Environmental enrichment (EE) is a process of brain stimulation by modifying the surroundings, for example, by changing the sensory, social, or physical conditions. Rodents have been used in such experimental strategies through exposure to diverse physical, social, and exploration conditions. The present study conducted an extensive analysis of the existing literature surrounding the impact of EE on dementia rodent models. The review emphasised the two principal aspects that are very closely related to dementia: cognitive function (learning and memory) as well as psychological factors (anxiety-related behaviours such as phobias and unrealistic worries). Also highlighted were the mechanisms involved in the rodent models of dementia showing EE effects. Two search engines, PubMed and Science Direct, were used for data collection using the following keywords: environmental enrichment, dementia, rodent model, cognitive performance, and anxiety-related behaviour. Fifty-five articles were chosen depending on the criteria for inclusion and exclusion. The rodent models with dementia demonstrated improved learning and memory in the form of hampered inflammatory responses, enhanced neuronal plasticity, and sustained neuronal activity. EE housing also prevented memory impairment through the prevention of amyloid beta (Aβ) seeding formation, an early stage of Aβ plaque formation. The rodents subjected to EE were observed to present increased exploratory activity and exert less anxiety-related behaviour, compared to those in standard housing. However, some studies have proposed that EE intervention through exercise would be too mild to counteract the anxiety-related behaviour and risk assessment behaviour deficits in the Alzheimer's disease rodent model. Future studies should be conducted on old-aged rodents and the duration of EE exposure that would elicit the greatest benefits since the existing studies have been conducted on a range of ages and EE durations. In summary, EE had a considerable effect on dementia rodent models, with the most evident being improved cognitive function.
Surveillance studies on cercarial dermatitis were carried out in paddy growing areas in Peninsular Malaysia. It was observed that dermatitis in paddy planters occurred in paddy fields which were cultivated using animals such as bafflos or fields where domestic animals were allowed to graze during the off planting season as these animals harbored the parasite. The causative agent of cercarial dermatitis was Schistosoma spindale. A total of 215 small mammals trapped from Alor Setar and 126 trapped from Labu were examined for the schistosome. In Alor Setar Bandicota indica, Rattus argentiventer and Rattus rattus diardii were the only wild mammals found to be infected with the parasite, while in the Labu areas only Rattus tiomanicus jalorensis was positive for the schistosome. The occurrence of S. spindale in R. argentiventer and R.r. diardii in Alor Setar and in R.t. jalorensis in Labu constitute new host and geographic distribution records of the schistosome.
APOBEC1 (A1) proteins from lagomorphs and rodents have deaminase-dependent restriction activity against HIV-1, whereas human A1 exerts a negligible effect. To investigate these differences in the restriction of HIV-1 by A1 proteins, a series of chimeric proteins combining rabbit and human A1s was constructed. Homology models of the A1s indicated that their activities derive from functional domains that likely act in tandem through a dimeric interface. The C-terminal region containing the leucine-rich motif and the dimerization domains of rabbit A1 is important for its anti-HIV-1 activity. The A1 chimeras with strong anti-HIV-1 activity were incorporated into virions more efficiently than those without anti-HIV-1 activity, and exhibited potent DNA-mutator activity. Therefore, the C-terminal region of rabbit A1 is involved in both its packaging into the HIV-1 virion and its deamination activity against both viral cDNA and genomic RNA. This study identifies the novel molecular mechanism underlying the target specificity of A1.
Blood meal analysis (BMA) from ticks allows for the identification of natural hosts of ticks (Acari: Ixodidae). The aim of this study is to identify the blood meal sources of field collected on-host ticks using PCR analysis. DNA of four genera of ticks was isolated and their cytochrome b (Cyt b) gene was amplified to identify host blood meals. A phylogenetic tree was constructed based on data of Cyt b sequences using Neighbor Joining (NJ) and Maximum Parsimony (MP) analysis using MEGA 5.05 for the clustering of hosts of tick species. Twenty out of 27 samples showed maximum similarity (99%) with GenBank sequences through a Basic Local Alignment Search Tool (BLAST) while 7 samples only showed a similarity range of between 91-98%. The phylogenetic trees showed that the blood meal samples were derived from small rodents (Leopoldamyssabanus, Rattustiomanicus and Sundamysmuelleri), shrews (Tupaiaglis) and mammals (Tapirusindicus and Prionailurusbengalensis), supported by 82-88% bootstrap values. In this study, Cyt b gene as a molecular target produced reliable results and was very significant for the effective identification of ticks' blood meal. The assay can be used as a tool for identifying unknown blood meals of field collected on-host ticks.
Diabetes mellitus remains an incurable disorder in spite of intense research. As result of limitations and unmet goals associated with the use of anti-diabetic drugs, an increased number of diabetic populations globally now resort to complementary and alternative medicine (CAM) such as herbs and other natural products. There has been a renewed interest in the use of honey in the treatment of diabetes mellitus, partly due to an increase in the availability of evidence-based data demonstrating its benefits in diabetic rodents and patients. This commentary aims to underscore some of the research implications, issues and questions raised from these studies which show the beneficial effects of honey in the treatment of diabetes mellitus. Some of the issues highlighted in this article include: considering honey is sweet and rich in sugars, how could it be beneficial in the management of diabetes mellitus? Are the observed effects of honey or combined with anti-diabetic drugs exclusive to certain honey such as tualang honey? Could these beneficial effects be reproduced with other honey samples? Anti-diabetic drugs in combination with honey improve glycemic control, enhance antioxidant defenses and reduce oxidative damage. These effects are believed to be mediated partly via antioxidant mechanism of honey. This raises another question. Could similar data be obtained if anti-diabetic drugs are co-administered with other potent antioxidants such as vitamin C or E? As the evidence has revealed, the prospect of managing diabetes mellitus with honey or antioxidants (such as vitamin C or E) as an adjunct to conventional diabetes therapy is vast. However, more well-designed, rigorously conducted randomized controlled studies are necessary to further validate these findings.
Major depression contributes significantly to the global disability burden. Since the first clinical study of deep brain stimulation (DBS), over 406 patients with depression have now undergone this neuromodulation therapy, and 30 animal studies have investigated the efficacy of subgenual cingulate DBS for depression. In this review, we aim to provide a comprehensive overview of the progress of DBS of the subcallosal cingulate in humans and the medial prefrontal cortex, its rodent homolog. For preclinical animal studies, we discuss the various antidepressant-like behaviors induced by medial prefrontal cortex DBS and examine the possible mechanisms including neuroplasticity-dependent/independent cellular and molecular changes. Interestingly, the response rate of subcallosal cingulate Deep brain stimulation marks a milestone in the treatment of depression. DBS among patients with treatment-resistant depression was estimated to be approximately 54% across clinical studies. Although some studies showed its stimulation efficacy was limited, it still holds great promise as a therapy for patients with treatment-resistant depression. Overall, further research is still needed, including more credible clinical research, preclinical mechanistic studies, precise selection of patients, and customized electrical stimulation paradigms.
1,2-dimethylhydrazine (DMH) is a member in the class of hydrazines, strong DNA alkylating agent, naturally present in cycads. DMH is widely used as a carcinogen to induce colon cancer in animal models. Exploration of DMH-induced colon carcinogenesis in rodent models provides the knowledge to perceive the biochemical, molecular, and histological mechanisms of different stages of colon carcinogenesis. The procarcinogen DMH, after a series of metabolic reactions, finally reaches the colon, there produces the ultimate carcinogen and reactive oxygen species (ROS), which further alkylate the DNA and initiate the development of colon carcinogenesis. The preneolpastic lesions and histopathological observations of DMH-induced colon tumors may provide typical understanding about the disease in rodents and humans. In addition, this review discusses about the action of biotransformation and antioxidant enzymes involved in DMH intoxication. This understanding is essential to accurately identify and interpret alterations that occur in the colonic mucosa when evaluating natural or pharmacological compounds in DMH-induced animal colon carcinogenesis.
Although inflammation is a reactive to injurious stimuli and considered as beneficial process in body, but it causes some discomforts, such as pain. Murine dietary contains appreciable amounts of fatty acids and antioxidants which encourages researchers to focus on their potential therapeutic effects. This study is aimed to examine the analgesic and anti-inflammatory activity of Neptune krill oil (NKO) and fish oil (FO) in rodent model which are two well-known sources of rich content of n-3 polyunsaturated fatty acids (n-3 PUFAs), mostly eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA). NKO and FO were used at the same dose of 500 mg and also balanced at similar doses of EPA: 12 in NKO vs. 12 in FO wt%, DHA: 7 NKO vs. 8 FO wt%. Application of NKO and FO in acetic acid-induced writhing effect, hot plate, and formalin induced test, indicated the nociceptive activity of the two tested drugs in comparison with normal saline. Also, the anti-inflammatory effect of these supplements was confirmed by carrageenan test. Analysis of cytokines levels in the blood samples of the mice after induction inflammation by carrageenan indicated decreased levels of those proteins compared to that in the normal groups. Both tested drugs, effectively could reduce severe inflammation and pain in rodents in comparison with the references drugs (depends on the tests); however, NKO was found to be more effective.
Introduction: Systemic inflammation is the major clinical problem which is constellation of communicable and non-communicable infection equipped with acute to chronic inflammation. It may lead to unfavourable conditions for instance, systemic inflammatory syndrome, burns and sepsis. Systemic inflammation might rotate the steering towards vital clinical maladies including cardiomyopathy, neuroinflammation, hepatitis, liver and kidney diseases and even diabetes. In order to elucidate the molecular insights in these clinical implications, there is an intensive need
to design rodent model of systemic inflammation having close association with systemic inflammatory conditions in humans. Methods: Presently, lipopolysaccharide (LPS) induced systemic inflammatory rodent model is widely established, reproducible and acceptable among scientists. In this model animals are treated with intraperitoneal injection of LPS ranging from 1-10 mg/kg which leads to instant release of proinflammatory cytokines to provide robust model of systemic inflammation in order to elucidate pathological conditions and their in-depth mechanism to uncover the new anti-inflammatory therapeutic targets. Conclusion: Robust model would open new window to explore anti-inflammatory activities of phytochemicals, small molecules and drug candidates along with crosstalk of different signaling pathways at molecular level.
Leptospirosis is an important zoonotic bacterial disease caused by Leptospira spp. Earlier studies from North Khorasan province (Iran) reported the presence of Leptospira in wild canines and rodents. To date, there is no data on the seroprevalence of leptospirosis among humans in this province. This study was performed to determine the prevalence of human leptospiral infection among people with different occupations. The study was conducted in urban and rural areas of the province. Among the serum samples collected from 278 subjects, 3 (1.1%) showed positive reaction with titer of 1:100 by the microscopic agglutination test (MAT). Positive reactions were detected against Leptospira interrogans Canicola and L. interrogans icterohemorrhagic and all these samples were from livestock farmers (n = 3/106, 2.7%). The current study revealed that, though Leptospira infection is low in North Khorasan province, regular monitoring of the livestock and the farmers are important.
Chronic stress has been associated with impairment of memory, learning, and social cognition. In animal studies, chronic stress has been shown to impair rodent sociability behaviour which mimics social withdrawal as observed in depression patients. The effect of chronic stress on social recognition, however, is uncertain. Moreover, with reference to spatial learning and memory, the effect of chronic stress is dependent on the type of behavioural task: an appetitively or aversively motivated tasks. The effect of chronic stress was consistent in impairing spatial learning and memory in the appetitive task; however, the effect was inconsistent in an aversive task like the Morris water maze. Thus, we aimed to investigate the effect of chronic restraint stress on sociability and social recognition by using a modified protocol of the three-chamber paradigm and the effect of chronic restraint stress on spatial learning and memory by using the Morris water maze test in young adult C57BL/6J male mice. The present report also describes a modified protocol of the three-chamber paradigm. Our modification is based on measurement of sniffing behaviour, which is a direct social interaction that represents sociability. We used the chronic restraint stress paradigm for 6 h/day for 21 days to induce depression-like symptoms in male C57BL/6J mice which were validated by forced-swim test. We observed that the stressed group had impairments in their sociability behaviour but that social recognition was not affected. Furthermore, we confirmed that chronic stress produced no significant impairment in spatial learning and memory of the mice in the water maze.
The possible depression of cell-mediated immunity by long-term Brugia malayi infection in jirds (Meriones unguiculatus) was investigated. Different groups of infected jirds were sensitized with dinitrofluorobenzene, sheep red blood cells, Dirofilaria immitis adult antigens and B. malayi adult antigens. The 24-hour delayed type hypersensitivity skin response to testing with antigen was measured as an in vivo correlate of cell-mediated immunity. The delayed-type hypersensitivity responses to dinitrofluorobenzene, sheep red blood cells and D. immitis antigens were normal but the response to B. malayi antigens was significantly depressed, confirming that long-term B. malayi infection depresses cell-mediated immunity and that this depression is specific to B. malayi antigens.
Insufficient use has been made of ecological data concerning potential hosts in studies to determine the life cycles of zoonotic parasites and pathogens. Factors such as the geographical distribution of hosts, the altitudes at which they live, their affinities for specific habitats, their vertical distribution within the habitat, and the periodicity of their activities have bearing on the hosts' predisposition to involvement in disease cycles. Diets and feeding habits may determine the likelihood of acquiring infection. Reproductive characteristics determine whether a species is suitable as a reservoir or as an amplifying host. Behavioral factors, such as selection of a particular kind of nest site, may also predispose the involvement of the host with parasites and pathogens. Behavior patterns may determine the maximum population densities of hosts. Estimates of population sizes, of relative abundances of species, and of the involvement of species in disease cycles may be strongly influenced by the collecting and sampling methods that are used and also by the behavioral response of the mammals toward collecting devices, such as traps.