Lijia An

Nimodipine protects dopaminergic neurons against inflammation-mediated degeneration through inhibition of microglial activation

Nimodipine, a calcium channel blocker, has been used mainly in the therapy of cardiovascular diseases. Recently, its indications have been extended experimentally to a wider range of disorders especially some central nervous system (CNS) disorders. In this study, we investigated whether nimodipine is neuroprotective to inflammation-mediated neurodegenerative diseases. Pretreatment with nimodipine reduced the degeneration of dopaminergic (DA) neurons induced by LPS in mesencephalic neuron-glia cultures in a dose-dependent manner. The neuroprotective effect of nimodipine was attributed to the inhibition of microglial activation, since nimodipine significantly inhibited the production of nitric oxide (NO), tumor necrosis factor-alpha (TNF-alpha), interleukin-1beta (IL-1beta) and prostaglandin E(2) (PGE(2)) from LPS-stimulated microglia. Moreover, nimodipine was not neuroprotective to 1-methyi-4-phenylpyridinium (MPP(+))-induced DA neurotoxicity in the absence of microglia. Mechanistic study showed that nimodipine failed to protect the degeneration of neurons in neuron-glia cultures from mice lacking functional NADPH oxidase (PHOX), a key enzyme for extracellular superoxide production in immune cells. Taken together these results suggest that nimodipine is protective to DA neurodegeneration via inhibiting the microglial-mediated oxidative stress and inflammatory response. Thus, nimodipine may be a potential therapeutic agent for the treatment of inflammation-related neurodegenerative disorders such as Parkinsons disease.

Catalpol protects primary cultured astrocytes from in vitro ischemia-induced damage.

Catalpol, an iridoid glycoside abundant in the roots of Rehmannia glutinosa, has been previously found to prevent the loss of CA1 hippocampal neurons and to reduce working errors in gerbils after ischemia‐reperfusion injury. In the present study, we investigated the effects of catalpol on astrocytes in an ischemic model to further characterize its neuroprotective mechanisms. Primary cultured astrocytes exposed to oxygen‐glucose deprivation (OGD) followed by reperfusion (adding back oxygen and glucose, OGD‐R), were used as an in vitro ischemic model. Treatment of the astrocytes with catalpol during ischemia‐reperfusion increased astrocyte survival significantly in a concentration‐dependent manner, as demonstrated by 3‐(4,5‐dimethylthiazol‐2‐yl)‐2,5‐diphenyltetrazolium bromide (MTT) assay, lactate dehydrogenase (LDH) release and morphological observation. In addition, catalpol prevented the decrease in mitochondrial membrane potential, inhibited the formation of reactive oxygen species (ROS) and the production of nitric oxide (NO), decreased the level of lipid peroxide and the activity of inducible nitric oxide synthase (iNOS), and elevated the activities of superoxide dismutase (SOD), glutathione peroxidase (GPx) and the content of glutathione (GSH). Our results suggest that catalpol exerts the most significant cytoprotective effect on astrocytes by suppressing the production of free radicals and elevating antioxidant capacity.

Protective effects of catalpol against H2O2-induced oxidative stress in astrocytes primary cultures

It has been proposed that ROS production, including H(2)O(2), may lead to neurodegenerative disorders such as Parkinsons disease and Alzheimers disease. Catalpol, an iridoid glycoside, presents in the root of Rehmannia glutinosa, protects cells and mice from damage caused by a variety of toxic stimuli. In this study, we investigated whether catalpol could protect astrocytes from oxidant stress induced by H(2)O(2) because of the critical role of astrocytes in the brain and found the possible mechanism of protection. The results showed that catalpol could significantly increase the cell viability and reduce the intracellular ROS formation. Furthermore, catalpol attenuated H(2)O(2)-induced oxidative stress via preventing the decrease in the activities of antioxidant enzymes in glutathione redox cycling such as glutathione peroxidase, glutathione reductase and glutathione content. However, the catalase activity did not appear to be elevated by catalpol adequately. Together, the main mechanism underlying the protective effects of catalpol in H(2)O(2)-injured astrocytes might be related to the maintenance of glutathione metabolism balance and the decrease of ROS formation. Therefore, catalpol may be developed as a potential preventive or therapeutic drug for neurodegenerative diseases associated with oxidative stress.

Further pharmacological evidence of the neuroprotective effect of catalpol from Rehmannia glutinosa.

We have previously evaluated the neuroprotective effect of catalpol on aging mice induced by d-galactose, in which catalpol treatment ameliorated cognition deficits and attenuated oxidative damage in mice brain. To thoroughly elucidate the anti-aging effects of catalpol, the liver and spleen antioxidative systems and energy metabolism in senescent mice induced by d-galactose have been studied. Except control group, mice were subcutaneously injected with d-galactose (150mgkg(-1)body weight) for 6 weeks. Meanwhile, drug group mice were treated with catalpol (2.5, 5, 10mgkg(-1)body weight) and piracetam (300mgkg(-1)body weight) for the last 2 weeks. The activities of endogenous antioxidants and the level of glutathione (GSH) and lipid peroxide in the liver and spleen were assayed. Compared to control group, model group mice had significantly lower spleen index (spleen weight/body weight), lower level of GSH, lower activities of superoxide dismutase (SOD) and glutathione peroxidase (GSH-PX), higher level of malondialdehyde (MDA) in the liver and spleen. However, catalpol administration markedly reversed these effects of senescence induced by d-galactose. Simultaneously, catalpol noticeably elevated the decreased activities of lactate dehydrogenase (LDH), glutamine synthetase (GS), Na(+)-K(+)-ATPase, Ca(2+)-Mg(2+)-ATPase and decreased the elevated activity of creatine kinase (CK) in mice liver or spleen. These results implied that the anti-aging effects of catalpol were achieved at least partly by promoting endogenous antioxidant enzyme activities and normalizing energy disturbance. Catalpol may be a potential anti-aging agent and worth testing for further preclinical study aimed for senescence or neurodegenerative diseases such as Alzheimers and Parkinsons diseases.

D-galactose administration induces memory loss and energy metabolism disturbance in mice : Protective effects of catalpol

The neuroprotective effects of catalpol, an iridoid glycoside isolated from the fresh rehmannia roots, on the behavior and brain energy metabolism in senescent mice induced by d-galactose were assessed. Except control group, mice were subcutaneously injected with d-galactose (150 mg/kg body weight) for 6 weeks. From the fifth week, drug group mice were treated with catalpol (2.5, 5, 10 mg/kg body weight) and piracetam (300 mg/kg body weight) for the last 2 weeks. Behavioral changes including open field test and passive avoidance were examined after drug administration. To determine the brain damage, pathological alterations were measured by hematoxylin and eosin (HE) staining. The activities of lactate dehydrogenase (LDH), glutathione S-transferase (GSH-ST), glutamine synthetase (GS), creatine kinase (CK) in brain cortex and hippocampus were determined using different biochemical methods. Consistent with the cognition deficits, the activities of GSH-ST, GS and CK decreased while the activity of LDH increased in aging mice brain. Administration of catalpol for 2-weeks not only ameliorated cognition deficit, but also reversed the biochemical markers mentioned above and reduced the histological lesions in mouse brain. These results suggest that catalpol has protective effects on memory damage and energy metabolism failure in aging model mice and is worth testing for further preclinical study aimed for senescence or neurodegenerative diseases such as Alzheimers disease (AD) and Parkinsons disease (PD).

Catalpol attenuates the neurotoxicity induced by β-amyloid1–42 in cortical neuron–glia cultures

A glia-mediated inflammation plays an important role in the pathogenesis of Alzheimers disease (AD). In vitro, besides a direct neurotoxic effect on neurons, Abeta activates glia to produce an array of inflammatory factors including tumor necrosis factor-alpha (TNF-alpha), reactive oxygen species (ROS), nitric oxide (NO) and inducible nitric oxide synthase (iNOS), which accelerate the progression of AD. Catalpol, an iridoid glycoside, isolated from the root of Rehmannia glutinosa, protects neuronal cells from damage caused by a variety of toxic stimulus. In the present study, the effect of catalpol against Abeta(1-42)-induced neurotoxicity in primary cortical neuron-glia cultures as well as its mechanism acting on cells was further investigated. Pretreatment with catalpol at the dosage of 500 microM for 30 min prior to 5 microM Abeta(1-42) not only attenuated the Abeta(1-42)-triggered neurotoxicity to neurons but also inhibited the glial activation to some extent, which was examined by inspecting the morphological changes and measuring the release of the above mentioned inflammatory factors. Therefore, the results demonstrated that catalpol might be a promising anti-inflammatory agent in the therapy or prevention of neurodegenerative diseases associated with inflammation.

Catalpol attenuates nitric oxide increase via ERK signaling pathways induced by rotenone in mesencephalic neurons

Catalpol has been shown to rescue neurons from kinds of damage in vitro and in vivo in previous reports. However, the effect of catalpol on the nitric oxide (NO) system via MAPKs signaling pathway of mesencephalic neurons largely remains to be verified. The current study examined that whether catalpol modulated NO and iNOS increase by rotenone in primary mesencephalic neurons and investigated its underlying signaling pathways. Present results indicated that catalpol inhibited primary mesencephalic neurons from apoptosis by morphological assay, immunocytochemistry and flow cytometric evaluation. Moreover, the ERK signaling pathway plays an important role in NO-mediated degeneration of neuron. The current results suggest that catalpol is a potential agent for the prevention of neurons apoptosis by regulating NO and iNOS increase in ERK-mediated neurodegenerative disorders.

Systemic administration of catalpol prevents d-galactose induced mitochondrial dysfunction in mice

The aim of this work was to evaluate the mechanisms involved in the effects of catalpol on mitochondrial function through the measurements of nitric oxide synthase (NOS) activity, reactive oxygen species (ROS) production, respiratory complex activities and mitochondrial membrane potential (MMP) in the brain cortex and hippocampus mitochondria of senescent mice induced by d-galactose. Except control group, mice were subcutaneously injected with d-galactose (150 mg/kg body weight) for 6 weeks. Meanwhile, drug group mice were treated with catalpol (2.5, 5, 10mg/kg body weight) and piracetam (300 mg/kg body weight) for the last 2 weeks. The results indicated that respiratory complex activities decreased while NOS activities increased in d-galactose treated mice brain. The production of ROS increased remarkably and MMP collapsed in the brain of senescent mice induced by d-galactose. Administration of catalpol for 2 weeks significantly decreased ROS production and NOS activities, in accordance with its increase on complex activities and MMP level. Our results suggest that in vivo effects of catalpol on mitochondrial function can occur through different mechanisms, involving inhibiting NOS activity and ROS production, increasing respiratory complex activities and MMP level.

Catalpol protects rat pheochromocytoma cells against oxygen and glucose deprivation-induced injury.

Abstract Objectives: Catalpol has been identified to have neuroprotective effect on gerbils subjected to transient global cerebral ischemia. However, the mechanism that catalpol prevents ischemia is still unclear. In the present study, PC12 cells, exposed to oxygen and glucose deprivation (OGD) followed by reperfusion, were used as an in vitro model of ischemia. The protective effects of catalpol were investigated in ischemic-induced apoptosis in PC12 cells. Methods: After OGD for 3 hours and reoxygenation for 18 hours, cell survival was quantified by the reduction of 3-(4,5-Dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT). The activities of superoxide dismutase (SOD) and glutathione peroxidase (GSH-PX) were determined using commercially available kits. Caspase-3 assay was performed using caspase-3 assay kit. Microplate reader was used to detect the intensities of rhodamine123 (Rh123) and reactive oxygen species (ROS). The level of Bcl-2 protein was measured by flow cytometry. Results: Catalpol attenuated ischemia-induced apoptotic death via preventing the decrease in the level of Bcl-2 protein and the activities of SOD and GSH-PX, inhibiting the reduction of mitochondrial membrane potential and suppressing activation of caspase-3. Discussion: The results suggest that the catalpol has the potential to prevent ischemic-induced apoptosis.

Purification and characterization of Ulva pertusa Kjellm alkaline phosphatase.

Abstract The activity of alkaline phosphatase (ALP, EC 3.1.3.1.) was found in seaweeds, including five kinds of green alga, eighteen kinds of red alga, and six kinds of brown alga, collected from the seaside of Dalian in China. The enzyme was purified 1230-fold from Ulva pertusa Kjellm. It had a specific activity of 48.6 U/mg protein and was proven to be homogeneous by SDS-PAGE with a subunit molecular mass of 19.5 kDa. The activity of ALP peaked at pH 9.8, and was completely inhibited by DTT and partly by NBS. The Michaelis-Menten constant Km and the maximum reaction velocity Vmax, at pH 9.8 and 37°C were 0.950 mM and 5.00 µM/min, respectively.