Cocaine- and Amphetamine-Regulated Transcript (CART) Peptide Plays Critical Role in Psychostimulant-Induced Depression

Cocaine- and amphetamine-regulated transcript (CART) peptide is a widely distributed neurotransmitter expressed in the central nervous systems. Previously, several reports demonstrated that nucleus accumbal-injected CART peptide positively modulated behavioral sensitization induced by psychostimulants and regulated the mesocorticolimbic dopaminergic pathway. It is confirmed that CART peptide exerted inhibitory effect on psychostimulant-enhanced dopamine receptors signaling, Ca²⁺/calmodulin-dependent kinase signaling and crucial transcription factors expression. Besides modulation of dopamine receptors-related pathways, CART peptide also exhibited elaborated interactions with other neurotransmitter receptors, such as glutamate receptors and γ-aminobutyric acid receptors, which further account for attribution of CART peptide to inhibition of psychostimulant-potentiated locomotor activity. Recently, CART peptide has been shown to have anxiolytic functions on the aversive mood and uncontrolled drug-seeking behaviors following drug withdrawal. Moreover, microinjection of CART peptide has been shown to have an anti-depressant effect, which suggests its potential utility in the mood regulation and avoidance of depression-like behaviors. In this review, we discuss CART pathways in neural circuits and their interactions with neurotransmitters associated with psychostimulant-induced depression.

Sleep-Aids Derived from Natural Products

Although drugs such as barbiturates and benzodiazepines are often used for the treatment of insomnia, they are associated with various side effects such as habituations, tolerance and addiction. Alternatively, natural products with minimal unwanted effects have been preferred for the treatment of acute and/or mild insomnia, with additional benefits of overall health-promotion. Basic and clinical researches on the mechanisms of action of natural products have been carried out so far in insomnia treatments. Recent studies have been focusing on diverse chemical components available in natural products, with an interest of developing drugs that can improve sleep duration and quality. In the last 15 years, our co-workers have been actively looking for candidate substances from natural products that can relieve insomnia. This review is, therefore, intended to bring pharmacological data regarding to the effects of natural products on sleep duration and quality, mainly through the activation of GABA_A receptors. It is imperative that phytochemicals will provide useful information during electroencephalography (EEG) analysis and serve as an alternative medications for insomnia patients who are reluctant to use conventional drugs.

Cocaine- and amphetamine-regulated transcript peptide in the nucleus accumbens shell inhibits cocaine-induced locomotor sensitization to transient over-expression of α-Ca2+ /calmodulin-dependent protein kinase II

Cocaine- and amphetamine-regulated transcript (CART) peptide is a widely distributed neurotransmitter that attenuates cocaine-induced locomotor activity when injected into the nucleus accumbens (NAc). Our previous work first confirmed that the inhibitory mechanism of the CART peptide on cocaine-induced locomotor activity is related to a reduction in cocaine-enhanced phosphorylated Ca²⁺ /calmodulin-dependent protein kinaseIIα (pCaMKIIα) and the enhancement of cocaine-induced D3R function. This study investigated whether CART peptide inhibited cocaine-induced locomotor activity via inhibition of interactions between pCaMKIIα and the D3 dopamine receptor (D3R). We demonstrated that lentivirus-mediated gene transfer transiently increased pCaMKIIα expression, which peaked at 10 days after microinjection into the rat NAc shell, and induced a significant increase in Ca²⁺ influx along with greater behavioral sensitivity in the open field test after intraperitoneal injections of cocaine (15 mg/kg). However, western blot analysis and coimmunoprecipitation demonstrated that CART peptide treatment in lentivirus-transfected CaMKIIα-over-expressing NAc rat tissues or cells prior to cocaine administration inhibited the cocaine-induced Ca²⁺ influx and attenuated the cocaine-increased pCaMKIIα expression in lentivirus-transfected CaMKIIα-over-expressing cells. CART peptide decreased the cocaine-enhanced phosphorylated cAMP response element binding protein (pCREB) expression via inhibition of the pCaMKIIα-D3R interaction, which may account for the prolonged locomotor sensitization induced by repeated cocaine treatment in lentivirus-transfected CaMKIIα-over-expressing cells. These results provide strong evidence for the inhibitory modulation of CART peptide in cocaine-induced locomotor sensitization. Cover Image for this issue: doi: 10.1111/jnc.14187.

Administration of Alphas1-Casein Hydrolysate Increases Sleep and Modulates GABAA Receptor Subunit Expression

Sleep is the most basic and essential physiological requirement for mental health, and sleep disorders pose potential risks of metabolic and neurodegenerative diseases. Tryptic hydrolysate of α_S1-casein (α_S1-CH) has been shown to possess stress relieving and sleep promoting effects. However, the differential effects of α_S1-CH on electroencephalographic wave patterns and its effects on the protein levels of γ-aminobutyric acid A (GABA_A) receptor subtypes in hypothalamic neurons are not well understood. We found α_S1-CH (120, 240 mg/kg) increased sleep duration in mice and reduced sleep-wake cycle numbers in rats. While α_S1-CH (300 mg/kg) increased total sleeping time in rats, it significantly decreased wakefulness. In addition, electroencephalographic theta (θ) power densities were increased whereas alpha (α) power densities were decreased by α_S1-CH (300 mg/kg) during sleep-wake cycles. Furthermore, protein expressions of GABA_A receptor β₁ subtypes were elevated in rat hypothalamus by α_S1-CH. These results suggest α_S1-CH, through GABA_A receptor modulation, might be useful for treating sleep disorders.

Inhibitory effect of thiacremonone on MPTP-induced dopaminergic neurodegeneration through inhibition of p38 activation

Neuroinflammation is implicated for dopaminergic neurodegeneration. Sulfur compounds extracted from garlic have been shown to have anti-inflammatory properties. Previously, we have investigated that thiacremonone, a sulfur compound isolated from garlic has anti-inflammatory effects on several inflammatory disease models. To investigate the protective effect of thiacremonone against 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP)-induced behavioral impairment and dopaminergic neurodegeneration, 8 week old ICR mice were given thiacremonone (10 mg/kg) in drinking water for 1 month and received intraperitoneal injection of MPTP (15 mg/kg, four times with 2 h interval) during the last 7 days of treatment. Our data showed that thiacremonone decreased MPTP-induced behavioral impairments (Rotarod test, Pole test, and Gait test), dopamine depletion and microglia and astrocytes activations as well as neuroinflammation. Higher activation of p38 was found in the substantia nigra and striatum after MPTP injection, but p38 activation was reduced in thiacremonone treated group. In an in vitro study, thiacremonone (1, 2, and 5 μg/ml) effectively decreased MPP+ (0.5 mM)-induced glial activation, inflammatory mediators generation and dopaminergic neurodegeneration in cultured astrocytes and microglial BV-2 cells. Moreover, treatment of p38 MAPK inhibitor SB203580 (10 μM) further inhibited thiacremonone induced reduction of neurodegeneration and neuroinflammation. These results indicated that the anti-inflammatory compound, thiacremonone, inhibited neuroinflammation and dopaminergic neurodegeneration through inhibition of p38 activation.

CCR5 deficiency accelerates lipopolysaccharide-induced astrogliosis, amyloid-beta deposit and impaired memory function

Chemokine receptors are implicated in inflammation and immune responses. Neuro-inflammation is associated with activation of astrocyte and amyloid-beta (Aβ) generations that lead to pathogenesis of Alzheimer disease (AD). Previous our study showed that deficiency of CC chemokine receptor 5 (CCR5) results in activation of astrocytes and Aβ deposit, and thus memory dysfunction through increase of CC chemokine receptor 2 (CCR2) expression. CCR5 knockout mice were used as an animal model with memory dysfunction. For the purpose LPS was injected i.p. daily (0.25 mg/kg/day). The memory dysfunctions were much higher in LPS-injected CCR5 knockout mice compared to CCR5 wild type mice as well as non-injected CCR5 knockout mice. Associated with severe memory dysfuction in LPS injected CCR5 knockout mice, LPS injection significant increase expression of inflammatory proteins, astrocyte activation, expressions of β-secretase as well as Aβ deposition in the brain of CCR5 knockout mice as compared with that of CCR5 wild type mice. In CCR5 knockout mice, CCR2 expressions were high and co-localized with GFAP which was significantly elevated by LPS. Expression of monocyte chemoattractant protein-1 (MCP-1) which ligands of CCR2 also increased by LPS injection, and increment of MCP-1 expression is much higher in CCR5 knockout mice. BV-2 cells treated with CCR5 antagonist, D-ala-peptide T-amide (DAPTA) and cultured astrocytes isolated from CCR5 knockout mice treated with LPS (1 μg/ml) and CCR2 antagonist, decreased the NF-ĸB activation and Aβ level. These findings suggest that the deficiency of CCR5 enhances response of LPS, which accelerates to neuro-inflammation and memory impairment.

Sinomenine, an Alkaloid Derived from Sinomenium acutum Potentiates Pentobarbital-Induced Sleep Behaviors and Non-Rapid Eye Movement (NREM) Sleep in Rodents

Sinomenium acutum has been long used in the preparations of traditional medicine in Japan, China and Korea for the treatment of various disorders including rheumatism, fever, pulmonary diseases and mood disorders. Recently, it was reported that Sinomenium acutum, has sedative and anxiolytic effects mediated by GABA-ergic systems. These experiments were performed to investigate whether sinomenine (SIN), an alkaloid derived from Sinomenium acutum enhances pentobarbital-induced sleep via γ-aminobutyric acid (GABA)-ergic systems, and modulates sleep architecture in mice. Oral administration of SIN (40 mg/kg) markedly reduced spontaneous locomotor activity, similar to diazepam (a benzodiazepine agonist) in mice. SIN shortened sleep latency, and increased total sleep time in a dose-dependent manner when co-administrated with pentobarbital (42 mg/kg, i.p.). SIN also increased the number of sleeping mice and total sleep time by concomitant administration with the sub-hypnotic dosage of pentobarbital (28 mg/kg, i.p.). SIN reduced the number of sleep-wake cycles, and increased total sleep time and non-rapid eye movement (NREM) sleep. In addition, SIN also increased chloride influx in the primary cultured hypothalamic neuronal cells. Furthermore, protein overexpression of glutamic acid decarboxylase (GAD_65/67) and GABA_A receptor subunits by western blot were found, being activated by SIN. In conclusion, SIN augments pentobarbital-induced sleeping behaviors through GABA_A-ergic systems, and increased NREM sleep. It could be a candidate for the treatment of insomnia.

A New Insight into the Role of CART in Cocaine Reward: Involvement of CaMKII and Inhibitory G-Protein Coupled Receptor Signaling

Cocaine- and amphetamine-regulated transcript (CART) peptides are neuropeptides that are expressed in brain regions associated with reward, such as the nucleus accumbens (NAc), and play a role in cocaine reward. Injection of CART into the NAc can inhibit the behavioral effects of cocaine, and injecting CART into the ventral tegmental area (VTA) reduces cocaine-seeking behavior. However, the exact mechanism of these effects is not clear. Recent research has demonstrated that Ca²⁺/calmodulin-dependent protein kinase II (CaMKII) and inhibitory G-protein coupled receptor (GPCR) signaling are involved in the mechanism of the effect of CART on cocaine reward. Hence, we review the role of CaMKII and inhibitory GPCR signaling in the effect of CART on cocaine reward and provide a new insight into the mechanism of that effect. In this article, we will first review the biological function of CART and discuss the role of CART in cocaine reward. Then, we will focus on the role of CaMKII and inhibitory GPCR signaling in cocaine reward. Furthermore, we will discuss how CaMKII and inhibitory GPCR signaling are involved in the mechanistic action of CART in cocaine reward. Finally, we will provide our opinions regarding the future directions of research on the role of CaMKII and inhibitory GPCR signaling in the effect of CART on cocaine reward.

Rosmarinic Acid Potentiates Pentobarbital-Induced Sleep Behaviors and Non-Rapid Eye Movement (NREM) Sleep through the Activation of GABAA-ergic Systems

It has been known that RA, one of major constituents of Perilla frutescens which has been used as a traditional folk remedy for sedation in oriental countries, shows the anxiolytic-like and sedative effects. This study was performed to know whether RA may enhance pentobarbital-induced sleep through γ-aminobutyric acid (GABA)_A-ergic systems in rodents. RA (0.5, 1.0 and 2.0 mg/ kg, p.o.) reduced the locomotor activity in mice. RA decreased sleep latency and increased the total sleep time in pentobarbital (42 mg/kg, i.p.)-induced sleeping mice. RA also increased sleeping time and number of falling sleep mice after treatment with sub-hypnotic pentobarbital (28 mg/kg, i.p.). In electroencephalogram (EEG) recording, RA (2.0 mg/kg) not only decreased the counts of sleep/wake cycles and REM sleep, but also increased the total and NREM sleep in rats. The power density of NREM sleep showed the increase in δ-waves and the decrease in α-waves. On the other hand, RA (0.1, 1.0 and 10 μg/ml) increased intracellular Cl^- influx in the primary cultured hypothalamic cells of rats. RA (p.o.) increased the protein expression of glutamic acid decarboxylase (GAD_65/67) and GABA_A receptors subunits except β1 subunit. In conclusion, RA augmented pentobarbital-induced sleeping behaviors through GABA_A-ergic transmission. Thus, it is suggested that RA may be useful for the treatment of insomnia.

Potentiation of decursinol angelate on pentobarbital-induced sleeping behaviors via the activation of GABAA-ergic systems in rodents

Angelicae Gigantis Radix (AGR, Angelica gigas) has been used for a long time as a traditional folk medicine in Korea and oriental countries. Decursinol angelate (DCA) is structurally isomeric decursin, one of the major components of AGR. This study was performed to confirm whether DCA augments pentobarbital-induced sleeping behaviors via the activation of GABA_A-ergic systems in animals. Oral administration of DCA (10, 25 and 50 mg/kg) markedly suppressed spontaneous locomotor activity. DCA also prolonged sleeping time, and decreased the sleep latency by pentobarbital (42 mg/kg), in a dose-dependent manner, similar to muscimol, both at the hypnotic (42 mg/kg) and sub-hypnotic (28 mg/kg) dosages. Especially, DCA increased the number of sleeping animals in the sub-hypnotic dosage. DCA (50 mg/kg, p.o.) itself modulated sleep architectures; DCA reduced the counts of sleep/wake cycles. At the same time, DCA increased total sleep time, but not non-rapid eye movement (NREM) and rapid eye movement (REM) sleep. In the molecular experiments. DCA (0.001, 0.01 and 0.1 µg/ml) increased intracellular Cl- influx level in hypothalamic primary cultured neuronal cells of rats. In addition, DCA increased the protein expression of glutamic acid decarboxylase (GAD_65/67) and GABA_A receptors subtypes. Taken together, these results suggest that DCA potentiates pentobarbital-induced sleeping behaviors through the activation of GABA_A-ergic systems, and can be useful in the treatment of insomnia.

Parkin deficiency exacerbate ethanol-induced dopaminergic neurodegeneration by P38 pathway dependent inhibition of autophagy and mitochondrial function

Parkinson's disease (PD) is a neurodegenerative disease characterized by selective degeneration of dopaminergic neurons in the substantia nigra. Parkin (which encoded by Park2), an E3 ubiquitin ligase, is the most frequently mutated gene that has casually been linked to autosomal recessive early onset familial PD. We tested the effect of Park2 on ethanol-induced dopaminergic neurodegeneration in Park2 knockout (KO) transgenic mice after chronic ethanol feeding. Male Park2 wild type (WT) and KO mice (8 weeks old) were fed on a Lieber-DeCarli diet containing 6.6% ethanol for 2 weeks, and compared their responses. We found that knockout of Park2 exacerbates ethanol-induced behavioral impairment as well as dopamine depletion. In the mechanism study, we found that knockout of Park2 increased reactive oxygen species (ROS) production, mitophagy formation, mitochondrial dysfunction, and expression of pro-apoptotic proteins, but decreased expression of pro-autophagic proteins. Knockout of Park2 also increased ethanol-induced activation of p38 mitogen-activated protein kinase. In addition, ROS production, mitophagy formation, mitochondrial dysfunction, and expression of pro-apoptotic proteins were increased, but expression of pro-autophagic proteins were decreased by a treatment of ethanol (100 μM) in Park2 siRNA-transfacted PC12 cells (5 μM). Moreover, the exacerbating effects of Park2 deletion on ethanol-induced ROS generation, mitophagy, mitochondrial dysfunction as well as cell death were reduced by p38 specific inhibitor (SB203580) in in vitro (10 μM) and in vivo 10 mg/kg). Park2 deficiency exacerbates ethanol-induced dopaminergic neuron damage through p38 kinase dependent inhibition of autophagy and mitochondrial function.

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EtOH consumption can induce the ROS formation through activation of p38 MAPK.

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ROS can cause the neurodegeneration through inhibition of the autophagy system.

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Park2 knock down amplifies EtOH-induced decrement of autophagy.

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Park2 knock down amplifies EtOH-induced mitochondrial dysfunction.

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Park2 has a neuroprotective effect against ROS mediated damage of neuron.

(-)-Epigallocatechin-3-O-gallate (EGCG) attenuates the hemodynamics stimulated by caffeine through decrease of catecholamines release

A human study of the effects on hemodynamics of caffeine and epigallocatechin-3-O-gallate (EGCG) was performed. Caffeine tablets (200 mg) were orally administered to healthy males aged between 25 and 35 years 30 min after oral administration of EGCG tablets (100 and 200 mg). The increase in BP induced by caffeine was inhibited when co-administrated with EGCG. We found that caffeine slightly decreased heart rate (HR) in the volunteers. Although EGCG enhanced HR reduction, the effect was not significant. In addition, caffeine increased blood catecholamine levels, but EGCG inhibited the increase in noradrenaline, adrenaline and dopamine levels induced by caffeine. Whether EGCG decreases the elevated HR and systolic perfusion pressure, and ventricular contractility induced by adrenergic agonists in the isolated rat heart was investigated. The modified Krebs-Henseleit solution was perfused through a Langendorff apparatus to the isolated hearts of rats. HR, systolic perfusion pressure, and developed maximal rates of contraction (+dP/dtmax) and relaxation (-dP/dtmax) were increased by epinephrine (EP) and isoproterenol (IP). In contrast, EGCG decreased the elevated HR, systolic perfusion pressure, and left ventricular ±dp/dtmax induced by EP and/or IP. In conclusion, EGCG could attenuate the hemodynamics stimulated by caffeine through decreasing catecholamine release.

Decreased Caffeine-Induced Locomotor Activity via Microinjection of CART Peptide into the Nucleus Accumbens Is Linked to Inhibition of the pCaMKIIa-D3R Interaction

The purpose of this study was to characterize the inhibitory modulation of cocaine- and amphetamine-regulated transcript (CART) peptides, particularly with respect to the function of the D3 dopamine receptor (D3R), which is activated by its interaction with phosphorylated CaMKIIα (pCaMKIIα) in the nucleus accumbens (NAc). After repeated oral administration of caffeine (30 mg/kg) for five days, microinjection of CART peptide (0.08 μM/0.5 μl/hemisphere) into the NAc affected locomotor behavior. The pCaMKIIα-D3R interaction, D3R phosphorylation and cAMP/PKA/phosphorylated CREB (pCREB) signaling pathway activity were measured in NAc tissues, and Ca2+ influx and pCaMKIIα levels were measured in cultured NAc neurons. We found that CART attenuated the caffeine-mediated enhancement of depolarization-induced Ca2+ influx and CaMKIIα phosphorylation in cultured NAc neurons. Repeated microinjection of CART peptides into the NAc decreased the caffeine-induced enhancement of Ca2+ channels activity, pCaMKIIα levels, the pCaMKIIα-D3R interaction, D3R phosphorylation, cAMP levels, PKA activity and pCREB levels in the NAc. Furthermore, behavioral sensitization was observed in rats that received five-day administration of caffeine following microinjection of saline but not in rats that were treated with caffeine following microinjection of CART peptide. These results suggest that caffeine-induced CREB phosphorylation in the NAc was ameliorated by CART peptide due to its inhibition of D3R phosphorylation. These effects of CART peptides may play a compensatory role by inhibiting locomotor behavior in rats.

Inhibition of p38 pathway-dependent MPTP-induced dopaminergic neurodegeneration in estrogen receptor alpha knockout mice

Approximately, 7-10 million people in the world suffer from Parkinson's disease (PD). Recently, increasing evidence has suggested the protective effect of estrogens against nigrostriatal dopaminergic damage in PD. In this study, we investigated whether estrogen affects 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP)-induced behavioral impairment in estrogen receptor alpha (ERα)-deficient mice. MPTP (15mg/kg, four times with 1.5-h interval)-induced dopaminergic neurodegeneration was evaluated in ERα wild-type (WT) and knockout (KO) mice. Larger dopamine depletion, behavioral impairments (Rotarod test, Pole test, and Gait test), activation of microglia and astrocytes, and neuroinflammation after MPTP injection were observed in ERα KO mice compared to those in WT mice. Immunostaining for tyrosine hydroxylase (TH) after MPTP injection showed fewer TH-positive neurons in ERα KO mice than WT mice. Levels of dopamine and 3,4-dihydroxyphenylacetic acid (DOPAC, metabolite of dopamine) were also lowered in ERα KO mice after MPTP injection. Interestingly, a higher immunoreactivity for monoamine oxidase (MAO) B was found in the substantia nigra and striatum of ERα KO mice after MPTP injection. We also found an increased activation of p38 kinase (which positively regulates MAO B expression) in ERα KO mice. In vitro estrogen treatment inhibited neuroinflammation in 1-methyl-4-phenyl pyridium (MPP+)-treated cultured astrocyte cells; however, these inhibitory effects were removed by p38 inhibitor. These results indicate that ERα might be important for dopaminergic neuronal survival through inhibition of p38 pathway.

Predominant D1 Receptors Involvement in the Over-expression of CART Peptides after Repeated Cocaine Administration

The aim of this study was to investigate the involvement of dopaminergic receptors (DR) in behavioral sensitization, as measured by locomotor activity, and the over-expression of cocaine- and amphetamine-regulated transcript (CART) peptides after repeated administration of cocaine in mice. Repeated administrations of cocaine induced behavioral sensitization and CART over-expression in mice. The levels of striatal CART mRNA were significantly increased on the 3^rd day. CART peptides were over-expressed on the 5^th day in the striata of behaviorally sensitized mice. A higher proportion of CART⁺ cells in the cocaine-treated mice were present in the nucleus accumbens (NAc) shell than in the dorsolateral (DL) part of caudate putamen (CP). The concomitant administration of both D₁R and D₂R antagonists, SCH 23390 (D₁R selective) and raclopride (D₂R selective), blocked cocaine induced-behavioral sensitization, CART over-expression, and cyclic adenosine 5'-monophosphate (cAMP)/protein kinase A (PKA)/phospho-cAMP response element-binding protein (pCREB) signal pathways. SCH 23390 more predominantly inhibited the locomotor activity, CART over-expression, pCREB and PKA activity than raclopride. Cocaine induced-behavioral sensitization was also attenuated in the both D₁R and D₂R knockout (KO) mice, respectively. CART over-expression and activated cAMP/PKA/pCREB signal pathways were inhibited in the D₁R-KO mice, but not in the D₂R-KO mice. It is suggested that behavioral sensitization, CART over-expression and activated cAMP/PKA/pCREB signal pathways induced by repeated administration of cocaine could be more predominantly mediated by D₁R.

Pachymic Acid Enhances Pentobarbital-Induced Sleeping Behaviors via GABAA-ergic Systems in Mice

This study was investigated to know whether pachymic acid (PA), one of the predominant triterpenoids in Poria cocos (Hoelen) has the sedative-hypnotic effects, and underlying mechanisms are mediated via γ-aminobutyric acid (GABA)-ergic systems. Oral administration of PA markedly suppressed locomotion activity in mice. This compound also prolonged sleeping time, and reduced sleep latency showing synergic effects with muscimol (0.2 mg/kg) in shortening sleep onset and enhancing sleep time induced by pentobarbital, both at the hypnotic (40 mg/kg) and sub-hypnotic (28 mg/kg) doses. Additionally, PA elevated intracellular chloride levels in hypothalamic primary cultured neuronal cells of rats. Moreover, Western blotting quantitative results showed that PA increased the amount of protein level expression of GAD_65/67 over a broader range of doses. PA increased α- and β-subunits protein levels, but decreased γ-subunit protein levels in GABA_A receptors. The present experiment provides evidence for the hypnotic effects as PA enhanced pentobarbital-induced sleeping behaviors via GABA_A-ergic mechanisms in rodents. Taken together, it is proposed that PA may be useful for the treatment of sleep disturbed subjects with insomnia.

Memory Impairment in Estrogen Receptor α Knockout Mice Through Accumulation of Amyloid-β Peptides

Estrogen has been known to reduce the development of Alzheimer’s disease (AD). However, exact mechanisms are not clear. We investigated whether estrogen can increase amyloid-beta (Aβ) degradation and affects Aβ-induced memory impairment in an estrogen deficiency model. Estrogen receptor alpha (ERα) knockout mice and wild-type mice were intracerebroventricular (ICV) infused with Aβ (300 pmol) for 2 weeks. Cognitive function was then assessed by the Morris water maze test and passive avoidance test. In addition, Western blot analysis, immunostaining, immunofluorescence staining, ELISA, and enzyme activity assays were used to examine the degree of Aβ deposition in the brains of ERα knockout mice. In our present study, Aβ was accumulated more in the ERα knockout mice brain and greatly worsened memory impairment and glial activation as well as neurogenic inflammation. These results suggest that estrogen may protect memory impairment by stimulating the degradation of Aβ and down-regulate neurogenic inflammation as well as amyloidogenesis.

Microinjection of CART (cocaine- and amphetamine-regulated transcript) peptide into the nucleus accumbens inhibits the cocaine-induced upregulation of dopamine receptors and locomotor sensitization

Repeated exposure to addictive drugs enhances dopamine receptor (DR) signaling and the ultimate phosphorylation of the cyclic adenosine 5'-monophosphate (cAMP)-response element-binding protein (CREB)-regulated cocaine- and amphetamine-regulated transcript (CART) expression in the nucleus accumbens (NAcc). These effects are known to contribute to the expression of behavioral sensitization. CART peptides are neuropeptides that modulate drug reward and reinforcement. The present experiments investigated the effects of CART 55-102 microinjection into the NAcc on (1) the phosphorylation of CREB, (2) cAMP/protein kinase A (PKA) signaling and (3) extracellular signal-regulated kinase (ERK) phosphorylated kinase signaling. Here, we show that repeated microinjections into the NAcc of CART 55-102 peptides (1.0 or 2.5μg, 0.5μl/side) attenuates cocaine-induced enhancements of D1R, D2R and D3R phosphorylation in this sites. Furthermore, the microinjection of CART 55-102 followed by repeated injections of cocaine (15mg/kg) dose-dependently blocked the enhancement of cAMP levels, PKA activity and pERK and pCREB levels on the fifth day of cocaine administration. The cocaine-induced locomotor activity and behavioral sensitization in rats were also inhibited by the 5-day-microinjection of CART peptides. These results suggest that the phosphorylation of CREB by cocaine in the NAcc was blocked by the CART 55-102 peptide via the inhibition of D1R and D2R stimulation, D3R phosphorylation, cAMP/PKA signaling and ERK phosphorylated kinase signaling. These effects may have played a compensatory inhibitory role in the behavioral sensitization of rats that received microinjections of CART 55-102.

A Comparison between Extract Products of Magnolia officinalis on Memory Impairment and Amyloidogenesis in a Transgenic Mouse Model of Alzheimer's Disease

The components of Magnolia officinalis have well known to act anti-inflammatory, anti-oxidative and neuroprotective activities. These efficacies have been sold many products as nutritional supplement extracted from bark of Magnolia officinalis. Thus, to assess and compare neuroprotective effect in the nutritional supplement (Magnolia Extract^TM, Health Freedom Nutrition LLC, USA) and our ethanol extract of Magnolia officinalis (BioLand LTD, Korea), we investigated memorial improving and anti-Alzheimer’s disease effects of extract products of Magnolia officinalis in a transgenic AD mice model. Oral pretreatment of two extract products of Magnolia officinalis (10 mg/kg/day in 0.05% ethanol) into drinking water for 3 months ameliorated memorial dysfunction and prevented Aβ accumulation in the brain of Tg2576 mice. In addition, extract products of Magnolia officinalis also decreased expression of β-site APP cleaving enzyme 1 (BACE1), amyloid precursor protein (APP) and its product, C99. Although both two extract products of Magnolia officinalis could show preventive effect of memorial dysfunction and Aβ accumulation, our ethanol extract of Magnolia officinalis (BioLand LTD, Korea) could be more effective than Magnolia Extract^TM (Health Freedom Nutrition LLC, USA). Therefore, our results showed that extract products of Magnolia officinalis were effective for prevention and treatment of AD through memorial improving and anti-amyloidogenic effects via down-regulating β-secretase activity, and neuroprotective efficacy of Magnolia extracts could be differed by cultivating area and manufacturing methods.

Effects of red ginseng extract on sleeping behaviors in human volunteers

ETHNOPHARMACOLOGICAL RELEVENCE

The ginseng root has been traditionally used as a sedative in oriental countries. However, the condition "ginseng abuse syndrome" (GAS), defined as hypertension, nervousness, sleeplessness, skin eruption, and morning diarrhea, was coined as a result of a study of people who had been using a variety of ginseng preparations. However, we reported that administration of RGE increased rapid eye movement (REM) and non rapid eye movement (NREM) sleep via GABAergic systems in animals. Therefore, this study was performed to investigate how red ginseng extract (RGE) affects sleeping behaviors in human volunteers.

MATERIALS AND METHODS

RGE (1500 mg) was orally administered to young male healthy volunteers (from 15 to 37 years old ages, n=15) three times a day for 7 days. Overnight polysomnographic (PSG) studies were performed two times, 1 day before and 7 days after RGE administration. We investigated differences in sleep architecture parameters such as total sleep time (TST), sleep efficacy (SE: total sleep time/time in bed), proportion of each sleep stage, and wakefulness after sleep onset (WASO) between baseline PSG and PSG after RGE administration.

RESULTS

Total wake time (TWT) was significantly reduced (P<0.05) and SE was increased (P<0.05), although slow wave sleep stage 1 (N1) was reduced (P<0.01) and non-rapid eye movement (REM) sleep was increased (P<0.03) after administration.

CONCLUSION

From these results, it is presumed that RGE intake would improve the quality of sleep, thus having beneficial effects on sleep disturbed subjects.

Inhibition of sphingolipid metabolism enhances resveratrol chemotherapy in human gastric cancer cells

Resveratrol, a chemopreventive agent, is rapidly metabolized in the intestine and liver via glucuronidation. Thus, the pharmacokinetics of resveratrol limits its efficacy. To improve efficacy, the activity of resveratrol was investigated in the context of sphingolipid metabolism in human gastric cancer cells. Diverse sphingolipid metabolites, including dihydroceramides (DHCer), were tested for their ability to induce resveratrol cytotoxicity. Exposure to resveratrol (100 μM) for 24 hr induced cell death and cell cycle arrest in gastric cancer cells. Exposure to the combination of resveratrol and dimethylsphingosine (DMS) increased cytotoxicity, demonstrating that sphingolipid metabolites intensify resveratrol activity. Specifically, DHCer accumulated in a resveratrol concentration-dependent manner in SNU-1 and HT-29 cells, but not in SNU-668 cells. LC-MS/MS analysis showed that specific DHCer species containing C24:0, C16:0, C24:1, and C22:0 fatty acids chain were increased by up to 30-fold by resveratrol, indicating that resveratrol may partially inhibit DHCer desaturase. Indeed, resveratrol mildly inhibited DHCer desaturase activity compared to the specific inhibitor GT-11 or to retinamide (4-HPR); however, in SNU-1 cells resveratrol alone exhibited a typical cell cycle arrest pattern, which GT-11 did not alter, indicating that inhibition of DHCer desaturase is not essential to the cytotoxicity induced by the combination of resveratrol and sphingolipid metabolites. Resveratrol-induced p53 expression strongly correlated with the enhancement of cytotoxicity observed upon combination of resveratrol with DMS or 4-HPR. Taken together, these results show that DHCer accumulation is a novel lipid biomarker of resveratrol-induced cytotoxicity in human gastric cancer cells.

Acceleration of the development of Alzheimer's disease in amyloid beta-infused peroxiredoxin 6 overexpression transgenic mice

The amyloid beta (Aβ) peptide in the brains of patients with Alzheimer's disease (AD) is cytotoxic to neurons and has a central role in the pathogenesis of the disease. Peroxiredoxin 6 (Prdx6) is an antioxidant protein and could act as a cytoprotective protein. However, the role of Prdx6 in neurodegenerative disease has not been studied. Thus, the roles and action mechanisms in the development of AD were examined. Aβ1-42-induced memory impairment in Prdx6 transgenic mice was worse than C57BL/6 mice, and the expression of amyloid precursor protein cleavage, C99, β-site APP-cleaving enzyme 1, inducible nitric oxide synthase, and cyclooxygenase-2 was greatly increased. In addition, the astrocytes and microglia cells of Aβ-infused Prdx6 transgenic mice were more activated, and Aβ also significantly increased lipid peroxidation and protein carbonyl levels, but decreased glutathione levels. Furthermore, we found that translocation of nuclear factor erythroid 2-related factor 2 (Nrf2) to the nucleus was increased in Aβ-infused Prdx6 transgenic mice. These results suggest that the overexpression of Prdx6 could accelerate the development of AD through increased amyloidogenesis through independent PLA2 activation and Nrf2 transcription.

Repeated Administration of Korea Red Ginseng Extract Increases Non-Rapid Eye Movement Sleep via GABAAergic Systems

The current inquiry was conducted to assess the change in sleep architecture after long periods of administration to determine whether ginseng can be used in the therapy of sleeplessness. Following post-surgical recovery, red ginseng extract (RGE, 200 mg/ kg) was orally administrated to rats for 9 d. Data were gathered on the 1st, 5th, and 9th day, and an electroencephalogram was recorded 24 h after RGE administration. Polygraphic signs of unobstructed sleep-wake activities were simultaneously recorded with sleep-wake recording electrodes from 11:00 a.m. to 5:00 p.m. for 6 h. Rodents were generally tamed to freely moving polygraphic recording conditions. Although the 1st and 5th day of RGE treatment showed no effect on power densities in non-rapid eye movement (NREM) and rapid eye movement (REM) sleep, the 9th day of RGE administration showed augmented α-wave (8.0 to 13.0 Hz) power densities in NREM and REM sleep. RGE increased total sleep and NREM sleep. The total percentage of wakefulness was only decreased on the 9th day, and the number of sleep-wake cycles was reduced after the repeated administration of RGE. Thus, the repeated administration of RGE increased NREM sleep in rats. The α-wave activities in the cortical electroencephalograms were increased in sleep architecture by RGE. Moreover, the levels of both α- and β-subunits of the γ-aminobutyric acid (GABA)_A receptor were reduced in the hypothalamus of the RGE-treated groups. The level of glutamic acid decarboxylase was over-expressed in the hypothalamus. These results demonstrate that RGE increases NREM sleep via GABA_Aergic systems.

Emodin prevents ethanol-induced developmental anomalies in cultured mouse fetus through multiple activities

BACKGROUND

Maternal alcohol ingestion on pregnant period causes fetal alcohol syndrome including psychological and behavioral problems, and developmental abnormality. In this study, we investigated the effect of emodin, an active anthraquinone component found in the roots and bark of the genus Rhamnus (Buckthorn), on ethanol-induced teratogenesis during embryonic organogenesis.

METHODS

We cultured mouse embryos on embryonic day 8.5 for 2 days with ethanol (5 μl/3 ml) and/or emodin (1×10(-5) and 1×10(-4) μg/ml) using a whole embryo culture system and then investigated the developmental evaluation, superoxide dismutase (SOD) activity, and expression patterns of cytoplasmic SOD (SOD1), mitochondrial SOD (SOD2), cytosolic glutathione peroxidase (cGPx), tumor necrosis factor-α (TNF-α), caspase 3, and hypoxia inducible factor 1α (HIF-1α).

RESULTS

Morphological parameters, including growth in yolk sac and fetal head, body length, and development of the central nervous system, circulation system, sensory organs, skeletal system, and limbs in embryos exposed to ethanol were significantly decreased compared to those of the normal control group, but co-treatment with emodin (1 × 10(-5) and 1 × 10(-4) μg/ml) significantly improved these parameters. Furthermore, the reduced levels of SOD activity, and SOD1, SOD2, cGPx, and HIF-1α and the increased gene levels of TNF-α and caspase-3 due to ethanol exposure were significantly restored by cotreatment with emodin. Birth Defects Res (Part B) 98:268-275, 2013. © 2013 Wiley Periodicals, Inc.

CONCLUSIONS

This study revealed that cotreatment with emodin significantly prevented teratogenesis induced by ethanol, not only by modulating hypoxia and antioxidant enzymes, but also by attenuating the enhanced levels of TNF-α and caspase 3 in cultured embryos. Therefore, emodin may be an effective preventive agent for ethanol-induced teratogenesis.

Serum 1,5-anhydroglucitol is associated with diabetic retinopathy in Type 2 diabetes

AIMS

To determine whether there is a relationship between 1,5-anhydroglucitol (1,5-AG), a marker of postprandial hyperglycaemia and glycaemic variability, and the presence of diabetic retinopathy and albuminuria in patients with Type 2 diabetes.

METHODS

Five hundred and sixty-seven patients with Type 2 diabetes (serum creatinine < 133 μmol/l), who were enrolled in the Seoul Metro-City Diabetes Prevention Program (SMC-DPP), were cross-sectionally assessed by multivariate logistic regression analysis.

RESULTS

After controlling for age, sex, binary HbA(1c) levels, duration of diabetes, triglyceride, systolic blood pressure, smoking status, history of hypertension and dyslipidaemia, and the use of angiotensin-converting enzyme inhibitor/angiotensin receptor blocker medication, the odds ratios (95% CI) of diabetic retinopathy were 2.86 (1.12-7.25) for the first (lowest) quartile of 1,5-anhydroglucitol, 2.87 (1.25-6.61) for the second quartile and 0.88 (0.35-2.22) for the third quartile compared with the fourth quartile (P for trend = 0.010). Conversely, the associations between 1,5-anhydroglucitol and clinical albuminuria were non-significant after adjustment. Subjects with low 1,5-anhydroglucitol (< 10.0 μg/ml) were more likely to experience diabetic retinopathy than those with high 1,5-anhydroglucitol (≥ 10.0 μg/ml) under moderate glucose control (HbA(1c) < 8%, 64 mmol/mol) and there were no significant differences in the prevalence of diabetic retinopathy between the subgroup with HbA(1c) < 8% (64 mmol/mol) and low 1,5-anhydroglucitol and the subgroup with HbA(1c) ≥ 8% (64 mmol/mol).

CONCLUSIONS

1,5-Anhydroglucitol levels show close associations with diabetic retinopathy, especially among patients under moderate glucose control, but not with albuminuria. These results suggest that 1,5-anhydroglucitol might be a complementary marker for targeting higher risk group.

Anti-amyloidogenic effect of thiacremonone through anti-inflamation in vitro and in vivo models

Neuroinflammation is implicated for amyloidogenesis. Sulfur compounds extracted from garlic have been shown to have anti-inflammatory properties. Previously, we have investigated that thiacremonone, a sulfur compound isolated from garlic has anti-inflammatory effects. To investigate thiacremonone's potential effect on anti-neuroinflammation and anti-amyloidogenesis, 4 week old ICR mice were given different doses of thiacremonone (1, 3, and 10 mg/kg) in drinking water for 1 month and received intraperitoneal injection of lipopolysaccharide (LPS) (250 μg/kg/day) at last 7 days of treatment. Our data show thiacremonone decreased LPS-induced memory impairment, glial activation, pro-inflammatory mediators' expression, and amyloidogenesis. In an in vitro study, we obtained similar results, with thiacremonone (1, 2, and 5 μg/ml) effectively decreased LPS (1 μg/ml)-induced glial activation and inflammatory mediators generation which are implicated in amyloidogenesis. Our data also demonstrated that thiacremonone inhibited LPS-induced amyloidogenesis in cultured astrocytes and microglial BV-2 cells. NF-κB, a critical transcriptional factor regulating not only inflammation but also amyloid-β generation, was inhibited by thiacremonone via blocking of phosphorylation of IκBα in mice brain as well as cultured astrocytes and microglial BV-2 cells. These results indicated that the anti-inflammatory compound, thiacremonone, inhibited neuroinflammation and amyloidogenesis through inhibition of NF-κB activity, and thus could be applied for intervention of inflammation-related neurodegenerative disease including Alzheimer's disease.

4-O-methylhonokiol prevents memory impairment in the Tg2576 transgenic mice model of Alzheimer's disease via regulation of β-secretase activity

Alzheimer's disease (AD), the most common form of dementia, is characterized by memory deficits and deposition of amyloid-β (Aβ) in the brain. It has been known that neuroinflammation and oxidative stress are critical factors in the development of AD. 4-O-methylhonokiol, an extract from Magnolia officinalis, is known to have anti-inflammatory and anti-oxidative effects. Thus, we investigated the properties of 4-O-methylhonokiol against progression and development of AD in Tg2576 mice. Tg2576 mice models show memory impairment and AD-like pathological features including Aβ deposition. Oral administration of 4-O-methylhonokiol through drinking water (1 mg/kg in 0.0002% Tween 80) for 12 weeks not only prevented memory impairment but also inhibited Aβ deposition. In addition, 4-O-methylhonokiol decreased β-secretase activity, oxidative lipid and protein damage levels, activation of astrocytes and microglia cells, and generation of IL-1β and TNF-α with increase of glutathione level in the brain. Our results showed that 4-O-methylhonokiol effectively prevented memory impairment by down-regulating β-secretase activity through inhibition of oxidative stress and neuroinflammatory responses in Tg2576 transgenic mice.

Attenuation of scopolamine-induced cognitive dysfunction by obovatol

Alzheimer's disease (AD) is the most prevalent cause of dementia in the elderly people. The disease is pathologically characterized by extracellular deposition of beta-amyloid peptide (Aβ), cholinergic neurodegeneration and elevation of acetylcholine esterase (AChE) activity in the affected regions. In this study, we investigated the effects of obovatol on memory dysfunction, which was caused by scopolamine. Obovatol (0.2, 0.5 and 1 mg/kg for 7 day) attenuated scopolamine (1 mg/kg, i.p.)-induced amnesia in a dose-dependent manner, as revealed by the Morris water maze test and step-through passive avoidance test. Mechanism studies exhibited that obovatol dose-dependently alleviated scopolamine-induced increase in Aβ generation and β-secretase activity in the cortex and hippocampus. Obovatol also attenuated scopolamine-induced rise in AChE activity in the cortex and hippocampus. Obovatol might rescue scopolamine-mediated impaired learning and memory function by attenuating Aβ accumulation and stabilizing cholinergic neurotransmission, which suggests that the natural compound could be a useful agent for the prevention of the development or progression of AD neurodegeneration.

Enhancement of pentobarbital-induced sleep by apigenin through chloride ion channel activation

This experiment was performed to investigate whether apigenin has hypnotic effects and/or enhances pentobarbital-induced sleep behaviors through the GABAergic systems. Apigenin prolonged sleep time induced by pentobarbital similar to muscimol, a GABA(A) receptors agonist. Apigenin also increased sleep rate and sleep time in the combined administration with pentobarbital at the sub-hypnotic dosage, and showed synergic effects with muscimol in potentiating sleep onset and enhancing sleep time induced by pentobarbital. In addition, both of apigeinin and pentobarbital increased chloride influx in primary cultured cerebellar granule cells. Apigenin increased glutamate decarboxylase (GAD) and had no effect on the expression of GABA(A) receptor α-, β-, γ-subunits in n hippocampus of mouse brain, showing different expression of subunits from pentobarbital treatment group. In conclusion, it is suggested that apigenin augments pentobarbital-induced sleep behaviors through chloride ion channel activation.

4-O-methylhonokiol attenuated memory impairment through modulation of oxidative damage of enzymes involving amyloid-β generation and accumulation in a mouse model of Alzheimer's disease

Accumulations of amyloid-β (Aβ) and oxidative damage are critical pathological mechanisms in the development of Alzheimer's disease (AD). We previously found that 4-O-methylhonokiol, a compound extracted from Magnolia officinalis, improved memory dysfunction in Aβ-injected and presenilin 2 mutant mice through the reduction of accumulated Aβ. To investigate mechanisms of the reduced Aβ accumulation, we examined generation, degradation, efflux and aggregation of Aβ in Swedish AβPP AD model (AβPPsw) mice pre-treated with 4-O-methylhonokiol (1.0 mg/kg) for 3 months. 4-O-methylhonokiol treatment recovered memory impairment and prevented neuronal cell death. This memory improving activity was associated with 4-O-methylhonokiol-induced reduction of Aβ1-42 accumulation in the brains of AβPPsw mice. According to the reduction of Aβ1-42 accumulation, 4-O-methylhonkiol modulated oxidative damage sensitive enzymes. 4-O-methylhonkiol decreased expression and activity of brain beta-site AβPP cleaving enzyme (BACE1), but increased clearance of Aβ in the brain through an increase of expressions and activities of Aβ degradation enzymes; insulin degrading enzyme and neprilysin. 4-O-methylhonkiol also increased expression of Aβ transport molecule, low density lipoprotein receptor-related protein-1 in the brain and liver. 4-O-methylhonkiol decreased carbonyl protein and lipid peroxidation, but increased glutathione levels in the brains of AβPPsw mice suggesting that oxidative damage of protein and lipid is critical in the impairment of those enzyme activities. 4-O-methylhonokiol treatment also prevented neuronal cell death in the AβPPsw mousee brain through inactivation of caspase-3 and BAX. These results suggest that 4-O-methylhonokiol might prevent the development and progression of AD by reducing Aβ accumulation through an increase of clearance and decrease of Aβ generation via antioxidant mechanisms.

Inhibitory effect of 4-O-methylhonokiol on lipopolysaccharide-induced neuroinflammation, amyloidogenesis and memory impairment via inhibition of nuclear factor-kappaB in vitro and in vivo models

Background

Neuroinflammation is important in the pathogenesis and progression of Alzheimer disease (AD). Previously, we demonstrated that lipopolysaccharide (LPS)-induced neuroinflammation caused memory impairments. In the present study, we investigated the possible preventive effects of 4-O-methylhonokiol, a constituent of Magnolia officinalis, on memory deficiency caused by LPS, along with the underlying mechanisms.

Methods

We investigated whether 4-O-methylhonokiol (0.5 and 1 mg/kg in 0.05% ethanol) prevents memory dysfunction and amyloidogenesis on AD model mice by intraperitoneal LPS (250 μg/kg daily 7 times) injection. In addition, LPS-treated cultured astrocytes and microglial BV-2 cells were investigated for anti-neuroinflammatory and anti-amyloidogenic effect of 4-O-methylhonkiol (0.5, 1 and 2 μM).

Results

Oral administration of 4-O-methylhonokiol ameliorated LPS-induced memory impairment in a dose-dependent manner. In addition, 4-O-methylhonokiol prevented the LPS-induced expression of inflammatory proteins; inducible nitric oxide synthase (iNOS) and cyclooxygenase-2 (COX-2) as well as activation of astrocytes (expression of glial fibrillary acidic protein; GFAP) in the brain. In in vitro study, we also found that 4-O-methylhonokiol suppressed the expression of iNOS and COX-2 as well as the production of reactive oxygen species, nitric oxide, prostaglandin E₂, tumor necrosis factor-α, and interleukin-1β in the LPS-stimulated cultured astrocytes. 4-O-methylhonokiol also inhibited transcriptional and DNA binding activity of NF-κB via inhibition of IκB degradation as well as p50 and p65 translocation into nucleus of the brain and cultured astrocytes. Consistent with the inhibitory effect on neuroinflammation, 4-O-methylhonokiol inhibited LPS-induced Aβ_1-42 generation, β- and γ-secretase activities, and expression of amyloid precursor protein (APP), BACE1 and C99 as well as activation of astrocytes and neuronal cell death in the brain, in cultured astrocytes and in microglial BV-2 cells.

Conclusion

These results suggest that 4-O-methylhonokiol inhibits LPS-induced amyloidogenesis via anti-inflammatory mechanisms. Thus, 4-O-methylhonokiol can be a useful agent against neuroinflammation-associated development or the progression of AD.

Obovatol improves cognitive functions in animal models for Alzheimer's disease

Etiology of Alzheimer's disease (AD) is obscure, but neuroinflammation and accumulation of β-amyloid (Aβ) are implicated in pathogenesis of AD. We have shown anti-inflammatory and neurotrophic properties of obovatol, a biphenolic compound isolated from Magnolia obovata. In this study, we examined the effect of obovatol on cognitive deficits in two separate AD models: (i) mice that received intracerebroventricular (i.c.v.) infusion of Aβ(1-42) (2.0 μg/mouse) and (ii) Tg2576 mice-expressing mutant human amyloid precursor protein (K670N, M671L). Injection of Aβ(1-42) into lateral ventricle caused memory impairments in the Morris water maze and passive avoidance tasks, being associated with neuroinflammation. Aβ(1-42) -induced abnormality was significantly attenuated by administration of obovatol. When we analyzed with Tg2576 mice, long-term treatment of obovatol (1 mg/kg/day for 3 months) significantly improved cognitive function. In parallel with the improvement, treatment suppressed astroglial activation, BACE1 expression and NF-κB activity in the transgenic mice. Furthermore, obovatol potently inhibited fibrillation of Aβin vitro in a dose-dependent manner, as determined by Thioflavin T fluorescence and electron microscopic analysis. In conclusion, our data demonstrated that obovatol prevented memory impairments in experimental AD models, which could be attributable to amelioration of neuroinflammation and amyloidogenesis by inhibition of NF-κB signaling pathway and anti-fibrillogenic activity of obovatol.

The time-dependent alteration of anti-diuretic hormone system in hindlimb unloaded rats

It is important to understand the mechanism on the fluid shift and volume regulation occurring in astronauts after spaceflight for future life in space. In the present study, we examined the time-dependent alteration of anti-diuretic hormone (ADH) concentrating on the water reabsorption system in hindlimb unloaded rats. Male Sprague-Dawley rats were hindlimb unloaded for 1 (HU1), 7(HU7), 14 days (HU14) or rested in the ground for 3 days after HU14 (HU14+3). The plasma ADH and angiotensin II level showed peak value at HU7, and the alterations were restored at HU14. However, several serum electrolytes (Na, K, Cl) were not changed regardless of HU period. In the immunohistochemical study, we examined that ADH and c-Fos immunoreactivities (IR) were maximized at HU7 in the paraventricular nucleus (PVN) and supraoptic nucleus (SON). Aquaporin 2 (AQP2) IR also was increased in the renal collecting duct for water re-absorption at HU7 showing a similar pattern with ADH. These results present a series of physiological ADH system alteration following to period of hindlimb unloading stimulus, indicating that ADH system is activated significantly at HU7. In addition, our results suggest that ADH system activation may be involved in anti-diuretic phenomenon in early spaceflight period. Furthermore, it is speculated that ADH system may require 14 days for adaptation to microgravity.

Inhibitory effect of a tyrosine-fructose Maillard reaction product, 2,4-bis(p-hydroxyphenyl)-2-butenal on amyloid-β generation and inflammatory reactions via inhibition of NF-κB and STAT3 activation in cultured astrocytes and microglial BV-2 cells

BACKGROUND

Amyloidogenesis is linked to neuroinflammation. The tyrosine-fructose Maillard reaction product, 2,4-bis(p-hydroxyphenyl)-2-butenal, possesses anti-inflammatory properties in cultured macrophages, and in an arthritis animal model. Because astrocytes and microglia are responsible for amyloidogenesis and inflammatory reactions in the brain, we investigated the anti-inflammatory and anti-amyloidogenic effects of 2,4-bis(p-hydroxyphenyl)-2-butenal in lipopolysaccharide (LPS)-stimulated astrocytes and microglial BV-2 cells.

METHODS

Cultured astrocytes and microglial BV-2 cells were treated with LPS (1 μg/ml) for 24 h, in the presence (1, 2, 5 μM) or absence of 2,4-bis(p-hydroxyphenyl)-2-butenal, and harvested. We performed molecular biological analyses to determine the levels of inflammatory and amyloid-related proteins and molecules, cytokines, Aβ, and secretases activity. Nuclear factor-kappa B (NF-κB) DNA binding activity was determined using gel mobility shift assays.

RESULTS

We found that 2,4-bis(p-hydroxyphenyl)-2-butenal (1, 2, 5 μM) suppresses the expression of inducible nitric oxide synthase (iNOS) and cyclooxygenase-2 (COX-2) as well as the production of nitric oxide (NO), reactive oxygen species (ROS), tumor necrosis factor-α (TNF-α), and interleukin-1β (IL-1β) in LPS (1 μg/ml)-stimulated astrocytes and microglial BV-2 cells. Further, 2,4-bis(p-hydroxyphenyl)-2-butenal inhibited the transcriptional and DNA binding activity of NF-κB--a transcription factor that regulates genes involved in neuroinflammation and amyloidogenesis via inhibition of IκB degradation as well as nuclear translocation of p50 and p65. Consistent with the inhibitory effect on inflammatory reactions, 2,4-bis(p-hydroxyphenyl)-2-butenal inhibited LPS-elevated Aβ42 levels through attenuation of β- and γ-secretase activities. Moreover, studies using signal transducer and activator of transcription 3 (STAT3) siRNA and a pharmacological inhibitor showed that 2,4-bis(p-hydroxyphenyl)-2-butenal inhibits LPS-induced activation of STAT3.

CONCLUSIONS

These results indicate that 2,4-bis(p-hydroxyphenyl)-2-butenal inhibits neuroinflammatory reactions and amyloidogenesis through inhibition of NF-κB and STAT3 activation, and suggest that 2,4-bis(p-hydroxyphenyl)-2-butenal may be useful for the treatment of neuroinflammatory diseases like Alzheimer's disease.

Anti-cancer effect of bee venom in prostate cancer cells through activation of caspase pathway via inactivation of NF-κB

BACKGROUND

Bee venom has been used as a traditional medicine to treat arthritis, rheumatism, back pain, cancerous tumors, and skin diseases. However, the effects of bee venom on the prostate cancer and their action mechanisms have not been reported yet.

METHODS

To determine the effect of bee venom and its major component, melittin on the prostate cancer cells, apoptosis is analyzed by tunnel assay and apoptotic gene expression. For xenograft studies, bee venom was administrated intraperitoneally twice per week for 4 weeks, and the tumor growth was measured and the tumor were analyzed by immunohistochemistry. To investigate whether bee venom and melittin can inactivate nuclear factor kappa B (NF-κB), we assessed NF-κB activity in vitro and in vivo.

RESULTS AND CONCLUSIONS

Bee venom (1-10 µg/ml) and melittin (0.5-2.5 µg/ml) inhibited cancer cell growth through induction of apoptotic cell death in LNCaP, DU145, and PC-3 human prostate cancer cells. These effects were mediated by the suppression of constitutively activated NF-κB. Bee venom and melittin decreased anti-apoptotic proteins but induced pro-apoptotic proteins. However, pan caspase inhibitor abolished bee venom and melittin-induced apoptotic cell death and NF-κB inactivation. Bee venom (3-6 mg/kg) administration to nude mice implanted with PC-3 cells resulted in inhibition of tumor growth and activity of NF-κB accompanied with apoptotic cell death. Therefore, these results indicated that bee venom and melittin could inhibit prostate cancer in in vitro and in vivo, and these effects may be related to NF-κB/caspase signal mediated induction of apoptotic cell death.

Impact of non-alcoholic fatty liver disease on microalbuminuria in patients with prediabetes and diabetes

BACKGROUND

It is unknown whether microalbuminuria is associated with non-alcoholic fatty liver disease (NAFLD) among patients with prediabetes and type 2 diabetes mellitus (DM). This study investigated the association of NAFLD with microalbuminuria among patients with prediabetes and diabetes.

METHODS

We evaluated 1361 subjects who had an abnormal oral glucose tolerance test (OGTT) on routine screening. All participants were divided into two groups, prediabetes and newly diagnosed type 2 DM, and the association of NAFLD with metabolic parameters on microalbuminuria was analysed.

RESULTS

The patients with NAFLD had higher prevalence rates of microalbuminuria (6.3% vs 19%; P = 0.001 in prediabetes, 4.5% vs 32.6%; P < 0.001 in diabetes) and also had a greater albumin-to-creatinine ratio (14.6 +/- 52.0 microg/mg Cr vs 27.7 +/- 63.9 microg/mg Cr; P = 0.051 in prediabetes, 11.4 +/- 21.4 microg/mg Cr vs 44.7 +/- 76.4 microg/mg Cr; P < 0.001 in diabetes) than those without NAFLD. The logistic regression analysis showed that NAFLD was associated with increased rates of microalbuminuria (odds ratio 3.66; 95%confidence interval (CI) 1.31-10.20, P = 0.013 in prediabetes, odds ratio 5.47;95% CI 1.01-29.61, P = 0.048 in diabetes), independently of age, sex, body mass index, waist circumference, liver enzymes, lipid profiles, HbA1c, insulin resistance as estimated by homeostasis model assessment, hypertension,smoking status and the metabolic syndrome.

CONCLUSIONS

The results of our study revealed a strong relationship between microalbuminuria and NAFLD in the patients with prediabetes and newly diagnosed diabetes. Further studies are required to confirm whether NAFLD is a predictor of the development of microalbuminuria in patients with prediabetes and diabetes.