Papaverine Exerts Neuroprotective Effect by Inhibiting NLRP3Inflammasome Activation in an MPTP-Induced Microglial Priming Mouse Model Challenged with LPS

Microglial priming is the process of microglial proliferation and activation in response to neurodegeneration and abnormal protein accumulation. Priming makes microglia susceptible to secondary inflammatory stimuli and causes exaggerated inflammatory responses. In the present study, we established a microglial priming model in mice by administering a single injection of 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP, 20 mg/kg). MPTP induced microglial activation without dopaminergic degeneration;however, subsequent treatment with a sub-toxic dose of lipopolysaccharides (LPS) induced an amplified inflammatory response and caused nigrostriatal dopaminergic degeneration. These pathological and inflammatory changes, including microglial activation and dopaminergic cell loss in the substantia nigra (SN) area were reversed by papaverine (PAP) administration. In addition, MPTP/LPS enhanced interleukin-1β (IL-1β) expression and processing via nod-like receptor protein 3 (NLRP3) inflammasome activation in the SN region of mice. However, PAP treatment suppressed inflammasome activation and subsequent IL-1β maturation. Moreover, PAP inhibited nuclear factor-κB (NF-κB) and enhanced cAMP-response element binding protein (CREB) activity in the SN of MPTP/LPS mice. These results suggest that PAP inhibits the activation of NLRP3 inflammasome by modulating NF-κB and CREB signaling pathways, which results in reduced microglial activation and neuronal cell death. Thus, PAP may be a potential candidate for the treatment of Parkinsons’s disease, which is aggravated by systemic inflammation.

Papaverine Exerts Neuroprotective Effect by Inhibiting NLRP3Inflammasome Activation in an MPTP-Induced Microglial Priming Mouse Model Challenged with LPS

Microglial priming is the process of microglial proliferation and activation in response to neurodegeneration and abnormal protein accumulation. Priming makes microglia susceptible to secondary inflammatory stimuli and causes exaggerated inflammatory responses. In the present study, we established a microglial priming model in mice by administering a single injection of 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP, 20 mg/kg). MPTP induced microglial activation without dopaminergic degeneration;however, subsequent treatment with a sub-toxic dose of lipopolysaccharides (LPS) induced an amplified inflammatory response and caused nigrostriatal dopaminergic degeneration. These pathological and inflammatory changes, including microglial activation and dopaminergic cell loss in the substantia nigra (SN) area were reversed by papaverine (PAP) administration. In addition, MPTP/LPS enhanced interleukin-1β (IL-1β) expression and processing via nod-like receptor protein 3 (NLRP3) inflammasome activation in the SN region of mice. However, PAP treatment suppressed inflammasome activation and subsequent IL-1β maturation. Moreover, PAP inhibited nuclear factor-κB (NF-κB) and enhanced cAMP-response element binding protein (CREB) activity in the SN of MPTP/LPS mice. These results suggest that PAP inhibits the activation of NLRP3 inflammasome by modulating NF-κB and CREB signaling pathways, which results in reduced microglial activation and neuronal cell death. Thus, PAP may be a potential candidate for the treatment of Parkinsons’s disease, which is aggravated by systemic inflammation.

Imipramine Ameliorates Depressive Symptoms by Blocking Differential Alteration of Dendritic Spine Structure in Amygdala and Prefrontal Cortex of Chronic Stress-Induced Mice

Previous studies have shown disrupted synaptic plasticity and neural activity in depression. Such alteration is strongly associated with disrupted synaptic structures. Chronic stress has been known to induce changes in dendritic structure in the basolateral amygdala (BLA) and medial prefrontal cortex (mPFC), but antidepressant effect on structure of these brain areas has been unclear. Here, the effects of imipramine on dendritic spine density and morphology in BLA and mPFC subregions of stressed mice were examined. Chronic restraint stress caused depressive-like behaviors such as enhanced social avoidance and despair level coincident with differential changes in dendritic spine structure. Chronic stress enhanced dendritic spine density in the lateral nucleus of BLA with no significant change in the basal nucleus of BLA, and altered the proportion of stubby or mushroom spines in both subregions. Conversely, in the apical and basal mPFC, chronic stress caused a significant reduction in spine density. The proportion of stubby or mushroom spines in these subregions overall reduced while the proportion of thin spines increased after repeated stress. Interestingly, most of these structural alterations by chronic stress were reversed by imipramine. In addition, structural changes caused by stress and blocking the changes by imipramine were corelated well with altered activation and expression of synaptic plasticity-promoting molecules such as phospho-CREB, phospho-CAMKII, and PSD-95. Collectively, our data suggest that imipramine modulates stress-induced changes in synaptic structure and synaptic plasticity-promoting molecules in a coordinated manner although structural and molecular alterations induced by stress are distinct in the BLA and mPFC.

Neuroprotective Effect of β-Lapachone in MPTP-Induced Parkinson's Disease Mouse Model: Involvement of Astroglial p-AMPK/Nrf2/HO-1 Signaling Pathways

Parkinson's disease is a neurodegenerative disease characterized by the progressive loss of dopaminergic neurons within the substantia nigra pars compacta. In the present study, we investigated whether β-Lapachone (β-LAP), a natural naphthoquinone compound isolated from the lapacho tree (Tabebuia avellanedae), elicits neuroprotective effects in a 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP)-induced Parkinson's disease mouse model. β-LAP reduced the tyrosine hydroxylase (TH)-immuno-reactive fiber loss induced by MPTP in the dorsolateral striatum, and alleviated motor dysfunction as determined by the rotarod test. In addition, β-LAP protected against MPTP-induced loss of TH positive neurons, and upregulated B-cell lymphoma 2 protein (Bcl-2) expression in the substantia nigra. Based on previous reports on the neuroprotective role of nuclear factor-E2-related factor-2 (Nrf2) in neurodegenerative diseases, we investigated whether β-LAP induces upregulation of the Nrf2-hemeoxygenae-1 (HO-1) signaling pathway molecules in MPTP-injected mouse brains. Western blot and immunohistochemical analyses indicated that β-LAP increased HO-1 expression in glial fibrillary acidic protein-positive astrocytes. Moreover, β-LAP increased the nuclear translocation and DNA binding activity of Nrf2, and the phosphorylation of upstream adenosine monophosphate-activated protein kinase (AMPK). β-LAP also increased the localization of p-AMPK and Nrf2 in astrocytes. Collectively, our data suggest that β-LAP exerts neuroprotective effect in MPTP-injected mice by upregulating the p-AMPK/Nrf2/HO-1 signaling pathways in astrocytes.

Administration of Alpha(s1)-Casein Hydrolysate Increases Sleep and Modulates GABA(A) 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.

Rosmarinic Acid Alleviates Neurological Symptoms in the G93A-SOD1 Transgenic Mouse Model of Amyotrophic Lateral Sclerosis

Amyotrophic lateral sclerosis (ALS) is a neurodegenerative disease that affects motor neurons in the brain and spinal cord, resulting in paralysis of voluntary skeletal muscles and eventually death, usually within 2~3 years of symptom onset. The pathophysiology mechanism underlying ALS is not yet clearly understood. Moreover the available medication for treating ALS, riluzole, only modestly improves neurological symptoms and increases survival by a few months. Therefore, improved therapeutic strategies are urgently needed. In the present study, we investigated whether rosmarinic acid has a therapeutic potential to alleviate neurological deterioration in the G93A-SOD1 transgenic mouse model of ALS. Treatment of G93A-SOD1 transgenic mice with rosmarinic acid from 7 weeks of age at the dose of 400 mg/kg/day significantly extended survival, and relieved motor function deficits. Specifically, disease onset and symptom progression were delayed by more than one month. These symptomatic improvements were correlated with decreased oxidative stress and reduced neuronal loss in the ventral horns of G93A-SOD1 mice. These results support that rosmarinic acid is a potentially useful supplement for relieving ALS symptoms.

The Effects of Extracellular pH on Proliferation and Differentiation of human Bone Marrow Stem Cells

OBJECTIVES: The purpose of this study is to identify whether the change of pH affects the proliferation and the differentiation of human bone marrow stem cells (hBMSCs) and what mechanism is underlied. METHODS: To achieve objective of this study, hBMSCs were cultivated in the conditioned media adjusted to potential of hydrogen (pH) ranging from 6.4 to 8.0 using addition of hydrochloric acid (HCl) and sodium hydroxide (NaOH). The ratio of proliferation of hBMSCs according to the change of pH was measured for 24 h, 48 h, and 72 h using water-soluble tetrazolium salt (WST)-8 method. To elucidate the mechanism involved, hBMSCs was subjected to blocking extracellular signal-regulated kinases (ERK) and calcium sensing receptor (CaSR) activation. The Osteogenic-related genes and alkaline phosphatase (ALP) activity were tested under the conditioned media. RESULTS: The proliferation of hBMSCs was promoted under extracellular alkali conditions (pH 7.6~8.0) via CaSR/ERK pathway. On the other hand, the differentiation was inhibited/delayed via decreased ALP activity besides gene expression at pH 8.0. CONCLUSION: Extracellular alkali or acidic surrounding according to pH alteration can play a crucial role in hBMSC behavior including the proliferation and the differentiation.

The Effects of Extracellular pH on Proliferation and Differentiation of human Bone Marrow Stem Cells

OBJECTIVES: The purpose of this study is to identify whether the change of pH affects the proliferation and the differentiation of human bone marrow stem cells (hBMSCs) and what mechanism is underlied. METHODS: To achieve objective of this study, hBMSCs were cultivated in the conditioned media adjusted to potential of hydrogen (pH) ranging from 6.4 to 8.0 using addition of hydrochloric acid (HCl) and sodium hydroxide (NaOH). The ratio of proliferation of hBMSCs according to the change of pH was measured for 24 h, 48 h, and 72 h using water-soluble tetrazolium salt (WST)-8 method. To elucidate the mechanism involved, hBMSCs was subjected to blocking extracellular signal-regulated kinases (ERK) and calcium sensing receptor (CaSR) activation. The Osteogenic-related genes and alkaline phosphatase (ALP) activity were tested under the conditioned media. RESULTS: The proliferation of hBMSCs was promoted under extracellular alkali conditions (pH 7.6~8.0) via CaSR/ERK pathway. On the other hand, the differentiation was inhibited/delayed via decreased ALP activity besides gene expression at pH 8.0. CONCLUSION: Extracellular alkali or acidic surrounding according to pH alteration can play a crucial role in hBMSC behavior including the proliferation and the differentiation.