Morris Water Maze and Contextual Fear Conditioning Tasks to Evaluate Cognitive Functions Associated With Adult Hippocampal Neurogenesis

New neurons are continuously generated and functionally integrated into the dentate gyrus (DG) network during the adult lifespan of most mammals. The hippocampus is a crucial structure for spatial learning and memory, and the addition of new neurons into the DG circuitry of rodents seems to be a key element for these processes to occur. The Morris water maze (MWM) and contextual fear conditioning (CFC) are among the most commonly used hippocampus-dependent behavioral tasks to study episodic-like learning and memory in rodents. While the functional contribution of adult hippocampal neurogenesis (AHN) through these paradigms has been widely addressed, results have generated controversial findings. In this review, we analyze and discuss possible factors in the experimental methods that could explain the inconsistent results among AHN studies; moreover, we provide specific suggestions for the design of more sensitive protocols to assess AHN-mediated learning and memory functions.

Evaluation effects of “An Tri Khang” hard capsule on scopolamine-induced memory impairment in experimental animals

This study was performed to investigate the effects of An Tri Khang (ATK) hard capsule on scopolamine-induced memory impairment in experimental animals. The effects on memory of oral administration ATK were evaluated on scopolamine-induced memory impairment in experimental animals. The memory improvement effects were conducted on 2 experimental models: the Morris water maze (MWM) and the Multi-T maze (MTM). In the MWM model, ATK significantly reduced the time spent and pathlength to platform, increased the percentage of time swimming in platform’s quadrant. Swiss mice performed the MTM with shorter in both the time spent and the pathlength to the goal box (p < 0.01). Both doses of ATK attenuated scopolamine-mediated impairment of memory. ATK has potential effects on memory improvement. It is suggested that further clinical trials should be undertaken to have thorough assessment on human.

Effects of Omega-3 Polyunsaturated Fatty Acids on Cognitive Function after Splenectomy in Rats

Background. Postoperative cognitive dysfunction (POCD) is a common complication after abdominal surgery. Several studies have reported that POCD is related to neuroinflammation caused by surgery. Omega-3 polyunsaturated fatty acids (PUFAs) can effectively inhibit the systematic inflammatory response. So, we use fish oil to study the effect of fish oil on inflammation, immunity, and cognitive behavior after splenectomy in rats. Methods. 60 SD (Sprague-Dawley) rats were randomly divided into control group (group C, n = 20 ), surgery group (group S, n = 20 ), and omega-3 (fish oil) intervention group (group F, n = 20 ). Omega-3 PUFA was injected intraperitoneally from 3 days before operation to 7 days after operation in group F, and normal saline was injected simultaneously in group S. Rats in group S and group F received splenectomy under general anesthesia. Morris water maze behavioral evaluation was performed on the first, third, fifth, and seventh day after operation. The levels of IL-1β (interleukin-1β), IL-6 (interleukin-6), TNF-α (tumor necrosis factor-α), SOD (superoxide dismutase), and GSH-PX (glutathione peroxidase) were detected. Results. Serums IL-1β, IL-6, and TNF-α concentrations in group S and group F were higher than those in group C ( P < 0.01 ), while those inflammatory cytokines in group F were significantly lower than those in group S ( P < 0.01 ); serum GSH-PX levels in group F were higher than group S ( P < 0.01 ). The Morris water maze behavior test performance of group F was better than that of group S ( P < 0.05 ). Conclusion. Omega-3 PUFA can effectively improve postoperative inflammatory response, reduce the damage of antioxidant defense system, and improve postoperative cognitive function.

Effects of oral ingestion of hyoscyamine from Daturastramonium seeds on the hippocampus in adult Wistar rats (Rattusnorvegicus)

The study aimed to evaluate the effects of oral ingestion of hyoscyamine fraction of Daturastramonium seeds on the hippocampus in adult Wistar rats. Fresh seeds of D. stramonium were procured and fractionated using high-performance liquid chromatography (HPLC). Twenty-four healthy adult Wistar rats weighed 230±0.50 grams, were procured and divided equally into four groups for the experiment. The group one received an equivalent bodyweight of normal saline, while three other groups received 200, 400 and 800 mg/kgbwt of hyoscyamine fraction of D. stramonium respectively for three weeks. At the end of the experiment, the animals were subjected to memory test using Morris water maze (MWM) and Novel object recognition test (NORT) test paradigms. The data obtained were expressed as mean ± SEM and repeated measures ANOVA with Fisher’s multiple comparisons post-hoc tests were used to obtain mean differences using Minitab 17 (LLC., U.K.) statistical package software. P < 0.05 was considered statistically significant. There was a statistically significant increase in the exploration time (p = 0.031) and escape latency period (p < 0.001) in the novel object recognition and Morris water maze test between the groups in the treated compared to the control group. The CA3 region of the treated group showed significant neuronal lesions, cytoplasmic vacuolations, pyknosis and necrosis. . In conclusion, exposure to hyoscyamine fraction of D.stramonium at adulthood impaired memory in Wistar rats.

Protective effect of quercetin against the metabolic dysfunction of glucose and lipids and its associated learning and memory impairments in NAFLD rats

Background Quercetin (QUE) is a flavonol reported with anti-inflammatory and antioxidant activities, and previous results from the group of this study have demonstrated its neuroprotective effect against lipopolysaccharide-induced neuropsychiatric injuries. However, little is known about its potential effect on neuropsychiatric injuries induced or accompanied by metabolic dysfunction of glucose and lipids. Methods A nonalcoholic fatty liver disease (NAFLD) rat model was induced via a high-fat diet (HFD), and glucolipid parameters and liver function were measured. Behavioral performance was observed via the open field test (OFT) and the Morris water maze (MWM). The plasma levels of triggering receptor expressed on myeloid cells-1 (TREM1) and TREM2 were measured via enzyme-linked immunosorbent assay (ELISA). The protein expression levels of Synapsin-1 (Syn-1), Synaptatogmin-1 (Syt-1), TREM1 and TREM2 in the hippocampus were detected using western blotting. Morphological changes in the liver and hippocampus were detected by HE and Oil red or silver staining. Results Compared with the control rats, HFD-induced NAFLD model rats presented significant metabolic dysfunction, hepatocyte steatosis, and impaired learning and memory ability, as indicated by the increased plasma concentrations of total cholesterol (TC) and triglyceride (TG), the impaired glucose tolerance, the accumulated fat droplets and balloon-like changes in the liver, and the increased escaping latency but decreased duration in the target quadrant in the Morris water maze. All these changes were reversed in QUE-treated rats. Moreover, apart from improving the morphological injuries in the hippocampus, treatment with QUE could increase the decreased plasma concentration and hippocampal protein expression of TREM1 in NAFLD rats and increase the decreased expression of Syn-1 and Syt-1 in the hippocampus. Conclusions These results suggested the therapeutic potential of QUE against NAFLD-associated impairment of learning and memory, and the mechanism might involve regulating the metabolic dysfunction of glucose and lipids and balancing the protein expression of synaptic plasticity markers and TREM1/2 in the hippocampus.

Neurotoxicity and Behavioral Changes Following Sub-Chronic Administration of Aqueous Extract of Erythrophleum Ivorense Stem Bark in Mice

Erythrophleum ivorense (EI) is a tree found across tropical Africa. The bark of EI is widely used as hunting poisons for animals and ordeal poison in humans. Ingestion of this plant causes paralysis, respiratory distress and amnesia. In folklore, these behavioral changes have been attributed to guilt in victims; nonetheless, scientific evidence in support of this claim does not exist. Thus, there is the need to validate the mechanism of neurotoxicity and behavioral alteration of this plant. Methods: BALB/c male mice (n=48) were randomly divided into four groups. The test groups were administered aqueous extract of EI in a single daily graded doses (5, 10 and 15 mg/kg according to the body weight) for a duration 28 days while the control received distilled water. Motor coordination, learning, memory and grip strength was thereafter accessed with wire grip, Morris water maze and inverted wire mesh grid grip tests respectively. Histological staining of brain sections was also carried out. At all tested doses aqueous extract of EI caused significant reduction in hanging latency, significantly increased escape latency and decreased duration in the target platform during the Morris water maze test relative to the control. Decreased grip strength was also observed in the test groups compared to control. Histology revealed dysmorphic and disoriented Purkinje cells and loss of Purkinje cell layer of the cerebellum. Erythrophleum ivorense administration altered motor coordination, learning and memory and grip strength in mice in a dose-dependent manner. It also caused disruption of granule cells layer, loss of Purkinje cells and altered cerebellar anatomy leading to motor deficits in mice.

Effect of Squalene in Morphometric and Cognitive Aspects in D-Galactose induced Alzheimers Disease in Male Albino Rats

Alzheimers disease is a type of dementia, even though extensive research work has been carried out since decades till now, there is no specific therapeutic drug available for the permanent cure of the Alzheimer’s Disease. Now a days the marine bioactive compound squalene plays a therapeutic role morphometric and cognitive aspects in D-Galactose induced alzheimers disease in male albino rats. The morphometric aspects which refer to the quantitative analysis of a concept that encompasses size, shape and other physical parameters is useful for assessing the impact of mutants on shape, their fossil records, developmental changes in the form between ecological factors and as well as evaluating the quantitative genetic aspects of shape. To evaluate the spatial or place learning in experimental rat, the most popularly known water maze test is Morris Water Maze (MWM) experiment. The most important utilization of the Morris Water Maze includes that its high reliability across a wide range of tank configurations and testing procedures, its cross-species utility in several chosen experimental animals such as mice and rats including humans in a virtual maze. The marine bioactive compound Squalene plays a major impact on brain function and behaviour by enhancing the learning and memory in the AD- Model rats.