Assessing the exploratory profile of two zebrafish populations: Influence of anxiety-like phenotypes and independent trials on homebase-related parameters and exploration.

Anxiety is a protective behavior when animals face aversive conditions. The open field test (OFT) is used to assess the spatio-temporal dynamics of exploration, in which both homebase formation and recognition of environmental cues may reflect habituation to unfamiliar conditions. Because emotional- and affective-like states influence exploration patterns and mnemonic aspects, we aimed to verify whether the exploratory behaviors of two zebrafish populations showing distinct baselines of anxiety differ in two OFT sessions. Firstly, we assessed the baseline anxiety-like responses of short fin (SF) and leopard (LEO) populations using the novel tank test (NTT) and light-dark test (LDT) in 6-min trials. Fish were later tested in two consecutive days in the OFT, where the spatial occupancy and exploratory profile were analyzed for 30 min. In general, LEO showed pronounced diving behavior and scototaxis in the NTT and LDT, respectively, in which an "anxiety index" corroborated their exacerbated anxiety-like behavior. In the OFT, the SF population spent less time to establish the homebase in the 1st trial, while only LEO showed a markedly reduction in the latency to homebase formation in the 2nd trial. Both locomotion and homebase-related activities were decreased in the 2nd trial, in which animals also revealed increased occupancy in the center area of the apparatus. Moreover, we verified a significant percentage of homebase conservation for both populations, while only SF showed reduced the number of trips and increased the average length of trips. Principal component analyses revealed that distinct factors accounted for total variances between trials for each population tested. While homebase exploration was reduced in the 2nd trial for SF, an increased occupancy in the center area and hypolocomotion were the main factors that contribute to the effects observed in LEO during re-exposure to the OFT. In conclusion, our novel data support the homebase conservation in zebrafish subjected to independent OFT sessions, as well as corroborate a population-dependent effect on specific behavioral parameters related to exploration.

Spermidine, a positive modulator of the NMDA receptor, facilitates extinction and prevents the reinstatement of morphine-induced conditioned place preference in mice.

RATIONALE: Individuals with opioid use disorders often relapse into drug-seeking behavior after recalling memories linked to the drug use experience. Improving extinction efficacy has been used as a strategy to treat substance use disorders and suppress relapse. Although N-methyl-D-aspartate receptor (NMDAr) agonists facilitate acquisition, consolidation, and extinction, no study has addressed whether spermidine (SPD), a natural polyamine ligand of the NMDA receptor, facilitates the extinction and reinstatement of morphine-induced conditioned place preference (CPP). OBJECTIVES AND METHODS: The aim of the present study was to investigate the effect of SPD, an NMDAr agonist, on the extinction and reinstatement of morphine-induced CPP in mice. Adult male albino Swiss mice received saline (0.9% NaCl) or morphine (5 mg/kg) intraperitoneally (i.p.) and were respectively confined to a black or a white compartment for 30 min for four consecutive days for CPP induction. SPD (10-30 mg/kg, i.p.) or ifenprodil (NMDAr antagonist, 0.1-1 mg/kg, i.p.) were injected 15 min before extinction training. RESULTS: SPD and ifenprodil facilitated the extinction of morphine-induced CPP. SPD treatment during the extinction period impaired reinstatement induced by a priming dose of morphine (1.25 mg/kg). Ifenprodil (0.1 mg/kg) prevented the facilitatory effect of spermidine on the extinction of morphine-induced CPP but did not prevent reinstatement induced by morphine. CONCLUSIONS: These results suggest that SPD facilitated the extinction of morphine-induced CPP by modulating the polyamine binding site of the NMDA receptor. Our findings reveal important effects of SPD and ifenprodil on the re-exposure-induced decrease in morphine-induced CPP, which may be promising for developing novel pharmacological strategies to treat opioid use disorder.

Spermine protects from LPS-induced memory deficit via BDNF and TrkB activation.

Lipopolysaccharide (LPS) has been long known to promote neuroinflammation and learning and memory deficits. Since spermine, one of the main natural polyamines in the central nervous system, protects from LPS-induced memory deficit by a mechanism that comprises GluN2B receptors, the aim of the present study was to determine whether brain-derived neurotrophic factor (BDNF), tropomyosin-related kinase B (TrkB) receptor and cAMP response element binding (CREB) are involved in this protective effect of spermine. Adult male Swiss albino mice received, immediately after training in the novel object recognition task, saline or LPS (250 µg/kg, i.p.); 5 min later they received saline or spermine (0.3 mg/kg, i.p.) and, when specified, 5 min thereafter saline or the TrkB receptor antagonist ANA-12 (0.5 mg/kg, i.p.) in different flanks. Animals were tested 24 h after training. Spermine protected from LPS-induced memory deficit and this protective effect was reversed by ANA-12. In a subset of animals BDNF, CREB and phospho-CREB immunoreactivity was determined in the hippocampi and cerebral cortex 4 h after spermine injection. Spermine reversed the decrease of mature BDNF levels induced by LPS in both hippocampus and cerebral cortex. Spermine increased phospho-CREB content and phospho-CREB/total CREB ratio in the cerebral cortex of LPS-treated mice. The results support that the protective effect of spermine on LPS-induced memory deficits depends on TrkB receptor activation and is accompanied by restoration of mature BDNF levels in hippocampus and cerebral cortex, as well as increased CREB phosphorylation in the cerebral cortex.

Extending the analysis of zebrafish behavioral endophenotypes for modeling psychiatric disorders: Fear conditioning to conspecific alarm response.

Anxiety, trauma- and stressor-related disorders are severe psychiatric conditions that affect human population worldwide. Given their genetic tractability, evolutionarily conserved neurotransmitter systems, and extensive behavioral repertoire, zebrafish have become an emergent model organism in translational neuroscience. Here, we investigate whether a single exposure to conspecific alarm substance (CAS) produces fear conditioning in zebrafish using a conditioned place aversion (CPA) paradigm, as well as the persistence of aversive responses at different time intervals. While CAS elicited freezing and erratic movements at conditioning phase, zebrafish showed a robust avoidance for the CAS-paired compartment and increased risk assessment up to 7 days postconditioning. Additionally, we observed the existence of two behavioral phenotypes (high- and low-avoider fish) that present different fear-like responses at conditioning phase and evasion of the conditioning side at postconditioning trials. Collectively, we show a prolonged conditioned place aversion in zebrafish after a single CAS conditioning session, reinforcing the use of fear conditioning protocols as valuable strategies for modeling psychiatric disorders-related phenotypes in zebrafish.

Caffeine prevents high-intensity exercise-induced increase in enzymatic antioxidant and Na+-K+-ATPase activities and reduction of anxiolytic like-behaviour in rats.

OBJECTIVE: Here we investigated the impact of chronic high-intensity interval training (HIIT) and caffeine consumption on the activities of Na+-K+-ATPase and enzymes of the antioxidant system, as well as anxiolytic-like behaviour in the rat brain. METHODS: Animals were divided into groups: control, caffeine (4 mg/kg), caffeine (8 mg/kg), HIIT, HIIT plus caffeine (4 mg/kg) and HIIT plus caffeine (8 mg/kg). Rats were trained three times per week for 6 weeks, and caffeine was administered 30 minutes before training. We assessed the anxiolytic-like behaviour, Na+-K+-ATPase, superoxide dismutase (SOD), catalase (CAT), and glutathione peroxidase (GPx) activities, levels of reduced glutathione (GSH) and thiobarbituric acid reactive substances (TBARS) in the brain. RESULTS AND DISCUSSION: HIIT-induced anxiolytic-like behaviour increased Na+-K+-ATPase and GPx activities and TBARS levels, altered the activities of SOD and CAT in different brain regions, and decreased GSH levels. Caffeine, however, elicited anxiogenic-like behaviour and blocked HIIT effects. The combination of caffeine and HIIT prevented the increase in SOD activity in the cerebral cortex and GPx activity in three brain regions. Our results show that caffeine promoted anxiogenic behaviour and prevented HIIT-induced changes in the antioxidant system and Na+-K+-ATPase activities.

Spermidine improves the persistence of reconsolidated fear memory and neural differentiation in vitro: Involvement of BDNF.

Putrescine, spermidine and spermine are organic cations implicated in learning, memory consolidation, reconsolidation and neurogenesis. These physiological processes are closely related, and convincing evidence indicates that neurogenesis is implicated both, in the establishment and maintenance of remote contextual fear memory. Although brain-derived neurotrophic factor (BDNF) is a key mediator involved in both neurogenesis and memory consolidation, effects of spermidine on persistence of memory after reactivation (reconsolidation) and possible involvement of BDNF have not been investigated. Here, we investigated whether the intrahippocampal infusion of spermidine improves the persistence of reconsolidated contextual fear conditioning memory in rats and whether these possible changes depend on BDNF/TrkB signaling in the hippocampus. The infusion of spermidine immediately and 12h post-reactivation improved fear memory of the animals tested seven but not two days after reactivation. The facilitatory effect of spermidine on the persistence of reconsolidated memory was blocked by the TrkB inhibitor ANA-12 (73.6pmol/site) and accompanied by mature BDNF level increase in the hippocampus, indicating that it depends on the BDNF/TrkB pathway. We also investigated whether spermidine alters BDNF levels and neural progenitor cell differentiation in vitro. Spermidine increased BDNF levels in vitro, facilitating neuritogenesis and neural migration. Spermidine-induced neuritogenesis in vitro was also blocked by ANA-12 (10µM). Since spermidine increases BDNF levels and facilitates neural differentiation in vitro, similar mechanisms may be involved in spermidine-induced facilitation of the persistence of reconsolidated memory.

Neuroprotective effects of pretreatment with quercetin as assessed by acetylcholinesterase assay and behavioral testing in poloxamer-407 induced hyperlipidemic rats.

Hyperlipidemia is a group of disorders characterized by excessive lipids in the bloodstream. It is associated with the incidence of cardiovascular diseases and recognized as the most important factor underlying the occurrence of atherosclerosis. This study was conducted to investigate whether pretreatment with quercetin can protect against possible memory impairment and deterioration of the cholinergic system in hyperlipidemic rats. Animals were divided into ten groups (n=7): saline/control, saline/quercetin 5mg/kg, saline/quercetin 25mg/kg, saline/quercetin 50mg/kg, saline/simvastatin (0.04mg/kg), hyperlipidemia, hyperlipidemia/quercetin 5mg/kg, hyperlipidemia/quercetin 25mg/kg, hyperlipidemia/quercetin 50mg/kg and hyperlipidemia/simvastatin. The animals were pretreated with quercetin by oral gavage for a period of 30days and hyperlipidemia was subsequently induced by intraperitoneal administration of a single dose of 500mg/kg of poloxamer-407. Simvastatin was administered after the induction of hyperlipidemia. The results demonstrated that hyperlipidemic rats had memory impairment compared with the saline control group (P<0.001). However, pretreatment with quercetin and simvastatin treatment attenuated the damage caused by hyperlipidemia compared with the hyperlipidemic group (P<0.05). Acetylcholinesterase (AChE) activity in the cerebral hippocampus was significantly (P<0.001) reduced in the hyperlipidemic group compared with the control saline group. Pretreatment with quercetin and simvastatin treatment in the hyperlipidemic groups significantly (P<0.05) increased AChE activity compared with the hyperlipidemic group. Our results thus suggest that quercetin may prevent memory impairment, alter lipid metabolism, and modulate AChE activity in an experimental model of hyperlipidemia.

Guarana (Paullinia cupana) ameliorates memory impairment and modulates acetylcholinesterase activity in Poloxamer-407-induced hyperlipidemia in rat brain.

Hyperlipidemia is a risk factor for the development of cognitive dysfunction and atherosclerosis. Natural compounds have recently received special attention in relation to the treatment of disease due to their low cost and wide margin of safety. Thus, the aim of this study was to determine the possible preventive effect of guarana powder (Paullinia cupana) on memory impairment and acetylcholinesterase (AChE) activity in the brain structures of rats with Poloxamer-407-induced hyperlipidemia. Adult male Wistar rats were pretreated with guarana (12.5, 25 and 50mg/kg/day) and caffeine (0.2mg/kg/day) by gavage for a period of 30days. Simvastatin (0.04mg/kg) was administered as a comparative standard. Acute hyperlipidemia was induced with intraperitoneal injections of 500mg/kg of Poloxamer-407. Memory tests and evaluations of anxiety were performed. The cortex, cerebellum, hippocampus, hypothalamus and striatum were separated to assess acetylcholinesterase activity. Our results revealed that guarana powder was able to reduce the levels of TC and LDL-C in a manner similar to simvastatin. Guarana powder also partially reduced the liver damage caused by hyperlipidemia. Guarana was able to prevent changes in the activity of AChE and improve memory impairment due to hyperlipidemia. Guarana powder may therefore be a source of promising phytochemicals that can be used as adjuvant therapy in the management of hyperlipidemia and cognitive disorders.

Curcumin attenuates memory deficits and the impairment of cholinergic and purinergic signaling in rats chronically exposed to cadmium.

This study investigated the protective effect of curcumin on memory loss and on the alteration of acetylcholinesterase and ectonucleotidases activities in rats exposed chronically to cadmium (Cd). Rats received Cd (1 mg/kg) and curcumin (30, 60, or 90 mg/kg) by oral gavage 5 days a week for 3 months. The animals were divided into eight groups: vehicle (saline/oil), saline/curcumin 30 mg/kg, saline/curcumin 60 mg/kg, saline/curcumin 90 mg/kg, Cd/oil, Cd/curcumin 30 mg/kg, Cd/curcumin 60 mg/kg, and Cd/curcumin 90 mg/kg. Curcumin prevented the decrease in the step-down latency induced by Cd. In cerebral cortex synaptosomes, Cd-exposed rats showed an increase in acetylcholinesterase and NTPDase (ATP and ADP as substrates) activities and a decrease in the 5'-nucleotidase activity. Curcumin was not able to prevent the effect of Cd on acetylcholinesterase activity, but it prevented the effects caused by Cd on NTPDase (ATP and ADP as substrate) and 5'-nucleotidase activities. Increased acetylcholinesterase activity was observed in different brain structures, whole blood and lymphocytes of the Cd-treated group. In addition, Cd increased lipid peroxidation in different brain structures. Higher doses of curcumin were more effective in preventing these effects. These findings show that curcumin prevented the Cd-mediated memory impairment, demonstrating that this compound has a neuroprotective role and is capable of modulating acetylcholinesterase, NTPDase, and 5'-nucleotidase activities. Finally, it highlights the possibility of using curcumin as an adjuvant against toxicological conditions involving Cd exposure. © 2015 Wiley Periodicals, Inc. Environ Toxicol 32: 70-83, 2017.

Neuroprotective effects of quercetin on memory and anxiogenic-like behavior in diabetic rats: Role of ectonucleotidases and acetylcholinesterase activities.

The present study investigated the protective effect of quercetin (Querc) on memory, anxiety-like behavior and impairment of ectonucleotidases and acetylcholinesterase (AChE) activities in brain of streptozotocin-induced diabetic rats (STZ-diabetes). The type 1 diabetes mellitus was induced by an intraperitoneal injection of 70mg/kg of streptozotocin (STZ), diluted in 0.1M sodium-citrate buffer (pH 4.5). Querc was dissolved in 25% ethanol and administered by gavage at the doses of 5, 25 and 50mg/kg once a day during 40days. The animals were distributed in eight groups of ten animals as follows: vehicle, Querc 5mg/kg, Querc 25mg/kg, Querc 50mg/kg, diabetes, diabetes plus Querc 5mg/kg, diabetes plus Querc 25mg/kg and diabetes plus Querc 50mg/kg. Querc was able to prevent the impairment of memory and the anxiogenic-like behavior induced by STZ-diabetes. In addition, Querc prevents the decrease in the NTPDase and increase in the adenosine deaminase (ADA) activities in SN from cerebral cortex of STZ-diabetes. STZ-diabetes increased the AChE activity in SN from cerebral cortex and hippocampus. Querc 50mg/kg was more effective to prevent the increase in AChE activity in the brain of STZ-diabetes. Querc also prevented an increase in the malondialdehyde levels in all the brain structures. In conclusion, the present findings showed that Querc could prevent the impairment of the enzymes that regulate the purinergic and cholinergic extracellular signaling and improve the memory and anxiety-like behavior induced by STZ-diabetes.

Diphenyl diselenide supplementation in infected mice by Toxoplasma gondii: Protective effect on behavior, neuromodulation and oxidative stress caused by disease.

The aim of this study was to evaluate the effect of subcutaneous administration of diphenyl diselenide (PhSe)2 on animal behavior and activities of acetylcholinesterase (AChE), adenylate kinase (AK), and creatine kinase (CK) in the brain of mice infected by Toxoplasma gondii. In addition, thiobarbituric acid reactive species (TBARS) levels and glutathione (GR, GPx and GST) activity were also evaluated. For the study, 40 female mice were divided into four groups of 10 animals each: group A (uninfected and untreated), group B (uninfected and treated with (PhSe)2), group C (infected and untreated) and group D (infected and treated with (PhSe)2). The mice were inoculated with 50 cysts of the ME49 strain of T. gondii. After infection the animals of the groups B and D were treated on days 1 and 20 post-infection (PI) with 5.0 µmol/kg of (PhSe)2 subcutaneously. Behavioral tests were conducted on days 29 PI to assess memory loss (object recognition), anxiety (elevated plus maze), locomotor and exploratory activity (Open Field) and it was found out that infected and untreated animals (group C) had developed anxiety and memory impairment, and the (PhSe)2 treatment did not reverse these behavioral changes on infected animals treated with (PhSe)2 (group D). The results showed an increase on AChE activity (P < 0.01) in the brain of infected and untreated animals (group C) compared to the uninfected and untreated animals (group A). The AK and CK activities decreased in infected and untreated animals (group C) compared to the uninfected and untreated animals (group A) (P < 0.01), however the (PhSe)2 treatment did not reverse these alterations. Infected and untreated animals (group C) showed increased TBARS levels and GR activity, and decreased GPx and GST activities when compared to uninfected and untreated animals (group A). Infected animals treated with (PhSe)2 (group D) decreased TBARS levels and GR activity, while increased GST activity when compared to infected and untreated animals (group C). It was concluded that (PhSe)2 showed antioxidant activity, but the dose used had no anti-inflammatory effect and failed to reverse the behavioral changes caused by the parasite.

Intrahippocampal infusion of spermidine improves memory persistence: Involvement of protein kinase A.

Spermidine (SPD) is an endogenous aliphatic amine that modulates GluN2B-containing NMDA receptors and improves memory. Recent evidence suggests that systemic SPD improves the persistence of the long term memory of fear. However, the role of hippocampal polyamines and its binding sites in the persistence of fear memory is to be determined, as well as its putative underlying mechanisms. This study investigated whether the intrahippocampal (i.h.) infusion of spermidine or arcaine, modulators of polyamine binding site at GluN2B-containing NMDA receptors, alters the persistence of the memory of contextual fear conditioning task in rats. We also investigated whether protein synthesis and cAMP dependent protein kinase (PKA) play a role in SPD-induced improvement of the fear memory persistence. While 12h post-training infusion of spermidine facilitated, arcaine and the inhibitor of protein synthesis (anisomycin) impaired the memory of fear assessed 7days after training. The infusion of arcaine, anisomycin or a selective PKA inhibitor (H-89), at doses that have no effect on memory per se, prevented the SPD-induced improvement of memory persistence. H-89 prevented the stimulatory effect of SPD on phospho-PKA/total-PKA ratio. These results suggests that the improvement of fear memory persistence induced by spermidine involves GluN2B-containing NMDA receptors, PKA pathway and protein synthesis in rats.

Inhibitory effect of Scutia buxifolia extracts, fractions, and ursolic acid on Na(+), K(+)-ATPase activity in vitro in membranes purified from rat hearts.

ETHNOPHARMACOLOGICAL RELEVANCE: Scutia buxifolia is a tree native to South America and is used as a cardiotonic agent; however, this property has not been associated with a clear mechanism or a specific compound. AIM OF THE STUDY: Given the importance of Na(+),K(+)-ATPase as a drug target in the treatment of heart failure, this study aimed to investigate the possible inhibitory effect of S. buxifolia crude extract and fractions (dichloromethane, ethyl acetate, and butanolic fractions), and identified compounds with effects on the activity of Na(+),K(+)-ATPase in vitro. MATERIALS AND METHODS: First, we characterized the crude extract and fractions by high-performance liquid chromatography, and then monitored their effects on the activity of Na(+),K(+)-ATPase obtained from heart muscle and brain membranes of adult male Wistar rats. RESULTS: We identified gallic acid, chlorogenic acid, caffeic acid, rutin, quercitrin, quercetin, and ursolic acid in S. buxifolia stem bark and leaves; quercitrin and ursolic acid were the main compounds in the ethyl acetate and dichloromethane fractions from leaves and stem bark. The crude extract (3 and 30mg/ml), and the ethyl acetate and dichloromethane fractions (0.1 and 1mg/ml) of both the stem bark and leaves inhibited Na(+),K(+)-ATPase activity in heart and brain samples. We found that, of the identified compounds, only ursolic acid (0.1mg/ml) was able to diminish Na(+), K(+)-ATPase activity in heart and brain samples. CONCLUSIONS: These data indicated that the cardiotonic effects of S. buxifolia may be due to the inhibition of Na(+),K(+)-ATPase activity in heart muscle, supporting the popular use of this plant as a treatment for heart failure.

Quercetin protects the impairment of memory and anxiogenic-like behavior in rats exposed to cadmium: Possible involvement of the acetylcholinesterase and Na(+),K(+)-ATPase activities.

The present study investigated the effects of quercetin in the impairment of memory and anxiogenic-like behavior induced by cadmium (Cd) exposure. We also investigated possible alterations in acetylcholinesterase (AChE), Na(+),K(+)-ATPase and δ-aminolevulinate dehydratase (δ-ALA-D) activities as well as in oxidative stress parameters in the CNS. Rats were exposed to Cd (2.5mg/kg) and quercetin (5, 25 or 50mg/kg) by gavage for 45days. Animals were divided into eight groups (n=10-14): saline/control, saline/Querc 5mg/kg, saline/Querc 25mg/kg, saline/Querc 50mg/kg, Cd/ethanol, Cd/Querc 5mg/kg, Cd/Querc 25mg/kg and Cd/Querc 50mg/kg. Results demonstrated that Cd impaired memory has an anxiogenic effect. Quercetin prevented these harmful effects induced by Cd. AChE activity decreased in the cerebral cortex and hippocampus and increased in the hypothalamus of Cd-exposed rats. The Na(+),K(+)-ATPase activity decreased in the cerebral cortex, hippocampus and hypothalamus of Cd-exposed rats. Quercetin prevented these effects in AChE and Na(+),K(+)-ATPase activities. Reactive oxygen species production, thiobarbituric acid reactive substance levels, protein carbonyl content and double-stranded DNA fractions increased in the cerebral cortex, hippocampus and hypothalamus of Cd-exposed rats. Quercetin totally or partially prevents these effects caused by Cd. Total thiols (T-SHs), reduced glutathione (GSH), and reductase glutathione (GR) activities decreased and glutathione S-transferase (GST) activity increased in Cd exposed rats. Co-treatment with quercetin prevented reduction in T-SH, GSH, and GR activities and the rise of GST activity. The present findings show that quercetin prevents alterations in oxidative stress parameters as well as AChE and Na(+),K(+)-ATPase activities, consequently preventing memory impairment and anxiogenic-like behavior displayed by Cd exposure. These results may contribute to a better understanding of the neuroprotective role of quercetin, emphasizing the influence of this flavonoid in the diet for human health, possibly preventing brain injury associated with Cd intoxication.

Effect of vitamin D3 on behavioural and biochemical parameters in diabetes type 1-induced rats.

Diabetes is associated with long-term complications in the brain and reduced cognitive ability. Vitamin D3 (VD3 ) appears to be involved in the amelioration of hyperglycaemia in streptozotocin (STZ)-induced diabetic rats. Our aim was to analyse the potential of VD3 in avoiding brain damage through evaluation of acetylcholinesterase (AChE), Na(+) K(+) -adenosine triphosphatase (ATPase) and delta aminolevulinate dehydratase (δ-ALA-D) activities and thiobarbituric acid reactive substance (TBARS) levels from cerebral cortex, as well as memory in STZ-induced diabetic rats. Animals were divided into eight groups (n = 5): control/saline, control/metformin (Metf), control/VD3 , control/Metf + VD3 , diabetic/saline, diabetic/Metf, diabetic/VD3 and diabetic/Metf + VD3 . Thirty days after treatment, animals were submitted to contextual fear-conditioning and open-field behavioural tests, after which they were sacrificed and the cerebral cortex was dissected. Our results demonstrate a significant memory deficit, an increase in AChE activity and TBARS levels and a decrease in δ-ALA-D and Na(+) K(+) -ATPase activities in diabetic rats when compared with the controls. Treatment of diabetic rats with Metf and VD3 prevented the increase in AChE activity when compared with the diabetic/saline group. In treated diabetic rats, the decrease in Na(+) K(+) -ATPase was reverted when compared with non-treated rats, but the increase in δ-ALA-D activity was not. VD3 prevented diabetes-induced TBARS level and improved memory. Our results show that VD3 can avoid cognitive deficit through prevention of changes in important enzymes such as Na(+) K(+) -ATPase and AChE in cerebral cortex in type 1 diabetic rats.

Spermidine improves fear memory persistence.

Persistence is the most characteristic attribute of long-term memory (LTM). For memory persistence, a second late event of consolidation, that occurs around 12h after the acquisition, is necessary. Although the N-methyl-d-aspartate (NMDA) receptor has been involved in the persistence of memory, whether endogenous modulators of the NMDA receptor actually modulate memory persistence is unknown. In the current study we investigated whether spermidine and arcaine, respectively agonist and antagonist of polyamine binding site at NMDA receptor, alter the persistence of the memory of contextual fear conditioning task in rats. While 12h post-training administration of spermidine (10 and 30mg/kg, i.p.) facilitated, arcaine (10mg/kg, i.p.) impaired the memory of fear assessed 2 and 7 days after training. Arcaine (0.1mg/kg) prevented the facilitatory effect of spermidine (10mg/kg, i.p.), and spermidine (1mg/kg), prevented the memory impairment induced by arcaine (10mg/kg, i.p.) when tested 2 and 7 days after training. These results suggest that endogenous polyamines improve the persistence of fear memory.

Anthocyanins restore behavioral and biochemical changes caused by streptozotocin-induced sporadic dementia of Alzheimer's type.

AIMS: The aim of this study was to analyze if the pre-administration of anthocyanin on memory and anxiety prevented the effects caused by intracerebroventricular streptozotocin (icv-STZ) administration-induced sporadic dementia of Alzheimer's type (SDAT) in rats. Moreover, we evaluated whether the levels of nitrite/nitrate (NOx), Na(+),K(+)-ATPase, Ca(2+)-ATPase and acethylcholinesterase (AChE) activities in the cerebral cortex (CC) and hippocampus (HC) are altered in this experimental SDAT. MAIN METHODS: Male Wistar rats were divided in 4 different groups: control (CTRL), anthocyanin (ANT), streptozotocin (STZ) and streptozotocin+anthocyanin (STZ+ANT). After seven days of treatment with ANT (200mg/kg; oral), the rats were icv-STZ injected (3mg/kg), and four days later the behavior parameters were performed and the animals submitted to euthanasia. KEY FINDINGS: A memory deficit was found in the STZ group, but ANT treatment showed that it prevents this impairment of memory (P<0.05). Our results showed a higher anxiety in the icv-STZ group, but treatment with ANT showed a per se effect and prevented the anxiogenic behavior induced by STZ. Our results reveal that the ANT treatment (100µM) tested displaces the specific binding of [(3)H] flunitrazepam to the benzodiazepinic site of GABAA receptors. AChE, Ca(+)-ATPase activities and NOx levels were found to be increased in HC and CC in the STZ group, which was attenuated by ANT (P<0.05). STZ decreased Na(+),K(+)-ATPase activity and ANT was able to prevent these effects (P<0.05). SIGNIFICANCE: In conclusion, these findings demonstrated that ANT is able to regulate ion pump activity and cholinergic neurotransmission, as well as being able to enhance memory and act as an anxiolytic compound in animals with SDAT.

Neuroprotective effect of anthocyanins on acetylcholinesterase activity and attenuation of scopolamine-induced amnesia in rats.

Anthocyanins are a group of natural phenolic compounds responsible for the color to plants and fruits. These compounds might have beneficial effects on memory and have antioxidant properties. In the present study we have investigated the therapeutic efficacy of anthocyanins in an animal model of cognitive deficits, associated to Alzheimer's disease, induced by scopolamine. We evaluated whether anthocyanins protect the effects caused by SCO on nitrite/nitrate (NOx) levels and Na(+),K(+)-ATPase and Ca(2+)-ATPase and acetylcholinesterase (AChE) activities in the cerebral cortex and hippocampus (of rats. We used 4 different groups of animals: control (CTRL), anthocyanins treated (ANT), scopolamine-challenged (SCO), and scopolamine+anthocyanins (SCO+ANT). After seven days of treatment with ANT (200mgkg(-1); oral), the animals were SCO injected (1mgkg(-1); IP) and were performed the behavior tests, and submitted to euthanasia. A memory deficit was found in SCO group, but ANT treatment prevented this impairment of memory (P<0.05). The ANT treatment per se had an anxiolytic effect. AChE activity was increased in both in cortex and hippocampus of SCO group, this effect was significantly attenuated by ANT (P<0.05). SCO decreased Na(+),K(+)-ATPase and Ca(2+)-ATPase activities in hippocampus, and ANT was able to significantly (P<0.05) prevent these effects. No significant alteration was found on NOx levels among the groups. In conclusion, the ANT is able to regulate cholinergic neurotransmission and restore the Na(+),K(+)-ATPase and Ca(2+)-ATPase activities, and also prevented memory deficits caused by scopolamine administration.

Effects of chlorogenic acid, caffeine, and coffee on behavioral and biochemical parameters of diabetic rats.

Diabetes mellitus (DM) is associated with brain alterations that may contribute to cognitive dysfunctions. Chlorogenic acid (CGA) and caffeine (CA), abundant in coffee (CF), are natural compounds that have showed important actions in the brain. The present study aimed to evaluate the effect of CGA, CA, and CF on acetylcholinesterase (AChE), Na(+), K(+)-ATPase, aminolevulinate dehydratase (δ-ALA-D) activities and TBARS levels from cerebral cortex, as well as memory and anxiety in streptozotocin-induced diabetic rats. Animals were divided into eight groups (n = 5-10): control; control/CGA 5 mg/kg; control/CA 15 mg/kg; control/CF 0.5 g/kg; diabetic; diabetic/CGA 5 mg/kg; diabetic/CA 15 mg/kg; and diabetic/CF 0.5 g/kg. Our results demonstrated an increase in AChE activity and TBARS levels in cerebral cortex, while δ-ALA-D and Na(+), K(+)-ATPase activities were decreased in the diabetic rats when compared to control water group. Furthermore, a memory deficit and an increase in anxiety in diabetic rats were observed. The treatment with CGA and CA prevented the increase in AChE activity in diabetic rats when compared to the diabetic water group. CGA, CA, and CF intake partially prevented cerebral δ-ALA-D and Na(+), K(+)-ATPase activity decrease due to diabetes. Moreover, CGA prevented diabetes-induced TBARS production, improved memory, and decreased anxiety. In conclusion, among the compounds studied CGA proved to be a compound which acts better in the prevention of brain disorders promoted by DM.

The selective A-type K+ current blocker Tx3-1 isolated from the Phoneutria nigriventer venom enhances memory of naïve and Aß(25-35)-treated mice.

Potassium channels regulate many neuronal functions, including neuronal excitability and synaptic plasticity, contributing, by these means, to mnemonic processes. In particular, A-type K(+) currents (IA) play a key role in hippocampal synaptic plasticity. Therefore, we evaluated the effect of the peptidic toxin Tx3-1, a selective blocker of IA currents, extracted from the venom of the spider Phoneutria nigriventer, on memory of mice. Administration of Tx3-1 (i.c.v., 300 pmol/site) enhanced both short- and long-term memory consolidation of mice tested in the novel object recognition task. In comparison, 4-aminopyridine (4-AP; i.c.v., 30-300 pmol/site), a non-selective K(+) channel blocker did not alter long-term memory and caused toxic side effects such as circling, freezing and tonic-clonic seizures. Moreover, Tx3-1 (i.c.v., 10-100 pmol/site) restored memory of Aß25-35-injected mice, and exhibited a higher potency to improve memory of Aß25-35-injected mice when compared to control group. These results show the effect of the selective blocker of IA currents Tx3-1 in both short- and long-term memory retention and in memory impairment caused by Aß25-35, reinforcing the role of IA in physiological and pathological memory processes.