Muhammed Khairujjaman Mazumder

A highly reproducible mice model of chronic kidney disease: Evidences of behavioural abnormalities and blood-brain barrier disruption

AIMS In the present study, a novel mice model of chronic kidney disease (CKD) was developed, and psycho-motor behavioural abnormalities, blood-brain barrier (BBB) integrity and brain histology were studied. MAIN METHODS Swiss albino female mice were given high adenine diet (0.3% w/w mixed with feed) for 4weeks. Serum urea and creatinine levels and renal histological studies were performed to validate the model. Psycho-motor behavioural abnormalities and neurological severity were studied. BBB integrity was assessed using Evans blue extravasation method. Nissl staining was performed to see possible morphological aberrations in brain. KEY FINDINGS There was a significant increase in serum urea and creatinine levels in mice given high adenine diet, and the mice had abnormal kidney morphology. Deposition of adenine and 2,8-dihydroxyadenine crystals, and increased collagen deposits in the renal tissues were found, which validate induction of CKD in the mice. Motor behavioural abnormalities, depression-like and anxiolytic behaviour and increase in neurological severity were prevalent in mice with CKD. Evans Blue dye extravasation was found to occur in the brain, which signifies disruption of BBB. However, Nissl staining did not reveal any morphological aberration in brain tissue. SIGNIFICANCE The present study puts forward a highly reproducible mice model of CKD validated with serum parameters and renal histopathological changes. The mice showed psycho-motor behavioural abnormalities and BBB disruption. It is a convenient model to study the disease pathology, and understanding the associated disorders, and their therapeutic interventions.

β-Phenethylamine—A Phenylalanine Derivative in Brain—Contributes to Oxidative Stress by Inhibiting Mitochondrial Complexes and DT-Diaphorase: An In Silico Study

Till date, the mode of action of β‐PEA on neurons is not well illustrated. We tested the hypothesis that β–PEA has the ability to cause oxidative stress by inhibiting the antioxidant enzyme DT‐diaphorase and mitochondrial complexes (Complex‐I and complex‐III).

Contribution of β-phenethylamine, a component of chocolate and wine, to dopaminergic neurodegeneration: implications for the pathogenesis of Parkinson's disease

While the cause of dopaminergic neuronal cell death in Parkinson’s disease (PD) is not yet understood, many endogenous molecules have been implicated in its pathogenesis. β-phenethylamine (β-PEA), a component of various food items including chocolate and wine, is an endogenous molecule produced from phenylalanine in the brain. It has been reported recently that long-term administration of β-PEA in rodents causes neurochemical and behavioral alterations similar to that produced by parkinsonian neurotoxins. The toxicity of β-PEA has been linked to the production of hydroxyl radical (.OH) and the generation of oxidative stress in dopaminergic areas of the brain, and this may be mediated by inhibition of mitochondrial complex-I. Another signifi cant observation is that administration of β-PEA to rodents reduces striatal dopamine content and induces movement disorders similar to those of parkinsonian rodents. However, no reports are available on the extent of dopaminergic neuronal cell death after administration of β-PEA. Based on the literature, we set out to establish β-PEA as an endogenous molecule that potentially contributes to the progressive development of PD. The sequence of molecular events that could be responsible for dopaminergic neuronal cell death in PD by consumption of β-PEA-containing foods is proposed here. Thus, long-term over-consumption of food items containing β-PEA could be a neurological risk factor having significant pathological consequences.

Inhibition of matrix metalloproteinase-2 and 9 by Piroxicam confer neuroprotection in cerebral ischemia: an in silico evaluation of the hypothesis.

Matrix metalloproteinases are zinc-containing endopeptidases that are involved in extracellular matrix (ECM) remodeling cascade in many neurological disorders, including cerebral ischemia (CI). Remodeling of the ECM followed by disruption of the blood-brain barrier (BBB) is one of the major factors contributing to the ultimate neurodegeneration in CI. BBB disruption causes a cascade of pathophysiologies that trigger Anoikis-like cell death. While inhibition of MMP-2 and MMP-9 decreases the extent of neuronal damage in CI, MMP-2/9 knock-out mice have reduced infarct volume in experimental animal models of CI. Piroxicam, which is a non-steroidal anti-inflammatory drug (NSAID), has been demonstrated to be protective against aquaporin-4 and acid-sensing ion channel 1a--mediated neurodegeneration in CI. However, no report exists on the inhibitory action of Piroxicam on MMPs. We tested the hypothesis that Piroxicam, with its larger molecular size and more number of interacting pharmacophores, can inhibit MMP-2 and MMP-9. A comparative study on the inhibitory potential of Piroxicam with other reported MMP-inhibitors, viz., Aspirin, Melatonin and Doxycycline, has also been performed. Since the drug has already been reported to be neuroprotective through its inhibitory action in other pathways, it can be the drug of choice in the therapeutic management and prevention of neurodegeneration in CI.

L-DOPA treatment in MPTP-mouse model of Parkinson’s disease potentiates homocysteine accumulation in substantia nigra

One of the intermediates of methionine cycle, the homocysteine (Hcy), elevates in plasma of Parkinsons disease (PD) patients undergoing L-DOPA (3,4-dihydroxyphenylalanine) therapy and has been regarded as a risk factor of the disease. Several evidences pointed out that Hcy causes degeneration of dopaminergic neurons. In rodent, elevated level of Hcy in brain or infusion of the same directly into the substantia nigra (SN) potentiates dopaminergic neurodegeneration. However, the influence of L-DOPA therapy on the levels of Hcy in dopamine-rich regions of the brain (striatum and SN) of experimental models of PD is not known. The present study, for the first time, tested the hypothesis that L-DOPA treatment in experimental mouse model of PD potentiates Hcy accumulation in the dopamine-rich regions of the brain. We found a significant elevation of Hcy level in nigrostriatum in naïve as well as parkinsonian mice as a result of chronic L-DOPA treatment. Interestingly, L-DOPA treatment significantly elevates Hcy level in nigra but not in striatum of parkinsonian mice, when compared with L-DOPA naïve group. However, there is no significant decrease in the number of dopaminergic neurons in SN region in the parkinsonian mice given L-DOPA treatment. Thus, the present study demonstrates that L-DOPA treatment potentiates the level of Hcy in the SN without causing aggravated neurodegeneration in parkinsonian mice model.

Cholesterol in Pancreatic β-Cell Death and Dysfunction: Underlying Mechanisms and Pathological Implications.

Abstract The mechanisms or causes of pancreatic &bgr;-cell death as well as impaired insulin secretion, which are the principal events of diabetic etiopathology, are largely unknown. Diabetic complications are known to be associated with abnormal plasma lipid profile, mainly elevated level of cholesterol and free fatty acids. However, in recent years, elevated plasma cholesterol has been implicated as a primary modulator of pancreatic &bgr;-cell functions as well as death. High-cholesterol diet in animal models or excess cholesterol in pancreatic &bgr;-cell causes transporter desensitization and results in morphometric changes in insulin granules. Moreover, cholesterol is also held responsible to cause oxidative stress, mitochondrial dysfunction, and activation of proapoptotic markers leading to &bgr;-cell death. The present review focuses on the pathways and molecularevents that occur in the &bgr;-cell under the influence of excess cholesterol that hampers the basal physiology of the cell leading to the progression of diabetes.

Piroxicam confer neuroprotection in Cerebral Ischemia by inhibiting Cyclooxygenases, Acid- Sensing Ion Channel-1a and Aquaporin-4: an in silico comparison with Aspirin and Nimesulide

Cerebral ischemia (CI), caused by the deprivation of oxygen and glucose to the brain, is the leading cause of permanent disability. Neuronal demise in CI has been linked to several pathways which include cyclooxygenases (COX) − mediated production of prostaglandins (PGs) and subsequently reactive oxygen species (ROS), aquaporin-4 (AQ-4) − mediated brain edema and acidsensing ion channel-1a (ASIC-1a) − mediated acidotoxicity, matrix remodeling, in addition to others. Several non-steroidal antiinflammatory drugs (NSAIDs) are presently in use to prevent these pathways. However, owing to the large number of processes involved, there is high drug load. So, identifying drugs with multimodal role has always been a frequently sought venture. The present in silico study has been performed to find out the relative efficacy of three different NSAIDs (Piroxicam, Aspirin and Nimesulide) in preventing neurodegeneration in CI, with respect to their inhibitory potential on COXs, AQ-4 and ASIC-1a. We find that piroxicam is the most potent inhibitor of these receptors as compared to the NSAIDs under investigation. Since piroxicam has already been reported to inhibit N-methyl-D-aspartate (NMDA) receptor and matrix metalloproteinases (MMPs), which are also linked to CI-induced neurodegeneration, we hereby propose piroxicam to be a gold-standard drug in preventing neurodegeneration in CI.

Piroxicam inhibits NMDA receptor-mediated excitotoxicity through allosteric inhibition of the GluN2B subunit: An in silico study elucidating a novel mechanism of action of the drug ☆

Hyperactivation of GluN2B subunit containing N-methyl-d-aspartate receptors (NMDARs) significantly contributes to the development of several neurodegenerative diseases through a process called excitotoxicity. NMDARs are voltage-gated Ca2+ channels which when activated lead to excessive influx of Ca2+ into neurons thereby exacerbating several calcium-dependent pathways that cause oxidative stress and apoptosis. Several drugs are presently in use to counter the NMDAR-mediated excitotoxic events among which Ifenprodil and its derivatives are GluN2B selective allosteric antagonists. Certain non-steroidal anti-inflammatory drugs (NSAIDs) have also been reported to inhibit NMDARs and the resultant pathologies. Meanwhile, Piroxicam, which is a NSAID, has been reported to be protective in cerebral ischemia-induced neurodegeneration through various pathways. Since Piroxicam has more number of interacting groups as compared to other NSAIDs and also has structural similarities with Ifenprodil, we thought it prudent that Piroxicam may inhibit NMDARs similar to Ifenprodil. By using molecular docking as a tool, we validated the hypothesis and hereby report for the first time that Piroxicam can inhibit GluN2B containing NMDARs through allosteric mode similar to the well known selective antagonist--Ifenprodil; and thus can be a therapeutic drug for the prevention of excitotoxic neurodegeneration.

Garcinol prevents hyperhomocysteinemia and enhances bioavailability of L-DOPA by inhibiting catechol-O-methyltransferase: an in silico approach

Inhibition of catechol-O-methyltransferase (COMT), with drugs like tolcapone and entacapone, has been in practice to reduce L-DOPA-induced hyperhomocysteinemia in Parkinson’s disease (PD) patients. During L-DOPA methylation, S-adenosylhomocysteine is produced which is further processed to synthesize homocysteine (Hcy). Hcy has been reported to cause oxidative stress, excitotoxicity, DNA damage and neurodegeneration and is surmised to exaggerate motor complications in PD patients undergoing L-DOPA therapy. Moreover, COMT catalyzes the conversion of L-DOPA into 3-O-methyldopa (3-OMD) and dopamine (DA) into 3-methoxytyramine (3-MT). 3-OMD inhibits penetration of L-DOPA in brain as well as striatal uptake of the drug, while 3-MT is a neuromodulator which during further metabolism produces reactive oxygen species. Thus, COMT inhibition enhances the levels of L-DOPA and DA, which may be exploited to reduce the effective dose of L-DOPA in maintaining the levels of DA in PD patients, and thereby in treating the motor disorders by enhancing the bioavailability of the drug. Since presently used COMT inhibitors elicit several side effects, development of novel drugs is highly sought. Garcinol, a phyto-constituent, is a potent antioxidant and anti-inflammatory molecule effective against several disorders. However, its role in PD is unknown. Here, the COMT inhibitory potential of garcinol has been investigated using computational tools. The 3D structure of COMT, garcinol and tolcapone was downloaded from respective databases, and molecular docking was performed to obtain docking scores and interactions which revealed that garcinol binds to the active site of COMT similar to tolcapone. While tolcapone forms three hydrogen bonds and seven weak interactions with a docking score of −25.3575, garcinol forms four hydrogen bonds and nine weak interactions and has a docking score of −17.0983. Thus, the present study demonstrated garcinol to potentially interact with the active site of COMT and therefore inhibit the enzyme. Since COMT inhibition reduces Hcy levels, in addition to 3-OMD and 3-MT, as well as increases the bioavailability of DA and L-DOPA, the present study is of immense importance in the treatment of PD. Moreover, since garcinol is an established antioxidant and anti-inflammatory molecule, it may confer further neuroprotection and may emerge as a therapeutic anti-Parkinsonian drug in the future.Graphical Abstract

Disturbed purine nucleotide metabolism in chronic kidney disease is a risk factor for cognitive impairment

Chronic kidney disease (CKD) is an increasing global health burden. Disturbance in purine metabolism pathway and a higher level of serum uric acid, called hyperuricemia, is a risk factor of CKD, and it has been linked to increased prevalence and progression of the disease. In a recent study, it has been demonstrated that purine nucleotides and uric acid alter the activity of acetylcholinesterase (AChE). Thus, we hypothesize that adenine, hypoxanthine, xanthine, 2,8-dihydroxyadenine and uric acid may potentially interfere with the activity of AChE. The hypothesis has been tested using computational tools. Uric acid has been found to be the most potent inhibitor of AChE, with a binding affinity higher than the known inhibitors of the enzyme. Further, since depleted AChE activity is associated with dementia and cognitive impairment, the present study suggest that disturbed purine nucleotide metabolism in CKD is a risk factor for cognitive impairment.