Minocycline modulates neuroprotective effect of hesperidin against quinolinic acid induced Huntington's disease like symptoms in rats: behavioral, biochemical, cellular and histological evidences

Effectiveness of Flavonoid-Rich Diet in Alleviating Symptoms of Neurodegenerative Diseases

Over the past decades, there has been a significant increase in the burden of neurological diseases, including neurodegenerative disorders, on a global scale. This is linked to a widespread demographic trend in which developed societies are aging, leading to an increased proportion of elderly individuals and, concurrently, an increase in the number of those afflicted, posing one of the main public health challenges for the coming decades. The complex pathomechanisms of neurodegenerative diseases and resulting varied symptoms, which differ depending on the disease, environment, and lifestyle of the patients, make searching for therapies for this group of disorders a formidable challenge. Currently, most neurodegenerative diseases are considered incurable. An important aspect in the fight against and prevention of neurodegenerative diseases may be broadly understood lifestyle choices, and more specifically, what we will focus on in this review, a diet. One proposal that may help in the fight against the spread of neurodegenerative diseases is a diet rich in flavonoids. Flavonoids are compounds widely found in products considered healthy, such as fruits, vegetables, and herbs. Many studies indicated not only the neuroprotective effects of these compounds but also their ability to reverse changes occurring during the progression of diseases such as Alzheimer's, Parkinson's and amyotrophic lateral sclerosis. Here, we present the main groups of flavonoids, discussing their characteristics and mechanisms of action. The most widely described mechanisms point to neuroprotective functions due to strong antioxidant and anti-inflammatory effects, accompanied with their ability to penetrate the blood-brain barrier, as well as the ability to inhibit the formation of protein aggregates. The latter feature, together with promoting removal of the aggregates is especially important in neurodegenerative diseases. We discuss a therapeutic potential of selected flavonoids in the fight against neurodegenerative diseases, based on in vitro studies, and their impact when included in the diet of animals (laboratory research) and humans (population studies). Thus, this review summarizes flavonoids' actions and impacts on neurodegenerative diseases. Therapeutic use of these compounds in the future is potentially possible but depends on overcoming key challenges such as low bioavailability, determining the therapeutic dose, and defining what a flavonoid-rich diet is and determining its potential negative effects. This review also suggests further research directions to address these challenges.

Minocycline as a prospective therapeutic agent for cancer and non-cancer diseases: a scoping review

Minocycline is an FDA-approved secondary-generation tetracycline antibiotic. It is a synthetic antibiotic having many biological effects, such as antioxidant, anti-inflammatory, anti-cancer, and neuroprotective functions. This study discusses the pharmacological mechanisms of preventive and therapeutic effects of minocycline. Specifically, it provides a comprehensive overview of the molecular pathways by which minocycline acts on the different cancers, including ovarian, breast, glioma, colorectal, liver, pancreatic, lung, prostate, melanoma, head and neck, leukemia, and non-cancer diseases such as Alzheimer's disease, Parkinson, schizophrenia, multiple sclerosis, Huntington, polycystic ovary syndrome, and coronavirus disease 19. Minocycline may be a potential medication for these disorders due to its strong blood-brain barrier penetrance. It is also widely accepted as a specific medication, has a well-known side-effect characteristic, is reasonably priced, making it appropriate for continuous use in managing diseases, and has been demonstrated as an oral approach because it is effectively absorbed and accomplished almost all of the body's parts.

Neuroprotective effects of levothyroxine on cognition deficits and memory in an experimental model of Huntington's disease in rats: An electrophysiological study

Huntington's disease (HD) is a neurodegenerative disorder characterized by cognitive deficits and motor function. Levothyroxine (L-T4) is a synthetic form of Thyroxine (T4), which can improve cognitive ability. The aim of the present study was to determine the neuroprotective effect of L-T4 administration in rats with 3-nitropropionic acid (3-NP)-induced Huntington's disease. Forty-eight Wistar male rats were divided into six groups (n = 8): Group 1 control group that received physiological saline, Group 2 and 3: which received L-T4 (30 and 100 μg/kg), Group 4: HD group that received 3-NP and Groups 5 and 6: The treatment of the HD rats with L-T4 (30 and 100 μg/kg). Spatial memory, locomotor activity, and frequency of neuronal firing were assessed. After decapitation, the Brain-Derived Neurotrophic Factor (BDNF) and Total antioxidant capacity (TAC) levels in the striatum was measured. The results showed that the indices of spatial memory (mean path length and latency time) and motor dysfunction (immobility time) significantly increased, while time spent in the goal quadrant, swimming speed, spike rate, and striatum levels of BDNF significantly decreased in the HD group compared to the control group. L-T4 treatment significantly enhanced time spent in the goal quadrant, swimming speed, motor activity (number of line crossing and rearing), spike rate and striatal BDNF level. This research showed that L-T4 prevented the disruption of motor activity and cognitive deficiencies induced by 3-NP. The beneficial effects of L-T4 may be due to an increase in the concentration of BDNF and enhancement of the spike rate in the striatum.

Neuroprotective Potential of Hesperidin as Therapeutic Agent in the Treatment of Brain Disorders: Preclinical Evidence-based Review

Neurodegenerative disorders (NDs) are progressive morbidities that represent a serious health issue in the aging world population. There is a contemporary upsurge in worldwide interest in the area of traditional remedies and phytomedicines are widely accepted by researchers due to their health-promoted effects and fewer side effects. Hesperidin, a flavanone glycoside present in the peels of citrus fruits, possesses various biological activities including anti-inflammatory and antioxidant actions. In various preclinical studies, hesperidin has provided significant protective actions in a variety of brain disorders such as Alzheimer's disease, epilepsy, Parkinson's disease, multiple sclerosis, depression, neuropathic pain, etc. as well as their underlying mechanisms. The findings indicate that the neuroprotective effects of hesperidin are mediated by modulating antioxidant defence activities and neural growth factors, diminishing apoptotic and neuro-inflammatory pathways. This review focuses on the potential role of hesperidin in managing and treating diverse brain disorders.

Intranasal trigeminal function in chronic rhinosinusitis: a review

INTRODUCTION

Chronic rhinosinusitis (CRS) affects 5-12% of the general population with significant effects on quality of life. Chronic inflammation also seems to affect intranasal trigeminal sensitivity.

AREAS COVERED

A systematic literature search was done in Scopus, Web of Science, and PubMed in February 2023. The review addressed intranasal trigeminal function in patients with CRS and summarized current knowledge on trigeminal function as it relates to the symptoms, assessment, and treatment of CRS.

EXPERT OPINION

Olfaction and trigeminal function are synergistic and this interaction may contribute to trigeminal dysfunction in CRS. Aside from anatomic blockage through polypoid mucosal changes, trigeminal dysfunction may affect the perception of nasal obstruction in CRS. Upregulated immune defense mechanisms leading to damage of nerve endings, changes in nerve growth factor release or other mechanisms may be responsible for trigeminal dysfunction in CRS. Since the pathophysiology of trigeminal dysfunction in CRS is poorly understood, current treatment recommendations are directed toward the therapy of CRS as an underlying cause, although the effect of surgery and corticosteroids on trigeminal function remains unclear. A standardized and validated trigeminal test that is accessible and easy to use in clinical settings would be beneficial for future studies.

Role of Phytoconstituents as PPAR Agonists: Implications for Neurodegenerative Disorders

Peroxisome proliferator-activated receptors (PPAR-γ, PPAR-α, and PPAR-β/δ) are ligand-dependent nuclear receptors that play a critical role in the regulation of hundreds of genes through their activation. Their expression and targeted activation play an important role in the treatment of a variety of diseases, including neurodegenerative, cardiovascular, diabetes, and cancer. In recent years, several reviews have been published describing the therapeutic potential of PPAR agonists (natural or synthetic) in the disorders listed above; however, no comprehensive report defining the role of naturally derived phytoconstituents as PPAR agonists targeting neurodegenerative diseases has been published. This review will focus on the role of phytoconstituents as PPAR agonists and the relevant preclinical studies and mechanistic insights into their neuroprotective effects. Exemplary research includes flavonoids, fatty acids, cannabinoids, curcumin, genistein, capsaicin, and piperine, all of which have been shown to be PPAR agonists either directly or indirectly. Additionally, a few studies have demonstrated the use of clinical samples in in vitro investigations. The role of the fruit fly Drosophila melanogaster as a potential model for studying neurodegenerative diseases has also been highlighted.

Animal Models of LED-Induced Phototoxicity. Short- and Long-Term In Vivo and Ex Vivo Retinal Alterations

Phototoxicity animal models have been largely studied due to their degenerative communalities with human pathologies, e.g., age-related macular degeneration (AMD). Studies have documented not only the effects of white light exposure, but also other wavelengths using LEDs, such as blue or green light. Recently, a blue LED-induced phototoxicity (LIP) model has been developed that causes focal damage in the outer layers of the superior-temporal region of the retina in rodents. In vivo studies described a progressive reduction in retinal thickness that affected the most extensively the photoreceptor layer. Functionally, a transient reduction in a- and b-wave amplitude of the ERG response was observed. Ex vivo studies showed a progressive reduction of cones and an involvement of retinal pigment epithelium cells in the area of the lesion and, in parallel, an activation of microglial cells that perfectly circumscribe the damage in the outer retinal layer. The use of neuroprotective strategies such as intravitreal administration of trophic factors, e.g., basic fibroblast growth factor (bFGF), brain-derived neurotrophic factor (BDNF), ciliary neurotrophic factor (CNTF) or pigment epithelium-derived factor (PEDF) and topical administration of the selective alpha-2 agonist (Brimonidine) have demonstrated to increase the survival of the cone population after LIP.

Sodium P-aminosalicylic Acid Inhibits Manganese-Induced Neuroinflammation in BV2 Microglial Cells via NLRP3-CASP1 Inflammasome Pathway

BACKGROUND

Sodium p-aminosalicylic acid (PAS-Na) was reported to exhibit anti-inflammatory effect in the nervous system. However, the mechanism by which PAS-Na exhibits anti-inflammatory effects on manganese (Mn)-stimulated BV2 microglia cells remains unclear. Thus, this study investigated the role of PAS-Na in Mn-stimulated BV2 microglial cells.

METHODS

Microglia-like BV2 were treated with MnCl₂ with or without the non-steroidal anti-inflammatory drug PAS-Na for 12 or 24 h to examine cell viability using MTT; for 24 or 48 h to examine levels of NLRP3, CASP1, IL-1β, and IL-18 mRNA using Real-Time quantitative PCR; for 48 h to examine levels of NLRP3 and CASP1 inflammasomes, measured by western blot analysis; and for 48 h to examine levels of inflammatory cytokines, measured by enzyme-linked immunosorbent assay.

RESULTS

The MTT assay showed that PAS-Na produced significant neuroprotective effect by preventing Mn-induced inflammation in BV2 microglial cells. PAS-Na significantly concentration and time dependently inhibited Mn-induced production of NLRP3, CASP1, IL-1β, and IL-18.

CONCLUSION

Taken together, our results suggest that PAS-Na exerts anti-inflammatory effects in Mn-stimulated BV2 microglial cells via downregulation of NLRP3, CASP1, IL-1β, and I L-18. Furthermore, a high concentration and prolonged PAS-Na treatment appear necessary for its therapeutic efficacy. Taken together, we conclude that PAS-Na affords therapeutic efficacy in mitigating neurological conditions associated with neuroinflammation.

An in vivo model of focal light emitting diode-induced cone photoreceptor phototoxicity in adult pigmented mice: Protection with bFGF

PURPOSE

To develop a model of focal injury by blue light-emitting diode (LED)-induced phototoxicity (LIP) in pigmented mouse retinas and to study the effects on cone, Iba-1⁺ cells and retinal pigment epithelium (RPE) cell populations after administration of basic fibroblast growth factor (bFGF) and minocycline, alone or combined.

METHODS

In anesthetized dark-adapted adult female pigmented C57BL/6 mice, left pupils were dilated and the eye exposed to LIP (500 lux, 45 s). The retina was monitored longitudinally in vivo with SD-OCT for 7 days (d). Ex vivo, the effects of LIP and its protection with bFGF (0.5 μg) administered alone or combined with minocycline (45 mg/kg) were studied in immunolabeled arrestin-cone outer segments (a⁺OS) and quantified within a predetermined fixed-size circular area (PCA) centered on the lesion in flattened retinas at 1, 3, 5 or 7d. Moreover, Iba-1⁺ cells and RPE cell morphology were analysed with Iba-1 and ZO-1 antibodies, respectively.

RESULTS

LIP caused a focal lesion within the superior-temporal retina with retinal thinning, particularly the outer retinal layers (116.5 ± 2.9 μm to 36.8 ± 6.3 μm at 7d), and with progressive diminution of a⁺OS within the PCA reaching minimum values at 7d (6218 ± 342 to 3966 ± 311). Administration of bFGF alone (4519 ± 320) or in combination with minocycline (4882 ± 446) had a significant effect on a⁺OS survival at 7d and Iba-1⁺ cell activation was attenuated in the groups treated with minocycline. In parallel, the RPE cell integrity was progressively altered after LIP and administration of neuroprotective components had no restorative effect at 7d.

CONCLUSIONS

LIP resulted in progressive outer retinal damage affecting the OS cone population and RPE. Administration of bFGF increased a⁺OS survival but did not prevent RPE deterioration.

Protective Effect of Lemon Peel Extract on Oxidative Stress in H9c2 Rat Heart Cell Injury

Aim

Lemon peel, a traditional Chinese medicine, was tested in this study for its novel application in inhibiting cellular oxidative stress, and the effect of lemon peel extract (LPE) on protecting H9c2 rat heart cells from oxidative stress was investigated.

Methods

The scavenging effects of LPE on 1,1-diphenyl-2-picryhydrazyl (DPPH) and 2,2’-azino-bis (3-ethylbenzthiazoline-6-sulfonic acid) (ABTS) free radicals were measured in extracellular experiments. The 3-(4,5-dimethyl-2-thiazolinyl)-2,5-diphenyl-2-h-tetrazolylammonium bromide (MTT) assay was used to detect the cell survival rate. The cell supernatant and intracellular oxidation-related indicators were detected by a kit, and the mRNA expression in H9c2 cells was detected by quantitative polymerase chain reaction (qPCR). The chemical substances of LPE were analyzed by high-performance liquid chromatography (HPLC).

Results

The results showed that LPE exhibited better DPPH and ABTS free radical scavenging abilities than vitamin C. Compared with the cells in the normal state (control group), the cell survival rate in the model group decreased, and the level of lactate dehydrogenase (LDH) increased, the levels of superoxide dismutase (SOD), catalase (CAT), and glutathione (GSH) decreased, and the content of malondialdehyde (MDA) increased. Compared with the control group, the expression of Bcl-2-related X protein (Bax), caspase-3, nuclear factor erythroid 2-related factor 2 (Nrf2), and heme oxygenase-1 (HO-1) in the model group was increased, and the expression of B-cell lymphoma-2 (Bcl-2) was reduced. Compared with the model group, LPE treatment improved the cell survival rate, reduced the levels of LDH and MDA, increased the levels of SOD, CAT, and GSH, downregulated the expression of Bax, caspase-3, Nrf2 and HO-1, and upregulated the expression of Bcl-2. The composition analysis showed that LPE contained catechin, rutin, naringin, quercetin, and hesperidin.

Conclusion

The results indicated that LPE could protect H9c2 cells from oxidative stress through five active components. LPE has the potential to be developed into natural medicine or health food for the inhibition of cell oxidative damage.

Neuroprotective effect of hesperidin against emamectin benzoate-induced neurobehavioral toxicity in rats

Emamectin Benzoate (EMB) is an avermectin insecticide widely used in agriculture and veterinary medicine. Hesperidin (HSP) is a flavanone glycoside predominantly found in citrus fruits and has various beneficial health effects. The current research was conducted to study the neurobehavioral toxic effects of EMB in rats and also to evaluate the protective effect of HSP against these toxic effects. Sixty Sprague-Dawley rats were randomly divided into 4 equal groups: control group, EMB group, HSP group, and EMB + HSP group. EMB (8.8. mg/kg) and/or HSP (100 mg/kg) were administered daily by gavage for 8 weeks. The behavioral assessment demonstrated the adverse effects of EMB on the behavioral, motor, and cognitive brain functions. Exposure to EMB also decreased the activity of antioxidants (catalase and reduced glutathione) and increased the malondialdehyde level in nervous tissue. Moreover, EMB increased the level of inflammatory cytokines (tumor necrosis factor-α and interleukin-1β) and decreased brain-derived neurotrophic factor (BDNF) levels in rats' brains. On the other hand, concurrent administration of HSP ameliorated the toxic effects of EMB as indicated by improvements in neural functions and reduction of oxidative stress and inflammation. The study concluded that exposure to EMB induces toxic effects in the brain of rats and that HSP has a protective effect against these toxic effects.

Tetracyclines, a promise for neuropsychiatric disorders: from adjunctive therapy to the discovery of new targets for rational drug design in psychiatry

Major mental disorders, such as schizophrenia, bipolar disorder, and major depressive disorder, represent the leading cause of disability worldwide. Nevertheless, the current pharmacotherapy has several limitations, and a large portion of patients do not respond appropriately to it or remain with disabling symptoms overtime. Traditionally, pharmacological interventions for psychiatric disorders modulate dysfunctional neurotransmitter systems. In the last decades, compelling evidence has advocated for chronic inflammatory mechanisms underlying these disorders. Therefore, the repurposing of anti-inflammatory agents has emerged as an attractive therapeutic tool for mental disorders. Minocycline (MINO) and doxycycline (DOXY) are semisynthetic second-generation tetracyclines with neuroprotective and anti-inflammatory properties. More recently, the most promising results obtained in clinical trials using tetracyclines for major psychiatric disorders were for schizophrenia. In a reverse translational approach, tetracyclines inhibit microglial reactivity and toxic inflammation by mechanisms related to the inhibition of nuclear factor kappa B signaling, cyclooxygenase 2, and matrix metalloproteinases. However, the molecular mechanism underlying the effects of these tetracyclines is not fully understood. Therefore, the present review sought to summarize the latest findings of MINO and DOXY use for major psychiatric disorders and present the possible targets to their molecular and behavioral effects. In conclusion, tetracyclines hold great promise as (ready-to-use) agents for being used as adjunctive therapy for human neuropsychiatric disorders. Hence, the understanding of their molecular mechanisms may contribute to the discovery of new targets for the rational drug design of novel psychoactive agents.

Minocycline in neurodegenerative and psychiatric diseases: An update

BACKGROUND AND PURPOSE

Minocycline is a broad-spectrum antibiotic, effective as a chronic treatment for recurrent bacterial infections. Beyond its antibiotic action, minocycline also has important anti-inflammatory, antioxidant and antiapoptotic properties. Its efficacy has therefore been evaluated in many neurodegenerative and psychiatric diseases that have an inflammatory basis. Our aim was to review preclinical and clinical studies performed in neurological and psychiatric diseases whose treatment involved the use of minocycline and thereby to discern the possible beneficial effect of minocycline in these disorders.

METHODS

Completed and ongoing preclinical studies and clinical trials of minocycline for both neurodegenerative diseases and psychiatric disorders, published from January 1995 to January 2020, were identified through searching relevant databases (https://www.ncbi.nlm.nih.gov/pubmed/, https://clinicaltrials.gov/). A total of 74 preclinical studies and 44 clinical trials and open-label studies were selected.

RESULTS

The results of the nearly 20 years of research identified are diverse. While minocycline mostly proved to be effective in animal models, clinical results showed divergent outcomes, with positive results in some studies counterbalanced by a number of cases with no significant improvements. Specific data for each disease are further individually described in this review.

CONCLUSIONS

Despite minocycline demonstrating antioxidant and anti-inflammatory effects, discrepancies between preclinical and clinical data indicate that we should be cautious in analyzing the outcomes. Improving and standardizing protocols and refining animal models could help us to determine if minocycline really is a useful drug in the treatment of these pathologies.

Antioxidant and Anti-Inflammatory Effects of Citrus Flavonoid Hesperetin: Special Focus on Neurological Disorders

Neurodegenerative disorders have emerged as a serious health issue in the current era. The most common neurodegenerative disorders are Alzheimer's disease (AD), Parkinson's disease, multiple sclerosis, and amyotrophic lateral sclerosis (ALS). These diseases involve progressive impairment of neurodegeneration and memory impairment. A wide range of compounds have been identified as potential neuroprotective agents against different models of neurodegeneration both in vivo and in vitro. Hesperetin, a flavanone class of citrus flavonoid, is a derivative of hesperidin found in citrus fruits such as oranges, grapes, and lemons. It has been extensively reported that hesperetin exerts neuroprotective effects in experimental models of neurodegenerative diseases. In this systematic review, we have compiled all the studies conducted on hesperetin in both in vivo and in vitro models of neurodegeneration. Here, we have used an approach to lessen the bias in each study, providing a least biased, broad understanding of findings and impartial conclusions of the strength of evidence and the reliability of findings. In this review, we collected different papers from a wide range of journals describing the beneficial effects of hesperetin on animal models of neurodegeneration. Our results demonstrated consistent neuroprotective effects of hesperetin against different models of neurodegeneration. In addition, we have summarized its underlying mechanisms. This study provides the foundations for future studies and recommendations of further mechanistic approaches to conduct preclinical studies on hesperetin in different models.

Neuroprotective Effects of Doxycycline in the R6/2 Mouse Model of Huntington's Disease

Mechanisms of tissue damage in Huntington’s disease involve excitotoxicity, mitochondrial damage, and inflammation, including microglia activation. Immunomodulatory and anti-protein aggregation properties of tetracyclines were demonstrated in several disease models. In the present study, the neuroprotective and anti-inflammatory effects of the tetracycline doxycycline were investigated in the mouse model of HD disease R6/2. Transgenic mice were daily treated with doxycycline 20 mg/kg, starting from 4 weeks of age. After sacrifice, histological and immunohistochemical studies were performed. We found that doxycycline-treated R6/2 mice survived longer and displayed less severe signs of neurological dysfunction than the saline-treated ones. Primary outcome measures such as striatal atrophy, neuronal intranuclear inclusions, and the negative modulation of microglial reaction revealed a neuroprotective effect of the compound. Doxycycline provided a significantly increase of activated CREB and BDNF in the striatal neurons, along with a down modulation of neuroinflammation, which, combined, might explain the beneficial effects observed in this model. Our findings show that doxycycline treatment could be considered as a valid therapeutic approach for HD.

Protein kinase C is involved in the neuroprotective effect of berberine against intrastriatal injection of quinolinic acid-induced biochemical alteration in mice

Protein kinase C (PKC) shows a neuronal protection effect in neurodegenerative diseases. In this study, we test whether berberine has a positive effect on the activity of PKC in quinolinic acid (QA)‐induced neuronal cell death. We used intrastriatal injections of QA mice model to test the effect of berberine on motor and cognitive deficits, and the PKC signalling pathway. Treatment with 50 mg/kg b.w of berberine for 2 weeks significantly prevented QA‐induced motor and cognitive impairment and related pathologic changes in the brain. QA inhibited the phosphorylation of PKC and its downstream molecules, GSK‐3β, ERK and CREB, enhanced the glutamate level and release of neuroinflammatory cytokines; these effects were attenuated by berberine. We used in vivo infusion of Go6983, a PKC inhibitor to disturb PKC activity in mice brain, and found that the effect of berberine to reverse motor and cognitive deficits was significantly reduced. Moreover, inhibition of PKC also blocked the anti‐excitotoxicity effect of berberine, which is induced by glutamate in PC12 cells and BV2 cells, as well as anti‐neuroinflammatory effect in LPS‐stimulated BV2 cells. Above all, berberine showed neuroprotective effect against QA‐induced acute neurotoxicity by activating PKC and its downstream molecules.

Intracerebroventricular administration of lupus serum induces microglia activation and leukocyte adhesion in the cerebromicrovasculature of mice

BACKGROUND

Central nervous system (CNS) involvement is commonly seen in the patients with system lupus erythematosus (SLE). Mechanisms underlying CNS damage in SLE remain largely unknown. Accumulating evidence suggest that activation of microglia in CNS plays an important role in the inflammatory responses in neurological diseases. The aim of this study is to examine the involvement of microglia in the CNS inflammatory responses induced by circulating serum of SLE patients.

METHODS

We performed intracerebroventricular (ICV) injection of serums collected from SLE patients or healthy controls to mice, and examined phenotypic changes of microglia, the levels of cytokines, chemokine and adhesion molecules in the brain. Intravital microscopy was used to observe leukocyte rolling and adhesion in the cerebromicrovasculature. We further examined whether minocycline can block inflammatory responses induced by SLE serum. In vitro experiments were conducted to examine whether IgGs from the sera of SLE patients or healthy control can activate the primary cultured microglia.

RESULTS

We found that ICV injection of SLE serum increases morphological activation of microglia in the cortex and hippocampus. Inflammatory mediators including pro-inflammatory cytokines (IL-1, IL-6 and TNF-α), chemokine (CCL2 and CCL5) and adhesion molecules (P-selectin and ICAM-1) were significantly elevated in the brains of SLE-serum-treated mice. Using intravital microscopy, we demonstrated that SLE serum promotes leukocyte rolling and adhesion. Furthermore, suppression of microglia activation by systemically using minocycline could decrease the levels of inflammatory molecular, and prevent leukocyte rolling and adhesion. The in vitro experiments revealed that IgG from SLE sera could be engulfed by microglia and stimulated the microglia to secret pro-inflammatory cytokines.

CONCLUSION

Our data suggest that the activation of microglia, which promotes leukocyte adhesion to the brain microvasculature, is an important pathological mechanism of CNS involvement in SLE.

Neuroprotective Effects of FGF2 and Minocycline in Two Animal Models of Inherited Retinal Degeneration

Purpose

The purpose of this study was to study the effect of minocycline and several neurotrophic factors, alone or in combination, on photoreceptor survival and macro/microglial reactivity in two rat models of retinal degeneration.

Methods

P23H-1 (rhodopsin mutation), Royal College of Surgeon (RCS, pigment epithelium malfunction), and age-matched control rats (Sprague-Dawley and Pievald Viro Glaxo, respectively) were divided into three groups that received at P10 for P23H-1 rats or P33 for RCS rats: (1) one intravitreal injection (IVI) of one of the following neurotrophic factors: ciliary neurotrophic factor (CNTF), pigment epithelium-derived factor (PEDF), or basic fibroblast growth factor (FGF2); (2) daily intraperitoneal administration of minocycline; or (3) a combination of IVI of FGF2 and intraperitoneal minocycline. All animals were processed 12 days after treatment initiation. Retinal microglial cells and cone photoreceptors were immunodetected and analyzed qualitatively in cross sections. The numbers of microglial cells in the different retinal layers and number of nuclei rows in the outer nuclear layer (ONL) were quantified.

Results

IVI of CNTF, PEDF, or FGF2 improved the morphology of the photoreceptors outer segment, but only FGF2 rescued a significant number of photoreceptors. None of the trophic factors had qualitative or quantitative effects on microglial cells. Minocycline treatment reduced activation and migration of microglia and produced a significant rescue of photoreceptors. Combined treatment with minocycline and FGF2 had higher neuroprotective effects than each of the treatments alone.

Conclusions

In two animal models of photoreceptor degeneration with different etiologies, minocycline reduces microglial activation and migration, and FGF2 and minocycline increase photoreceptor survival. The combination of FGF2 and minocycline show greater neuroprotective effects than their isolated effects.

Prevention of Huntington's Disease-Like Behavioral Deficits in R6/1 Mouse by Tolfenamic Acid Is Associated with Decreases in Mutant Huntingtin and Oxidative Stress

Tolfenamic acid is a nonsteroidal anti-inflammatory drug with neuroprotective properties, and it alleviates learning and memory deficits in the APP transgenic mouse model of Alzheimer's disease. However, whether tolfenamic acid can prevent motor and memory dysfunction in transgenic animal models of Huntington's disease (HD) remains unclear. To this end, tolfenamic acid was orally administered to transgenic R6/1 mice from 10 to 20 weeks of age, followed by several behavioral tests to evaluate motor and memory function. Tolfenamic acid improved motor coordination in R6/1 mice as tested by rotarod, grip strength, and locomotor behavior tests and attenuated memory dysfunction as analyzed using the novel object recognition test and passive avoidance test. Tolfenamic acid decreased the expression of mutant huntingtin in the striatum of 20-week-old R6/1 mice by inhibiting specificity protein 1 expression and enhancing autophagic function. Furthermore, tolfenamic acid exhibited antioxidant effects in both R6/1 mice and PC12 cell models. Collectively, these results suggest that tolfenamic acid has a good therapeutic effect on R6/1 mice, and may be a potentially useful agent in the treatment of HD.

Hesperidin as a Neuroprotective Agent: A Review of Animal and Clinical Evidence

Neuroprotection is the preservation of function and networks of neural tissues from damages caused by various agents, as well as neurodegenerative diseases such as Parkinson's, Alzheimer's, Huntington's diseases, and multiple sclerosis. Hesperidin, a flavanone glycoside, is a natural phenolic compound with a wide range of biological effects. Mounting evidence has demonstrated that hesperidin possesses inhibitory effect against development of neurodegenerative diseases. Our review discusses neuropharmacological mechanisms for preventive and therapeutic effects of hesperidin in neurodegenerative diseases. In addition, the review examines clinical evidence confirming its neuroprotective function. Various cellular and animal models specific to neurodegenerative diseases have been conducted to evaluate the underlying neuropharmacological mechanisms of hesperidin. Neuroprotective potential of this flavonoid is mediated by improvement of neural growth factors and endogenous antioxidant defense functions, diminishing neuro-inflammatory and apoptotic pathways. Despite the various preclinical studies on the role of hesperidin in the neurodegenerative diseases, less is known about its definite effect on humans. A limited number of clinical trials showed that hesperidin-enriched dietary supplements can significantly improve cerebral blood flow, cognition, and memory performance. Further clinical trials are also required for confirming neuroprotective efficacy of this natural flavonoid and evaluating its safety profile.

Involvement of the Cholinergic Parameters and Glial Cells in Learning Delay Induced by Glutaric Acid: Protection by N-Acetylcysteine

Dysfunction of basal ganglia neurons is a characteristic of glutaric acidemia type I (GA-I), an autosomal recessive inherited neurometabolic disease characterized by deficiency of glutaryl-CoA dehydrogenase (GCDH) and accumulation of glutaric acid (GA). The affected patients present clinical manifestations such as motor dysfunction and memory impairment followed by extensive striatal neurodegeneration. Knowing that there is relevant striatal dysfunction in GA-I, the purpose of the present study was to verify the performance of young rats chronically injected with GA in working and procedural memory test, and whether N-acetylcysteine (NAC) would protect against impairment induced by GA. Rat pups were injected with GA (5 μmol g body weight^-1, subcutaneously; twice per day; from the 5th to the 28th day of life) and were supplemented with NAC (150 mg/kg/day; intragastric gavage; for the same period). We found that GA injection caused delay procedural learning; increase of cytokine concentration, oxidative markers, and caspase levels; decrease of antioxidant defenses; and alteration of acetylcholinesterase (AChE) activity. Interestingly, we found an increase in glial cell immunoreactivity and decrease in the immunoreactivity of nuclear factor-erythroid 2-related factor 2 (Nrf2), nicotinic acetylcholine receptor subunit alpha 7 (α7nAChR), and neuronal nuclei (NeuN) in the striatum. Indeed, NAC administration improved the cognitive performance, ROS production, neuroinflammation, and caspase activation induced by GA. NAC did not prevent neuronal death, however protected against alterations induced by GA on Iba-1 and GFAP immunoreactivities and AChE activity. Then, this study suggests possible therapeutic strategies that could help in GA-I treatment and the importance of the striatum in the learning tasks.

Quinolinic Acid-Induced Huntington Disease-Like Symptoms Mitigated by Potent Free Radical Scavenger Edaravone-a Pilot Study on Neurobehavioral, Biochemical, and Histological Approach in Male Wistar Rats

In this study, we demonstrated for the first time the neuroprotective role of edaravone (Eda) (5 and 10 mg/kg b.w.), a potent free radical scavenger against the unilateral stereotaxic induction of quinolinic acid (QA) (300 nm/4 μl saline)-induced Huntington disease (HD)-like symptoms in behavioral, biochemical, and histological features in male Wistar rats striatum. QA induction, which mimics the early stage of HD, commonly causes oxidative stress to the cell and decreases the antioxidant defense mechanism by altering the level of lipid peroxidation (LPO), protein carbonyls, and nitrate concentration (NO) and the activities of glutathione family enzymes (GPx, GST, GR) and acetyl choline esterase concentration (AChE) which was found to be ameliorated by Eda treatment in both the tested doses 5 and 10 mg/kg b.w. in the significance of P < 0.05 and P < 0.01, respectively. Finally histopathological analysis by hematoxylin and eosin stain concluded the promising neurodefensive role of Eda in rat striatum at the dosage of 10 mg/kg b.w., with the decreased tissue damage and the number of damaged granular cells when compared to QA-induced groups.

Hesperidin protects against IL-1β-induced inflammation in human osteoarthritis chondrocytes

Hesperidin is a vitamin P flavonoid compound primarily present in citrus fruits, which possesses an anti-inflammatory effect. The functional role of hesperidin in interleukin (IL)-1β-stimulated human osteoarthritis (OA) chondrocytes is still unknown. In the present study, anti-inflammatory effects of hesperidin in IL-1β-stimulated chondrocytes were investigated. The results demonstrated that hesperidin treatment markedly decreased nitric oxide and prostaglandin E2 production and markedly downregulated inducible nitric oxide synthase and cyclooxygenase-2 expression in IL-1β-stimulated OA chondrocytes. In addition, hesperidin markedly reduced IL-1β-induced matrix metalloproteinase (MMP)-3 and MMP-13 expression in human OA chondrocytes. Furthermore, hesperidin markedly decreased the activation of nuclear factor (NF)-κB in human OA chondrocytes. In conclusion, it was revealed for the first time that hesperidin inhibited inflammatory responses in IL-1β-stimulated human chondrocytes, potentially through inhibiting the activation of the NF-κB signaling pathway. These data suggest that hesperidin may be a potential agent for the treatment of OA.

Antimanic activity of minocycline in a GBR12909-induced model of mania in mice: Possible role of antioxidant and neurotrophic mechanisms

BACKGROUND

Mania/hypomania is the cardinal feature of bipolar disorder. Recently, single administration of the dopamine transporter (DAT) inhibitor, GBR12909, was related to mania-like alterations. In the present study we aimed at testing behavioral and brain oxidant/neurotrophic alterations induced by the repeated administration of GBR12909 and its prevention/reversal by the mood stabilizing drugs, lithium (Li) and valproate (VAL) as well as by the neuroprotective drug, minocycline (Mino).

METHODS

Adult Swiss mice were submitted to 14 days protocols namely prevention and reversal. In the reversal protocol mice were given GBR12909 or saline and between days 8 and 14 received Li, VAL, Mino (25 or 50mg/kg) or saline. In the prevention treatment, mice were pretreated with Li, VAL, Mino or saline prior to GBR12909.

RESULTS

GBR12909 repeated administration induced hyperlocomotion and increased risk taking behavior that were prevented and reversed by the mood stabilizers and both doses of Mino. Li, VAL or Mino were more effective in the reversal of striatal GSH alterations induced by GBR12909. Regarding lipid peroxidation Mino was more effective in the prevention and reversal of lipid peroxidation in the hippocampus whereas Li and VAL prevented this alteration in the striatum and PFC. Li, VAL and Mino25 reversed the decrease in BDNF levels induced by GBR12909.

CONCLUSION

GBR12909 repeated administration resembles manic phenotype. Similarly to classical mood-stabilizing agents, Mino prevented and reversed GBR12909 manic-like behavior in mice. Thus, our data provide preclinical support to the design of trials investigating Mino's possible antimanic effects.

Impact of minocycline on vascularization and visual function in an immature mouse model of ischemic retinopathy

The role of microglia in the pathophysiology of ischemic retinal diseases has been extensively studied. Retinal microglial activation may be correlated with retinal neovascularization in oxygen-induced retinopathy (OIR), an animal model that has been widely used in retinopathy of prematurity (ROP) research. Minocycline is an antibiotic that decreases microglial activation following hyperoxic and hypoxic-ischemic phases in neonatal rodents. Here, we investigated the effects of minocycline on vascularization and visual function. In our results, we found that after the administration of minocycline, microglial reactivity was reduced in the retina, which was accompanied by an increase in the avascular area at P12, P14 and P17. Although microglial reactivity was reduced at P17, minocycline treatment did not attenuate retinal neovascularization. A changing trend in microglial number was observed, and the apoptosis and proliferation states on different days partly contributed to this change. Further study also revealed that although minocycline downregulated the levels of proinflammatory factors, visual function appeared to be significantly worsened. Collectively, we demonstrated that minocycline disturbed the physiological vascularization of the avascular area and exacerbated visual dysfunction, indicating that minocycline may not be an effective drug and may even be detrimental for the treatment of ischemic retinopathy in immature mammals.

The Isotropic Fractionator as a Tool for Quantitative Analysis in Central Nervous System Diseases

One major aim in quantitative and translational neuroscience is to achieve a precise and fast neuronal counting method to work on high throughput scale to obtain reliable results. Here, we tested the isotropic fractionator (IF) method for evaluating neuronal and non-neuronal cell loss in different models of central nervous system (CNS) pathologies. Sprague-Dawley rats underwent: (i) ischemic brain damage; (ii) intraperitoneal injection with kainic acid (KA) to induce epileptic seizures; and (iii) monolateral striatal injection with quinolinic acid (QA) mimicking human Huntington's disease. All specimens were processed for IF method and cell loss assessed. Hippocampus from KA-treated rats and striatum from QA-treated rats were carefully dissected using a dissection microscope and a rat brain matrix. Ischemic rat brains slices were first processed for TTC staining and then for IF. In the ischemic group the cell loss corresponded to the neuronal loss suggesting that hypoxia primarily affects neurons. Combining IF with TTC staining we could correlate the volume of lesion to the neuronal loss; by IF, we could assess that neuronal loss also occurs contralaterally to the ischemic side. In the epileptic group we observed a reduction of neuronal cells in treated rats, but also evaluated the changes in the number of non-neuronal cells in response to the hippocampal damage. In the QA model, there was a robust reduction of neuronal cells on ipsilateral striatum. This neuronal cell loss was not related to a drastic change in the total number of cells, being overcome by the increase in non-neuronal cells, thus suggesting that excitotoxic damage in the striatum strongly activates inflammation and glial proliferation. We concluded that the IF method could represent a simple and reliable quantitative technique to evaluate the effects of experimental lesions mimicking human diseases, and to consider the neuroprotective/anti-inflammatory effects of different treatments in the whole brain and also in discrete regions of interest, with the potential to investigate non-neuronal alterations. Moreover, IF could be used in addition or in substitution to classical stereological techniques or TTC staining used so far, since it is fast, precise and easily combined with complex molecular analysis.

Neurodegeneration Alters Metabolic Profile and Sirt 1 Signaling in High-Fat-Induced Obese Mice

Different factors may contribute to the development of neurodegenerative diseases. Among them, metabolic syndrome (MS), which has reached epidemic proportions, has emerged as a potential element that may be involved in neurodegeneration. Furthermore, studies have shown the importance of the sirtuin family in neuronal survival and MS, which opens the possibility of new pharmacological targets. This study investigates the influence of sirtuin metabolic pathways by examining the functional capacities of glucose-induced obesity in an excitotoxic state induced by a quinolinic acid (QA) animal model. Mice were divided into two groups that received different diets for 8 weeks: one group received a regular diet, and the other group received a high-fat diet (HF) to induce MS. The animals were submitted to a stereotaxic surgery and subdivided into four groups: Standard (ST), Standard-QA (ST-QA), HF and HF-QA. The QA groups were given a 250 nL quinolinic acid injection in the right striatum and PBS was injected in the other groups. Obese mice presented with a weight gain of 40 % more than the ST group beyond acquiring an insulin resistance. QA induced motor impairment and neurodegeneration in both ST-QA and HF-QA, although no difference was observed between these groups. The HF-QA group showed a reduction in adiposity when compared with the groups that received PBS. Therefore, the HF-QA group demonstrated a commitment-dependent metabolic pathway. The results suggest that an obesogenic diet does not aggravate the neurodegeneration induced by QA. However, the excitotoxicity induced by QA promotes a sirtuin pathway impairment that contributes to metabolic changes.

Neurodegenerative diseases: From available treatments to prospective herbal therapy

Neurodegenerative diseases such as Alzheimer's disease, Parkinson's disease and many others represent a relevant health problem with age worldwide. Efforts have been made in recent years to discover the mechanism of neurodegenerative diseases and prospective therapy that can help to slow down the effects of the aging and prevent these diseases. Since pathogenesis of these diseases involves multiple factors therefore the important task for neuroscientists is to identify such multiple factors and prevent age-associated neurodegenerative diseases. For these neurodegenerative diseases yet we have only palliative therapies and none of them significantly capable to slow down or halt the underlying pathology. Polyphenolic compounds such as flavonoids present in vegetables and fruits are believed to have anti-aging properties and reduce the risk of neurodegenerative diseases. Despite their abundance, investigations into the benefits of these polyphenolic compounds in human health have only recently begun. Preclinical and clinical studies have demonstrated the potential beneficial effects of flavonoids in neurons. Although clinical trials on the effectiveness of dietary flavonoids to treat human diseases are limited but various animal models and cell culture studies have shown a great promise in developing these compounds as suitable therapeutic targets. In this review, we elaborate the neuroprotective properties of flavonoids especially their applications in prevention and intervention of different neurodegenerative diseases. Their multi-target properties may allow them to be potential dietary supplement in prevention and treatment of the age-associated neurodegenerative diseases.

Hesperidin and Silibinin Ameliorate Aluminum-Induced Neurotoxicity: Modulation of Antioxidants and Inflammatory Cytokines Level in Mice Hippocampus

Mounting evidence suggests that long-term aluminum exposure results in severe toxic effects, including neurobehavioral and neurochemical anomalies. The present study was performed to examine the neuroprotective potential of hesperidin and silibinin against aluminum chloride (AlCl3)-induced neurotoxicity in mice. AlCl3 (100 mg/kg/day) was injected daily through oral gavage for 42 days. Concomitantly, hesperidin (50 and 100 mg/kg/day, p.o.) and silibinin (100 and 200 mg/kg/day, p.o.) was administered for 42 days in different groups. The extent of cognitive impairment was assessed by Morris water maze and novel object recognition test on the 43rd day. Neurotoxicity was assessed by measuring oxido-nitrosative stress and proinflammatory cytokines in the hippocampus of mice. Six weeks treatment with AlCl3 caused cognitive impairment as indicated by an increase in the retention latency time and reduction in the percentage of recognition index. AlCl3-treated group showed oxido-nitrosative stress as indicated by increase in the level of lipid peroxidation, nitrite and depleted reduced glutathione, catalase activity in the hippocampus. Moreover, the chronic AlCl3 administration raised the proinflammatory cytokines (interleukin-1β and tumor necrosis factor-α) level and increased acetylcholinesterase activity and reduced the BDNF content in the hippocampus of AlCl3-treated animals. However, chronic treatment with hesperidin and silibinin at higher doses significantly ameliorated the AlCl3-induced cognitive impairment and hippocampal biochemical anomalies. The present study clearly indicated that hesperidin and silibinin exert neuroprotective effects against AlCl3-induced cognitive impairment and neurochemical changes. Amelioration of cognitive impairment may be attributed to the impediment of oxido-nitrosative stress and inflammation in the hippocampus.

Quantitative-profiling of neurotransmitter abnormalities in the disease progression of experimental diabetic encephalopathy rat

Diabetic encephalopathy (DE) is one of the most prevalent chronic complications of diabetes mellitus (DM), with neither effective prevention nor proven therapeutic regimen. This study aims to uncover the potential dysregulation pattern of the neurotransmitters in a rat model of streptozotocin (STZ)-induced experimental DE. For that purpose, male Sprague–Dawley (SD) rats were treated with a single intraperitoneal injection of STZ. Cognitive performance was detected with the Morris water maze (MWM) test. Serum, cerebrospinal fluid (CSF), and brain tissues were collected to measure the levels of neurotransmitters. Compared with the control rats, the acetylcholine (ACh) levels in serum, CSF, hippocampus, and cortex were all significantly down-regulated as early as 6 weeks in the STZ treatment group. In contrast, the glutamate (Glu) levels were decreased in CSF and the hippocampus, but unaffected in the serum and cortex of STZ-treated rats. As for γ-aminobutyric acid (GABA), it was down-regulated in serum, but up-regulated in CSF, hippocampus, and the cortex in the STZ-treated group. The mRNA expressions of neurotransmitter-related rate limiting enzymes (including AChE, GAD1, and GAD2) and pro-inflammatory cytokines (including IL-1β and TNF-α) were all increased in the DE rats. Our data suggest that DM induces isoform-dependent and tissue-specific neurotransmitter abnormalities, and that neuroinflammation may underlay the nervous system dysfunction observed in the progression of DE.

Protective effects of 3-alkyl luteolin derivatives are mediated by Nrf2 transcriptional activity and decreased oxidative stress in Huntington's disease mouse striatal cells

Huntington's disease (HD) is a polyglutamine-expansion neurodegenerative disorder caused by increased number of CAG repeats in the HTT gene, encoding for the huntingtin protein. The mutation is linked to several intracellular mechanisms, including oxidative stress. Flavones are compounds with a protective role in neurodegenerative pathologies. In the present study we analyzed the protective effect of luteolin (Lut, 3',4',5,7-tetrahydroxyflavone) and four luteolin derivatives bearing 3-alkyl chains of 1, 4, 6 and 10 carbons (Lut-C1, Lut-C4, Lut-C6, Lut-C10) in striatal cells derived from HD knock-in mice expressing mutant Htt (STHdh(Q111/Q111)) versus wild-type striatal cells (STHdh(Q7/Q7)). HD cells showed increased caspase-3-like activity and intracellular reactive oxygen species (ROS), which were significantly decreased following treatment with Lut-C4 and Lut-C6 under concentrations that enhanced cell viability. Interestingly, Lut-C4 and Lut-C6 rose the nuclear levels of phospho(Ser40)-nuclear factor (erythroid-derived-2)-like 2 (Nrf2) and Nrf2/ARE transcriptional activity. Concordantly with increased Nrf2/ARE transcription, Lut-C6 enhanced superoxide dismutase 1 (SOD1) mRNA and SOD activity and glutamate-cysteine ligase catalytic subunit (GCLc) mRNA and protein levels, while Lut-C4 induced mRNA levels of GCLc only in mutant striatal cells. Data suggest that Lut-C6 luteolin derivative (in particular) might be relevant for the development of antioxidant strategies in HD.

Minocycline upregulates cyclic AMP response element binding protein and brain-derived neurotrophic factor in the hippocampus of cerebral ischemia rats and improves behavioral deficits

BACKGROUND AND PURPOSE

The cAMP response element binding protein (CREB) plays an important role in the mechanism of cognitive impairment and is also pivotal in the switch from short-term to long-term memory. Brain-derived neurotrophic factor (BDNF) seems a promising avenue in the treatment of cerebral ischemia injury since this neurotrophin could stimulate structural plasticity and repair cognitive impairment. Several findings have displayed that the dysregulation of the CREB-BDNF cascade has been involved in cognitive impairment. The aim of this study was to investigate the effect of cerebral ischemia on learning and memory as well as on the levels of CREB, phosphorylated CREB (pCREB), and BDNF, and to determine the effect of minocycline on CREB, pCREB, BDNF, and behavioral functional recovery after cerebral ischemia.

METHODS

The animal model was established by permanent bilateral occlusion of both common carotid arteries. Behavior was evaluated 5 days before decapitation with Morris water maze and open-field task. Four days after permanent bilateral occlusion of both common carotid arteries, minocycline was administered by douche via the stomach for 4 weeks. CREB and pCREB were examined by Western blotting, reverse transcription polymerase chain reaction, and immunohistochemistry. BDNF was measured by immunohistochemistry and Western blotting.

RESULTS

The model rats after minocycline treatment swam shorter distances than control rats before finding the platform (P=0.0007). The number of times the platform position was crossed for sham-operation rats was more than that of the model groups in the corresponding platform location (P=0.0021). The number of times the platform position was crossed for minocycline treatment animals was significantly increased compared to the model groups in the corresponding platform position (P=0.0016). CREB, pCREB, and BDNF were downregulated after permanent bilateral occlusion of both common carotid arteries in the model group. Minocycline increased the expression of CREB, pCREB, and BDNF, and improved cognitive suffered from impairment of permanent bilateral occlusion of both common carotid arteries.

CONCLUSION

Minocycline improved cognitive impairment from cerebral ischemia via enhancing CREB, pCREB, and BDNF activity in the hippocampus.

Improvement of mitochondrial NAD(+)/FAD(+)-linked state-3 respiration by caffeine attenuates quinolinic acid induced motor impairment in rats: implications in Huntington's disease

BACKGROUND

Chronic quinolinic acid (QA) lesions in rats closely resemble Huntington's disease like conditions. Oxidative stress and mitochondrial dysfunction have long been implicated in the neurotoxic effects of QA acting through N-methyl-d-aspartate (NMDA) receptors. Reports suggest that inhibition of adenosine A2A receptor function elicits neuroprotective effect in QA induced neurotoxicity in rats. Caffeine, a preferential A2A receptor antagonist imitates antioxidant like actions and exerts neuroprotective effects in various neurodegenerative conditions. Thus, the present study was designed to evaluate the neuroprotective effects of caffeine against QA induced neurotoxicity in rats.

METHODS

In the present study, QA (200nmol/2μl saline) has been administered bilaterally to the striatum of rats followed by chronic caffeine (10, 20 and 40mg/kg) administration for 21 days. Motor performance of the animals was evaluated in weekly intervals and subsequently after 21 days, the animals were sacrificed and measurement of mitochondrial complexes activity, respiration rate and endogenous antioxidant levels were carried out in the striatal region.

RESULTS

Single intrastriatal QA administration resulted in drastic reduction in body weight, marked motor impairment (decreased total locomotor activity in actophotometer and impaired grip strength in rotarod), increased oxidative stress, impaired mitochondrial complexes activities and decreased state 3 respiration (NAD(+)/FAD(+)-linked) in rats. However, chronic treatment of caffeine for 21 days significantly attenuated the QA induced behavioural, biochemical and mitochondrial alterations displaying neuroprotective efficacy.

CONCLUSION

The study highlights the possible involvement of A2A receptor antagonism in the neuroprotective effect of caffeine against QA induced mitochondrial dysfunction and oxidative stress in rats.