Oxidative stress associated with impaired autonomic control and severity of lung function in chronic obstructive pulmonary disease patients.

Oxidative stress has been suggested to play a role in the pathogenesis of chronic obstructive pulmonary disease (COPD). This study aimed to investigate a link between malondialdehyde (MDA) levels, pulmonary function, and cardiac autonomic control in patients with COPD. Plasma levels of MDA, heart rate variability, and pulmonary function were measured in 50 clinically stable COPD patients and 50 normal male controls. COPD patients exhibited lower means of the standard deviations of all normal to normal (NN) intervals (SDNN), the square root of the mean of the sum of the squares of differences between adjacent NN intervals (RMSSD), and high frequency (HF). Nevertheless, they presented greater low frequency (LF) and low frequency/high frequency ratio (LF/HF ratio) in supine and head-up tilt positions than controls (P<0.001). More-over, a negative correlation between MDA levels with SDNN (P<0.001) and a positive correlation with LF (P<0.01) and LF/HF ratio (P<0.05) were observed in both positions. In COPD patients, plasma MDA levels were 2.3 times greater than controls (4.33±2.03 µM vs. 1.89±0.39 µM, P<0.001), and they were inversely correlated with forced vital capacity, forced expiratory volume in 1 sec, midexpiratory flow, and peak expiratory flow (P<0.001). Our findings suggest a potential role for oxidative stress in impaired cardiac autonomic control and clinical relevance of plasma MDA levels as a predictor of severity of COPD in COPD patients.

Pinostrobin alleviates chronic restraint stress­induced cognitive impairment by modulating oxidative stress and the function of astrocytes in the hippocampus of rats.

Chronic stress has been recognized to induce the alterations of neuronal and glial cells in the hippocampus, and is thus implicated in cognitive dysfunction. There is increasing evidence to indicate that natural compounds capable of exerting neuroprotective and antioxidant activities, may function as potential therapeutic agents for cognitive impairment. The present study examined the neuroprotective effects of pinostrobin from Boesenbergia rotunda (L.) against chronic restraint stress (CRS)-induced cognitive impairment associated with the alterations of oxidative stress, neuronal density and glial fibrillary acidic protein (GFAP) of astrocytes in the hippocampus. For this purpose, male Wistar rats were administered once daily with pinostrobin (20 and 40 mg/kg, per os) prior to exposure to CRS (6 h/day) for 21 days. The cognitive behaviors, the concentration of malondialdehyde, and the activities of superoxide dismutase and catalase were determined. Histologically, the alterations in astrocytic GFAP and excitatory amino acid transporter 2 (EAAT2) in the hippocampus were examined. The results revealed that pinostrobin potentially attenuated cognitive impairment in the Y-maze and in novel object recognition tests, with a reduction in oxidative stress. Furthermore, pinostrobin effectively increased neuronal density, as well as the immunoreactivities of GFAP and EAAT2 in the hippocampus. Taken together, these findings indicate that treatment with pinostrobin alleviates chronic stress-induced cognitive impairment by exerting antioxidant effects, reducing neuronal cell damage, and improving the function of astrocytic GFAP and EAAT2. Thus, pinostrobin may have potential for use as a neuroprotective agent to protect against chronic stress-induced brain dysfunction and cognitive deficits.

Pinostrobin mitigates neurodegeneration through an up-regulation of antioxidants and GDNF in a rat model of Parkinson's disease.

Background: One of the most common neurodegenerative diseases is Parkinson's disease (PD); PD is characterized by a reduction of neurons containing dopamine in the substantia nigra (SN), which leads to a lack of dopamine (DA) in nigrostriatal pathways, resulting in motor function disorders. Oxidative stress is considered as one of the etiologies involved in dopaminergic neuronal loss. Thus, we aimed to investigate the neuroprotective effects of pinostrobin (PB), a bioflavonoid extracted from Boesenbergia rotunda with antioxidative activity in PD. Methods: Rats were treated with 40 mg/kg of PB for seven consecutive days before and after 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP)-induced PD. After completing the experiment, the brains including SN and striatum were used for histological studies and biochemical assays. Results: PB treatment demonstrated a reduction of free radicals in the SN as indicated by significantly decreased MDA levels, whereas the antioxidative enzymes (SOD and GSH) were significantly increased. Furthermore, PB treatment significantly increased glial cell line-derived neurotrophic factor (GDNF) immunolabelling which has neurotrophic and neuroprotective effects on the survival of dopaminergic neurons. Furthermore, PB treatment was shown to protect CA1 and CA3 neurons in the hippocampus and dopaminergic neurons in the SN. DA levels in the SN were increased after PB treatment, leading to the improvement of motor function of PD rats. Conclusions: These results imply that PB prevents MPTP-induced neurotoxicity via its antioxidant activities and increases GDNF levels, which may contribute to the therapeutic strategy for PD.

Lotus essential oil improves neurite elongation and facilitates functional recovery after peripheral nerve injury.

Injury to the peripheral nerve may lead to deficits in nerve function. An increase in the levels of free radicals plays a role in inhibition of nerve regeneration following damage. The aim of this study was to investigate the effects of lotus essential oil (LEO) on neurite outgrowth in vitro and nerve regeneration in vivo in a rat model of sciatic nerve crush injury. Gas chromatography-mass spectrometry analysis showed that the principal constituent of LEO was palmitic acid ethyl ester (25.12%). The radical scavenging activity of LEO was evaluated using the DPPH method, and was determined to be IC50=29.01±2.93 µg/ml. LEO-treated sensory neurons exhibited increased neurite outgrowth and upregulated levels of phospho-ERK. Sensory and motor functions were improved in rats treated with 50 and 100 mg/kg LEO, and this was accompanied by an increase in the number of neurons in the dorsal root ganglia, as well as an increase in the nerve axon diameters following nerve injury. Taken together, these results suggests that LEO may serve as a novel pharmacological option for the management of peripheral nerve injury.

The Neuroprotective Effect of Zingiber cassumunar Roxb. Extract on LPS-Induced Neuronal Cell Loss and Astroglial Activation within the Hippocampus.

The systemic administration of lipopolysaccharide (LPS) has been recognized to induce neuroinflammation which plays a significant role in the pathogenesis of neurodegenerative diseases such as Alzheimer's disease and Parkinson's disease. In this study, we aimed to determine the protective effect of Zingiber cassumunar (Z. cassumunar) or Phlai (in Thai) against LPS-induced neuronal cell loss and the upregulation of glial fibrillary acidic protein (GFAP) of astrocytes in the hippocampus. Adult male Wistar rats were orally administered with Z. cassumunar extract at various doses (50, 100, and 200 mg/kg body weight) for 14 days before a single injection of LPS (250 µg/kg/i.p.). The results indicated that LPS-treated animals exhibited neuronal cell loss and the activation of astrocytes and also increased proinflammatory cytokine interleukin- (IL-) 1ß in the hippocampus. Pretreatment with Z. cassumunar markedly reduced neuronal cell loss in the hippocampus. In addition, Z. cassumunar extract at a dose of 200 mg/kg BW significantly suppressed the inflammatory response by reducing the expression of GFAP and IL-1ß in the hippocampus. Therefore, the results suggested that Z. cassumunar extract might be valuable as a neuroprotective agent in neuroinflammation-induced brain damage. However, further investigations are essential to validate the possible active ingredients and mechanisms of its neuroprotective effect.

Effect of Azadirachta indica flower extract on functional recovery of sciatic nerve crush injury in rat models of DM.

Chronic hyperglycemia causes nerves to be more susceptible to compression, which often occurs as a result of hyperglycemia-induced oxidative stress. Oxidative stress impairs nerve function and delays nerve recovery. Azadirachta indica, a herb from Thailand, possesses antioxidant and antidiabetic properties. The aim of the present study was therefore to investigate the effect of A. indica flower extract on the functional recovery of a sciatic nerve crush injury in rat models of diabetes mellitus (DM). Male Wistar rats were randomly assigned into seven groups including the control rats, rats with DM subjected to sham surgery and treated with vehicle, and rats with DM subjected to the crush surgery and treated with vehicle or A. indica flower extract at a dose of 250, 500 or 750 mg/kg animal body weight, or with vitamin C. DM was induced using a single intraperitoneal injection of streptozotocin (55 mg/kg animal body weight). Rats subjected to a sciatic nerve crush injury or sham surgery were orally treated with either vehicle, A. indica flower extract or vitamin C for 21 days. Functional recovery was assessed every 3 days using a walking track analysis, foot withdrawal reflex test and rotarod test. At the end of the study, the rats were sacrificed and their left sciatic nerves were harvested in order to determine malondialdehyde levels, superoxide dismutase activity and axon density. The treatment with A. indica flower extract significantly improved functional recovery, especially motor and sensory functions. The extract significantly decreased malondialdehyde levels, and increased superoxide dismutase activity and axon density. The results of the current study indicate that the mechanism underlying the enhanced functional recovery of the sciatic nerve following treatment with A. indica flower extract may be associated with an antioxidative effect. However, further studies are required to confirm the current results.

Sprouty2 and -4 hypomorphism promotes neuronal survival and astrocytosis in a mouse model of kainic acid induced neuronal damage.

Sprouty (Spry) proteins play a key role as negative feedback inhibitors of the Ras/Raf/MAPK/ERK pathway downstream of various receptor tyrosine kinases. Among the four Sprouty isoforms, Spry2 and Spry4 are expressed in the hippocampus. In this study, possible effects of Spry2 and Spry4 hypomorphism on neurodegeneration and seizure thresholds in a mouse model of epileptogenesis was analyzed. The Spry2/4 hypomorphs exhibited stronger ERK activation which was limited to the CA3 pyramidal cell layer and to the hilar region. The seizure threshold of Spry2/4(+/-) mice was significantly reduced at naive state but no difference to wildtype mice was observed 1 month following KA treatment. Histomorphological analysis revealed that dentate granule cell dispersion (GCD) was diminished in Spry2/4(+/-) mice in the subchronic phase after KA injection. Neuronal degeneration was reduced in CA1 and CA3 principal neuron layers as well as in scattered neurons of the contralateral CA1 and hilar regions. Moreover, Spry2/4 reduction resulted in enhanced survival of somatostatin and neuropeptide Y expressing interneurons. GFAP staining intensity and number of reactive astrocytes markedly increased in lesioned areas of Spry2/4(+/-) mice as compared with wildtype mice. Taken together, although the seizure threshold is reduced in naive Spry2/4(+/-) mice, neurodegeneration and GCD is mitigated following KA induced hippocampal lesions, identifying Spry proteins as possible pharmacological targets in brain injuries resulting in neurodegeneration. The present data are consistent with the established functions of the ERK pathway in astrocyte proliferation as well as protection from neuronal cell death and suggest a novel role of Spry proteins in the migration of differentiated neurons.

Enhanced axon outgrowth and improved long-distance axon regeneration in sprouty2 deficient mice.

Sprouty (Spry) proteins are negative feedback inhibitors of receptor tyrosine kinase signaling. Downregulation of Spry2 has been demonstrated to promote elongative axon growth of cultured peripheral and central neurons. Here, we analyzed Spry2 global knockout mice with respect to axon outgrowth in vitro and peripheral axon regeneration in vivo. Neurons dissociated from adult Spry2 deficient sensory ganglia revealed stronger extracellular signal-regulated kinase activation and enhanced axon outgrowth. Prominent axon elongation was observed in heterozygous Spry2(+/-) neuron cultures, whereas homozygous Spry2(-/-) neurons predominantly exhibited a branching phenotype. Following sciatic nerve crush, Spry2(+/-) mice recovered faster in motor but not sensory testing paradigms (Spry2(-/-) mice did not tolerate anesthesia required for nerve surgery). We attribute the improvement in the rotarod test to higher numbers of myelinated fibers in the regenerating sciatic nerve, higher densities of motor endplates in hind limb muscles and increased levels of GAP-43 mRNA, a downstream target of extracellular regulated kinase signaling. Conversely, homozygous Spry2(-/-) mice revealed enhanced mechanosensory function (von Frey's test) that was accompanied by an increased innervation of the epidermis, elevated numbers of nonmyelinated axons and more IB4-positive neurons in dorsal root ganglia. The present results corroborate the functional significance of receptor tyrosine kinase signaling inhibitors for axon outgrowth during development and nerve regeneration and propose Spry2 as a novel potential target for pharmacological inhibition to accelerate long-distance axon regeneration in injured peripheral nerves.

Rho-independent stimulation of axon outgrowth and activation of the ERK and Akt signaling pathways by C3 transferase in sensory neurons.

Peripheral nerve injury triggers the activation of RhoA in spinal motor and peripheral sensory neurons. RhoA activates a number of effector proteins including the Rho-associated kinase, ROCK, which targets the cytoskeleton and leads to inhibition of neurite outgrowth. Blockade of the Rho/ROCK pathway by pharmacological means improves axon regeneration after experimental injury. C3(bot) transferase, an exoenzyme produced by Clostridium botulinum, inactivates RhoA by ADP-ribosylation. It has been successfully applied in experimental CNS lesions to facilitate axon regeneration. Up to now it was not investigated thoroughly whether C3(bot) exerts positive effects on peripheral axon regeneration as well. In the present study, recombinant membrane permeable C3(bot) produced a small, but significant, axon outgrowth effect on peripheral sensory neurons dissociated from adult dorsal root ganglia (DRG) of the rat. Neuronal overexpression of C3, however, did not enhance axonal growth. Moreover, transfection of plasmids encoding dominant negative RhoA or RhoA specific shRNAs failed to increase axonal growth. Furthermore, we show that the C3(bot) mutant, C3(E174Q), which lacks RhoA inhibitory activity, still stimulates axonal growth. When analyzing possible signaling mechanisms we found that extracellular signal-regulated kinase (ERK) and Akt are activated by C3(bot) and ERK is induced by the C3(E174Q) mutant. Upregulation of kinase activities by C3(bot) occurs significantly faster than inactivation of RhoA indicating a RhoA-independent pathway of action by C3(bot). The induction of ERK signaling by C3(bot) was detected in embryonic hippocampal neurons, too. Taken together, although RhoA plays a central role for inhibition of axon outgrowth by myelin-derived inhibitors, it does not interfere with axonal growth of sensory neurons on a permissive substrate in vitro. C3(bot) blocks neuronal RhoA activity, but its positive effects on axon elongation and branching appear to be mediated by Rho independent mechanisms involving activation of axon growth promoting ERK and Akt kinases.