those with an epithelial one. However, the effect of statins on epithelial cancer cells treated with EMT-inducing growth factors such as transforming growth factor-ß (TGF-ß) remains unclear. Here, we examined the effect of atorvastatin on two epithelial cancer cell lines following TGF-ß treatment. Atorvastatin-induced growth inhibition was stronger in TGF-ß-treated cells than in cells not thusly treated. Moreover, treatment of cells with atorvastatin prior to TGF-ß treatment enhanced this effect, which was further potentiated by the simultaneous reduction in the expression of the statin target enzyme, 3-hydroxy-3-methylglutaryl coenzyme A reductase (HMGCR). Dual pharmacological targeting of HMGCR can thus strongly inhibit the growth and proliferation of epithelial cancer cells treated with TGF-ß and may also improve statin therapy-mediated attenuation of metastasis formation in vivo.

Meganuclease-Based Artificial Transcription Factors.

Embedding middle-scale artificial gene networks in live mammalian cells is one of the most important future goals for cell engineering. However, the applications of the highly orthogonal and conventional artificial transcription factors currently available are limited. In this study, we present a scalable pipeline to produce artificial transcription factors based on homing endonucleases, also known as meganucleases. The introduction of mutations at critical sites for nuclease activity renders these homing endonucleases a simple but highly specific DNA binding domain for their specific DNA target. The introduction of inactivated meganucleases linked to transcriptional activator domains strongly induced reporter gene expression, while their fusion to transcriptional repressor domains suppressed them. In addition, we show that inactivated meganuclease-based transcription factors could be embedded in the synthetic membrane receptor synNotch and used to construct synthetic circuits. These results suggest that inactivated meganucleases are useful DNA-binding domains for the construction of synthetic transcription factors in mammalian cells.

Repeated maternal separation causes transient reduction in BDNF expression in the medial prefrontal cortex during early brain development, affecting inhibitory neuron development.

It is widely accepted that maternal separation (MS) induces stress in children and disrupts neural circuit formation during early brain development. Even though such disruption occurs transiently early in life, its influence persists after maturation, and could lead to various neurodevelopmental disorders. Our recent study revealed that repeated MS reduces the number of inhibitory neurons and synapses in the medial prefrontal cortex (mPFC) and causes mPFC-related social deficits after maturation. However, how MS impedes mPFC development during early brain development remains poorly understood. Here, we focused on brain-derived neurotrophic factor (BDNF) involved in the development of inhibitory neurons, and examined time-dependent BDNF expression in the mPFC during the pre-weaning period in male rats exposed to MS. Our results show that MS attenuates BDNF expression only around the end of the first postnatal week. Likewise, mRNA expression of activity-regulated cytoskeleton-associated protein (Arc), an immediate-early gene whose expression is partly regulated by BDNF, also decreased in the MS group along with the reduction in BDNF expression. On the contrary, mRNA expression of tropomyosin-related kinase B (TrkB), which is a BDNF receptor, was scarcely altered, while its protein expression decreased in the MS group only during the weaning period. In addition, MS reduced mRNA levels of glutamic acid decarboxylase (GAD) 65, a GABA synthesizing enzyme, only during the weaning period. Our results suggest that repeated MS temporarily attenuates BDNF signaling in the mPFC during early brain development. BDNF plays a crucial role in the development of inhibitory neurons; therefore, transient attenuation of BDNF signaling may cause delays in GABAergic neuron development in the mPFC.

Vexin is upregulated in cerebral cortical neurons by brain-derived neurotrophic factor.

AIM: Chromosome 8 open reading frame 46 (C8orf46), a human protein-coding gene, has recently been named Vexin. A recent study indicated that Vexin is involved in embryonic neurogenesis. Additionally, some transcriptomic studies detected changes in the mRNA levels of patients with psychiatric and neurological diseases. In our previous study, we sought for target genes of brain-derived neurotrophic factor (BDNF) in cultured rat cortical neurons, finding that BDNF potentially leads to the upregulation of Vexin mRNA. However, its underlying mechanisms are unknown. In the present study, we assessed the regulatory mechanisms of the BDNF-induced gene expression of Vexin in vitro. METHODS: We reanalyzed ChIP-seq data in various human organs provided by the ENCODE project, evaluating acetylation levels of the 27th lysine residue of the histone H3 (H3K27ac) at the Vexin locus. The transcriptomic effects of BDNF on rat Vexin (RGD1561849) were evaluated by real-time quantitative PCR (RT-qPCR) in primary cultures of cerebral cortical neurons, in the presence or absence of inhibitors for signaling molecules activated by BDNF. RESULTS: The Vexin locus and its promoter region in the brain angular gyrus show higher acetylation levels of the H3K27 than those in other organs. Stimulation of cultured rat cortical neurons, but not astrocyte, with BDNF, led to marked elevations in the mRNA levels of Vexin, which was inhibited in the presence of K252a and U0126. CONCLUSION: The upregulated H3K27ac in the brain may be associated with the enriched gene expression of Vexin in the brain. It is indicated that BDNF induces the gene expression of Vexin in the cortical neurons via the TrkB-MEK signaling pathway.

The effects of early life stress on the excitatory/inhibitory balance of the medial prefrontal cortex.

Aversive environmental conditions during early life are known to cause long-lasting social deficits, similar to those observed in patients with neurodevelopmental disorders. However, the mechanism of how early life stress can cause social deficits is not well understood. To clarify how being in an aversive environment during development affects sociability, we conducted various analyses focusing on the excitatory and inhibitory (E/I) balance in the medial prefrontal cortex (mPFC) and how it is related to social deficits, with young adult male rats that had been exposed to maternal separation (MS). In our MS procedure, part of the pups were separated from each dam for 3 h, twice a day, during postnatal days 2-20, and then were used for each analysis at 9 weeks old. We identified that MS mainly reduced pre- and post-synaptic protein expression of inhibitory neurons in the mPFC, and that decreased the number of GAD67-positive interneurons and inhibitory synapses in the mPFC. Furthermore, MS impaired social behavior related to social recognition, which is closely linked to the mPFC, in the three-chamber sociability and social novelty test (3-CST). With relation to this social deficit, immunohistological analysis revealed that c-fos-positive cells in the mPFC of rats exposed to MS decreased during the 3-CST. Considering that inhibitory neurons in the mPFC play a role in synchronizing neural activation for information processing, our findings demonstrate that MS-induced E/I imbalance associated with cell activity in the mPFC leads to deficits in social recognition.

Corticotropin-releasing hormone-binding protein is up-regulated by brain-derived neurotrophic factor and is secreted in an activity-dependent manner in rat cerebral cortical neurons.

A recent study revealed that corticotropin-releasing hormone (CRH) in the cerebral cortex (CTX) plays a regulatory role in emotional behaviors in rodents. Given the functional interaction between brain-derived neurotrophic factor (BDNF) and the CRH-signaling pathway in the hypothalamic-pituitary-adrenal axis, we hypothesized that BDNF may regulate gene expression of CRH and its related molecules in the CTX. Findings of real-time quantitative PCR (RT-qPCR) indicated that stimulation of cultured rat cortical neurons with BDNF led to marked elevations in the mRNA levels of CRH and CRH-binding protein (CRH-BP). The BDNF-induced up-regulation of CRH-BP mRNA was attenuated by inhibitors of tropomyosin related kinase (Trk) and MEK, but not by an inhibitor for PI3K and Phospholipase C gamma (PLCγ). The up-regulation was partially blocked by an inhibitor of lysine-specific demethylase (KDM) 6B. Fluorescent imaging identified the vesicular pattern of pH-sensitive green fluorescent protein-fused CRH-BP (CRH-BP-pHluorin), which co-localized with mCherry-tagged BDNF in cortical neurons. In addition, live-cell imaging detected drastic increases of pHluorin fluorescence in neurites upon membrane depolarization. Finally, we confirmed that tetrodotoxin partially attenuated the BDNF-induced up-regulation of CRH-BP mRNA, but not that of the protein. These observations indicate the following: In cortical neurons, BDNF led to gene expression of CRH-BP and CRH. TrkB, MEK, presumably ERK, and KDM6B are involved in the BDNF-induced gene expression of CRH-BP, and BDNF is able to induce the up-regulation in a neuronal activity-independent manner. It is suggested that CRH-BP is stored into BDNF-containing secretory granules in cortical neurons, and is secreted in response to membrane depolarization.

Prolonged maternal separation attenuates BDNF-ERK signaling correlated with spine formation in the hippocampus during early brain development.

Maternal separation (MS) is known to affect hippocampal function such as learning and memory, yet the molecular mechanism remains unknown. We hypothesized that these impairments are attributed to abnormities of neural circuit formation by MS, and focused on brain-derived neurotrophic factor (BDNF) as key factor because BDNF signaling has an essential role in synapse formation during early brain development. Using rat offspring exposed to MS for 6 h/day during postnatal days (PD) 2-20, we estimated BDNF signaling in the hippocampus during brain development. Our results show that MS attenuated BDNF expression and activation of extracellular signal-regulated kinase (ERK) around PD 7. Moreover, plasticity-related immediate early genes, which are transcriptionally regulated by BDNF-ERK signaling, were also reduced by MS around PD 7. Interestingly, detailed analysis revealed that MS particularly reduced expression of BDNF gene and immediate early genes in the cornu ammonis 1 (CA1) of hippocampus at PD 7. Considering that BDNF-ERK signaling is involved in spine formation, we next evaluated spine formation in the hippocampus during the weaning period. Our results show that MS particularly reduced mature spine density in proximal apical dendrites of CA1 pyramidal neurons at PD 21. These results suggest that MS could attenuate BDNF-ERK signaling during primary synaptogenesis with a region-specific manner, which is likely to lead to decreased spine formation and maturation observed in the hippocampal CA1 region. It is speculated that this incomplete spine formation during early brain development has an influence on learning capabilities throughout adulthood.

Functional interaction between BDNF and mGluR II in vitro: BDNF down-regulated mGluR II gene expression and an mGluR II agonist enhanced BDNF-induced BDNF gene expression in rat cerebral cortical neurons.

Accumulating evidence suggests functional interaction between brain-derived neurotrophic factor (BDNF) and metabotropic glutamate receptor (mGluR) signaling pathways in the central nervous system (CNS). To date, eight subtypes of mGluRs, mGluR1-8, have been identified, and a previous study suggested that BDNF leads to down-regulation of GluR2 mRNA in rat cerebral cortical cultures. However, precise transcriptomic effects of BDNF on other mGluRs and their cellular significance on the BDNF signaling pathway remain largely unknown. In this study, we assessed the transcriptomic effects of BDNF on mGluR1-8 in primary cultures of rat cerebral cortical neurons, and transcriptomic impacts of mGluR(s) whose expression is regulated by BDNF, on BDNF target genes. Real-time quantitative PCR (RT-qPCR) revealed that stimulation of the cultures with 100ng/mL BDNF led to marked reductions not only in the gene expression levels of mGluR2, but also in those of mGluR3, both of which belong to group II mGluRs (mGluR II). There were, on the other hand, no changes in the amounts of mGluR I (mGluR1 and 5) and III (mGluR4, 6, 7, and 8) mRNA. Further, 10ng/mL of BDNF, which mainly activates the high-affinity BDNF receptor, TrkB, but not the low-affinity receptor, p75NTR, was able to induce down-regulation of mGluR II mRNA. The BDNF-induced suppression of mGluR II was not significantly attenuated in the presence of tetrodotoxin (TTX), a blocker for voltage-gated sodium channels. In addition, on stimulation with BDNF (100ng/mL), no significant down-regulation of mGluR II mRNA was seen in cultured astrocytes, which only express the truncated form of TrkB. Finally, we assessed the transcriptomic effect of mGluR II on the expressions of BDNF target genes, BDNF and activity-regulated cytoskeleton-associated protein (Arc). LY404039, an mGluR II agonist, enhanced the BDNF-induced up-regulation of BDNF, but not Arc. On the other hand, LY341495, an mGluR II antagonist, down-regulated BDNF mRNA levels. Collectively, these observations demonstrated the detailed functional interaction between BDNF and mGluR II: Activation of mGluR II positively regulates self-induced BDNF expression, and, in turn, BDNF negatively regulates the gene expression of mGluR II in a neuronal activity-independent manner, in cortical neurons, but not in astrocytes.

A unique pattern of bisphenol a effects on nerve growth factor gene expression in embryonic mouse hypothalamic cell line N-44.

We investigated the toxicity of bisphenol A (BPA) by determining the gene expression of nerve growth factor (Ngf in the embryonic mouse cell line mHypoE-N44 derived from the hypothalamus exposed to BPA dose range between 0.02 and 200 µmol L-1 for 3 h. Ngf mRNA levels decreased in a dose-dependent manner, with significant reductions observed in the 2 to 50 µmol L-1 BPA treatment groups compared to controls. However, at 100 to 200 µmol L-1 the NgfmRNA gradually increased and was significantly higher than control, while the expression of the apoptosis-related genes Caspase 3 and transformation-related protein 73 decreased significantly. These results suggest that in an embryonic hypothalamic cell line the higher doses of BPA induce a unique pattern of Ngf gene expression and that BPA has the potential to suppress apoptosis essential for early-stage brain development.

Development of an artificial calcium-dependent transcription factor to detect sustained intracellular calcium elevation.

The development of a synthetic transcription factor that responds to intracellular calcium signals enables analyzing cellular events at the single-cell level or "rewiring" the intracellular information networks. In this study, we developed the calcium-dependent transcription factor (CaTF), which was cleaved by calpain and then translocated to the nuclei where it induced reporter expression. Our results demonstrated that CaTF-mediated reporter expression was stable and responded to the intracellular calcium level and calpain activity. In addition, CaTF detected the sustained calcium increase that was induced by physiological stimulation with epidermal growth factor (EGF). These results suggest that CaTF could be a useful tool to analyze intracellular calcium signals and be an interface between an endogenous signal network and synthetic gene network.

Early postnatal repeated maternal deprivation causes a transient increase in OMpg and BDNF in rat cerebellum suggesting precocious myelination.

Repetitive maternal deprivation (MD) of neonatal rats during early life is known as one of the strongest stressors to pre-weaned animals. There is increasing evidence that the cerebellum is involved in cognition and emotion. In the present study, we examined how neurotrophic factors and myelin-associated molecules and their receptors (NGF, BDNF, OMgp, TrkA, TrkB, p75 NTR, and NgR) in the cerebellum are affected by early postnatal maternal separation. Rat pups were separated from their mothers for 3h/day during postnatal days (PND) 10-15. At PND 16 and 30, the levels of mRNA and protein in the cerebellum were determined using real-time PCR and Western blot analysis. Cerebellar mRNA and protein levels of BDNF, TrkB, and OMgp were significantly increased in MD rats at PND 16. However, by PND 30 these variables normalized to control levels. In contrast, the levels of mRNA and protein for NGF, TrkA, p75 NTR, and NgR were unchanged at both ages examined. Transient enhancement of neurotrophic system and myelin-associated molecule expression may cause interference of normal development of the cerebellum such as precocious myelination, which may lead to functional and cognitive deficits later in life.

Prolonged maternal separation disturbs the serotonergic system during early brain development.

Early life stress interrupts brain development through the disturbance of various neurotransmitter and neurotrophic factor activities, but the details remain unclear. In the current study, we focused on the serotonergic system, which plays a critical role in brain development, and examined the time-dependent influence of prolonged maternal separation on male Sprague-Dawley rats. The rats were separated from their dams for 3h twice-daily during postnatal days (PDs) 2-20. The influence of prolonged maternal separation was analyzed on PDs 7, 14, 21, and 28 using HPLC to assess concentrations of serotonin and 5-hydroxyindoleacetic acid and using real-time RT-PCR to measure mRNA expression of the serotonin 1A and 2A receptors in various brain regions. HPLC revealed imbalance between serotonin and 5-hydroxyindoleacetic acid in midbrain raphe nuclei, the amygdala, the hippocampus, and the medial prefrontal cortex (mPFC) on PDs 7 and 14. Furthermore, real-time RT-PCR showed attenuation of mRNA expression of the serotonin 1A receptor in the hippocampus and the mPFC and of the serotonin 2A receptor only in the mPFC on PDs 7 and 14. The observed alterations returned to control levels after maternal separation ended. These findings suggest that the early life stress of prolonged maternal separation disturbs the serotonergic system during a crucial period of brain development, which might in part be responsible for emotional abnormalities later in life.