Neurogenic Interventions for Fear Memory via Modulation of the Hippocampal Function and Neural Circuits.

Fear memory helps animals and humans avoid harm from certain stimuli and coordinate adaptive behavior. However, excessive consolidation of fear memory, caused by the dysfunction of cellular mechanisms and neural circuits in the brain, is responsible for post-traumatic stress disorder and anxiety-related disorders. Dysregulation of specific brain regions and neural circuits, particularly the hippocampus, amygdala, and medial prefrontal cortex, have been demonstrated in patients with these disorders. These regions are involved in learning, memory, consolidation, and extinction. These are also the brain regions where new neurons are generated and are crucial for memory formation and integration. Therefore, these three brain regions and neural circuits have contributed greatly to studies on neural plasticity and structural remodeling in patients with psychiatric disorders. In this review, we provide an understanding of fear memory and its underlying cellular mechanisms and describe how neural circuits are involved in fear memory. Additionally, we discuss therapeutic interventions for these disorders based on their proneurogenic efficacy and the neural circuits involved in fear memory.

Learning, memory deficits, and impaired neuronal maturation attributed to acrylamide.

Acrylamide (ACR) is a neurotoxin known to produce neurotoxicity characterized by ataxia, skeletal muscle weakness, cognitive impairment, and numbness of the extremities. Previously, investigators reported that high-dose (50 mg/kg) ACR impaired hippocampal neurogenesis and increased neural progenitor cell death; however, the influence of subchronic environmentally relevant low dose-(2, 20, or 200 µg/kg) ACRs have not been examined in adult neurogenesis or cognitive function in mice. Accordingly, the aim of the present study was to investigate whether low-dose ACR adversely affected mouse hippocampal neurogenesis and neurocognitive functions. Male C57BL/6 mice were orally administered vehicle or ACR at 2, 20, or 200 µg/kg/day for 4 weeks. ACR did not significantly alter the number of newly generated cells or produce neuroinflammation or neuronal loss in hippocampi. However, behavioral studies revealed that 200 µg/kg ACR produced learning and memory impairment. Furthermore, incubation of ACR with primary cultured neurons during the developmental stage was found to delay neuronal maturation without affecting cell viability indicating the presence of developmental neurotoxicity. These findings indicate that although exposure to in vivo low-dose ACR daily for 4 weeks exerted no apparent marked effect on hippocampal neurogenesis, in vitro observations in primary cultured neurons noted adverse effects on learning and memory impairment suggestive of neurotoxic actions.

Enhancement of neuroprotective activity of Sagunja-tang by fermentation with lactobacillus strains.

BACKGROUND: Sagunja-tang (SGT) is widely used in traditional herbal medicine to treat immune system and gastrointestinal disorders and reportedly has protective effects against inflammation, cancer, and osteoporosis. In this study, we fermented SGT with different Latobacillus strains and investigated the change in phytochemical compositions in SGT and enhancement of it neuroprotective effects in SH-SY5Y human neuroblastoma. METHODS: Marker components, including ginsenoside Rg1, glycyrrhizin, liquiritin, liquiritigenin, atractylenolide I, atractylenolide II, atractylenolide III, and pachymic acid, in SGT, were qualitatively and quantitatively analyzed using high-performance liquid chromatography-diode array detection and liquid chromatography-mass spectrometry. SGT was fermented with eight different Lactobacillus strains to yield eight fermented SGTs (FSGTs). The conversion efficiencies of SGT marker components were determined in each FSGT. To detect the protective effect of SGT and FSGT, reactive oxygen species (ROS) assay and mitochondrial membrane potentials (MMPs) assay were performed in SH-SY5Y cells. RESULTS: Compared with the other FSGTs, SGT166, i.e., SGT fermented with L. plantarum 166, had high conversion efficiency, as indicated by increased amounts of glycyrrhizin, liquiritigenin, and atractylenolides I-III. In SH-SY5Y cells, protection against cell death induced by H2O2 and etoposide was high using SGT166 and very low using SGT. Furthermore, ROS production and mitochondrial membrane potential disruption in SH-SY5Y cells were markedly suppressed by SGT166 treatment, which demonstrated that inhibition of ROS generation may be one of the neuroprotective mechanisms of SGT166. CONCLUSIONS: This study demonstrated that fermentation of SGT with L. plantarum 166 enhanced suppression of oxidative stress and MMP loss. This enhanced neuroprotective effect was thought to be caused by the conversion of SGT phytochemicals by fermentation. SGT166 shows potential for treating neurological damage-related diseases.

The mitochondrial uncoupler DNP triggers brain cell mTOR signaling network reprogramming and CREB pathway up-regulation.

Mitochondrial metabolism is highly responsive to nutrient availability and ongoing activity in neuronal circuits. The molecular mechanisms by which brain cells respond to an increase in cellular energy expenditure are largely unknown. Mild mitochondrial uncoupling enhances cellular energy expenditure in mitochondria and can be induced with 2,4-dinitrophenol (DNP), a proton ionophore previously used for weight loss. We found that DNP treatment reduces mitochondrial membrane potential, increases intracellular Ca(2+) levels and reduces oxidative stress in cerebral cortical neurons. Gene expression profiling of the cerebral cortex of DNP-treated mice revealed reprogramming of signaling cascades that included suppression of the mammalian target of rapamycin (mTOR) and insulin--PI3K - MAPK pathways, and up-regulation of tuberous sclerosis complex 2, a negative regulator of mTOR. Genes encoding proteins involved in autophagy processes were up-regulated in response to DNP. CREB (cAMP-response element-binding protein) signaling, Arc and brain-derived neurotrophic factor, which play important roles in synaptic plasticity and adaptive cellular stress responses, were up-regulated in response to DNP, and DNP-treated mice exhibited improved performance in a test of learning and memory. Immunoblot analysis verified that key DNP-induced changes in gene expression resulted in corresponding changes at the protein level. Our findings suggest that mild mitochondrial uncoupling triggers an integrated signaling response in brain cells characterized by reprogramming of mTOR and insulin signaling, and up-regulation of pathways involved in adaptive stress responses, molecular waste disposal, and synaptic plasticity. Physiological bioenergetic challenges such as exercise and fasting can enhance neuroplasticity and protect neurons against injury and neurodegeneration. Here, we show that the mitochondrial uncoupling agent 2,4-dinitrophenol (DNP) elicits adaptive signaling responses in the cerebral cortex involving activation of Ca(2+) -CREB and autophagy pathways, and inhibition of mTOR and insulin signaling pathways. The molecular reprogramming induced by DNP, which is similar to that of exercise and fasting, is associated with improved learning and memory, suggesting potential therapeutic applications for DNP.

Silibinin prevents dopaminergic neuronal loss in a mouse model of Parkinson's disease via mitochondrial stabilization.

Parkinson's disease (PD) is a progressive neurodegenerative disease characterized by the selective loss of dopaminergic neurons in the nigrostriatal pathway. The lipophile 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP) can cross the blood-brain barrier and is subsequently metabolized into toxic1-methyl-4-phenylpyridine (MPP(+) ), which causes mitochondrial dysfunction and the selective cell death of dopaminergic neurons. The present article reports the neuroprotective effects of silibinin in a murine MPTP model of PD. The flavonoid silibinin is the major active constituent of silymarin, an extract of milk thistle seeds, and is known to have hepatoprotective, anticancer, antioxidative, and neuroprotective effects. In the present study, silibinin effectively attenuated motor deficit and dopaminergic neuronal loss caused by MPTP. Furthermore, in vitro study confirmed that silibinin protects primary cultured neurons against MPP(+) -induced cell death and mitochondrial membrane disruption. The findings of the present study indicate that silibinin has neuroprotective effects in MPTP-induced models of PD rather than antioxidative or anti-inflammatory effects and that the neuroprotection afforded might be mediated by the stabilization of mitochondrial membrane potential. Furthermore, these findings suggest that silibinin protects mitochondria in MPTP-induced PD models and that it offers a starting point for the development of treatments that ameliorate the symptoms of PD.

Neuroprotective effects of Liriope platyphylla extract against hydrogen peroxide-induced cytotoxicity in human neuroblastoma SH-SY5Y cells.

BACKGROUND: Oxidative stress is involved in neuronal cell death and mitochondrial dysfunction in neurodegenerative diseases. Liriope platyphylla (LP) has been suggested to have anti-inflammation, anti-bacterial, and anti-cancer effects. However, whether LP exerts neuroprotective effects on neuronal cells is unknown. METHODS: The present study was performed to investigate the neuroprotective effects of LP extract (LPE) against hydrogen peroxide (H2O2)-induced injury in human neuroblastoma cells SH-SY5Y. To test neuroprotective effects of LPE, we performed cell viability assay, flow cytometry analysis and western blot analysis. In addition, mitochondrial membrane potential (MMP) and oxidative stress were performed to evaluate the anti-apoptotic and anti-oxidant effects. RESULTS: LPE pretreatment conferred significant protection against the H2O2-induced decrease of SH-SY5Y cell viability. H2O2-induced increases of intracellular oxidative stress and mitochondrial dysfunction were attenuated by LPE pretreatment. Therefore, LPE pretreatment prevented SH-SY5Y cell injury. Treatment with H2O2 significantly induced poly(ADP ribose) polymerase (PARP) and caspase-3 cleavage, which was blocked by LPE. We found that p38 activation was involved in the neuroprotective effects of LPE. CONCLUSIONS: Current findings suggest that LPE exerts neuroprotective effects against H2O2-induced apoptotic cell death by modulating p38 activation in SH-SY5Y cells. Therefore, LPE has potential anti-apoptotic effects that may be neuroprotective in neurodegenerative diseases and aging-related dementia.

Baicalein attenuates astroglial activation in the 1-methyl-4-phenyl-1,2,3,4-tetrahydropyridine-induced Parkinson's disease model by downregulating the activations of nuclear factor-κB, ERK, and JNK.

In Parkinson's disease (PD), neuroinflammation plays a critical role in the neurodegenerative process. Furthermore, activated microglia and astrocytes, responsible for activated immune response in the central nervous system, are found in regions associated with dopaminergic neuronal death. The flavonoid baicalein is known to have antibacterial, antiviral, and antiinflammatory activities. In the present study, the neuroprotective effects of baicalein were examined in a murine 1-methyl-4-phenyl-1,2,3,4-tetrahydropyridine (MPTP) model of PD. Low doses of baicalein improved motor ability and prevented dopaminergic neuron loss caused by MPTP. In addition, microglial and astrocyte activations were reduced in PD mice pretreated with baicalein. Further study of primary astrocytes revealed that baicalein suppressed the 1-methyl-4-phenylpyridine-induced nuclear translocation of nuclear factor-κB and reduced the activations of JNK and ERK, suggesting that the neuroprotective effects of baicalein in our PD model were due to attenuated astrocyte activation. The findings of this study indicate that baicalein could be useful for the treatment of PD and other neuroinflammation-related neurodegenerative diseases.

Antiseizure effects of Lilii Bulbus on pentylenetetrazol kindling-induced seizures in mice: Involvement of Reelin, Netrin-1, and semaphorin.

Lilii Bulbus (Lilium lancifolium Thunberg) has a proneurogenic effect on the hippocampus. However, its effects on epilepsy and associated pathological features remain unknown. In this study, we investigated the antiseizure effects of a water extract of Lilii Bulbus (WELB) in mouse model of pentylenetetrazol (PTZ)-induced seizure. Mice were injected with PTZ once every 48 h until full kindling was achieved. WELB (100 and 500 mg/kg) was orally administered once daily before PTZ administration and during the kindling process. We found that WELB treatment protected against PTZ-induced low seizure thresholds and high seizure severity. Further, WELB-treated mice showed attenuated PTZ kindling-induced anxiety and memory impairment. Immunostaining and immunoblots showed that hyperactivation and ectopic migration of dentate granule cells (DGCs) were significantly reduced by WELB treatment in PTZ kindling-induced seizure mice. Staining for mossy fiber sprouting (MFS) using Timm staining and ZnT3 showed that WELB treatment significantly decreased PTZ kindling-induced MFS. Furthermore, the increased or decreased expression of proteins related to ectopic DGCs (Reelin and Dab-1), MFS (Netrin-1, Sema3A, and Sema3F), and their downstream effectors (ERK, AKT, and CREB) in the hippocampus of PTZ kindling mice was significantly restored by WELB treatment. Overall, our findings suggest that WELB is a potential antiseizure drug that acts by reducing ectopic DGCs and MFS and modulating epileptogenesis-related signaling in the hippocampus.

Hominis Placenta modulates PTSD-like behaviors in SPSS-induced PTSD mice: Regulating energy metabolism and neuronal activity.

The symptoms of post-traumatic stress disorder (PTSD) include re-experiencing trauma, avoidance behaviors, negative alterations in cognition and mood. However, the underlying molecular mechanisms are unclear. Dysfunction of hypothalamic-pituitary-adrenal axis (HPA-axis) and dysregulation of glutamatergic and GABAergic systems were shown during PTSD. Therefore, regulating hormonal change or glutamate energy metabolism are considered as a therapeutic approach to alleviate this condition. Herbal medicine may be effective in treating PTSD due to its ability to target multiple underlying mechanisms with various compounds. Hominis placenta (HP) is a traditional medicine widely used in East Asia for various conditions. However, the effect on PTSD has not been clarified. We aimed to investigate the effects of HP treatment in single-prolonged stress with shock (SPSS)-induced PTSD mice and explore its possible mechanisms. HP treatment at ST36 acupoints, combined with herbal medicine and acupuncture point stimulation, was applied three times/week for 2 weeks. HP treatment effectively alleviated anxiety and cognitive decline in SPSS-induced PTSD mice, as detected by Open field and the Y-maze test. Additionally, HP decreased the corticosterone levels and proinflammatory cytokines in the serum, modulated brain energy metabolism, and inhibited glutamate excitotoxicity, while regulating neuronal activity through modulating brain-derived neurotrophic factor (BDNF) levels, as demonstrated by western blot and immunohistochemistry, and flow cytometry analyses. These findings reveal that HP treatment effectively alleviates PTSD-like behaviors by regulating energy metabolism and neuronal activity though modulation of the HPA-axis and BDNF levels in PTSD mice, indicating that HP treatment is a promising therapeutic approach for PTSD.

Herbal Formula Extract Ameliorates Anxiety and Cognitive Impairment via Regulation of the Reelin/Dab-1 Pathway in a Murine Model of Post-Traumatic Stress Disorder.

We investigated the effects of epigenetic modifications on post-traumatic stress disorder (PTSD) using a novel combination of herbal medicines from Panax ginseng, Astragalus membranaceus, Atractylodes macrocephala, and Glycyrrhiza uralensis. The herbal formula extract (HFE) (250 mg/kg) was administered orally once daily for 14 days to determine its effects on PTSD in mice by combining prolonged stress and foot shock. The open field and Y-maze tests determined the effect of HFE on PTSD-induced anxiety and cognition. Hippocampal neuronal plastic changes and molecular mechanism were verified. Treatment with HFE decreased anxiety-like behavior and enhanced cognition. Moreover, it reduced the number of PTSD-related hilar ectopic granule cells in the dentate gyrus (DG). PTSD mice showed reduced neuronal plasticity of doublecortin+ cells in the DG, which was restored by HFE treatment. HFE reversed PTSD-induced inhibition of the Reelin/Dab1 pathway, a critical signaling cascade involved in brain development, and regulated Reelin methylation. Furthermore, DNA methylation, methyl-CpG binding protein 2, and DNA methyltransferase 1, which were elevated in the hippocampus of PTSD mice, were restored following HFE treatment. HFE increased the expression of synaptic plasticity-related factors in the hippocampus of PTSD mice. Our findings suggest that HFE can facilitate PTSD treatment by alleviating behavioral abnormalities through the restoration of hippocampal dysfunction via regulation of the Reelin/Dab-1 pathway and DNA methylation in the hippocampus.

Resveratrol inhibits the proliferation of neural progenitor cells and hippocampal neurogenesis.

Resveratrol is a phytoalexin and natural phenol that is present at relatively high concentrations in peanuts and red grapes and wine. Based upon studies of yeast and invertebrate models, it has been proposed that ingestion of resveratrol may also have anti-aging actions in mammals including humans. It has been suggested that resveratrol exerts its beneficial effects on health by activating the same cellular signaling pathways that are activated by dietary energy restriction (DR). Some studies have reported therapeutic actions of resveratrol in animal models of metabolic and neurodegenerative disorders. However, the effects of resveratrol on cell, tissue and organ function in healthy subjects are largely unknown. In the present study, we evaluated the potential effects of resveratrol on the proliferation and survival of neural progenitor cells (NPCs) in culture, and in the hippocampus of healthy young adult mice. Resveratrol reduced the proliferation of cultured mouse multi-potent NPCs, and activated AMP-activated protein kinase (AMPK), in a concentration-dependent manner. Administration of resveratrol to mice (1-10 mg/kg) resulted in activation of AMPK, and reduced the proliferation and survival of NPCs in the dentate gyrus of the hippocampus. Resveratrol down-regulated the levels of the phosphorylated form of cyclic AMP response element-binding protein (pCREB) and brain-derived neurotrophic factor (BDNF) in the hippocampus. Finally, resveratrol-treated mice exhibited deficits in hippocampus-dependent spatial learning and memory. Our findings suggest that resveratrol, unlike DR, adversely affects hippocampal neurogenesis and cognitive function by a mechanism involving activation of AMPK and suppression of CREB and BDNF signaling.

Elevated TRAF2/6 expression in Parkinson's disease is caused by the loss of Parkin E3 ligase activity.

Parkinson's disease (PD) is the second leading neurodegenerative disease, and is known to be induced by environmental factors or genetic mutations. Among the verified genetic mutations of PD, Parkin, isolated from the PARK2 locus, shows an autosomal recessive inheritance pattern and is known to be an E3 ligase. However, the physiological target of Parkin and the molecular mechanism of Parkin-deficiency-induced PD have not been clearly demonstrated until now. It has recently been proposed that inflammation, suggesting as a causal factor for PD, is enhanced by Parkin deficiency. Thus, we examined the relationship between inflammation-related factors and Parkin. Here, we provide the evidence that Parkin suppresses inflammation and cytokine-induced cell death by promoting the proteasomal degradation of TRAF2/6 (TNF-α receptor-associated factor 2/6). Overexpression of Parkin can reduce the half-lives of TRAF2 and TRAF6, whereas si-Parkin can extend them. However, mutant Parkins did not alter the expression of TRAF2/6. Thus, loss of Parkin enhances sensitivity to TNF-α- or IL-1ß-induced JNK activation and NF-κB activation. Indeed, si-Parkin-induced apoptosis is suppressed by the knockdown of TRAF6 or TRAF2. We also observed elevated expression levels of TRAF6 and a reduction of IκB in an 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine-induced PD mouse model. Moreover, elevated expression levels or aggregation of TRAF6 were detected in approximately half of the human PD tissues (7/15 cases) and 2 cases, respectively. In addition, TRAF6 and Parkin expression levels show a reverse relationship in human PD tissues. Our results strongly suggest that the reduction of Parkin or overexpression of TRAF2/6 by chronic inflammation would be the reason for occurrence of PD.

Novel Psychopharmacological Herbs Relieve Behavioral Abnormalities and Hippocampal Dysfunctions in an Animal Model of Post-Traumatic Stress Disorder.

Post-traumatic stress disorder (PTSD) is an anxiety disorder caused by traumatic or frightening events, with intensified anxiety, fear memories, and cognitive impairment caused by a dysfunctional hippocampus. Owing to its complex phenotype, currently prescribed treatments for PTSD are limited. This study investigated the psychopharmacological effects of novel COMBINATION herbal medicines on the hippocampus of a PTSD murine model induced by combining single prolonged stress (SPS) and foot shock (FS). We designed a novel herbal formula extract (HFE) from Chaenomeles sinensis, Glycyrrhiza uralensis, and Atractylodes macrocephala. SPS+FS mice were administered HFE (500 and 1000 mg/kg) once daily for 14 days. The effects of HFE of HFE on the hippocampus were analyzed using behavioral tests, immunostaining, Golgi staining, and Western blotting. HFE alleviated anxiety-like behavior and fear response, improved short-term memory, and restored hippocampal dysfunction, including hippocampal neurogenesis alteration and aberrant migration and hyperactivation of dentate granule cells in SPS+FS mice. HFE increased phosphorylation of the Kv4.2 potassium channel, extracellular signal-regulated kinase, and cAMP response element-binding protein, which were reduced in the hippocampus of SPS+FS mice. Therefore, our study suggests HFE as a potential therapeutic drug for PTSD by improving behavioral impairment and hippocampal dysfunction and regulating Kv4.2 potassium channel-related pathways in the hippocampus.

Electroacupuncture modulates glutamate neurotransmission to alleviate PTSD-like behaviors in a PTSD animal model.

Post-traumatic stress disorder (PTSD) is a mental disorder that develops after exposure to a traumatic event. Owing to the relatively low rates of response and remission with selective serotonin reuptake inhibitors as the primary treatment for PTSD, there is a recognized need for alternative strategies to effectively address the symptoms of PTSD. Dysregulation of glutamatergic neurotransmission plays a critical role in various disorders, including anxiety, depression, PTSD, and Alzheimer's disease. Therefore, the regulation of glutamate levels holds great promise as a therapeutic target for the treatment of mental disorders. Electroacupuncture (EA) has become increasingly popular as a complementary and alternative medicine approach. It maintains the homeostasis of central nervous system (CNS) function and alleviates symptoms associated with anxiety, depression, and insomnia. This study investigated the effects of EA at the GV29 (Yintang) acupoint three times per week for 2 weeks in an animal model of PTSD. PTSD was induced using single prolonged stress/shock (SPSS) in mice, that is, SPS with additional foot shock stimulation. EA treatment significantly reduced PTSD-like behavior and effectively regulated serum corticosterone and serotonin levels in the PTSD model. Additionally, EA treatment decreased glutamate levels and glutamate neurotransmission-related proteins (pNR1 and NR2B) in the hippocampus of a PTSD model. In addition, neuronal activity and the number of Golgi-impregnated dendritic spines were significantly lower in the EA treatment group than in the SPSS group. Notably, EA treatment effectively reduced glutamate-induced excitotoxicity (caspase-3, Bax, and pJNK). These findings suggest that EA treatment at the GV29 acupoint holds promise as a potential therapeutic approach for PTSD, possibly through the regulation of NR2B receptor-mediated glutamate neurotransmission to reduce PTSD-like behaviors.

Pro-neurogenic effects of Lilii Bulbus on hippocampal neurogenesis and memory.

Lilii Bulbus, the bulb of tiger lily, has anti-oxidant and anti-tumorigenic properties. However, the effects of Lilii Bulbus on learning, memory, and hippocampal neurogenesis remain unknown. This study investigated whether water extract of Lilii Bulbus (WELB) affects memory ability and hippocampal neurogenesis. Behavioral analyses (Morris water maze and passive avoidance test), immunohistochemistry, cell proliferation assay, and immunoblot analysis were performed. WELB (50 and 100 mg/kg; for 14 days) enhanced memory retention and spatial memory in normal mice as well as in scopolamine-treated mice with memory deficits. Furthermore, the administration of WELB significantly increased the number of proliferating cells and surviving newborn cells in the dentate gyrus of the hippocampus in normal mice. We found that WELB has a pro-neurogenic effect by increasing the activation of brain-derived neurotrophic factor (BDNF)/cAMP response element-binding protein (CREB) and mitogen-activated protein kinase kinase/extracellular signal-regulated kinase (MEK/ERK) in the hippocampus. Moreover, we confirmed that WELB (100 and 200 µg/ml) significantly increased NE-4 C and primary embryonic NSCs proliferation. Inhibition/knockdown of MEK/ERK blocked WELB-induced MEK/ERK phosphorylation and NSCs proliferation. Hence, MEK/ERK activation was required in WELB-induced NSCs proliferation. Our study demonstrates the first evidence for WELB promoting hippocampal neurogenesis and memory; pro-neurogenic activity may enhance brain plasticity, with implications for treating neurodegenerative diseases.

Low-dose curcumin enhances hippocampal neurogenesis and memory retention in young mice.

Adult neurogenesis generates new functional neurons from adult neural stem cells in various regions, including the subventricular zone (SVZ) of the lateral ventricles and subgranular zone (SGZ) of hippocampal dentate gyrus (DG). Available evidence shows hippocampal neurogenesis can be negatively or positively regulated by dietary components. In a previous study, we reported that curcumin (diferuloylmethane; a polyphenolic found in curry spice) stimulates the proliferation of embryonic neural stem cells (NSCs) by activating adaptive cellular stress responses. Here, we investigated whether subchronic administration of curcumin (once daily at 0.4, 2, or 10 mg/kg for 14 days) promotes hippocampal neurogenesis and neurocognitive function in young (5-week-old) mice. Oral administration of low-dose curcumin (0.4 mg/kg) increased the proliferation and survival of newly generated cells in hippocampus, but surprisingly, high-dose curcumin (10 mg/kg) did not effectively upregulate the proliferation or survival of newborn cells. Furthermore, hippocampal BDNF levels and phosphorylated CREB activity were elevated in only low-dose curcumin-treated mice. Passive avoidance testing revealed that low-dose curcumin increased cross-over latency times, indicating enhanced memory retention, and an in vitro study showed that low-concentration curcumin increased the proliferative activity of neural progenitor cells (NPCs) by upregulating NF1X levels. Collectively, our findings suggest that low-dose curcumin has neurogenic effects and that it may prevent age and neurodegenerative disease-related cognitive deficits.

Naphthazarin has a protective effect on the 1-methyl-4-phenyl-1,2,3,4-tetrahydropyridine-induced Parkinson's disease model.

"Neurohormesis" refers to a response to a moderate level of stress that enhances the ability of the nervous systems to resist more severe stress that might be lethal or cause dysfunction or disease. Neurohormetic phytochemicals, such as, resveratrol, sulforaphane, curcumin, and catechins, protect neurons against injury and disease. Naphthoquinones, such as, juglone and plumbagin, induce robust hormetic stress responses. However, the possibility that subtoxic dose of 5,8-dihydroxy-1,4-naphthoquinone (naphthazarin) may protect against brain diseases via the activation of an adaptive stress response pathway in the brain has not been investigated. In this study, we examined the neurohormetic effect of a subtoxic dose of naphthazarin in a Parkinson's disease model. It was found that, under these conditions, naphthazarin enhanced movement ability, prevented loss of dopaminergic neurons, and attenuated neuroinflammation in a 1-methyl-4-phenyl-1,2,3,4-tetrahydropyridine-induced Parkinson's disease model. Furthermore, it was found that the neuroprotective effect of naphthazarin was mediated by the suppression of astroglial activation in response to 1-methyl-4-phenylpyridine treatment. In conclusion, we suggest that naphthazarin, in view of its hormetic effect on neuroprotection, be viewed as a potential treatment for Parkinson's disease and other neurodegenerative diseases associated with neuroinflammation.

Combined Treatment with Herbal Medicine and Drug Ameliorates Inflammation and Metabolic Abnormalities in the Liver of an Amyotrophic Lateral Sclerosis Mouse Model.

To date, no effective drugs exist for amyotrophic lateral sclerosis (ALS), although riluzole (RZ) and edaravone have been approved for treatment. We previously reported that Bojungikgi-tang (BJIGT) improved motor activity through anti-inflammatory effects in the muscle and spinal cord of hSOD1G93A mice. Therefore, whether combined treatment with BJIGT and RZ synergistically affects liver function in hSOD1G93A mice was investigated. Two-month-old male hSOD1G93A mice were treated with BJIGT (1 mg/g) and RZ (8 µg/g) administered orally for 5 weeks. Drug metabolism and liver function tests of serum and liver homogenates were conducted. mRNA expression levels of cytochrome P450 (CYP) isozymes, inflammatory cytokines, metabolic factors, and mitochondrial oxidative phosphorylation (OXPHOS) subunits were examined using qPCR and Western blotting. Combined administration of BJIGT and RZ did not alter mRNA expression levels of drug-metabolism-related isozymes (CYP1A2 and CYP3A4) but significantly decreased the activity of liver-function-related enzymes (AST, ALT, ALP, and LDH). Increased expression of inflammatory cytokines (IL-1ß, TNF-α, and IL-6) and of intracellular stress-related proteins (Bax, AMPKα, JNK, and p38) was reduced by the combined treatment in hSOD1G93A mice compared to that in control mice. Combined administration reduced the mRNA expression of metabolism-related factors and the expression of OXPHOS subunits. Elevated ATP levels and mitochondrial-fusion-associated protein were decreased after co-administration. Co-administration of BJIGT and RZ did not cause liver damage or toxicity but rather restored liver function in hSOD1G93A mice. This suggests that this combination can be considered a candidate therapeutic agent for ALS.

Nutraceutical Interventions for Post-Traumatic Stress Disorder in Animal Models: A Focus on the Hypothalamic-Pituitary-Adrenal Axis.

Post-traumatic stress disorder (PTSD) occurs after exposure to traumatic events and is characterized by overwhelming fear and anxiety. Disturbances in the hypothalamic-pituitary-adrenal (HPA) axis are involved in the pathogenesis of mood disorders, including anxiety, PTSD, and major depressive disorders. Studies have demonstrated the relationship between the HPA axis response and stress vulnerability, indicating that the HPA axis regulates the immune system, fear memory, and neurotransmission. The selective serotonin reuptake inhibitors (SSRIs), sertraline and paroxetine, are the only drugs that have been approved by the United States Food and Drug Administration for the treatment of PTSD. However, SSRIs require long treatment times and are associated with lower response and remission rates; therefore, additional pharmacological interventions are required. Complementary and alternative medicine therapies ameliorate HPA axis disturbances through regulation of gut dysbiosis, insomnia, chronic stress, and depression. We have described the cellular and molecular mechanisms through which the HPA axis is involved in PTSD pathogenesis and have evaluated the potential of herbal medicines for PTSD treatment. Herbal medicines could comprise a good therapeutic strategy for HPA axis regulation and can simultaneously improve PTSD-related symptoms. Finally, herbal medicines may lead to novel biologically driven approaches for the treatment and prevention of PTSD.

Mitochondrial genome mutations and neuronal dysfunction of induced pluripotent stem cells derived from patients with Alzheimer's disease.

OBJECTIVES: Patient-derived induced pluripotent stem cells (iPSCs) are materials that can be used for autologous stem cell therapy. We screened mtDNA mutations in iPSCs and iPSC-derived neuronal cells from patients with Alzheimer's disease (AD). Also, we investigated whether the mutations could affect mitochondrial function and deposition of ß-amyloid (Aß) in differentiated neuronal cells. MATERIALS AND METHODS: mtDNA mutations were measured and compared among iPSCs and iPSC-derived neuronal cells. The selected iPSCs carrying mtDNA mutations were subcloned, and then their growth rate and neuronal differentiation pattern were analyzed. The differentiated cells were measured for mitochondrial respiration and membrane potential, as well as deposition of Aß. RESULTS: Most iPSCs from subjects with AD harbored ≥1 mtDNA mutations, and the number of mutations was significantly higher than that from umbilical cord blood. About 35% and 40% of mutations in iPSCs were shared with isogenic iPSCs and their differentiated neuronal precursor cells, respectively, with similar or different heteroplasmy. Furthermore, the mutations in clonal iPSCs were stable during extended culture and neuronal differentiation. Finally, mtDNA mutations could induce a growth advantage with higher viability and proliferation, lower mitochondrial respiration and membrane potential, as well as increased Aß deposition. CONCLUSION: This study demonstrates that mtDNA mutations in patients with AD could lead to mitochondrial dysfunction and accelerated Aß deposition. Therefore, early screening for mtDNA mutations in iPSC lines would be essential for developing autologous cell therapy or drug screening for patients with AD.