Effect of potassium channel blocker 4-aminopyridine pretreatment on the 6-OHDAinduced Parkinson's disease in rats

Background: Nuclease and caspase enzymes activities which promote death signals and lead to apoptosis are dependent to potassium ions. Objective: The aim of this study was to determine the effect of 4-aminopyridine (4-AP) potassium channel blocker on the animal model of Parkinson's disease. Methods: This experimental study was performed in Qazvin University of Medical Sciences, 2013. Male Rats were received different doses of 4-AP twice daily from half an hour before injection of 6- hydroxydopamine (6-OHDA) to 7 or 15 days after that. 6-OHDA was injected into medial forebrain bundle (MFB) in acute model groups and into striatum in chronic model groups. The severity of Parkinsonism was assessed by standard behavioral methods. Data were analyzed using KruskalWallis and Mann Whitney U tests. Findings: In acute model groups, administration of 0.5 mg/kg 4-AP (n=9) had no remarkable effect on behavioral symptoms, but 1 mg/kg 4-AP (n=8) significantly reduced the severity of apomorphine-induced rotations and improved motor learning in rotarod test. In chronic model groups, although 1 mg/kg 4-AP (n=7) significantly reduced the severity of rotations and improved motor learning, but 0.5 mg/kg 4-AP (n=8) was more effective. Conclusion: Pretreatment with 4-AP can reduce 6-OHDA-induced dopaminergic neuron death. Since the chronic model of 6-OHDA is more similar to Parkinson's disease in human, the low dose of 4-AP is recommended for treatment of this disease. Keywords: Parkinson Disease, Potassium Channel Blockers, Oxidopamine, Substantia Nigr

Prolonged hyperoxia preconditioning attenuates behavioral symptoms of 6-hydroxydopamine-induced Parkinsonism

Objectives: Several lines of evidences show that hyperoxia preconditioning provides neuronal protection against central nervous system ischemic damages. Common pathways including mitochondrial dysfunction, apoptosis, and caspase activation are involved in acute neurodegeneration (e.g. after cerebral ischemia) and chronic neurodegeneration (e.g. neuronal death in Parkinson's disease). The aim of the present research was to study the effect of hyperoxia preconditioning on 6-hydroxydopamine (6- OHDA)-induced Parkinsonism. Methods: Male Wistar rats were first subjected to either air with high oxygen concentration (> 90) or atmospheric air for prolonged (24 hours) or intermittent (six consecutive days, 4 hours each day) periods and then 6-OHDA was injected into their left striatums by stereotaxic surgery. Development and severity of the 6-OHDA-induced Parkinsonism was assessed using apomorphine-induced rotational test, elevated body swing test, and rotarod test within 2-5 weeks after the surgery. Results: Significant data obtained in rats treated with prolonged hyperoxia, but not the intermittent hyperoxia. In these rats, the number of apomorphine-induced rotations was ~ 60 lower than that in control and sham groups. Rats belonging to the prolonged hyperoxia group also showed considerably better motor performance and learning pattern in rotarod test. These results were confirmed by the data obtained in the elevated body swing test. Discussion: Our findings show that the prolonged hyperoxia preconditioning attenuates the behavioral symptoms of 6-OHDA-induced Parkinsonism. Considering the well-known correlation between dopaminergic neuronal death in the substantia nigra and the behavioral symptoms of 6-OHDA-induced Parkinsonism, it could be speculated that the prolonged hyperoxia preconditioning induces the mechanisms that provide dopaminergic neuroprotection against Parkinsonism-induced toxins. © W. S. Maney & Son Ltd 2012

The role of potassium channels in the regulation of calcium spike configuration in the cerebellar Purkinje neurons

Background: Calcium spikes play important roles in the control of neuronal spontaneous activity. Cerebellar Purkinje neurons fire spontaneous calcium spikes. In this study, the role of potassium channels in the regulation of these spikes was studied. Materials & Methods: Brain slices from the cerebellum of young rats were prepared and the Purkinje cells were visualized using an upright microscope. Using borosilicate micropipettes and Axoclamp 2B amplifier, intracellular recordings were taken from the cells. The role of different K+ channels in the regulation of calcium spikes configuration was determined using different K+ channels blockers and precise analysis of the recorded calcium spikes in the presence of blockers. Results: Application of wide-range 4-aminophyridine and tetraethylammonium blockers increased duration and amplitude of afterhyperpolarization (AHP) of the calcium spikes and converted them from one-peak spike to two- or multiple-peaks spikes. Blockade of small conductance calcium dependent potassium channels increased duration of the spikes but had no effect on the AHP amplitude Blockade of large conductance calcium dependent potassium channels increased duration of the calcium spikes and decreased the AHP amplitude. Conclusion: Our results showed that properties of the calcium spikes in the cerebellar Purkinje neurons were largely controlled by different potassium channels, including calcium dependent types

Trehalose and carnosic acid induced LC3I, LC3II ratio, P62 down-regulation and cleaved caspase 3 expression in neural stem cells

BACKGROUND: Using neural stem cells ( NSCs) in cell therapy and regenerative medicine is a growing knowledge. In this study, the protective role of carnosic acid and trehalose against H2O2-induced oxidative stress in autophagy induction and apoptosis inhibition in NSCs was investigated. MATERIAL AND METHODS: The bone marrow stromal cells (BMSCs) were isolated from the femur of the rat and differentiated into NSCs using basic fi broblast and epidermal growth factors (bFGF and EGF), and B27 serum free media. To evaluate the autophagy, the P62 protein was assessed by immunocytochemistry and LC3II / LC3I ratio by Western blotting. Further, we used 3-Methyladenine (3-MA), a widely used autophagy inhibitor to study whether combined treatment of 3-MA with carnosic acid and trehalose modulates autophagy in NSCs. For studying apoptosis, the cleaved caspase-3 protein was evaluated. Carnosic acid and trehalose increased the survival of the NSCs. RESULTS: The H2O2 decreased the autophagy and induced apoptosis with increasing time during 24 hours, however, a pre-treatment with 2 μM carnosic acid and trehalose 3 induced the autophagy proteins (while increasing the LC3II / LC3I ratio and decreasing the P62) and decreased the apoptosis (while decreasing the expression of the cleaved caspase-3). The results showed that the carnosic acid and trehalose increased the survival of NSCs against the oxidative stress caused by H2O2, decreased apoptosis, and induced autophagy. CONCLUSION: Due to the carnosic acid and trehalose unique properties and its low toxicity, it can be used as an agent in cellular transplantation for reducing oxidative stress and inducing autophagy © 2022, Bratislava Medical Journal. All Rights Reserved

Fatty acid modulated human serum albumin binding of the β-carboline alkaloids norharmane and harmane

Harmane and norharmane are representative members of the large group of natural β-carboline alkaloids featured with diverse pharmacological activities. In blood, these agents are transported by human serum albumin (HSA) which has a profound impact on the pharmacokinetic and pharmacodynamic properties of many therapeutic drugs and xenobiotics. By combination of various spectroscopic methods, the present contribution is aimed to elucidate how non-esterified fatty acids (FAs), the primary endogenous ligands of HSA, affect the binding properties of harmane and norharmane. Analysis of induced circular dichroism (CD) and fluorescence spectroscopic data indicates the inclusion of the neutral form of both molecules into the binding pocket of subdomain IIIA, which hosts two FA binding sites, too. The induced CD and UV absorption spectra of harmane and norharmane exhibit peculiar changes upon addition of FAs suggesting the formation of ternary complexes in which the lipid ligands significantly alter the binding mode of the alkaloids via cooperative allosteric mechanism. To our knowledge, it is the first instance of the demonstration of drug-FA co-binding at site IIIA. In line with these results, molecular docking calculations showed two distinct binding positions of norharmane within subdomain IIIA. The profound increase in the affinity constants of β-carbolines estimated in the presence of FAs predicts that the unbound, pharmacologically active serum fraction of these compounds strongly depends on the actual lipid binding profile of HSA