Mechanism of Salvia miltiorrhiza Bunge extract to alleviate Chronic Sleep Deprivation-Induced cognitive dysfunction in rats.

BACKGROUND: Bidirectional communication between the gut microbiota and the brain may play an essential role in the cognitive dysfunction associated with chronic sleep deprivation(CSD). Salvia miltiorrhiza Bunge (Danshen, DS), a famous Chinese medicine and functional tea, is extensively used to protect learning and memory capacities, although the mechanism of action remains unknown. PURPOSE: The purpose of this research was to explore the efficacy and the underlying mechanism of DS in cognitive dysfunction caused by CSD. METHODS: DS chemical composition was analyzed by UPLC-QTOF-MS/MS. Forty rats were randomly assigned to five groups (n = 8): control (CON), model (MOD), low- (1.35 g/kg, DSL), high-dose (2.70 g/kg, DSH) DS group, and Melatonin(100 mg/kg, MT) group. A CSD rat model was established over 21 days. DS's effects and the underlying mechanism were explored using the open-field test(OFT), Morris water-maze(MWM), tissue staining(Hematoxylin and Eosin Staining, Nissl staining, Alcian blue-periodic acid SCHIFF staining, and Immunofluorescence), enzyme-linked immunosorbent assay, Western blot, quantitative real-time polymerase chain reaction(qPCR), and 16S rRNA sequencing. RESULTS: We demonstrated that CSD caused gut dysbiosis and cognitive dysfunction. Furthermore, 16S rRNA sequencing demonstrated that Firmicutes and Proteobacteria were more in fecal samples from model group rats, whereas Bacteroidota and Spirochaetota were less. DS therapy, on the contrary hand, greatly restored the gut microbial community, consequently alleviating cognitive impairment in rats. Further research revealed that DS administration reduced systemic inflammation via lowering intestinal inflammation and barrier disruption. Following that, DS therapy reduced Blood Brain Barrier(BBB) and neuronal damage, further decreasing neuroinflammation in the hippocampus(HP). Mechanistic studies revealed that DS therapy lowered lipopolysaccharide (LPS) levels in the HP, serum, and colon, consequently blocking the TLR4/MyD88/NF-κB signaling pathway and its downstream pro-inflammatory products(IL-1ß, IL-6, TNF-α, iNOS, and COX2) in the HP and colon. CONCLUSION: DS treatment dramatically improved spatial learning and memory impairments in rats with CSD by regulating the composition of the intestinal flora, preserving gut and brain barrier function, and reducing inflammation mediated by the LPS-TLR4 signaling pathway. Our findings provide novel insight into the mechanisms by which DS treats cognitive dysfunction caused by CSD.

Neuroprotective effects of Anshen Bunao Syrup on cognitive dysfunction in Alzheimer's disease rat models.

Alzheimer's disease (AD) presents a significant challenge due to its prevalence and lack of cure, driving the quest for effective treatments. Anshen Bunao Syrup, a traditional Chinese medicine known for its neuroprotective properties, shows promise in addressing this need. However, understanding its precise mechanisms in AD remains elusive. This study aimed to investigate Anshen Bunao Syrup's therapeutic potential in AD treatment using a scopolamine-induced AD rat model. Assessments included novel-object recognition and Morris water maze tasks to evaluate spatial learning and memory, alongside Nissl staining and ELISA analyses for neuronal damage and biomarker levels. Results demonstrated that Anshen Bunao Syrup effectively mitigated cognitive dysfunction by inhibiting amyloid-ß and phosphorylation Tau aggregation, thereby reducing neuronal damage. Metabolomics profiling of rats cortex revealed alterations in key metabolites implicated in tryptophan and fatty acid metabolism pathways, suggesting a role in the therapeutic effects of Anshen Bunao Syrup. Additionally, ELISA and correlation analyses indicated attenuation of oxidative stress and immune response through metabolic remodeling. In conclusion, this study provides compelling evidence for the neuroprotective effects of Anshen Bunao Syrup in AD models, shedding light on its potential as a therapeutic agent for AD prevention and treatment.

Kai-xin-san improves cognitive impairment in D-gal and Aß25-35 induced ad rats by regulating gut microbiota and reducing neuronal damage.

ETHNOPHARMACOLOGICAL RELEVANCE: Kai-Xin-San (KXS) is a classic herbal formula for the treatment and prevention of AD (Alzheimer's disease) with definite curative effect, but its mechanism, which involves multiple components, pathways, and targets, is not yet fully understood. AIM OF THE STUDY: To verify the effect of KXS on gut microbiota and explore its anti-AD mechanism related with gut microbiota. MATERIALS AND METHODS: AD rat model was established and evaluated by intraperitoneal injection of D-gal and bilateral hippocampal CA1 injections of Aß25-35. The pharmacodynamics of KXS in vivo includes general behavior, Morris water maze test, ELISA, Nissl & HE staining and immunofluorescence. Systematic analysis of gut microbiota was conducted using 16S rRNA gene sequencing technology. The potential role of gut microbiota in the anti-AD effect of KXS was validated with fecal microbiota transplantation (FMT) experiments. RESULTS: KXS could significantly improve cognitive impairment, reduce neuronal damage and attenuate neuroinflammation and colonic inflammation in vivo in AD model rats. Nine differential intestinal bacteria associated with AD were screened, in which four bacteria (Lactobacillus murinus, Ligilactobacillus, Alloprevotella, Prevotellaceae_NK3B31_group) were very significant. CONCLUSION: KXS can maintain the ecological balance of intestinal microbiota and exert its anti-AD effect by regulating the composition and proportion of gut microbiota in AD rats through the microbiota-gut-brain axis.

Investigating navigation strategies in the Morris Water Maze through deep reinforcement learning.

Navigation is a complex skill with a long history of research in animals and humans. In this work, we simulate the Morris Water Maze in 2D to train deep reinforcement learning agents. We perform automatic classification of navigation strategies, analyze the distribution of strategies used by artificial agents, and compare them with experimental data to show similar learning dynamics as those seen in humans and rodents. We develop environment-specific auxiliary tasks and examine factors affecting their usefulness. We suggest that the most beneficial tasks are potentially more biologically feasible for real agents to use. Lastly, we explore the development of internal representations in the activations of artificial agent neural networks. These representations resemble place cells and head-direction cells found in mouse brains, and their presence has correlation to the navigation strategies that artificial agents employ.

Refinement of the Barnes and Morris water maze protocols improves characterization of spatial cognitive deficits in the lithium-pilocarpine rat model of epilepsy.

Temporal lobe epilepsy (TLE) often causes cognitive impairment, especially a decline in spatial memory. Reductions in spatial memory and learning are also common in rodent models of TLE. The Morris water maze and the Barnes maze are the standard methods for evaluating spatial learning and memory in rodents. However, animals with TLE may exhibit agitation, distress, and fail to follow the paradigmatic context of these tests, making the interpretation of experimental data difficult. This study optimized the procedure of the Morris water maze and the Barnes maze to evaluate spatial learning and memory in rats with the lithium-pilocarpine TLE model (LPM rats). It was demonstrated that LPM rats required a mandatory and prolonged habituation stage for both tests. Therefore, the experimental rats performed relatively well on these tests. Nevertheless, LPM rats exhibited a slower learning process compared to the control rats. LPM rats also showed a reduction in spatial memory formation. This was more pronounced in the Barnes maze. Also, LPM rats utilized a sequential strategy for searching in the Barnes maze and were incapable of developing a more efficient spatial search strategy that is common in control animals. The Barnes maze may be a better choice for assessing search strategies, learning deficits, and spatial memory in rats with TLE when choosing between the two tests. This is because of the risk of unexpected seizure occurrence during the Morris water maze tests, and the potential risks for animal welfare.

Activation of Metabotropic Glutamate Receptor (mGlu2) and Muscarinic Receptors (M1, M4, and M5), Alone or in Combination, and Its Impact on the Acquisition and Retention of Learning in the Morris Water Maze, NMDA Expression and cGMP Synthesis.

The Morris water maze (MWM) is regarded as one of the most popular tests for detecting spatial memory in rodents. Long-term potentiation and cGMP synthesis seem to be among the crucial factors involved in this type of learning. Muscarinic (M1, M4, and M5 receptors) and metabotropic glutamate (mGlu) receptors are important targets in the search for antipsychotic drugs with the potency to treat cognitive disabilities associated with the disorder. Here, we show that muscarinic receptor activators (VU0357017, VU0152100, and VU0238429) and an mGlu2 receptor activator, LY487379, dose-dependently prevented the development of cognitive disorders as a result of MK-801 administration in the MWM. The dose-ranges of the compounds were as follows: VU0357017, 0.25, 0.5, and 1 mg/kg; VU0152100, 0.05, 0.25, and 1 mg/kg; VU0238429, 1, 5, and 20 mg/kg; and LY487379, 0.5, 3, and 5 mg/kg. The co-administration of LY487379 with each of the individual muscarinic receptor ligands showed no synergistic effect, which contradicts the results obtained earlier in the novel object recognition (NOR) test. MWM learning resulted in increased cGMP synthesis, both in the cortex and hippocampi, when compared to that in intact animals, which was prevented by MK-801 administration. The investigated compounds at the highest doses reversed this MK-801-induced effect. Neither the procedure nor the treatment resulted in changes in GluN2B-NMDA expression.

Differential effects of exposure to toxic or nontoxic mold spores on brain inflammation and Morris water maze performance.

People who live or work in moldy buildings often complain of "brain fog" that interferes with cognitive performance. Until recently, there was no published research on the effects of controlled exposure to mold stimuli on cognitive function or an obvious mechanism of action, fueling controversy over these claims. The constellation of health problems reported by mold-exposed individuals (respiratory issues, fatigue, pain, anxiety, depression, and cognitive deficits) correspond to those caused by innate immune activation following exposure to bacterial or viral stimuli. To determine if mold-induced innate immune activation might cause cognitive issues, we quantified the effects of both toxic and nontoxic mold on brain immune activation and spatial memory in the Morris water maze. We intranasally administered either 1) intact, toxic Stachybotrys chartarum spores; 2) ethanol-extracted, nontoxic Stachybotrys chartarum spores; or 3) control saline vehicle to mice. Inhalation of nontoxic spores caused significant deficits in the test of long-term memory of platform location, while not affecting short-term memory. Inhalation of toxic spores increased motivation to reach the platform. Interestingly, in both groups of mold-exposed males, numbers of interleukin-1ß-immunoreactive cells in many areas of the hippocampus significantly correlated with latency to find the platform, path length, and swimming speed during training, but not during testing for long-term memory. These data add to our prior evidence that mold inhalation can interfere with cognitive processing in different ways depending on the task, and that brain inflammation is significantly correlated with changes in behavior.

Effects of liraglutide on depressive behavior in a mouse depression model and cognition in the probe trial of Morris water maze test.

BACKGROUND: We investigated the effects of liraglutide, a glucagon-like peptide-1 (GLP-1) agonist, on a depression-like phenotype in mice exposed to chronic unpredictable stress (CUS). Learning and memory were also assessed using the Morris water maze (MWM) test. METHODS: Liraglutide (0.3 mg/kg/day for 21 days) was administered to mice with or without exposure to CUS. After 21 days of CUS, the forced swim test (FST) was performed to assess its antidepressant effect. To evaluate cognitive function, liraglutide was administered to mice under stress-free conditions for 21 days, and then the MWM test was performed on 6 consecutive days. RESULTS: Chronic liraglutide treatment reduced FST immobility in mice with and without CUS. In the probe trial of the Morris water maze test, the search error rate was reduced and the time spent and path length in the target quadrant and the number of platform crossings were increased. LIMITATION: Additional animal model experiments and molecular level studies are needed to support the results obtained in this study. CONCLUSIONS: Liraglutide appears to exert antidepressant effects and could improve cognitive function. Based on these results, GLP-1 agonists could have potential as novel antidepressants.

Cannabidiol Impairs Brain Mitochondrial Metabolism and Neuronal Integrity.

Background: The mechanisms underlying the clinical effects of CBD remain poorly understood. Given the increasing evidence for CBD's effects on mitochondria, we sought to examine in more detail whether CBD impacts mitochondrial function and neuronal integrity. Methods: We utilized BE(2)-M17 neuroblastoma cells or acutely isolated brain mitochondria from rodents using a Seahorse extracellular flux analyzer and a fluorescent spectrofluorophotometer assay. Mitochondrial ion channel activity and hippocampal long-term potentiation were measured using standard cellular electrophysiological methods. Spatial learning/memory function was evaluated using the Morris water maze task. Plasma concentrations of CBD were assessed with liquid chromatography-mass spectrometry, and cellular viability was evaluated using the 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) reduction neuronal injury assay. Results: At low micromolar concentrations, CBD reduced mitochondrial respiration, the threshold for mitochondrial permeability transition, and calcium uptake, blocked a novel mitochondrial chloride channel, and reduced the viability of hippocampal cells. These effects were paralleled by in vitro and in vivo learning/memory deficits. We further found that these effects were independent of cannabinoid receptor 1 and mitochondrial G-protein-coupled receptor 55. Conclusion: Our results provide evidence for concentration- and dose-dependent toxicological effects of CBD, findings that may bear potential relevance to clinical populations.

Search strategy analysis of Tg4-42 Alzheimer Mice in the Morris Water Maze reveals early spatial navigation deficits.

Spatial disorientation is one of the earliest symptoms in Alzheimer's disease and allocentric deficits can already be detected in the asymptomatic preclinical stages of the disease. The Morris Water Maze (MWM) is used to study spatial learning in rodent models. Here we investigated the spatial memory of female 3, 7 and 12 month-old Alzheimer Tg4-42 mice in comparison to wild-type control animals. Conventional behavior analysis of escape latencies and quadrant preference revealed spatial memory and reference memory deficits in female 7 and 12 month-old Tg4-42 mice. In contrast, conventional analysis of the MWM indicated an intact spatial memory in 3 month-old Tg4-42 mice. However, a detailed analysis of the swimming strategies demonstrated allocentric-specific memory deficits in 3 month-old Tg4-42 mice before the onset of severe memory deficits. Furthermore, we could show that the spatial reference memory deficits in aged Tg4-42 animals are caused by the lack of allocentric and spatial strategies. Analyzing search strategies in the MWM allows to differentiate between hippocampus-dependent allocentric and hippocampus-independent egocentric search strategies. The spatial navigation impairments in young Tg4-42 mice are well in line with the hypometabolism and synaptic deficits in the hippocampus. Therefore, analyzing search strategies in the Tg4-42 model can be a powerful tool for preclinical drug testing and identifying early therapeutic successes.

Morris water maze: a versatile and pertinent tool for assessing spatial learning and memory.

Since its development about 40 years ago (1981-2021), Morris water maze has turned into a very popular tool for assessing spatial learning and memory. Its many advantages have ensured its pertinence to date. These include its effectiveness in evaluating hippocampal-dependent learning and memory, exemption from motivational differences across diverse experimental manipulations, reliability in various cross-species studies, and adaptability to many experimental conditions with various test protocols. Nonetheless, throughout its establishment, several experimental and analysis loopholes have galvanized researchers to assess ways in which it could be improved and adapted to fill this gap. Therefore, in this review, we briefly summarize these developments since the early years of its establishment through to the most recent advancements in computerized analysis, offering more comprehensive analysis paradigms. In addition, we discuss the adaptability of the Morris water maze across different test versions and analysis paradigms, providing suggestions with regard to the best paradigms for particular experimental conditions. Hence, the proper selection of the experimental protocols, analysis paradigms, and consideration of the assay's limitations should be carefully considered. Given that appropriate measures are taken, with various adaptations made, the Morris water maze will likely remain a relevant tool to assess the mechanisms of spatial learning and memory.

Role of RGS2 in sevoflurane-induced cognitive dysfunction in aged rats.

After undergoing inhalation anesthesia, some patients, especially elderly patients, experience postoperative cognitive dysfunction, such as personality changes and memory impairment. In the present study, 20-month-old rats were randomly allocated to sevoflurane (Sevo group) and control groups (Con group), and they inhaled 3% sevoflurane or 40% oxygen for 8 hours, respectively. The Morris water maze test found that the cognitive function of rats in the Sevo group were significantly different on 1d and 3d after anesthesia than that of rats in the Con group. The expression of RGS2 mRNA and protein in hippocampus of Sevo group was lower compared to the Con group, while Ca2 + was higher than con group. The expression of CaM and CaMK II in Sevo group was higher compared to the Con group. We found that Bcl-2 reduced, but the expression of Bax and Caspase-3 increased, indicating that apoptosis of hippocampal neurons was increased after sevoflurane inhalation. Both the expression of NGF and BDNF was depressed in the Sevo group. After continuous inhalation of 3% sevoflurane for 8h, the expression of RGS2 in the hippocampi of aged rats is down regulated. RGS2 may be an important factor that leads to cognitive dysfunction in rats.

Late-stage rescue of visually guided behavior in the context of a significantly remodeled retinitis pigmentosa mouse model.

Patients with progressive neurodegenerative disorder retinitis pigmentosa (RP) are diagnosed in the midst of ongoing retinal degeneration and remodeling. Here, we used a Pde6b-deficient RP gene therapy mouse model to test whether treatment at late disease stages can halt photoreceptor degeneration and degradative remodeling, while sustaining constructive remodeling and restoring function. We demonstrated that when fewer than 13% of rods remain, our genetic rescue halts photoreceptor degeneration, electroretinography (ERG) functional decline and inner retinal remodeling. In addition, in a water maze test, the performance of mice treated at 16 weeks of age or earlier was indistinguishable from wild type. In contrast, no efficacy was apparent in mice treated at 24 weeks of age, suggesting the photoreceptors had reached a point of no return. Further, remodeling in the retinal pigment epithelium (RPE) and retinal vasculature was not halted at 16 or 24 weeks of age, although there appeared to be some slowing of blood vessel degradation. These data suggest a novel working model in which restoration of clinically significant visual function requires only modest threshold numbers of resilient photoreceptors, halting of destructive remodeling and sustained constructive remodeling. These novel findings define the potential and limitations of RP treatment and suggest possible nonphotoreceptor targets for gene therapy optimization.

The combination of nicotinamide mononucleotide and lycopene prevents cognitive impairment and attenuates oxidative damage in D-galactose induced aging models via Keap1-Nrf2 signaling.

Aging is referred to progressive dysfunction of body organs, including the brain. This study aims to explore the anti-aging effect of combing nicotinamide mononucleotide (NMN) and lycopene (Lyco) (NMN + Lyco) on aging rats and senescent PC12 cells. Both in vivo and in vitro aging models were established using D-galactose (D-gal). The combination showed a trend to superiority over monotherapy in preventing aging in vivo and in vitro. Morris water maze test showed that NMN + Lyco effectively improved the ability of spatial location learning and memory of aging model rats. NMN + Lyco mitigated the oxidative stress of rat brains, livers, and PC12 cells by elevating the levels of superoxide dismutase (SOD), catalase (CAT), glutathione peroxidase (GSH-Px), GSH, as well as total antioxidant capacity (T-AOC), and reducing malondialdehyde (MDA) content. CCK-8 assay, senescence-associated ß-galactosidase staining, and flow cytometer confirmed the cellular senescence of PC12 cells after exposing D-gal, and indicated the anti-senescence effect of NMN + Lyco in vitro. Moreover, NMN + Lyco effectively down-regulated the expressions of p53, p21, and p16 (senescence-related genes), and activated Keap1-Nrf2 signaling in both in vivo and in vitro aging models. In total, NMN + Lyco protected rats and PC12 cells from cognitive impairment and cellular senescence induced by D-gal, of which effects might be linked to the reduction of oxidative stress and the activation of Keap1-Nrf2 signaling.

In vitro and in vivo evaluations of antioxidative, anti-Alzheimer, antidiabetic and anticancer potentials of hydroponically and soil grown Lactuca sativa.

BACKGROUND: Lactuca sativa is an edible plant commonly used by local communities to manage diabetes and stomach problems. METHODS: This work aimed to investigate the anti-oxidant, anticancer, antidiabetic and Anti-Alzheimer effects of hydroponically (HyL) and soil-grown (SoL) Lactuca sativa. Streptozotocin-induced diabetes and AlCl3-induced Alzheimer's disease model was used to evaluate the medicinal effects of Lactuca sativa. RESULTS: HyL showed significant activity in lipid peroxidation assay, DPPH and DNA protection assay, while SoL extract showed moderated activity, respectively. A similar activity response was quantified for α-glucosidase, α-amylase, acetylcholinesterase and butyrylcholinesterase inhibition assays. The cytotoxic potential of HyL and SoL extracts against MCF7, and HePG2 cancer cell lines exhibited significant activity. HyL and SoL showed a substantial decrease in blood glucose levels in streptozotocin-induced diabetic rats. Diabetes-related liver/kidney biomarkers and anti-oxidant enzyme trends moved toward normal after HyL and SoL treatment. In Anti-Alzheimer's based Morris water and elevated plus maze tests, HyL and SoL displayed memory-enhancing response and anti-anxiety behaviour, respectively. HPLC quantification of dopamine and serotonin revealed a moderate but significant (p<0.05) increase in the level of these neurotransmitters in HyL and SoL groups. CONCLUSION: Overall, the study revealed that hydroponic Lactuca sativa possesses the therapeutic potential to treat diseases like Alzheimer's and diabetes.

Novel measures of Morris water maze performance that use vector field maps to assess accuracy, uncertainty, and intention of navigational searches.

Most commonly used behavioral measures for testing learning and memory in the Morris water maze (MWM) involve comparisons of an animal's residence time in different quadrants of the pool. Such measures are limited in their ability to test different aspects of the animal's performance. Here, we describe novel measures of performance in the MWM that use vector fields to capture the motion of mice as well as their search pattern in the maze. Using these vector fields, we develop quantitative measures of performance that are intuitive and more sensitive than classical measures. First, we describe search patterns in terms of vector field properties and use these properties to define three metrics of spatial memory namely Spatial Accuracy, Uncertainty and, Intensity of Search. We demonstrate the usefulness of these measures using four different data sets including comparisons between different strains of mice, an analysis of two mouse models of Noonan syndrome (NS; Ptpn11 D61G and Ptpn11 N308D/+), and a study of goal reversal training. Importantly, besides highlighting novel aspects of performance in this widely used spatial task, our measures were able to uncover previously undetected differences, including in an animal model of NS, which we rescued with the mitogen activated protein kinase kinase (MEK) inhibitor SL327. Thus, our results show that our approach breaks down performance in the MWM into sensitive measurable independent components that highlight differences in spatial learning and memory in the MWM that were undetected by conventional measures.

Influence of diurnal phase on behavioral tests of sensorimotor performance, anxiety, learning and memory in mice.

Behavioral measurements in mice are critical tools used to evaluate the effects of interventions. Whilst mice are nocturnal animals, many studies conduct behavioral tests during the day. To better understand the effects of diurnal rhythm on mouse behaviors, we compared the results from behavioral tests conducted in the active and inactive phases. C57BL/6 mice were used in this study; we focus on sensorimotor performance, anxiety, learning and memory. Overall, our results show mice exhibit slightly higher cutaneous sensitivity, better long-term contextual memory, and a greater active avoidance escape response during the active phase. We did not observe significant differences in motor coordination, anxiety, or spatial learning and memory. Furthermore, apart from the elevated-O-maze, there was no remarkable sex effect among these tests. This study provides information on the effects of different diurnal phases on types of behavior and demonstrates the importance of the circadian cycle on learning and memory. Although we did not detect differences in anxiety and spatial learning/memory, diurnal rhythm may interact with other factors to influence these behaviors.

Intrahippocampal co-administration of nicotine and O-acetyl-L-carnitine prevents the H-89-induced spatial learning deficits in Morris water maze.

OBJECTIVES: H-89 (a protein kinase AII [PKA II] inhibitor) impairs the spatial memory in the Morris water maze task in rats. In the present study, we aimed to study the protective effects of nicotine and O-acetyl-L-carnitine against H-89-induced spatial memory deficits. METHODS: Spatial memory impairment was induced by the bilateral intrahippocampal administration of 10 µM H-89 (dissolved in dimethyl sulfoxide, DMSO) to rats. The rats then received bilateral administrations of either nicotine (1 µg/µL, dissolved in saline) or O-acetyl-L-carnitine (100 µM/side, dissolved in deionized water) alone and in combination. Control groups received either saline, deionized water, or DMSO. RESULTS: The H-89-treated animals showed significant increases in the time and distance travelled to find hidden platforms, and there was also a significant decrease in the time spent in the target quadrant compared to DMSO-treated animals. Nicotine and O-acetyl-L-carnitine had no significant effects on H-89-induced spatial learning impairments alone, but the bilateral intrahippocampal co-administration of nicotine and O-acetyl-L-carnitine prevented H-89-induced spatial learning deficits and increased the time spent in the target quadrant in comparison with H-89-treated animals. CONCLUSIONS: Our results indicated the potential synergistic effects of nicotine and O-acetyl-L-carnitine in preventing protein kinase AII inhibitor (H-89)-induced spatial learning impairments.

Paeoniflorin ameliorates ischemic injury in rat brain via inhibiting cytochrome c/caspase3/HDAC4 pathway.

Paeoniflorin (PF), a bioactive monoterpene glucoside, has shown a variety of pharmacological effects such as anti-inflammation and autophagy modulation etc. In this study, we investigated whether and how PF exerted a protective effect against ischemic brain injury in vivo and in vitro. Primary rat cortical neurons underwent oxygen/glucose deprivation/reperfusion (OGD/R) for 90 min. We showed that after OGD/R, a short fragment of histone deacetylase 4 (HDAC4) produced by caspase3-mediated degradation was markedly accumulated in the nucleus and the activity of caspase3 was increased. Treatment with PF (100 nM, 1 µM) significantly improved the viability of cortical neurons after OGD/R. Furthermore, PF treatment could maintain HDAC4 intrinsic subcellular localization and reduce the caspase3 activity without changing the HDAC4 at the transcriptional level. PF treatment significantly reduced OGD/R-caused inhibition of transcriptional factor MEF2 expression and increased the expression of downstream proteins such as GDNF, BDNF, and Bcl-xl, thus exerting a great anti-apoptosis effect as revealed by TUNEL staining. The beneficial effects of PF were almost canceled in HDAC4 (D289E)-transfected PC12 cells after OGD/R. In addition, PF treatment reduced the caspase9 activity, rescued the release of cytochrome c from mitochondria, and maintained the integrity of mitochondria membrane. We conducted in vivo experiments in 90-min-middle cerebral artery occlusion (MCAO) rat model. The rats were administered PF (20, 40 mg/kg, ip, 3 times at the reperfusion, 24 h and 48 h after the surgery). We showed that PF administration dose-dependently reduced infarction area, improved neurological symptoms, and maintained HDAC4 localization in rats after MCAO. These results demonstrate that PF is effective in protecting against ischemic brain injury and inhibit apoptosis through inhibiting the cytochrome c/caspase3/HDAC4 pathway.

Estradiol effects on spatial memory in women.

To examine the role of estradiol in hippocampal-dependent spatial memory in women, 86 female undergraduates were tested in a virtual Morris water task (VMWT), a virtual radial arm maze (VRAM), and a mental rotation task (MRT) within a single daily session. The VMWT and RAM were also administered 24 h later to examine the effects of estradiol on memory consolidation. Women on oral contraceptives (OCs) or those who were naturally cycling and exhibited low estradiol (LE) or high estradiol (HE), as determined by salivary assays, were included. At the start of day two, the HE group showed superior spatial reference memory on the VMWT relative to the LE group, as evidenced by significantly shorter distances navigating to the hidden platform. The LE group also had the poorest probe trial performance at the start of day two compared to both other groups. There were no group differences in performance on the RAM or MRT. These results provide support for estradiol's role in the consolidation of spatial reference memory in women, and emphasize the differential sensitivities of various virtual memory tasks in assessing spatial memory function in women.