Alzheimer's disease (AD), a neurodegenerative disorder with complex etiologies, manifests through a cascade of pathological changes before clinical symptoms become apparent. Among these early changes, alterations in the expression of non-coding RNAs (ncRNAs) have emerged as pivotal events. In this study, we focused on the aberrant expression of ncRNAs and revealed that Lamr1-ps1, a pseudogene of the laminin receptor, significantly exacerbates early spatial learning and memory deficits in APP/PS1 mice. Through a combination of bioinformatics prediction and experimental validation, we identified the miR-29c/Bace1 pathway as a potential regulatory mechanism by which Lamr1-ps1 influences AD pathology. Importantly, augmenting the miR-29c-3p levels in mice ameliorated memory deficits, underscoring the therapeutic potential of targeting miR-29c-3p in early AD intervention. This study not only provides new insights into the role of pseudogenes in AD but also consolidates a foundational basis for considering miR-29c as a viable therapeutic target, offering a novel avenue for AD research and treatment strategies.
Animals ; Alzheimer Disease/pathology* ; Pseudogenes/genetics* ; Mice ; Memory Disorders/metabolism* ; MicroRNAs/genetics* ; Disease Models, Animal ; Spatial Learning/physiology* ; Mice, Transgenic ; Presenilin-1/genetics* ; Male ; Amyloid Precursor Protein Secretases/metabolism* ; Mice, Inbred C57BL ; Aspartic Acid Endopeptidases/metabolism*

The purpose of this study was to investigate the effects of acute fear stress on the spatial memory and neuronal plasticity of medial prefrontal cortex (mPFC) neurons in mice, and to elucidate the mechanisms underlying mPFC plasticity and post-stress memory regulation. Male C57BL/6 mice (6 weeks old) were randomly divided into control group and stress group. Foot shock stress was applied to establish an acute fear stress model. Changes in spatial memory were examined by the Morris water maze test, and the dynamic changes in the spike encoding of pyramidal neurons and GABAergic neurons in the prelimbic cortex (PrL) and infralimbic cortex (IL) of mPFC were detected by whole-cell recording. The results showed that acute fear stress significantly enhanced the percentage of freezing and the number of freezing, reduced the average speed, decreased the escape latency during acquisition phase, extended the probing time in the first quadrant and shortened the probing time in the third quadrant during probe trial, increased inter-spike interval, energy barrier and absolute refractory period of GABAergic neurons in the PrL and pyramidal neurons in the IL, while decreased inter-spike interval, energy barrier and absolute refractory period of pyramidal neurons in the PrL and GABAergic neurons in the IL. These results suggest that acute fear stress can enhance the spatial memory of mice, elevate the excitability and function of the PrL, while deteriorate the excitability and function of the IL, and the underlying mechanism may involve the role of mPFC microcircuitry plasticity in spatial memory after stress.
Animals ; Male ; Mice ; Fear ; Mice, Inbred C57BL ; Neuronal Plasticity ; Prefrontal Cortex ; Spatial Memory

Alzheimer's disease (AD) is the most common neurodegenerative disorder causing dementia worldwide, and is mainly characterized by aggregated β-amyloid (Aβ). Increasing evidence has shown that plant extracts have the potential to delay AD development. The plant sterol β-Sitosterol has a potential role in inhibiting the production of platelet Aβ, suggesting that it may be useful for AD prevention. In the present study, we aimed to investigate the effect and mechanism of β-Sitosterol on deficits in learning and memory in amyloid protein precursor/presenilin 1 (APP/PS1) double transgenic mice. APP/PS1 mice were treated with β-Sitosterol for four weeks, from the age of seven months. Brain Aβ metabolism was evaluated using ELISA and Western blotting. We found that β-Sitosterol treatment can improve spatial learning and recognition memory ability, and reduce plaque load in APP/PS1 mice. β-Sitosterol treatment helped reverse dendritic spine loss in APP/PS1 mice and reversed the decreased hippocampal neuron miniature excitatory postsynaptic current frequency. Our research helps to explain and support the neuroprotective effect of β-Sitosterol, which may offer a novel pharmaceutical agent for the treatment of AD. Taken together, these findings suggest that β-Sitosterol ameliorates memory and learning impairment in APP/PS1 mice and possibly decreases Aβ deposition.
Alzheimer Disease ; Amyloid ; Animals ; Blood Platelets ; Blotting, Western ; Brain ; Cognition Disorders ; Dementia ; Dendritic Spines ; Enzyme-Linked Immunosorbent Assay ; Excitatory Postsynaptic Potentials ; Learning ; Memory ; Metabolism ; Mice ; Mice, Transgenic ; Neurodegenerative Diseases ; Neurons ; Neuroprotective Agents ; Plant Extracts ; Plants ; Plaque, Amyloid ; Spatial Learning

Long-term exposure to high altitude affects spatial working memory. Previous studies have focused on the analysis of electroencephalogram (EEG) components in time domain rather than in frequency domain. To explore the influence of long-term high altitude exposure on time dynamic characteristics and neural oscillation process of the spatial working memory, n-back task combined with the technology of event related potential recording was performed on 20 young migrants who grew at low altitude before the age of 18 and moved to high altitude more than three years ago, and 21 young people who had never been to the high altitude. EEG data were recorded, and the time domain and frequency domain analyses were performed. The results showed that the response time was longer and the accuracy rate was lower under the 2-back condition in the high altitude group compared with those in low altitude group. The late positive potential (LPP) amplitude was more negative, P2 amplitude was more positive in the 2-back condition, and the power value of early delta frequency band (1-4 Hz, 160-300 ms) was larger, while the power values of late delta frequency band (1-4 Hz, 450-650 ms) and theta frequency band (4-8 Hz, 450-650 ms) were smaller in the high altitude group compared with those in low altitude group. The results suggested that long-term exposure to high altitude affected the spatial working memory ability of the migrants, which was reflected in the lack of attention resources in the later matching stage, decreased response inhibition ability and information maintenance ability, and thus resulted in impaired spatial working memory.
Altitude ; Brain ; physiopathology ; Electroencephalography ; Humans ; Memory, Short-Term ; Reaction Time ; Spatial Memory ; Transients and Migrants

The objective of this study was to elucidate the effect of chronic stress (CS) on dopamine (DA) level and synaptic efficiency in the hippocampal dentate gyrus (DG) during spatial learning and memory. Sprague Dawley (SD) male rats were randomly divided into control group and CS group (n = 10). CS group was treated with chronic mild unpredictable stress, and control group did not receive any treatments. The levels of epinephrine and corticosterone (CORT) in serum were measured by using enzyme-linked immunosorbent assay (ELISA); the spatial learning and memory abilities of rats were measured by Morris water maze (MWM) test. Meanwhile, the amplitude of field excitatory postsynaptic potential (fEPSP) and concentration of DA in the DG region were determined by in vivo electrophysiology, microdialysis and HPLC techniques during MWM test in rats. After that, the DA D1 receptor (D1R) and its key downstream members in DG were examined by immunohistochemistry or Western blot assay. The results showed that the levels of epinephrine and CORT in the serum of the rats in CS group were significantly increased compared with those in the control group (P < 0.05). In CS group rats, the escape latency was significantly prolonged and the number of platform crossing was markedly decreased during MWM test, compared with those in control group (P < 0.05). Furthermore, the amplitude of fEPSP in the DG was not changed during MWM test in CS rats, while it was significantly increased on the 3rd day of MWM test in control group (P < 0.05). Compared with baseline or control group, CS group showed significantly increased DA level from the 1st to 3rd days of MWM test in the DG (P < 0.05). In addition, the protein expression of D1R was markedly up-regulated in the DG in CS group, while the protein expression levels of p-PKA, p-CREB and BDNF were significantly reduced, compared with those in control group. These results suggest that CS may impair spatial learning and memory abilities in rats through the enhancement of the DA levels in the hippocampal DG.
Animals ; Dentate Gyrus ; Dopamine ; Hippocampus ; Male ; Maze Learning ; Rats ; Rats, Sprague-Dawley ; Spatial Learning ; Spatial Memory

The formation, consolidation and retrieval of spatial memory depend on sequential firing patterns of place cells assembling in the hippocampus. Theta sequences of place cells during behavior play a role in acquisition of spatial memory, trajectory prediction and decision making. In awake rest and slow wave sleep, place cell sequences occur during the sharp wave-ripples (SWRs), called "replay", which is crucial for memory consolidation and retrieval. In this review, we summarize the functional significances of theta sequences and SWRs replay sequences and the mechanism of these sequences. We also discuss the relationship between theta and replay sequences with the formation of spatial memory. We propose the research direction in this field in future and aim to provide new ideas for related researches.
Hippocampus ; Sleep ; Spatial Memory ; Wakefulness

PURPOSE: The purpose of this study was to identify the effect of ghrelin on memory impairment in a rat model of vascular dementia induced by chronic cerebral hypoperfusion. METHODS: Randomized controlled groups and the posttest design were used. We established the representative animal model of vascular dementia caused by bilateral common carotid artery occlusion and administered 80 µg/kg ghrelin intraperitoneally for 4 weeks. First, behavioral studies were performed to evaluate spatial memory. Second, we used molecular biology techniques to determine whether ghrelin ameliorates the damage to the structure and function of the white matter and hippocampus, which are crucial to learning and memory. RESULTS: Ghrelin improved the spatial memory impairment in the Y-maze and Morris water maze test. In the white matter, demyelination and atrophy of the corpus callosum were significantly decreased in the ghrelin-treated group. In the hippocampus, ghrelin increased the length of hippocampal microvessels and reduced the microvessels pathology. Further, we confirmed angiogenesis enhancement through the fact that ghrelin treatment increased vascular endothelial growth factor (VEGF)-related protein levels, which are the most powerful mediators of angiogenesis in the hippocampus. CONCLUSION: We found that ghrelin affected the damaged myelin sheaths and microvessels by increasing angiogenesis, which then led to neuroprotection and improved memory function. We suggest that further studies continue to accumulate evidence of the effect of ghrelin. Further, we believe that the development of therapeutic interventions that increase ghrelin may contribute to memory improvement in patients with vascular dementia.
Animals ; Atrophy ; Carotid Artery, Common ; Corpus Callosum ; Dementia ; Dementia, Vascular ; Demyelinating Diseases ; Ghrelin ; Hippocampus ; Humans ; Learning ; Memory Disorders ; Memory ; Microvessels ; Models, Animal ; Molecular Biology ; Myelin Sheath ; Neuroprotection ; Pathology ; Rats ; Spatial Memory ; Vascular Endothelial Growth Factor A ; Water ; White Matter

As the elderly population is increasing, Alzheimer's disease (AD) has become a global issue and many clinical trials have been conducted to evaluate treatments for AD. As these clinical trials have been conducted and have failed, the development of new theraphies for AD with fewer adverse effects remains a challenge. In this study, we examined the effects of Theracurmin on cognitive decline using 5XFAD mice, an AD mouse model. Theracurmin is more bioavailable form of curcumin, generated with submicron colloidal dispersion. Mice were treated with Theracurmin (100, 300 and 1,000 mg/kg) for 12 weeks and were subjected to the novel object recognition test and the Barnes maze test. Theracurmin-treated mice showed significant amelioration in recognition and spatial memories compared those of the vehicle-treated controls. In addition, the antioxidant activities of Theracurmin were investigated by measuring the superoxide dismutase (SOD) activity, malondialdehyde (MDA) and glutathione (GSH) levels. The increased MDA level and decreased SOD and GSH levels in the vehicle-treated 5XFAD mice were significantly reversed by the administration of Theracurmin. Moreover, we observed that Theracurmin administration elevated the expression levels of synaptic components, including synaptophysin and post synaptic density protein 95, and decreased the expression levels of ionized calcium-binding adapter molecule 1 (Iba-1), a marker of activated microglia. These results suggest that Theracurmin ameliorates cognitive function by increasing the expression of synaptic components and by preventing neuronal cell damage from oxidative stress or from the activation of microglia. Thus, Theracurmin would be useful for treating the cognitive dysfunctions observed in AD.
Aged ; Alzheimer Disease ; Animals ; Cognition ; Colloids ; Curcumin ; Glutathione ; Humans ; Malondialdehyde ; Mice ; Microglia ; Neurons ; Oxidative Stress ; Post-Synaptic Density ; Spatial Memory ; Superoxide Dismutase ; Synaptophysin

OBJECTIVE: Although, accumulating evidence is delineating a neuroprotective and neurotrophic role for lithium (Li), inconsistent findings have also been reported in human studies especially. Moreover, the effects of Li infusion into the hippocampus are still unknown. The aims of this work were (a) to assess whether basal synaptic activity and long-term potentiation (LTP) in the hippocampus are different in regard to intrahippocampal Li infusion; (b) to assess spatial learning and memory in rats chronically treated with LiCO₃ in the Morris water maze. METHODS: Field potentials were recorded form the dentate gyrus, stimulating perforant pathways, in rats chronically (20 mg/kg for 40 days) or acutely treated with LiCO₃ and their corresponding control rats. In addition, performance of rats in a Morris water maze was measured to link behaviour of rats to electrophysiological findings. RESULTS: LiCO₃ infusion into the hippocampus resulted in enhanced LTP, especially in the late phases, but attenuated LTP was observed in rats chronically treated with Li as compared to controls. Li-treated rats equally performed a spatial learning task, but did spend less time in target quadrant than saline-treated rats in Morris water maze. CONCLUSION: Despite most data suggest that Li always yields neuroprotective effects against neuropathological conditions; we concluded that a 40-day treatment of Li disrupts hippocampal synaptic plasticity underlying memory processes, and that these effects of prolonged treatment are not associated with its direct chemical effect, but are likely to be associated with the molecular actions of Li at genetic levels, because its short-term effect preserves synaptic plasticity.
Adult ; Animals ; Dentate Gyrus ; Hippocampus ; Humans ; Learning ; Lithium ; Long-Term Potentiation ; Memory ; Neuronal Plasticity ; Neuroprotective Agents ; Perforant Pathway ; Rats ; Spatial Learning ; Spatial Memory ; Water

OBJECTIVE: Hypoxic-ischemic (HI) brain injury in the human perinatal period often leads to significant long-term neurobehavioral dysfunction in the cognitive and sensory-motor domains. Using a neonatal HI injury model (unilateral carotid ligation followed by hypoxia) in postnatal day seven rats, the present study investigated the long-term effects of HI and potential behavioral protective effect of pentoxifylline. METHODS: Seven-day-old rats underwent right carotid ligation, followed by hypoxia (FiO2 = 0.08). Rats received pentoxifylline immediately after and again 2 hours after hypoxia (two doses, 60–100 mg/kg/dose), or serum physiologic. Another set of seven-day-old rats was included to sham group exposed to surgical stress but not ligated. These rats were tested for spatial learning and memory on the simple place task in the Morris water maze from postnatal days 77 to 85. RESULTS: HI rats displayed significant tissue loss in the right hippocampus, as well as severe spatial memory deficits. Low-dose treatment with pentoxifylline resulted in significant protection against both HI-induced hippocampus tissue losses and spatial memory impairments. Beneficial effects are, however, negated if pentoxifylline is administered at high dose. CONCLUSION: These findings indicate that unilateral HI brain injury in a neonatal rodent model is associated with cognitive deficits, and that low dose pentoxifylline treatment is protective against spatial memory impairment.
Animals ; Anoxia ; Brain Injuries ; Brain ; Cognition Disorders ; Hippocampus ; Humans ; Hypoxia-Ischemia, Brain ; Learning ; Ligation ; Memory ; Pentoxifylline ; Rats ; Rodentia ; Spatial Learning ; Spatial Memory ; Water