The effects of captopril on lipopolysaccharide induced learning and memory impairments and the brain cytokine levels and oxidative damage in rats

Captopril attenuates oxidative stress and neuroinflammation implicated in cisplatin-induced cognitive deficits in rats

RATIONALE

One of the most debilitating drawbacks of cisplatin chemotherapy is neurotoxicity which elicits memory impairment and cognitive dysfunction (chemobrain). This is primarily triggered by oxidative stress and inflammation. Captopril, an angiotensin-converting enzyme inhibitor, has been reported as a neuroprotective agent owing to its antioxidant and anti-inflammatory effects.

OBJECTIVE

We examined the possible neuroprotective effect of captopril against cisplatin-induced neurological and behavioral abnormalities in rats.

METHODS

Chemobrain was induced in rats by cisplatin (5 mg/kg, i.p.) on the 7th and 14th days of the study while captopril was administered orally (25 mg/kg) daily for three weeks. The effects of captopril were assessed by performing behavioral tests, histological examination, and evaluation of oxidative stress and inflammatory markers.

RESULTS

Cisplatin caused learning/memory dysfunction assessed by passive avoidance and Y-maze tests, decline in locomotion, and rotarod motor balance loss which were further verified by neurodegeneration observed in histological examination. Also, cisplatin aggravated oxidative stress by elevating lipid peroxidation (MDA) levels and diminishing catalase activity. Moreover, cisplatin upregulated the neuroinflammatory markers (TNF, IL-6, GFAP, and NF-κB). Captopril successfully ameliorated cisplatin damage on the levels of neurobehavioral and histopathological changes. Mechanistically, captopril significantly diminished MDA production and preserved catalase antioxidant activity. Captopril also counteracted neuroinflammation through inhibiting NF-κB and its downstream proinflammatory cytokines besides repressing astrocyte activity by reducing GFAP expression.

CONCLUSION

Our findings revealed that captopril could abrogate cisplatin neurotoxicity via reducing oxidative stress and neuroinflammation thus enhancing cognitive and behavioral performance. This could suggest the repurposing of captopril as a neuroprotective agent, especially in hypertensive cancer patients receiving cisplatin.

Gallic acid attenuates lipopolysaccharide - induced memory deficits, neurochemical changes, and peripheral alterations in purinergic signaling

Neuroinflammation is associated with many neurological disorders. Gallic acid (GA) has attracted significant attention due to its biological properties, such as neuroprotective, anti-inflammatory, and antioxidant effects. In this study, we evaluated the effects of GA in memory, TNF-α levels, oxidative stress, and activities of acetylcholinesterase (AChE), Na+, K+-ATPase and Ca2+-ATPase in the brain of mice exposed to lipopolysaccharide (LPS). Additionally, we evaluated alterations in adenine nucleotides and nucleosides in the serum. Male mice were orally pretreated with vehicle or GA (50 or 100 mg/kg) for 14 days. Between days 8 and 14, the animals also received LPS injection (250 µg/kg) or saline. At the end of the experimental protocol, the animals were submitted to object recognition test, euthanized and cerebral cortex, hippocampus, striatum and blood were collected. LPS induced memory deficits, which were prevented by GA treatment. GA protected against LPS-induced oxidative damage in the cerebral cortex, hippocampus and striatum by reducing reactive oxygen species and nitrite levels, while increasing total thiol content and activities of antioxidant enzymes. GA also prevented LPS-induced alterations in AChE, Na+, K+-ATPase, and Ca2+-ATPase activities in brain structures. LPS elevated TNF-α levels in the hippocampus and cerebral cortex, which were attenuated by GA treatment. Furthermore, LPS caused a reduction in ADP and AMP hydrolysis and an increase in adenosine deamination in the serum, which were also prevented by GA. The effects of GA against neuroinflammation may be attributed to its potent antioxidant and anti-inflammatory properties, which modulate various pathways, including those involved in memory mechanisms.

The protective effect of angiotensin II type I receptor blocker (valsartan) on behavioral impairment, NLRP3, BDNF, and oxidative stress in the brain tissue of ovariectomized female rats

Depression and anxiety are common mental health disorders affecting thoughts, behaviors, and emotions. This study aimed to investigate the effect of the angiotensin II type I receptor blocker (AT1RB), valsartan, on menopause-induced depression and anxiety-like behaviors, and to elucidate possible mechanisms of action by measuring levels of nod-like receptor protein 3 (NLRP3), interleukin-1beta (IL-1β), brain-derived neurotrophic factor (BDNF), and oxidative stress in brain tissue. Thirty-two Wistar albino female rats were randomly divided into four groups (n = 8 per group): Control, AT1RB, OVX, and AT1RB + OVX. Following the bilateral ovariectomy (OVX) protocol, physiological saline was used as valsartan solvent, in a maximum volume of 0.4 mL, and valsartan was administered via intragastric gavage at a dose of 40 mg/kg/day. Depression and anxiety-like behaviors were assessed using the forced swimming test and open field test. Levels of oxidative stress markers, NLRP3, IL-1β, BDNF, and CREB were analyzed in the hippocampus and prefrontal cortex tissues. Behavioral tests indicated that depression and anxiety-like behaviors significantly increased in OVX rats (p < 0.01), while AT1RB treatment significantly reduced these behaviors (p < 0.05). In the hippocampus of OVX rats, oxidative stress (p < 0.01), NLRP3 (p < 0.05), and IL-1β (p < 0.01) levels were elevated, whereas BDNF levels were significantly decreased (p < 0.01). AT1RB treatment significantly improved oxidative stress parameters (p < 0.05) and BDNF levels (p < 0.01) but did not significantly affect the increased levels of NLRP3 and IL-1β in OVX rats. In conclusion, AT1RB has a therapeutic effect on menopause-induced depression and anxiety-like behaviors, likely by reducing oxidative stress and increasing BDNF production in the hippocampus.

Sodium nitroprusside restored lipopolysaccharide-induced learning and memory impairment in male rats via attenuating inflammation and oxidative stress

Inflammation and oxidative stress upset memory. We explored influence of sodium nitroprusside (SNP) on memory deficits resulted from lipopolysaccharide (LPS).Groups include control, LPS, LPS + SNP 1 mg/kg, LPS + SNP 2 mg/kg, and LPS + SNP 3 mg/kg. Morris water maze and passive avoidance tests and biochemical measurements were carried out.In Morris water maze, LPS prolonged time and distance for finding the platform. In probe trial, it diminished time spent and traveled distance in the target zone. Injection of 2 and 3 mg/kg of SNP overturned the effect of LPS. In passive avoidance task, LPS postponed entrance into darkroom and reduced time spent in light room and incremented time spent in darkroom in 3, 24, and 72 h after electrical shock. All three doses of SNP restored the effects of LPS. Biochemical experiments confirmed that LPS elevated interleukin-6 and malondialdehyde concentration and declined total thiol content and superoxide dismutase and catalase activity in the hippocampus and cortex tissues. SNP particularly at a 3 mg/kg dose ameliorated LPS effects on these parameters.SNP attenuated memory disabilities resulting from LPS through modifying inflammation and boosting antioxidant defense.

Hippocampus-prefrontal cortex inputs modulate spatial learning and memory in a mouse model of sepsis induced by cecal ligation puncture

AIMS

Sepsis-associated encephalopathy (SAE) often leads to cognitive impairments. However, the pathophysiology of SAE is complex and unclear. Here, we investigated the role of hippocampus (HPC)-prefrontal cortex (PFC) in cognitive dysfunction in sepsis induced by cecal ligation puncture (CLP) in mice.

METHODS

The neural projections from the HPC to PFC were first identified via retrograde tracing and viral expression. Chemogenetic activation of the HPC-PFC pathway was shown via immunofluorescent staining of c-Fos-positive neurons in PFC. Morris Water Maze (MWM) and Barnes maze (BM) were used to evaluate cognitive function. Western blotting analysis was used to determine the expression of glutamate receptors and related molecules in PFC and HPC.

RESULTS

Chemogenetic activation of the HPC-PFC pathway enhanced cognitive dysfunction in CLP-induced septic mice. Glutamate receptors mediated the effects of HPC-PFC pathway activation in CLP mice. The activation of the HPC-PFC pathway resulted in significantly increased levels of NMDAR, AMPAR, and downstream signaling molecules including CaMKIIa, pCREB, and BDNF in PFC. However, inhibition of glutamate receptors using 2,3-dihydroxy-6-nitro-7-sulphamoyl-benzo (F)quinoxaline (NBQX), which is an α-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid receptor (AMPAR inhibitor), or D-2-amino-5-phosphonopentanoate (D-AP5), which is an NMDA receptor antagonist abolished this increase.

CONCLUSION

Our study reveals the important role of the HPC-PFC pathway in improving cognitive dysfunction in a mouse model of CLP sepsis and provides a novel pathogenetic mechanism for SAE.

Immunomodulatory Activity of the Most Commonly Used Antihypertensive Drugs-Angiotensin Converting Enzyme Inhibitors and Angiotensin II Receptor Blockers

This review article is focused on antihypertensive drugs, namely angiotensin converting enzyme inhibitors (ACEI) and angiotensin II receptor blockers (ARB), and their immunomodulatory properties reported in hypertensive patients as well as in experimental settings involving studies on animal models and cell lines. The immune regulatory action of ACEI and ARB is mainly connected with the inhibition of proinflammatory cytokine secretion, diminished expression of adhesion molecules, and normalization of CRP concentration in the blood plasma. The topic has significant importance in future medical practice in the therapy of patients with comorbidities with underlying chronic inflammatory responses. Thus, this additional effect of immune regulatory action of ACEI and ARB may also benefit the treatment of patients with metabolic syndrome, allergies, or autoimmune disorders.

Captopril Combined with Furosemide or Hydrochlorothiazide Affects Macrophage Functions in Mouse Contact Hypersensitivity Response

Hypertension is a chronic disease associated with chronic inflammation involving activated macrophages. Antihypertensive drugs (for example, angiotensin-converting enzyme inhibitors—ACEIs) used in the treatment of hypertension have immunomodulatory properties. On the other hand, the immunological effect of diuretics and combined drugs (diuretics + ACEI) is unclear. Therefore, we examined the influence of diuretics and combination drugs (ACEI + diuretic) on cellular response (contact hypersensitivity), production of reactive oxygen intermediates (ROIs), and nitric oxide (NO), and the secretion of interleukin-12 (IL-12). CBA mice were administered i.p. captopril (5 mg/kg) with or without hydrochlorothiazide (10 mg/kg) or furosemide (5 mg/kg) for 8 days. On the third day, the mice were administered i.p. mineral oil, and macrophages were collected 5 days later. In the presented results, we show that diuretics administered alone or with captopril increase the generation of ROIs and reduce the formation of NO by macrophages. Moreover, tested drugs inhibit the secretion of IL-12. Diuretics and combined drugs reduce the activity of contact hypersensitivity (both activation and induction phases). Our research shows that the tested drugs modulate the cellular response by influencing the function of macrophages, which is important in assessing the safety of antihypertensive therapy.

LINCS Dataset-Based Repositioning of Dutasteride as an Anti-Neuroinflammation Agent

Neuroinflammation is often accompanied by central nervous system (CNS) injury seen in various CNS diseases, with no specific treatment. Drug repurposing is a strategy of finding new uses for approved or investigational drugs, and can be enabled by the Library of Integrated Network-based Cellular Signatures (LINCS), a large drug perturbation database. In this study, the signatures of Lipopolysaccharide (LPS) were compared with the signatures of compounds contained in the LINCS dataset. To the top 100 compounds obtained, the Quantitative Structure-Activity Relationship (QSAR)-based tool admetSAR was used to identify the top 10 candidate compounds with relatively high blood-brain barrier (BBB) penetration. Furthermore, the seventh-ranked compound, dutasteride, a 5-α-reductase inhibitor, was selected for in vitro and in vivo validation of its anti-neuroinflammation activity. The results showed that dutasteride significantly reduced the levels of IL-6 and TNF-α in the supernatants of LPS-stimulated BV2 cells, and decreased the levels of IL-6 in the hippocampus and plasma, and the number of activated microglia in the brain of LPS administration mice. Furthermore, dutasteride also attenuated the cognitive impairment caused by LPS stimulation in mice. Taken together, this study demonstrates that the LINCS dataset-based drug repurposing strategy is an effective approach, and the predicted candidate, dutasteride, has the potential to ameliorate LPS-induced neuroinflammation and cognitive impairment.

Anti-Inflammatory Activities of Captopril and Diuretics on Macrophage Activity in Mouse Humoral Immune Response

Hypertension is accompanied by the over-activation of macrophages. Diuretics administered alone or in combination with hypotensive drugs may have immunomodulatory effects. Thus, the influence of tested drugs on mouse macrophage-mediated humoral immunity was investigated. Mice were treated intraperitoneally with captopril (5 mg/kg) with or without hydrochlorothiazide (10 mg/kg) or furosemide (5 mg/kg) by 8 days. Mineral oil-induced peritoneal macrophages were harvested to assess the generation of cytokines in ELISA, and the expression of surface markers was analyzed cytometrically. Macrophages were also pulsed with sheep red blood cells (SRBC) and transferred to naive mice for evaluation of their ability to induce a humoral immune response. Tested drugs increase the expression of surface markers important for the antigen phagocytosis and presentation. SRBC-pulsed macrophages from mice treated with captopril combined with diuretics increased the secretion of antigen-specific antibodies by recipient B cells, while macrophages of mice treated with hydrochlorothiazide or furosemide with captopril increased the number of antigen-specific B cells. Tested drugs alter the macrophage secretory profile in favor of anti-inflammatory cytokines. Our results showed that diuretics with or without captopril modulate the humoral response by affecting the function of macrophages, which has significant translational potential in assessing the safety of antihypertensive therapy.

Captopril suppresses hepatic mammalian target of rapamycin cell signaling and biomarkers of inflammation and oxidative stress in thioacetamide-induced hepatotoxicity in rats

BACKGROUND

The potential inhibitory effects of captopril, the angiotensin-converting enzyme inhibitor, on thioacetamide (TAA)-induced hepatic mammalian target of rapamycin (mTOR), liver injury enzymes, blood pressure, and biomarkers of inflammation and oxidative stress have not been investigated before.

MATERIALS AND METHODS

Rats were either injected with TAA (200 mg/kg; twice a week for 8 weeks) before being sacrificed after 10 weeks (model group) or were pretreated with captopril (150 mg/kg) daily for two weeks prior to TAA injections and continued receiving both agents until the end of the experiment (protective group).

RESULTS

Captopril significantly (p < .05) inhibited TAA-induced hypertension, liver tissue levels of mTOR, TIMP-1, TNF-α, IL-6, MDA; and blood levels of lipids, ALT, and AST. We further demonstrated a significant (p < .01) positive correlation between mTOR scoring and the levels of inflammatory, oxidative and liver injury biomarkers.

CONCLUSIONS

Captopril protects against TAA-induced mTOR, liver injury enzymes, dyslipidemia, hypertension, inflammation, and oxidative stress.

Effects of Combined Anti-Hypertensive and Statin Treatment on Memory, Fear Extinction, Adult Neurogenesis, and Angiogenesis in Adult and Middle-Aged Mice

Hyperlipidemia and hypertension are modifiable risk factors for cognitive decline. About 25% of adults over age 65 use both antihypertensives (AHTs) and statins to treat these conditions. Recent research in humans suggests that their combined use may delay or prevent dementia onset. However, it is not clear whether and how combination treatment may benefit brain function. To begin to address this question, we examined effects of atorvastatin, a 3-hydroxy-3-methylglutaryl coenzyme A (HMG-CoA) reductase inhibitor, and Captopril, an angiotensin-converting enzyme inhibitor (ACEI), administration on memory function, anxiety-like behavior, adult hippocampal neurogenesis and angiogenesis in adult and middle-aged male C57Bl/6J mice. In adult mice (3-months-old) combination (combo) treatment, as well as administration of each compound individually, for six weeks, accelerated memory extinction in contextual fear conditioning. However, pattern separation in the touchscreen-based location discrimination test, a behavior linked to adult hippocampal neurogenesis, was unchanged. In addition, dentate gyrus (DG) neurogenesis and vascularization were unaffected. In middle-aged mice (10-months-old) combo treatment had no effect on spatial memory in the Morris water maze, but did reduce anxiety in the open field test. A potential underlying mechanism may be the modest increase in new hippocampal neurons (~20%) in the combo as compared to the control group. DG vascularization was not altered. Overall, our findings suggest that statin and anti-hypertensive treatment may serve as a potential pharmacotherapeutic approach for anxiety, in particular for post-traumatic stress disorder (PTSD) patients who have impairments in extinction of aversive memories.

Protective effects of vitamin D on learning and memory deficit induced by scopolamine in male rats: the roles of brain-derived neurotrophic factor and oxidative stress

The beneficial effects of vitamin D (vit D) on central nervous system disorders have been suggested. In the current research, the protective effects of vit D on learning and memory deficit induced by scopolamine, oxidative stress criteria, brain-derived neurotrophic factor (BDNF), and nitric oxide (NO) in the brain were investigated. Rats were divided into five groups, including (1) Control, (2) Scopolamine (2 mg/kg), (3-5) Scopolamine + Vit D (100, 1000, and 10,000 IU/kg) groups. Vit D administrated for 2 weeks and in the third week scopolamine co-administrated with vit D and behavioral tests, including Morris water maze (MWM) and passive avoidance (PA) tests, were carried out. The cortical and hippocampal tissues were analyzed for BDNF, catalase (CAT), and superoxide dismutase (SOD) activities, thiol content, NO metabolites, and malondialdehyde (MDA) concentration. Scopolamine injection significantly impaired rats' performance on the MWM and PA test. It further enhanced the MDA and nitrite level while decreased thiol content and BDNF levels and SOD and CAT activities in the brain. Administration of both 1000 and 10,000 IU/kg vit D improved cognitive outcome in MWM and PA tests. In addition, vit D elevated thiol content, SOD and CAT activities, and BDNF levels, while reduced nitrite and MDA concentration. Vit D also increased the levels of vit D and calcium in the serum. The results demonstrated that vit D has protective effects on scopolamine-associated learning and memory impairment by improving BDNF levels and attenuating NO and brain tissue oxidative damage.

Conventional cardiovascular risk factors in Transient Global Amnesia: Systematic review and proposition of a novel hypothesis

Transient Global Amnesia (TGA) is an enigmatic amnestic syndrome. We conducted a systematic review to investigate the relationship between the conventional cardiovascular risk factors and TGA. MEDLINE, CENTRAL, EMBASE and PsycINFO were comprehensively searched and 23 controlled observational studies were retrieved. The prevalence of hypertension, diabetes mellitus, dyslipidemia and smoking was lower among patients with TGA compared to Transient Ischemic Attack. Regarding the comparison of TGA with healthy individuals, there was strong evidence suggesting a protective effect of diabetes mellitus on TGA and weaker evidence for a protective effect of smoking. Hypertension was associated with TGA only in more severe stages, while dyslipidemia was not related. In view of these findings, a novel pathophysiological hypothesis is proposed, in which the functional interactions of Angiotensin-II type-1 and N-methyl-D-aspartate receptors are of pivotal importance. The whole body of clinical evidence (nature of precipitating events, associations with migraine, gender-based association patterns) was integrated.

Beneficial effects of angiotensin converting enzyme inhibition on scopolamine-induced learning and memory impairment in rats, the roles of brain-derived neurotrophic factor, nitric oxide and neuroinflammation

The effect of the brain-derived neurotrophic factor (BDNF), cytokines, and renin angiotensin system (RAS) on memory function have been demonstrated. In this study, the effects of RAS inhibitor captopril (Capto) on hippocampal BDNF, interleukin -6 (IL-6), oxidative stress indicators, and nitric oxide (NO) in scopolamine (Sco)-induced memory impairment in rats were examined. The groups were (1) control, (2) Sco in which Sco was applied 30 min prior to the behavioral tests, and (3-5) Sco-Capto 10, 50, and 100 groups, where Capto (10, 50, or 100 mg/kg), were applied 2 weeks prior to the experiment, as well as 30 min prior to each Sco injection. The Morris Water Maze (MWM) test was conducted, and BDNF, IL-6, NO metabolites, malondialdehyde (MDA), thiol, superoxide dismutase (SOD), and catalase (CAT) were measured. Sco increased the delay and distance to the platform in the MWM test (P < .01 to P < .001), while shortening the time and distance in the target area (P < .01 to P < .001). Additionally, Sco increased IL-6, NO metabolites, and MDA, while decreasing BDNF, thiol, SOD, and CAT (P < .01 to P < .001). Although the Capto reduced the latency and distance traveled to the platform (P < .05 to P < .001), it elevated the time and distance traveled in the target area (P < .05 to P < .01). Furthermore, Capto improved BDNF, thiol, SOD, and CAT levels, and decreased IL-6, NO metabolites, and MDA (P < .05 to P < .001). RAS has a role in learning and memory impairment due to cholinergic system dysfunction. The possible mechanism(s) are including its effects on BDNF, neuro-inflammation and oxidative stress.

What animal models can tell us about long-term cognitive dysfunction following sepsis: A systematic review

Survivors of sepsis often develop long-term cognitive impairments. This review aimed at exploring the results of the behavioral tools and tests which have been used to evaluate cognitive dysfunction in different animal models of sepsis. Two independent investigators searched for sepsis- and cognition-related keywords. 6323 publications were found, of which 355 were selected based on their title, and 226 of these were chosen based on manuscript review. LPS was used to induce sepsis in 171 studies, while CLP was used in 55 studies. Inhibitory avoidance was the most widely used method for assessing aversive memory, followed by fear conditioning and continuous multi-trial inhibitory avoidance. With regard to non-aversive memory, most studies used the water maze, open-field, object recognition, Y-maze, plus maze, and radial maze tests. Both CLP and LPS models of sepsis were effective in inducing short- and long-term behavioral impairment. Our findings help elucidate the mechanisms involved in the pathophysiology of sepsis-induced cognitive changes, as well as the available methods and tests used to study this in animal models.

Neuronal Nitric Oxide Inhibitor 7-Nitroindazole Improved Brain-Derived Neurotrophic Factor and Attenuated Brain Tissues Oxidative Damage and Learning and Memory Impairments of Hypothyroid Juvenile Rats

Hypothyroidism-associated learning and memory impairment is reported to be connected to oxidative stress and reduced levels of brain-derived neurotrophic factor (BDNF). The effects of neuronal nitric oxide inhibitor 7-nitroindazole (7NI) on brain tissues oxidative damage, nitric oxide (NO), BDNF and memory impairments in hypothyroid juvenile rats were investigated. Male Wistar juvenile rats (20 days old) were divided into five groups, including Martinez et al. (J Neurochem 78 (5):1054-1063, 2001). Control in which vehicle was injected instead of 7NI, (Jackson in Thyroid 8 (10):951-956, 1998) Propylthiouracil (PTU) where 0.05% PTU was added in drinking water and vehicle was injected instead of 7NI, (Gong et al. in BMC Neurosci 11 (1):50, 2010; Alva-Sánchez et al. in Brain Res 1271:27-35, 2009; Anaeigoudari et al. in Pharmacol Rep 68 (2): 243-249, 2016) PTU-7NI 5, PTU-7NI 10 and PTU-7NI 20 in which 5, 10, or 20 mg/kg7NI was injected intraperitoneally (i.p.). Following 6 weeks, Morris water maze (MMW) and passive avoidance learning (PAL) tests were used to evaluate the memory. Finally, the hippocampus and the cortex of the rats were removed after anesthesia by urethane to be used for future analysis. The escape latency and traveled path in MWM test was increased in PTU group (P < 0.001). PTU also reduced the latency to enter the dark box of PAL and the time spent and the distance in the target quadrant in MWM test (P < 0.001 and P < 0.01). Treatment with 7NI attenuated all adverse effects of PTU (P < 0.05 to P < 0.001). PTU lowered BDNF and thiol content and superoxide dismutase (SOD) and catalase (CAT) activities in the brain but increased malondialdehyde (MDA) and nitric oxide (NO) metabolites. In addition, 7NI improved thiol, SOD, CAT, thiol, and BDNF but attenuated MDA and NO metabolites. The results of the current study showed that 7NI improvement in the learning and memory of the hypothyroid juvenile rats, which was accompanied with improving of BDNF and attenuation of NO and brain tissues oxidative damage.

Vitamin D3 attenuates lipopolysaccharide-induced cognitive impairment in rats by inhibiting inflammation and oxidative stress

AIMS

Vitamin D is a well-known endocrine regulator of calcium/phosphate homeostasis and has been reported as having a wide range of activities that are potentially beneficial for human health. This study aimed to investigate the effects of pretreatment of vitamin D₃ (100, 1000, and 10,000 IU/kg) against lipopolysaccharide (LPS)-induced cognitive impairment in rats.

MAIN METHODS

Male Wistar rats were divided into five groups. The passive avoidance test and Morris water maze (MWM) test were conducted to evaluate the learning and memory function. Oxidative stress markers including malondialdehyde (MDA), catalase (CAT), superoxide dismutase (SOD), total thiol content as well as interleukin (IL)-6 were evaluated in the hippocampus tissue.

KEY FINDINGS

The intraperitoneal (i.p.) injection of LPS (1 mg/kg) correlates with deficits in passive avoidance and spatial learning in the systemic inflammation model. However, pretreatment with vitamin D₃ improved LPS-induced cognitive impairment. In addition, vitamin D₃ decreased IL-6 and MDA levels, whereas the activities of CAT, SOD, and total thiol content in the hippocampus tissue were significantly increased.

SIGNIFICANCE

In conclusion, our results suggest that vitamin D₃ plays a protective role against memory dysfunction caused by LPS-induced inflammation through inhibition of oxidative stress and inflammation in the hippocampus. Vitamin D may be a promising potential therapeutic supplement for the treatment or prevention of learning and memory disorders.

Medicinal Thiols: Current Status and New Perspectives

The thiol (-SH) functional group is found in a number of drug compounds and confers a unique combination of useful properties. Thiol-containing drugs can reduce radicals and other toxic electrophiles, restore cellular thiol pools, and form stable complexes with heavy metals such as lead, arsenic, and copper. Thus, thiols can treat a variety of conditions by serving as radical scavengers, GSH prodrugs, or metal chelators. Many of the compounds discussed here have been in use for decades, yet continued exploration of their properties has yielded new understanding in recent years, which can be used to optimize their clinical application and provide insights into the development of new treatments. The purpose of this narrative review is to highlight the biochemistry of currently used thiol drugs within the context of developments reported in the last five years. More specifically, this review focuses on thiol drugs that represent the standard of care for their associated conditions, including N-acetylcysteine, 2,3-meso-dimercaptosuccinic acid, British anti-Lewisite, D-penicillamine, amifostine, and others. Reports of novel dosing regimens, delivery strategies, and clinical applications for these compounds were examined with an eye toward emerging approaches to address a wide range of medical conditions in the future.

Protective Effects of Carvacrol on Brain Tissue Inflammation and Oxidative Stress as well as Learning and Memory in Lipopolysaccharide-Challenged Rats

Inflammation can cause memory impairment. In the present study, the effect of carvacrol on brain tissue inflammation and oxidative stress as well as learning and memory in lipopolysaccharide (LPS)-challenged rats was evaluated. The animals were grouped and treated: (1) control which received vehicle instead of LPS and carvacrol, (2) LPS (1 mg/kg; i.p. 120 min before behavioral tests), and (3-5) in these groups, 25, 50, or 100 mg/kg of carvacrol (i.p.) was administered 30 min prior to LPS. In a Morris water maze test, compared to LPS group, administration of all three doses of carvacrol shortened the elapsed time and the traveled distance to find the platform, while it prolonged the traveled time in the target area. In a passive avoidance test, administration of all 25, 50, and 100 mg/kg carvacrol significantly increased the latency at the 3 h, 24 h, 48 h, and 72 h after the shock compared to the LPS group. Interleukin (IL)-6, malondialdehyde (MDA), and NO (nitric oxide) metabolites were increased in the brain by LPS injection, while thiol, superoxide dismutase (SOD), and catalase (CAT) were decreased. Pretreatment with carvacrol reduced IL-6, NO metabolites, and MDA, while it improved thiol content, CAT, and SOD. The results indicated that carvacrol protected from learning and memory impairment and the brain tissue inflammation and oxidative stress in LPS-challenged rats.

Effect of Captopril on Brain Oxidative Damage in Pentylenetetrazole-Induced Seizures in Mice

Background: Frequent seizure is followed by overproduction of free radicals and brain oxidative stress. Renin angiotensin system (RAS) has some effects on central nervous system. We designed this research to challenge the effect of captopril as an angiotensin converting enzyme (ACE) inhibitor against brain oxidative stress in pentylenetetrazole (PTZ) -induced seizures in mice. Methods: The groups were including (1) Control (saline); (2) PTZ (100 mg/kg, i.p.), (3-5) PTZ- captopril (Capto) that received three doses of Capto 10, 50 and 100 mg/kg 30 min before PTZ injection. Latency time in the onset minimal clonic seizures (MCS) and generalized tonic-clonic seizures (GTCS) were recorded. The level of malondialdehyde (MDA) and total thiol, as well as superoxide dismutase (SOD) and catalase (CAT) activity in the hippocampus and cortex were measured. Results: All doses of captopril postponed the onset of MCS and GTCS. Accumulation of MDA in the brain tissues of PTZ group was higher than control group, while total thiol content and CAT activity were lower. Pretreatment with captopril (100 mg/kg) diminished MDA concentration compared with PTZ group. Captopril (50 and 100 mg/kg) also increased the level of total thiol groups versus PTZ group. Captopril injection (50 and 100 mg/kg) elevated the activity of SOD and CAT in the brain tissues. In addition captopril administration diminished mortality rate caused by PTZ. Conclusion: Findings demonstrated that convulsions caused by PTZ were followed by oxidative stress status in the brain tissues. Pretreatment with captopril attenuated the effect of PTZ on brain tissue oxidative damage.<br />

The effects of captopril on lipopolysaccharide-induced sickness behaviors in rats

Neuro-immune mediators play an important role in the development of sickness behaviors. In the present study, the effect of captopril on sickness behaviors caused by lipopolysaccharide (LPS) was studied in the rats. The animals were randomized into the following groups: control, sham, 10 mg kg^-1 captopril - LPS (Capto 10-LPS), 50 mg kg^-1 captopril - LPS (Capto 50-LPS), and 100 mg kg^-1 captopril - LPS (Capto 100-LPS). Behavioral tests including open-field (OF), elevated plus maze (EPM) and forced swimming (FS) test were performed, and the serum level of interleukin-6 (IL-6) was assessed. In OF, the number of crossings in the central zone in Capto 10-LPS, Capto 50-LPS, and Capto 100-LPS groups was higher than that of the sham group. In EPM, the open arm entry numbers in the sham group were lower compared to the control group. Furthermore, pretreatment by captopril increased the entries to the open arms. In FS test, the immobility time of the sham group was longer than that of the control group. In Capto 10-LPS, Capto 50-LPS, and Capto 100-LPS groups, immobility was shorter compared to the sham group. In addition, the IL-6 level was higher in the sham group compared to the control group, and treatment with 50 and 100 mg kg^-1 of captopril restored the IL-6 level in comparison with the sham group. Results confirmed that pretreatment with captopril ameliorated LPS-caused sickness behaviors and attenuated IL-6 as an inflammatory marker in the rats.

Neuroprotective effects of exercise in rodent models of memory deficit and Alzheimer's

Alzheimer's disease (AD) is a fastest growing neurodegenerative condition with no standard treatment. There are growing evidence about the beneficial effects of exercise in brain health promotion and slowing the cognitive decline. The aim of this study was to review the protective mechanisms of treadmill exercise in different models of rodent memory deficits. Online literature database, including PubMed-Medline, Scopus, Google scholar were searched from 2003 till 2017. Original article with English language were chosen according to following key words in the title: (exercise OR physical activity) AND (memory OR learning). Ninety studies were finally included in the qualitative synthesis. The results of these studies showed the protective effects of exercise on AD induced neurodegerative and neuroinflammatory process. Neuroperotective effects of exercise on the hippocampus seem to be increasing in immediate-early gene c-Fos expression in dentate gyrus; enhancing the Wnt3 expression and inhibiting glycogen synthase kinase-3β expression; increasing the 5-bro-mo-2'-deoxyridine-positive and doublecortin-positive cells (dentate gyrus); increasing the level of astrocytes glial fibrillary acidic protein and decrease in S100B protein, increasing in blood brain barrier integrity; prevention of oxidative stress injury, inducing morphological changes in astrocytes in the stratum radiatum of cornu ammonis 1(CA1) area; increase in cell proliferation and suppress apoptosis in dentate gyrus; increase in brain-derived neurotrophic factor and tropomyosin receptor kinase B expressions; enhancing the glycogen levels and normalizing the monocarboxylate transporter 2 expression.

Protective effect of aminoguanidine against lipopolysaccharide-induced hepatotoxicity and liver dysfunction in rat

Lipopolysaccharide (LPS) as the major component of the outer membrane of Gram-negative bacteria activates macrophages to produce a high level of pro-inflammatory cytokines which is considered as a cause of liver dysfunction. Overproduction of nitric oxide (NO) has been suggested to have a role in hepatic injury. The aim of the present study was to explore the protective effects of aminoguanidine (AG) as inducible nitric oxide synthase (iNOS) inhibitor against LPS -induced liver dysfunction in rat. The animals were divided into five groups: (1) control (2) LPS (3) LPS-AG50, (4) LPS-AG100 and (5) LPS-AG150. LPS (1 mg/kg) was injected for 5 weeks and AG (50, 100 and 150 mg/kg) was administered 30 min before LPS. Drugs were injected intraperitoneally. LPS induced liver dysfunction presented by increasing the serum level of alkaline phosphatase (ALK-P), alanine aminotransferase (ALT), aspartate aminotransferase (AST). Pretreatment with AG restored harmful effects of LPS on liver function. In addition, LPS resulted in hepatotoxicity, accompanied by enhancing the level of interleukin (IL)-6, malondialdehyde (MDA) and nitric oxide (NO) metabolites and decreasing the content of total thiol groups and superoxide dismutase (SOD) and catalase (CAT) activity. Injection of AG before LPS attenuated LPS-induced hepatotoxicity through decreasing the level of IL-6, MDA and NO metabolites and increasing total thiols and SOD and CAT activity. Considering the protective effect of AG which was seen in the present study, it seems that increased levels of NO due to activation of iNOS has a role in LPS-induced hepatic injury.

Thymoquinone reverses learning and memory impairments and brain tissue oxidative damage in hypothyroid juvenile rats

In this study, the effect of thymoquinone (TQ) on propylthiouracil (PTU)-induced memory impairment was investigated in juvenile rats. The rats were grouped into control, Hypo, Hypo-TQ5 and Hypo-TQ10. Propylthiouracil increased latency time in the Morris water maze test and decreased delay in entering the dark compartment in the passive avoidance test. Both 5 mg/kg and 10 mg/kg doses of TQ decreased latency time in the Morris water maze test and increased delay in entering the dark compartment in a passive avoidance test. The PTU also increased malondialdehyde and nitric oxide metabolites in the brain while reduced the thiol content and superoxide dismutase and catalase activities and serum T4 level. Both doses of TQ decreased malondialdehyde and nitric oxide metabolites in the brain while enhanced the thiol content and superoxide dismutase and catalase activities and serum T4 level. The results of the present study showed that TQ protected against PTU-induced memory impairments in rats.

Trigonelline mitigates lipopolysaccharide-induced learning and memory impairment in the rat due to its anti-oxidative and anti-inflammatory effect

Brain inflammation is associated with cognitive dysfunction, especially in elderly. Trigonelline is a plant alkaloid and a major component of coffee and fenugreek with anti-diabetic, antioxidant, anti-inflammatory, and neuroprotective effects. In this study, the beneficial effect of trigonelline against lipopolysaccharide (LPS)-induced cognitive decline was assessed in the rat. LPS was injected i.p. at a dose of 500 μg/kg to induce neuroinflammation and trigonelline was administered p.o. at doses of 20, 40, or 80 mg/kg/day 1 h after LPS that continued for one week. Trigonelline-treated LPS-challenged rats showed improved spatial recognition memory in Y maze, discrimination ratio in novel object discrimination test, and retention and recall in passive avoidance paradigm. Additionally, trigonelline lowered hippocampal malondialdehyde (MDA) and acetylcholinesterase (AChE) activity and improved superoxide dismutase (SOD), catalase, and glutathione (GSH). Furthermore, trigonelline depressed hippocampal nuclear factor-kappaB (NF-κB), toll-like receptor 4 (TLR4), and tumor necrosis factor α (TNF α) in LPS-challenged rats. All of the effects of trigonelline followed a dose-dependent pattern and in some aspects, it acted even better than the routinely-used anti-inflammatory drug dexamethasone. Collectively, trigonelline is capable to diminish LPS-induced cognitive decline via suppression of hippocampal oxidative stress and inflammation and appropriate modulation of NF-κB/TLR4 and AChE activity.

Inducible nitric oxide inhibitor aminoguanidine, ameliorated oxidative stress, interleukin-6 concentration and improved brain-derived neurotrophic factor in the brain tissues of neonates born from titanium dioxide nanoparticles exposed rats

Introduction: An interaction between oxidative stress, neuroinflammation, and nitric oxide (NO) has been suggested to have a role neurotoxicity. The aim of current research was to investigate the effect of aminoguanidine (AG) as an inducible NO synthase (iNOS) inhibitor, on brain-derived neurotrophic factor (BDNF), oxidative stress, and interleukin-6 (IL-6) concentrations in the brain tissues of neonates born from the rats exposed to titanium dioxide nanoparticles (TiO2 NPs) during gestation. Methods: The pregnant rats were grouped into three and received: (1) saline, (2) TiO2 (200 mg/kg, gavage), and (3) TiO2-AG [200 mg/kg intraperitoneal (IP)]. The treatment was started since the second gestation day up to the delivery time. The neonates born from the rats were deeply anesthetized, sacrificed, and the brains were collected for biochemical evaluations. Results: The neonates born from the rats exposed to TiO₂ showed a lower BDNF (p < .001) but a higher IL-6 (p < .01) concentrations in their hippocampal tissue. TiO₂ exposure also increased malondialdehyde (MDA) (p < .001) and NO metabolites (p < .001), while diminished thiol (p < .001), superoxide (SOD) (p < .001), and catalase (CAT) (p < .001) in all hippocampal, cortical, and cerebellar tissues. Administration of AG improved BDNF (p < .01) but attenuated IL-6 (p < .01) concentrations in the hippocampal tissue. AG also decreased MDA (p < .001) and NO metabolites (p < .01-p < .001), while increased thiol (p < .01-p < .001), SOD (p < .001), and CAT (p < .05-p < .001) in all cerebellar, hippocampal, cortical, and tissues. Conclusion: The results of the current research revealed that iNOS inhibitor AG, ameliorated oxidative stress, IL-6 concentration, and improved BDNF in the brain tissues of neonates born from TiO₂ NPs exposed rats.

Memory enhancing effect of Nigella Sativa hydro-alcoholic extract on lipopolysaccharide-induced memory impairment in rats

In this study, the effects of Nigella Sativa (NS) hydro-alcoholic extract on lipopolysaccharide (LPS)-induced learning and memory impairments, hippocampal cytokine levels, and brain tissues oxidative damage were investigated in rats. The rats were grouped and treated: (1) control (saline), (2) LPS (1 mg/kg i.p.), and (3-5) 100, 200, or 400 mg/kg NS hydro-alcoholic extract 30 min before LPS injection. The treatment was started since 6 days before the behavioral experiments and continued during the behavioral tests (LPS injection 2 h before each behavioral experiment). Finally, the brains were removed for biochemical assessments. In Morris water maze (MWM) test, LPS increased the escape latency and traveled path compared to control group, whereas all doses of NS hydro-alcoholic extract decreased them compared to LPS group. In passive avoidance (PA) test, the latency to enter the dark compartment in LPS group was shorter than control group while in all treated groups it was longer than LPS group. LPS increased tumor necrosis factor-α (TNF-α), interleukin-6 (IL-6), malondialdehyde (MDA), and nitric oxide (NO) metabolites, and decreased thiol content, superoxide dismutase (SOD), and catalase (CAT) in the hippocampal tissues compared to control group while NS hydro-alcoholic extract decreased MDA and NO metabolites and increased thiol content, SOD, and CAT compared to LPS group. Findings of the current study indicated that the hydro-alcoholic extract of NS improved the LPS-induced learning and memory impairments induced by LPS in rats by improving hippocampal cytokine levels and brain tissues oxidative damage.