Activation of alpha-7 nicotinic acetylcholine receptor by tropisetron mitigates 3-nitropropionic acid-induced Huntington's disease in rats: Role of PI3K/Akt and JAK2/NF-κB signaling pathways.

Huntington's disease (HD) is an inheritable autosomal-dominant disorder that targets mainly the striatum. 3-Nitropropionic acid (3-NP) induces obvious deleterious behavioral, neurochemical, and histological effects similar to the symptoms of HD. Our study aimed to examine the neuroprotective activity of tropisetron, an alpha-7 neuronal nicotinic acetylcholine receptor (α-7nAChR) agonist, against neurotoxic events associated with 3-NP-induced HD in rats. Forty-eight rats were randomly allocated into four groups. Group I received normal saline, while Groups II, III and IV received 3-NP for 2 weeks. In addition, Group III and IV were treated with tropisetron 1 h after 3-NP administration. Meanwhile, Group IV received methyllycaconitine (MLA), an α-7nAChR antagonist, 30 min before tropisetron administration. Treatment with tropisetron improved motor deficits as confirmed by the behavioral tests and restored normal histopathological features of the striatum. Moreover, tropisetron showed an anti-oxidant activity via increasing the activities of SDH and HO-1 as well as Nrf2 expression along with reducing MDA level. Tropisetron also markedly upregulated the protein expression of p-PI3K and p-Akt which in turn hampered JAK2/NF-κB inflammatory cascade. In addition, tropisetron showed an anti-apoptotic activity through boosting the expression of Bcl-2 and reducing Bax expression and caspase-3 level. Interestingly, all the aforementioned effects of tropisetron were blocked by pre-administration of MLA, which confirms that such neuroprotective effects are mediated via activating of α-7nAChR. In conclusion, tropisetron showed a neuroprotective activity against 3-NP-induced HD via activating PI3K/Akt signaling and suppressing JAK2/NF-κB inflammatory axis. Thus, repositioning of tropisetron could represent a promising therapeutic strategy in management of HD.

Implication of M2 macrophage on NLRP3 inflammasome signaling in mediating the neuroprotective effect of Canagliflozin against methotrexate-induced cognitive impairment.

Methotrexate (MTX), a chemotherapeutic antimetabolite, has been linked to cognitive impairment in cancer patients. MTX-induced metabolic pathway disruption may result in decreased antioxidant activity and increased oxidative stress, influencing hippocampal neurogenesis and microglial activation. Nuclear factor-kappa B (NF-κB), an oxidative stress byproduct, has been linked to MTX toxicity via the activation of NLRP3 inflammasome signaling. Macrophage activation and polarization plays an important role in tissue injury. This differentiation may be mediated via either the Toll-like receptor 4 (TLR4) or NLRP3 inflammasome. Interestingly, Canagliflozin (CANA), a sodium-glucose cotransporter 2 (SGLT2) inhibitor has been recently reported to exert anti-inflammatory effects by modulating macrophage polarization balance. This study aimed to investigate CANA's protective effect against MTX-induced cognitive impairment, highlighting the possible involvement of TLR4/ NF-κB crosstalk with NLRP3 inflammasome activation and macrophage polarization. Forty-eight Male Wistar rats were divided into 4 groups; (1) received saline orally for 30 days and intravenously on days 8 and 15. (2) received Canagliflozin (CANA; 20 mg/kg/day; p.o.) for 30 days. (3) received MTX (75 mg/kg, i.v.) on day 8 and 15, then they were injected with four i.p. injections of leucovorin (LCV): the first dose was 6 mg/ kg after 18 h, and the remaining doses were 3 mg/kg after 26, 42, and 50 h of MTX administration. (4) received MTX and LCV as in group 3 in addition to CANA as in group 2. MTX-treated rats showed cognitive deficits in spatial and learning memory as evidenced in the novel object recognition and Morris water maze tests. MTX exerted an oxidative effect which was evident by the increase in MDA and decline in SOD, GSH and GPx. Moreover, it exerted an inflammatory effect via elevated caspase-1, IL-1ß and IL-8. CANA treatment restored cognitive ability, reduced MTX-induced oxidative stress and neuroinflammation via attenuation of TLR4/NF-κB/NLRP3 signaling, and rebalanced macrophage polarization by promoting the M2 phenotype. Hence, targeting molecular mechanisms manipulating macrophage polarization may offer novel neuroprotective strategies for preventing or treating MTX-induced immune modulation and its detrimental sequel.

Mirabegron, dependent on ß3-adrenergic receptor, alleviates mercuric chloride-induced kidney injury by reversing the impact on the inflammatory network, M1/M2 macrophages, and claudin-2.

The ß3-adrenergic receptor (ß3-AR) agonism mirabegron is used to treat overactive urinary bladder syndrome; however, its role against acute kidney injury (AKI) is not unveiled, hence, we aim to repurpose mirabegron in the treatment of mercuric chloride (HgCl2)-induced AKI. Rats were allocated into normal, normal + mirabegron, HgCl2 untreated, HgCl2 + mirabegron, and HgCl2 + the ß3-AR blocker SR59230A + mirabegron. The latter increased the mRNA of ß3-AR and miR-127 besides downregulating NF-κB p65 protein expression and the contents of its downstream targets iNOS, IL-4, -13, and -17 but increased that of IL-10 to attest its anti-inflammatory capacity. Besides, mirabegron downregulated the protein expression of STAT-6, PI3K, and ERK1/2, the downstream targets of the above cytokines. Additionally, it enhanced the transcription factor PPAR-α but turned off the harmful hub HNF-4α/HNF-1α and the lipid peroxide marker MDA. Mirabegron also downregulated the CD-163 protein expression, which besides the inhibited correlated cytokines of M1 (NF-κB p65, iNOS, IL-17) and M2 (IL-4, IL-13, CD163, STAT6, ERK1/2), inactivated the macrophage phenotypes. The crosstalk between these parameters was echoed in the maintenance of claudin-2, kidney function-related early (cystatin-C, KIM-1, NGAL), and late (creatinine, BUN) injury markers, besides recovering the microscopic structures. Nonetheless, the pre-administration of SR59230A has nullified the beneficial effects of mirabegron on the aforementioned parameters. Here we verified that mirabegron can berepurposedto treat HgCl2-induced AKI by activating the ß3-AR. Mirabegron signified its effect by inhibiting inflammation, oxidative stress, and the activated M1/M2 macrophages, events that preserved the proximal tubular tight junction claudin-2 via the intersection of several trajectories.

Neuroprotective effect of curcumin against experimental autoimmune encephalomyelitis-induced cognitive and physical impairments in mice: an insight into the role of the AMPK/SIRT1 pathway.

Multiple sclerosis (MS) is an incurable chronic neurodegenerative disease where autoimmunity, oxidative stress, and neuroinflammation collaboration predispose myelin sheath destruction. Interestingly, curcumin, a natural polyphenol, showed a neuroprotective effect in numerous neurodegenerative diseases, including MS. Nevertheless, the influence of curcumin against MS-induced cognitive impairment is still vague. Hence, we induced experimental autoimmune encephalomyelitis (EAE) in mice using spinal cord homogenate (SCH) and complete Freund's adjuvant, which eventually mimic MS. This study aimed not only to evaluate curcumin efficacy against EAE-induced cognitive and motor dysfunction, but also to explore a novel mechanism of action, by which curcumin exerts its beneficial effects in MS. Curcumin (200 mg/kg/day) efficacy was evaluated by behavioral tests, histopathological examination, and biochemical tests. Concisely, curcumin amended EAE-induced cognitive and motor impairments, as demonstrated by the behavioral tests and histopathological examination of the hippocampus. Interestingly, curcumin activated the adenosine monophosphate (AMP)-activated protein kinase/silent mating type information regulation 2 homolog 1 (AMPK/SIRT1) axis, which triggered cyclic AMP response element-binding protein/brain-derived neurotrophic factor/myelin basic protein (CREB/BDNF/MBP) pathway, hindering demyelination of the corpus callosum. Furthermore, AMPK/SIRT1 activation augmented nuclear factor erythroid 2-related factor 2 (Nrf2), a powerful antioxidant, amending EAE-induced oxidative stress. Additionally, curcumin abolished EAE-induced neuroinflammation by inhibiting Janus kinase 2 /signal transducers and activators of transcription 3 (JAK2/STAT3) axis, by various pathways, including AMPK/SIRT1 activation. JAK2/STAT3 inhibition halts inflammatory cytokines synthesis. In conclusion, curcumin's neuroprotective effect in EAE is controlled, at least in part, by AMPK/SIRT1 activation, which ultimately minimizes EAE-induced neuronal demyelination, oxidative stress, and neuroinflammation.

Nicorandil and carvedilol mitigates motor deficits in experimental autoimmune encephalomyelitis-induced multiple sclerosis: Role of TLR4/TRAF6/MAPK/NF-κB signalling cascade.

Multiple sclerosis (MS) is an inflammatory demyelinating neurodegenerative disease that negatively affects neurotransmission. It can be pathologically mimicked by experimental autoimmune encephalomyelitis (EAE) animal model. ATP-sensitive potassium channels (KATP) plays a crucial role in the control of neuronal damage, however their role in MS are still obscure. Additionally, Carvedilol showed a promising neuroprotective activity against several neurological disorders. Therefore, the present study aimed to investigate the potential neuroprotective effect of KATP channel opener (nicorandil) as well as α and ß adrenoceptor antagonist (Carvedilol) against EAE induced neurodegeneration in mice. Mice was treated with nicorandil (6 mg/kg/day; p.o.) and carvedilol (10 mg/kg/day; p.o.) for 14 days. Nicorandil and carvedilol showed improvement in clinical scoring, behaviour and motor coordination as established by histopathological investigation and immunohistochemical detection of MBP. Furthermore, both treatments downregulated the protein expression of TLR4/ MYD88/TRAF6 signalling cascade with downstream inhibition of (pT183/Y185)-JNK/p38 (pT180/Y182)-MAPK axis leading to reduction of neuroinflammatory status, as witnessed by reduction of NF-κB, TNF-α, IL-1ß and IL-6 contents. Moreover, nicorandil and carvedilol attenuated oxidative damage by increasing Nrf2 content and SOD activity together with reduction of MDA content. In addition, an immunomodulating effect via inhibiting the gene expression of CD4, TGF-ß, and IL-17 as well as TGF-ß, IL-17, and IL-23 contents along with anti-apoptotic effect by decreasing Bax protein expression and Caspase-3 content and increasing Bcl-2 protein expression was observed with nicorandil and carvedilol treatments. In conclusion, nicorandil and carvedilol exerted a neuroprotective activity against EAE induced neuronal loss via inhibition of TLR4/MYD88/TRAF6/JNK/p38-MAPK axis besides antioxidant and anti-apoptotic effects.

Formoterol attenuated mitochondrial dysfunction in rotenone-induced Parkinson's disease in a rat model: Role of PINK-1/PARKIN and PI3K/Akt/CREB/BDNF/TrKB axis.

ß2-adrenoreceptors (ß2AR have been identified recently as regulators of the α-synuclein gene (SNCA), one of the key milieus endorsed in injury of dopamine neurons in Parkinson's disease (PD). Accumulation of α-synuclein leads to mitochondrial dysfunction via downregulation of mitophagy proteins (PINK-1 and PARKIN) and inhibition of mitochondria biogenesis (PGC-1α) along with an increase in the master inflammatory regulator NF-κB p65 production that provokes neurodegeneration and diminishes neuroprotective signaling pathway (PI3k/Akt/CREB/BDNF). Recently, formoterol exhibited a promising neuroprotective effect against neurodegenerative conditions associated with brain inflammation. Therefore, the present investigation aims to unveil the possible neuroprotective activity of formoterol, ß2AR agonist, against rotenone-induced PD in rats. Rats received rotenone (1.5 mg/kg; s.c.) every other day for 3 weeks and cured with formoterol (25 µg/kg/day; i.p.) 1 hr. after rotenone administration, starting from day 11. Formoterol treatment succeeded in upregulating ß2-adrenoreceptor expression in PD rats and preserving the function and integrity of dopaminergic neurons as witnessed by enhancement of muscular performance in tests, open field, grip strength-meter, and Rotarod, besides the increment in substantia nigra and striatal tyrosine hydroxylase immunoexpression. In parallel, formoterol boosted mitophagy by activation of PINK1 and PARKIN and preserved mitochondrial membrane potential. Additionally, formoterol stimulated the neuro-survival signaling axis via stimulation of PI3k/pS473-Akt/pS133-CREB/BDNF cascade to attenuate neuronal loss. Noteworthy formoterol reduces neuro-inflammatory status by decreasing NFκBp65 immunoexpression and TNF-α content. Finally, formoterol's potential as a stimulant therapy of mitophagy via the PINK1/PARKIN axis and regulation of mitochondrial biogenesis by increasing PGC-1α to maintain mitochondrial homeostasis along with stimulation of PI3k/Akt/CREB/BDNF axis.

Inosine attenuates rotenone-induced Parkinson's disease in rats by alleviating the imbalance between autophagy and apoptosis.

Growing evidence points to impaired autophagy as one of the major factors implicated in the pathophysiology of Parkinson's disease (PD). Autophagy is a downstream target of adenosine monophosphate-activated protein kinase (AMPK). Inosine has already demonstrated a neuroprotective effect against neuronal loss in neurodegenerative diseases, mainly due its anti-inflammatory and antioxidant properties. We, herein, aimed at investigating the neuroprotective effects of inosine against rotenone-induced PD in rats and to focus on the activation of AMPK-mediated autophagy. Inosine successfully increased p-AMPK/AMPK ratio in PD rats and improved their motor performance and muscular co-ordination (assessed by rotarod, open field, and grip strength tests, as well as by manual gait analysis). Furthermore, inosine was able to mitigate the rotenone-induced histopathological alterations and to restore the tyrosine hydroxylase immunoreactivity in PD rats' substantia nigra. Inosine-induced AMPK activation resulted in an autophagy enhancement, as demonstrated by the increased striatal Unc-S1-like kinase1 and beclin-1 expression, and also by the increment light chain 3II to light chain 3I ratio, along with the decline in striatal mammalian target of rapamycin and p62 protein expressions. The inosine-induced stimulation of AMPK also attenuated neuronal apoptosis and promoted antioxidant activity. Unsurprisingly, these neuroprotective effects were antagonized by a preadministration of dorsomorphin (an AMPK inhibitor). In conclusion, inosine exerted neuroprotective effects against the rotenone-induced neuronal loss via an AMPK activation and through the restoration of the imbalance between autophagy and apoptosis. These findings support potential application of inosine in PD treatment.

Cyclocreatine Phosphate: A Novel Bioenergetic/Anti-Inflammatory Drug That Resuscitates Poorly Functioning Hearts and Protects against Development of Heart Failure.

Irreversible myocardial injury causes the exhaustion of cellular adenosine triphosphate (ATP) contributing to heart failure (HF). Cyclocreatine phosphate (CCrP) was shown to preserve myocardial ATP during ischemia and maintain cardiac function in various animal models of ischemia/reperfusion. We tested whether CCrP administered prophylactically/therapeutically prevents HF secondary to ischemic injury in an isoproterenol (ISO) rat model. Thirty-nine rats were allocated into five groups: control/saline, control/CCrP, ISO/saline (85 and 170 mg/kg/day s.c. for 2 consecutive days), and ISO/CCrP (0.8 g/kg/day i.p.) either administrated 24 h or 1 h before ISO administration (prophylactic regimen) or 1 h after the last ISO injection (therapeutic regimen) and then daily for 2 weeks. CCrP protected against ISO-induced CK-MB elevation and ECG/ST changes when administered prophylactically or therapeutically. CCrP administered prophylactically decreased heart weight, hs-TnI, TNF-α, TGF-ß, and caspase-3, as well as increased EF%, eNOS, and connexin-43, and maintained physical activity. Histology indicated a marked decrease in cardiac remodeling (fibrin and collagen deposition) in the ISO/CCrP rats. Similarly, therapeutically administered CCrP showed normal EF% and physical activity, as well as normal serum levels of hs-TnI and BNP. In conclusion, the bioenergetic/anti-inflammatory CCrP is a promising safe drug against myocardial ischemic sequelae, including HF, promoting its clinical application to salvage poorly functioning hearts.

Adenosine A1 receptor agonist, N6-cyclohexyladenosine, attenuates Huntington's disease via stimulation of TrKB/PI3K/Akt/CREB/BDNF pathway in 3-nitropropionic acid rat model.

Huntington's disease (HD) is an inherited neurodegenerative disease characterized by progressive motor, behavioral, and cognitive impairments. Intrastriatal injection of 3- nitropropionic acid (3NP) was used to induce HD-like symptoms by inhibiting succinate dehydrogenase enzyme (SDH) in the mitochondrial complex II. The adenosine A1 receptor has long been known to have a crucial role in neuroprotection, mainly by blocking Ca2+ influx, which causes inhibition of glutamate (Glu) and a decline in its excitatory effects at the postsynaptic level. To this end, this study investigated the possible involvement of TrKB/PI3K/Akt/CREB/BDNF pathway in mediating protection afforded by the central N6-cyclohexyladenosine (CHA), an adenosine A1 receptor agonist. A single intrastriatal CHA injection (6.25 nM/1 µL); 45min after 3-NP injection, attenuated neuronal death, and improved cognitive and motor deficits caused by 3-NP neurotoxin. This effect was shown to parallel an enhanced activation of PI3K/Akt/CREB/BDNF axis as well as boosting pERK1/2 levels. Moreover, CHA attenuated neuroinflammatory and oxidative stress status via reducing NFκB p65, TNFα and iNOS contents and increasing SOD. Furthermore, immunohistochemical data showed a reduction in the glial fibrillary acidic protein (GFAP) immunoreactivity to a marker for astrocyte and microglia activation following CHA treatment. The results of this study suggest that CHA may have protective effect against HD via modulating oxidative stress, excitotoxic and inflammatory pathways.

Neuroprotective effect of secukinumab against rotenone induced Parkinson's disease in rat model: Involvement of IL-17, HMGB-1/TLR4 axis and BDNF/TrKB cascade.

Neuroinflammatory status produced via activation of toll like receptor-4 (TLR-4) and interleukin-17 receptor (IL-17R) is one of the principal mechanisms involved in dopaminergic neuronal loss in Parkinson's disease (PD). Activation of TLR-4 and IL-17R stimulates reactive oxygen species (ROS) and proinflammatory cytokines (IL-17, IL-1ß, TNFα, IL-6) production that augments neurodegeneration and reduces neuro-survival axis (TrKB/Akt/CREB/BDNF). So, reducing IL-17-driven neuroinflammation via secukinumab, monoclonal antibody against IL-17A, may be one of therapeutic approach for PD. Moreover, the aim was extended to delineate the possible neuroprotective mechanism involved against neuronal loss in rotenone induced PD in rats. Rats received 11 subcutaneous injection of rotenone (1.5 mg/kg) every other day for 21 consecutive days and treated with 2 subcutaneous injections of secukinumab (15 mg/kg) on day 9 and 15, one hour after rotenone administration. Treatment with secukinumab improved motor impairment and muscle incoordination induced by rotenone, as verified by open field and rotarod tests. Moreover, secukinumab attenuated neuronal loss and improve histopathological profile. Noteworthy, secukinumab reduces neuro-inflammatory status by hindering the interaction between IL and 17A and IL-17RA together with inhibiting the activation of TLR-4 and its downstream cascade including pS536-NFκB p65, IL-1ß and HMGB-1. Additionally, secukinumab stimulated neuro-survival signalling cascade via activation pY515-TrKB receptor and triggered upsurge in its downstream targets (pS473-Akt/pS133-CREB/BDNF). Furthermore, secukinumab increased striatal tyrosine hydroxylase immunoexpression, the rate limiting step in dopamine biosynthesis, to guard against dopaminergic neuronal loss. In conclusion, secukinumab exerts a neuroprotective effect against rotenone induced neuronal loss via inhibition IL17A/IL17RA interaction and HMGB-1/TLR-4/NF-κBp65/IL1ß signalling cascade, together with activation of TrKB/ Akt/CREB/BDNF axis.

Semaglutide, a novel glucagon-like peptide-1 agonist, amends experimental autoimmune encephalomyelitis-induced multiple sclerosis in mice: Involvement of the PI3K/Akt/GSK-3ß pathway.

Multiple sclerosis (MS) is a disabling neurodegenerative disease that causes demyelination and axonal degeneration of the central nervous system. Current treatments are partially effective in managing MS relapses and have a negligible impact on treating MS cognitive deficits and cannot enhance neuronal remyelination, imposing a need for a new MS remedy. Semaglutide, a novel glucagon-like peptide-1 agonist, has recently displayed a neuroprotective effect on several neurodegenerative diseases, suggesting that it may have a protective effect in MS. Therefore, this study was conducted to investigate the influence of semaglutide on experimental autoimmune encephalomyelitis (EAE)-induced MS in mice. Here, EAE was induced in mice using spinal cord homogenate, which eventually altered the mice's cognitive and motor functions, similar to what is observed in MS. Interestingly, intraperitoneally administered semaglutide (25 nmol/kg/day) amended EAE-induced cognitive and motor deficits observed in novel object recognition, open field, rotarod, and grip strength tests. Moreover, histological examination revealed that semaglutide treatment attenuated hippocampal damage and corpus callosum demyelination caused by EAE. Additionally, biochemical testing revealed that semaglutide activates the PI3K/Akt axis, which eventually hampers GSK-3ß activity. GSK-3ß activity inhibition attenuates demyelination and triggers remyelination through CREB/BDNF; furthermore, it boosts Nrf2 and SOD levels, protecting the mice from EAE-induced oxidative stress. Additionally, GSK-3ß inhibition minimizes neuroinflammation, as reflected by decreased NF-kß and TNF-α levels. In conclusion, semaglutide has a neuroprotective effect in EAE-induced MS in mice, which is mediated by activating the ramified PI3K/Akt/GSK-3ß pathway.

Intra-articular injection of rAAV-hFGF-2 ameliorates monosodium iodoacetate-induced osteoarthritis in rats via inhibiting TLR-4 signaling and activating TIMP-1.

Osteoarthritis (OA) is a chronic debilitating degenerative disorder leading to structural, and functional anomaly of the joint. The present study tests the hypothesis that overexpression of the basic fibroblast growth factor (FGF-2) via direct rAAV-mediated gene transfer suppresses monosodium iodoacetate (MIA)-induced knee OA in rats relative to control (reporter rAAV-lacZ vector) gene transfer by intra-articular injection. Rats were treated with 20 µl rAAV-hFGF-2 on weekly basis; on days 7, 14, and 21 after single intra-articular injection of MIA (3 mg/50 µl saline). FGF-2 reduced knee joint swelling and improved motor performance and muscle coordination as evidenced by increased distance travelled, mean speed, rearing frequency in open field test (OFT) as well as fall-off latency in rotarod test together with reduced immobility time in OFT. Moreover, FGF-2 attenuated MIA-related radiological and histological alterations. Indeed, FGF-2 decreased knee joint inflammatory biomarker as demonstrated by reduced mRNA expression of toll like receptor (TLR)-4 and its downstream mediators such as tumor necrosis factor alpha (TNF-α), interleukin 1 beta (IL-1ß) and high motility group box (HMGB) 1. In parallel, FGF-2 attenuated knee joint degradation biomarkers as reflected by the downregulation of ADAMTS-5 mRNA expression and matrix metalloproteinase 13 (MMP-13) content together with the up-regulation of tissue inhibitor of metalloproteinase (TIMP)-1 mRNA expression. These findings suggest a potential therapeutic role for FGF-2 against MIA-induced knee OA in rats via inhibition of TLR4 signaling and activating TIMP-1, resulting in down-regulation of ADAMTS-5 and MMP-13.

Experimental Evidence for Diiodohydroxyquinoline-Induced Neurotoxicity: Characterization of Age and Gender as Predisposing Factors.

Though quinoline anti-infective agents-associated neurotoxicity has been reported in the early 1970s, it only recently received regulatory recognition. In 2019, the European Medicines Agency enforced strict use for quinoline antibiotics. Thus, the current study evaluates the relation between subacute exposure to diiodohydroxyquinoline (DHQ), a commonly misused amebicide, with the development of motor and sensory abnormalities, highlighting age and gender as possible predisposing factors. Eighty rats were randomly assigned to eight groups according to their gender, age, and drug exposure; namely, four control groups received saline (adult male, adult female, young male, and young female), and the other four groups received DHQ. Young and adult rats received DHQ in doses of 176.7 and 247.4 mg/kg/day, respectively. After 4 weeks, rats were tested for sensory abnormality using analgesiometer, hot plate, and hind paw cold allodynia tests, and for motor function using open field and rotarod tests. Herein, the complex behavioral data were analyzed by principal component analysis to reduce the high number of variables to a lower number of representative factors that extracted components related to sensory, motor, and anxiety-like behavior. Behavioral outcomes were reflected in a histopathological examination of the cerebral cortex, striatum, spinal cord, and sciatic nerve, which revealed degenerative changes as well demyelination. Noteworthy, young female rats were more susceptible to DHQ's toxicity than their counterparts. Taken together, these findings confirm previous safety concerns regarding quinoline-associated neurotoxicity and provide an impetus to review risk/benefit balance for their use.

Nourin-Associated miRNAs: Novel Inflammatory Monitoring Markers for Cyclocreatine Phosphate Therapy in Heart Failure.

BACKGROUND: Cyclocreatine phosphate (CCrP) is a potent bioenergetic cardioprotective compound known to preserve high levels of cellular adenosine triphosphate during ischemia. Using the standard Isoproterenol (ISO) rat model of heart failure (HF), we recently demonstrated that the administration of CCrP prevented the development of HF by markedly reducing cardiac remodeling (fibrosis and collagen deposition) and maintaining normal ejection fraction and heart weight, as well as physical activity. The novel inflammatory mediator, Nourin is a 3-KDa formyl peptide rapidly released by ischemic myocardium and is associated with post-ischemic cardiac inflammation. We reported that the Nourin-associated miR-137 (marker of cell damage) and miR-106b-5p (marker of inflammation) are significantly upregulated in unstable angina patients and patients with acute myocardial infarction, but not in healthy subjects. OBJECTIVES: To test the hypothesis that Nourin-associated miR-137 and miR-106b-5p are upregulated in ISO-induced "HF rats" and that the administration of CCrP prevents myocardial injury (MI) and reduces Nourin gene expression in "non-HF rats". METHODS: 25 male Wistar rats (180-220 g) were used: ISO/saline (n = 6), ISO/CCrP (0.8 g/kg/day) (n = 5), control/saline (n = 5), and control/CCrP (0.8 g/kg/day) (n = 4). In a limited study, CCrP at a lower dose of 0.4 g/kg/day (n = 3) and a higher dose of 1.2 g/kg/day (n = 2) were also tested. The Rats were injected SC with ISO for two consecutive days at doses of 85 and 170 mg/kg/day, respectively, then allowed to survive for an additional two weeks. CCrP and saline were injected IP (1 mL) 24 h and 1 h before first ISO administration, then daily for two weeks. Serum CK-MB (U/L) was measured 24 h after the second ISO injection to confirm myocardial injury. After 14 days, gene expression levels of miR-137 and miR-106b-5p were measured in serum samples using quantitative real-time PCR (qPCR). RESULTS: While high levels of CK-MB were detected after 24 h in the ISO/saline rats indicative of MI, the ISO/CCrP rats showed normal CK-MB levels, supporting prevention of MI by CCrP. After 14 days, gene expression profiles showed significant upregulation of miR-137 and miR-106b-5p by 8.6-fold and 8.7-fold increase, respectively, in the ISO/saline rats, "HF rats," compared to the control/saline group. On the contrary, CCrP treatment at 0.8 g/kg/day markedly reduced gene expression of miR-137 by 75% and of miR-106b-5p by 44% in the ISO/CCrP rats, "non-HF rats," compared to the ISO/Saline rats, "HF rats." Additionally, healthy rats treated with CCrP for 14 days showed no toxicity in heart, liver, and renal function. CONCLUSIONS: Results suggest a role of Nourin-associated miR-137 and miR-106b-5p in the pathogenesis of HF and that CCrP treatment prevented ischemic injury in "non-HF rats" and significantly reduced Nourin gene expression levels in a dose-response manner. The Nourin gene-based mRNAs may, therefore, potentially be used as monitoring markers of drug therapy response in HF, and CCrP-as a novel preventive therapy of HF due to ischemia.

Inhibition of Brain GTP Cyclohydrolase I Attenuates 3-Nitropropionic Acid-Induced Striatal Toxicity: Involvement of Mas Receptor/PI3k/Akt/CREB/ BDNF Axis.

GTP cyclohydrolase I (GTPCH I) is the rate-limiting enzyme for tetrahydrobiopterin (BH4) biosynthesis; the latter is an essential factor for iNOS activation that contributes neuronal loss in Huntington's disease (HD). The aim of the study was to investigate the neuroprotective effect of 2,4-diamino-6-hydroxypyrimidine (DAHP), GTPCH I enzyme inhibitor, against neuronal loss in 3-nitropropinic acid (3-NP)-induced HD in rats and to reveal the possible involved mechanisms mediated through PI3K/Akt axis and its correlation to Mas receptor (MasR). Rats received 3-NP (10 mg/kg/day; i.p.) with or without administration of DAHP (0.5 g/kg/day; i.p.) or wortmannin (WM), a PI3K inhibitor, (15 µg/kg/day; i.v.) for 14 days. DAHP improved cognitive, memory, and motor abnormalities induced by 3-NP, as confirmed by striatal histopathological specimens and immunohistochemical examination of GFAP. Moreover, DAHP treatment inhibited GTPCH I activity, resulting in decreased BH4 levels and iNOS activation. Also, DAHP upregulated the protein expression of survival protein; p85/p55 (pY458/199)-PI3K and pS473-Akt that, in turn, boosted the activation of striatal neurotrophic factors and receptor, pS133-CREB, BDNF and pY515-TrKB, which positively affect MasR protein expression and improve mitochondrial dysfunction, as indicated by enhancing both SDH and PGC-1α levels. Indeed, DAHP attenuates oxidative stress by increasing SOD activity and Nrf2 expression in addition to reducing neuro-inflammatory status by inhibiting NF-κB p65 and TNF-α expression. Interestingly, all the previous effects were blocked by co-administration of WM with DAHP. In conclusion, DAHP exerts neuroprotective effect against neuronal loss induced by 3-NP administration via inhibition of GTPCH I and iNOS activity and activation of MasR/PI3K/Akt/CREB/BDNF/TrKB axis besides its antioxidant and anti-inflammatory effect.

Correlation between angiotensin 1-7-mediated Mas receptor expression with motor improvement, activated STAT3/SOCS3 cascade, and suppressed HMGB-1/RAGE/NF-κB signaling in 6-hydroxydopamine hemiparkinsonian rats.

In the current investigation, a Parkinson's disease (PD) model was established by a single direct right intrastriatal injection of the 6-hydroxydopamine (OHDA) in male Wistar rats followed by 7 daily unilateral injection of angiotensin (Ang) 1-7 in the striatum. To confirm the putative role of Mas receptor (MasR), the selective antagonist A779 was also injected intrastriatally prior to Ang 1-7 injections and a correlation analysis was performed between MasR expression and the assessed parameters. Ang 1-7 upregulated MasR expression to correlate strongly with the improved rotarod (r = 0.95, p = 0.003) and spontaneous activity task (r = 0.99, p < 0.0001). This correlation extends to involve other effects of Ang 1-7, such as the increased striatal dopamine content (r = 0.98, p = 0.0005), substantia nigra pars compacta tyrosine hydroxylase immune-reactivity (r = 0.97, p = 0.001), active pY705-STAT3 (r = 0.99, p < 0.0001) and SOCS3 (r = 0.99, p < 0.0001). Conversely, Ang 1-7 inhibited inflammatory markers to correlate negatively with NF-κBp65 (r = -0.99, p < 0.0003) and its downstream targets, high mobility group box-1 (HMGB-1; r = -0.97, p = 0.002), receptor for advanced glycation end products (RAGE; r = -0.98, p = 0.0004), and TNF-α (r = -0.99, p < 0.0003), besides poly-ADP-ribose polymerase-1 (r = -0.99, p = 0.0002). In confirmation, the pre-administration of the selective MasR antagonist, A779, partially attenuated Ang 1-7-induced alterations towards 6-OHDA neurodegeneration. Collectively, our findings support a novel role for the anti-inflammatory capacity of the MasR axis to prove potential therapeutic relevance in PD via the upregulation/activation of MasR-dependent STAT3/SOCS3 cascade to negatively control the HMGB-1/RAGE/NF-κB axis hindering PD associated neuro-inflammation along with DA depletion and motor deficits.

Vildagliptin Attenuates Huntington's Disease through Activation of GLP-1 Receptor/PI3K/Akt/BDNF Pathway in 3-Nitropropionic Acid Rat Model.

Vildagliptin (Vilda), a dipeptidyl peptidase-4 (DPP-4) inhibitor, has been highlighted as a promising therapeutic agent for neurodegenerative diseases as Alzheimer's and Parkinson's diseases. Vilda's effect is mostly linked to PI3K/Akt signaling in CNS. Moreover, PI3K/Akt activation reportedly enhanced survival and dampened progression of Huntington's disease (HD). However, Vilda's role in HD is yet to be elucidated. Thus, the aim of the study is to uncover the potentiality of Vilda in HD and unfold its link with PI3K/Akt pathway in 3-nitropropionic acid (3NP) rat model. Rats were randomly assigned into 4 groups; group 1 received saline, whereas, groups 2, 3 and 4 received 3NP (10 mg/kg/day; i.p.) for 14 days, concomitantly with Vilda (5 mg/kg/day; p.o.) in groups 3 and 4, and wortmannin (WM), a PI3K inhibitor, (15 µg/kg/day; i.v.) in group 4. Vilda improved cognitive and motor perturbations induced by 3NP, as confirmed by striatal histopathological specimens and immunohistochemical examination of GFAP. The molecular signaling of Vilda was estimated by elevation of GLP-1 level and protein expressions of survival proteins; p85/p55 (pY458/199)-PI3K, pS473-Akt. Together, it boosted striatal neurotrophic factors and receptor; pS133-CREB, BDNF, pY515-TrKB, which subsequently maintained mitochondrial integrity, as indicated by enhancing both SDH and COX activities, and the redox modulators; Sirt1, Nrf2. Such neuroprotection restored imbalance of neurotransmitters through increasing GABA and suppressing glutamate as well PDE10A. These effects were reversed by WM pre-administration. In conclusion, Vilda purveyed significant anti-Huntington effect which may be mediated, at least in part, via activation of GLP-1/PI3K/Akt pathway in 3NP rat model.

Telluric acid ameliorates hepatic ischemia reperfusion-induced injury in rats: Involvement of TLR4, Nrf2, and PI3K/Akt signaling pathways.

In past tellurium-based compounds had limited use, however, their therapeutic potential have been target of interest recently due to antioxidant and anti-inflammatory capabilities in experimental endotoxemia. Nevertheless, their potential hepatoprotective effect against ischemia reperfusion (IR) injury is still obscure. This study examined the possible hepatoprotective effect of telluric acid (TELL), one of tellurium-based compound, against the deteriorating effect hepatic IR injury in rats through directing toll like receptor-4 (TLR4) cascade, phosphoinositide 3-kinase(PI3K)/Akt axis, and nuclear erythroid-related factor-2 (Nrf-2) pathway as possible mechanisms contributed to TELL's effect. Indeed, male Wistar rats were randomized into 3 groups: sham-operated, control IR and TELL (50 µg/kg). TELL was administrated once daily for seven consecutive days prior to the IR induction. Pretreatment with TELL attenuated hepatic IR injury as manifested by hampered plasma aminotransaminases and lactate dehydrogenase activities. Also, TELL opposed IR induced elevation in tissue expression/activity of high-mobility group box protein-1 (HMGB1), TLR4, myeloid differentiation primary-response protein 88 (MyD88), phospho-nuclear factor-kappa B p65 (p-NF-κB p65), phospho-mitogen activated protein kinasep38 (p-MAPKp38) and tumor necrosis factor-alpha (TNF-α). Moreover, TELL reduced the elevated thiobarbituric acid reactive substances along with increased both Nrf-2 and endothelial nitric oxide synthase (eNOS) protein expression, beside replenishment of hepatic reduced glutathione. In addition, TELL induced obvious upregulation of p-PI3K and p-Akt protein expressions together with restoration of histopathological changes in IR injury. In conclusion, TELL purveyed conceivable novel hepatoprotective mechanisms and attenuated events associated with acute hepatic injury via inhibition of TLR4 downstream axis and activation of Nrf-2 and PI3K/Akt signaling cascades. Thus, TELL may provide a novel therapeutic potential for complications of hepatic IR injury.

Angiotensin 1-7 ameliorates 6-hydroxydopamine lesions in hemiparkinsonian rats through activation of MAS receptor/PI3K/Akt/BDNF pathway and inhibition of angiotensin II type-1 receptor/NF-κB axis.

MAS receptor (MASR), expressed in several brain areas, conferred neuroprotection against neurodegenerative disorders when activated by angiotensin (Ang) 1-7; however, its role in Parkinson's disease (PD) remains elusive. Intra-striatal post-administration of Ang1-7, using a 6-hydroxydopamine (OHDA) PD model, improved motor performance and muscle coordination. On the molecular level, Ang1-7 upregulated the striatal expression of MASR and caused upsurge in its downstream targets (p-PI3K/p-Akt/p-CREB/BDNF) to phosphorylate TrKB, which in a positive feedback upregulates MASR. Moreover, Ang1-7 increased substantia nigral tyrosine hydroxylase (TH) expression and striatal dopamine (DA) content to indicate the preservation of the dopaminergic neuronal signal. This effect extended to inhibit the striatal expression of Ang II type-1 receptor (AT-1R) to hold the neurodegenerative effect and to boost Ang1-7 anti-inflammatory/antioxidant effects by abating NADPH oxidase, along with lipid peroxidation. Indeed, Ang1-7 was able to decrease p-MAPK p38/NF-κB p65 to level the inflammatory and oxidative stress events off. The Ang1-7-mediated activation of MASR cue and the suppression of the AT-1R cascade were partially reversed by the intrastartial injection of A-779, a MASR antagonist. The current data suggests a novel therapeutic potential for the Ang1-7 against neurotoxicity associated motor impairment related to PD. The anti-parkinsonian effect of Ang1-7, is in part, mediated by its binding to MASR and the initiation of PI3K/Akt/CREB/BDNF/TrKB cue to increase DA synthesis, besides the downregulation/inhibition of AT-1R/MAPK p38/NF-κB p65/NADPH oxidase pathway.