A guide to open science practices for animal research.

Translational biomedical research relies on animal experiments and provides the underlying proof of practice for clinical trials, which places an increased duty of care on translational researchers to derive the maximum possible output from every experiment performed. The implementation of open science practices has the potential to initiate a change in research culture that could improve the transparency and quality of translational research in general, as well as increasing the audience and scientific reach of published research. However, open science has become a buzzword in the scientific community that can often miss mark when it comes to practical implementation. In this Essay, we provide a guide to open science practices that can be applied throughout the research process, from study design, through data collection and analysis, to publication and dissemination, to help scientists improve the transparency and quality of their work. As open science practices continue to evolve, we also provide an online toolbox of resources that we will update continually.

A systematic review of the development and application of home cage monitoring in laboratory mice and rats.

BACKGROUND: Traditionally, in biomedical animal research, laboratory rodents are individually examined in test apparatuses outside of their home cages at selected time points. However, the outcome of such tests can be influenced by various factors and valuable information may be missed when the animals are only monitored for short periods. These issues can be overcome by longitudinally monitoring mice and rats in their home cages. To shed light on the development of home cage monitoring (HCM) and the current state-of-the-art, a systematic review was carried out on 521 publications retrieved through PubMed and Web of Science. RESULTS: Both the absolute (~ × 26) and relative (~ × 7) number of HCM-related publications increased from 1974 to 2020. There was a clear bias towards males and individually housed animals, but during the past decade (2011-2020), an increasing number of studies used both sexes and group housing. In most studies, animals were kept for short (up to 4 weeks) time periods in the HCM systems; intermediate time periods (4-12 weeks) increased in frequency in the years between 2011 and 2020. Before the 2000s, HCM techniques were predominantly applied for less than 12 h, while 24-h measurements have been more frequent since the 2000s. The systematic review demonstrated that manual monitoring is decreasing in relation to automatic techniques but still relevant. Until (and including) the 1990s, most techniques were applied manually but have been progressively replaced by automation since the 2000s. Independent of the year of publication, the main behavioral parameters measured were locomotor activity, feeding, and social behaviors; the main physiological parameters were heart rate and electrocardiography. External appearance-related parameters were rarely examined in the home cages. Due to technological progress and application of artificial intelligence, more refined and detailed behavioral parameters have been investigated in the home cage more recently. CONCLUSIONS: Over the period covered in this study, techniques for HCM of mice and rats have improved considerably. This development is ongoing and further progress as well as validation of HCM systems will extend the applications to allow for continuous, longitudinal, non-invasive monitoring of an increasing range of parameters in group-housed small rodents in their home cages.

Determining the value of preferred goods based on consumer demand in a home-cage based test for mice.

From the preference of one good over another, the strength of the preference cannot automatically be inferred. While money is the common denominator to assess the value of goods in humans, it appears difficult at first glance to put a price tag on the decisions of laboratory animals. Here we used consumer demand tests to measure how much work female mice expend to obtain access to different liquids. The mice could each choose between two liquids, one of which was free. The amount of work required to access the other liquid, by contrast, increased daily. In this way, the value of the liquid can be determined from a mouse's microeconomic perspective. The unique feature is that our test was carried out in a home-cage based setup. The mice lived in a group but could individually access the test-cage, which was connected to the home-cage via a gate. Thereby the mice were able to perform their task undisturbed by group members and on a self-chosen schedule with minimal influence by the experimenter. Our results show that the maximum number of nosepokes depends on the liquids presented. Mice worked incredibly hard for access to water while a bitter-tasting solution was offered for free whereas they made less nosepokes for sweetened liquids while water was offered for free. The results demonstrate that it is possible to perform automated and home-cage based consumer demand tests in order to ask the mice not only what they like best but also how strong their preference is.

Defining mechanisms of neural plasticity after brainstem ischemia in rats.

OBJECTIVE: Neurological recovery after stroke mainly depends on the location of the lesion. A substantial portion of strokes affects the brainstem. However, patterns of neural plasticity following brainstem ischemia are almost unknown. METHODS: Here, we established a rat brainstem ischemia model that resembles key features of the human disease and investigated mechanisms of neural plasticity, including neurogenesis and axonal sprouting as well as secondary neurodegeneration. RESULTS: Spontaneous functional recovery was accompanied by a distinct pattern of axonal sprouting, for example, an increased bilateral fiber outgrowth from the corticorubral tract to the respective contralesional red nucleus suggesting a compensatory role of extrapyramidal pathways after damage to pyramid tracts within the brainstem. Using different markers for DNA replication, we showed that the brainstem displays a remarkable ability to undergo specific plastic cellular changes after injury, highlighting a yet unknown pattern of neurogenesis. Neural progenitor cells proliferated within the dorsal brainstem and migrated toward the lesion, whereas neurogenesis in classic neurogenic niches, the subventricular zone of the lateral ventricle and the hippocampus, remained, in contrast to what is known from hemispheric stroke, unaffected. These beneficial changes were paralleled by long-term degenerative processes, that is, corticospinal fiber loss superior to the lesion, degeneration of spinal tracts, and a decreased neuron density within the ipsilesional substantia nigra and the contralesional red nucleus that might have limited further functional recovery. INTERPRETATION: Our findings provide knowledge of elementary plastic adaptions after brainstem stroke, which is fundamental for understanding the human disease and for the development of new treatments. Ann Neurol 2018;83:1003-1015.

Targeting Different Monocyte/Macrophage Subsets Has No Impact on Outcome in Experimental Stroke.

BACKGROUND AND PURPOSE: Peripheral immune cell infiltration contributes to neural injury after ischemic stroke. However, in contrast to lymphocytes and neutrophils, the role of different monocyte/macrophage subsets remains to be clarified. Therefore, we evaluated the effects of selective and unselective monocyte/macrophage depletion and proinflammatory (M1-) and anti-inflammatory (M2-) macrophage transfer on the outcome after experimental cerebral ischemia. METHODS: To assess short-term effects of monocytes/macrophages in acute ischemic stroke, mice underwent transient middle cerebral artery occlusion and received either clodronate liposomes for unselective macrophage depletion, MC-21-antibody for selective depletion of proinflammatory Ly-6Chigh monocytes, or proinflammatory (M1-) or anti-inflammatory (M2-) macrophage transfer. In addition, the impact of MC-21-antibody administration and M2-macrophage transfer on long-term neural recovery was investigated after photothrombotic stroke. Neurobehavioral tests were used to analyze functional outcomes, infarct volumes were determined, and immunohistochemical analyses were performed to characterize the postischemic inflammatory reaction. RESULTS: Selective and unselective monocyte/macrophage depletion and M1- and M2-macrophage transfer did not influence tissue damage and neurobehavioral outcomes in the acute phase after middle cerebral artery occlusion. Beyond, selective depletion of Ly-6Chigh monocytes and M2-macrophage transfer did not have an impact on neural recovery after photothrombotic stroke. CONCLUSIONS: Targeting different monocyte/macrophage subsets has no impact on outcome after ischemic stroke in mice. Altogether, our study could not identify monocytes/macrophages as relevant therapeutic targets in acute ischemic stroke.

Environmental enrichment and physical exercise revert behavioral and electrophysiological impairments caused by reduced adult neurogenesis.

It is well known that adult neurogenesis occurs in two distinct regions, the subgranular zone of the dentate gyrus and the subventricular zone along the walls of the lateral ventricles. Until now, the contribution of these newly born neurons to behavior and cognition is still uncertain. The current study tested the functional impacts of diminished hippocampal neurogenesis on emotional and cognitive functions in transgenic Gfap-tk mice. Our results showed that anxiety-related behavior evaluated both in the elevated plus maze as well as in the open field, social interaction in the sociability test, and spatial working memory in the spontaneous alternation test were not affected. On the other hand, recognition and emotional memory in the object recognition test and contextual fear conditioning, and hippocampal long-term potentiation were impaired in transgenic mice. Furthermore, we evaluated whether environmental enrichment together with physical exercise could improve or even restore the level of adult neurogenesis, as well as the behavioral functions. Our results clearly demonstrated that environmental enrichment together with physical exercise successfully elevated the overall number of progenitor cells and young neurons in the dentate gyrus of transgenic mice. Furthermore, it led to a significant improvement in object recognition memory and contextual fear conditioning, and reverted impairments in hippocampal long-term potentiation. Thus, our results confirm the importance of adult neurogenesis for learning and memory processes and for hippocampal circuitry in general. Environmental enrichment and physical exercise beneficially influenced adult neurogenesis after it had been disrupted and most importantly recovered cognitive functions and long-term potentiation. © 2016 Wiley Periodicals, Inc.

Combining Growth Factor and Bone Marrow Cell Therapy Induces Bleeding and Alters Immune Response After Stroke in Mice.

BACKGROUND AND PURPOSE: Bone marrow cell (BMC)-based therapies, either the transplantation of exogenous cells or stimulation of endogenous cells by growth factors like the granulocyte colony-stimulating factor (G-CSF), are considered a promising means of treating stroke. In contrast to large preclinical evidence, however, a recent clinical stroke trial on G-CSF was neutral. We, therefore, aimed to investigate possible synergistic effects of co-administration of G-CSF and BMCs after experimental stroke in mice to enhance the efficacy compared with single treatments. METHODS: We used an animal model for experimental stroke as paradigm to study possible synergistic effects of co-administration of G-CSF and BMCs on the functional outcome and the pathophysiological mechanism. RESULTS: G-CSF treatment alone led to an improved functional outcome, a reduced infarct volume, increased blood vessel stabilization, and decreased overall inflammation. Surprisingly, the combination of G-CSF and BMCs abrogated G-CSFs' beneficial effects and resulted in increased hemorrhagic infarct transformation, altered blood-brain barrier, excessive astrogliosis, and altered immune cell polarization. These increased rates of infarct bleeding were mainly mediated by elevated matrix metalloproteinase-9-mediated blood-brain barrier breakdown in G-CSF- and BMCs-treated animals combined with an increased number of dilated and thus likely more fragile vessels in the subacute phase after cerebral ischemia. CONCLUSIONS: Our results provide new insights into both BMC-based therapies and immune cell biology and help to understand potential adverse and unexpected side effects.

Progressive cognitive deficits in a mouse model of recurrent photothrombotic stroke.

BACKGROUND AND PURPOSE: In spite of its high disease burden, there is no specific treatment for multi-infarct dementia. The preclinical evaluation of candidate drugs is limited because an appropriate animal model is lacking. Therefore, we aimed to evaluate whether a mouse model of recurrent photothrombotic stroke is suitable for the preclinical investigation of multi-infarct dementia. METHODS: Recurrent photothrombotic cortical infarcts were induced in 25 adult C57BL/6 mice. Twenty-five sham-operated animals served as controls. The object recognition test and the Morris water maze test were performed >6 weeks to assess cognitive deficits. Afterward, histological analyses were performed to characterize histopathologic changes associated with recurrent photothrombotic infarcts. RESULTS: After the first infarct, the object recognition test showed a trend toward an impaired formation of recognition memories (P=0.08), and the Morris Water Maze test revealed significantly impaired spatial learning and memory functions (P<0.05). After recurrent infarcts, the object recognition test showed significant recognition memory deficits (P<0.001) and the Morris water maze test demonstrated persisting spatial learning and memory deficits (P<0.05). Histological analyses revealed remote astrogliosis in the hippocampus. CONCLUSIONS: Our results show progressive cognitive deficits in a mouse model of recurrent photothrombotic stroke. The presented model resembles the clinical features of human multi-infarct dementia and enables the investigation of its pathophysiological mechanisms and the evaluation of treatment strategies.

Cortical photothrombotic infarcts impair the recall of previously acquired memories but spare the formation of new ones.

BACKGROUND AND PURPOSE: Despite a high incidence of poststroke dementia, there is no specific treatment for this condition. Because the evaluation of poststroke cognitive deficits in animal models of stroke is exceedingly challenging, the preclinical evaluation of candidate drugs is limited. We aimed to explore the impact of small cortical photothrombotic strokes on poststroke cognition, thereby assessing the suitability of this experimental stroke model for the investigation of cognitive impairment after stroke. METHODS: Photothrombotic cortical infarcts were induced in 19 adult male Wistar rats. Nineteen sham-operated animals served as controls. Using the Morris water maze, we analyzed the impact of photothrombotic stroke on both the acquisition of new memories and the recall of previously acquired memories. The cylinder test, the adhesive tape removal test, and the rotarod test were performed to investigate sensorimotor deficits. RESULTS: Photothrombotic stroke significantly impaired the recall of previously acquired memories (P<0.05), whereas the acquisition of new memories remained largely intact. The analysis of the animals' swimming speed in the water maze and the rotarod test showed no confounding motor impairments after photothrombotic stroke. The adhesive tape removal test and the cylinder test revealed mild sensorimotor deficits in lesioned animals (P<0.05). CONCLUSIONS: Photothrombotic cortical infarcts impair the recall of memories acquired before stroke, whereas the formation of new memories remains unimpaired. The observed deficits in the water maze are not confounded by disturbed motor functions. Overall, experimental photothrombotic strokes are well suited for the investigation of specific cognitive impairments after stroke.

Meta-analysis of the efficacy of different training strategies in animal models of ischemic stroke.

BACKGROUND AND PURPOSE: Although several studies have shown beneficial effects of training in animal stroke models, the most effective training strategy and the optimal time to initiate training have not been identified. The present meta-analysis was performed to compare the efficacy of different training strategies and to determine the optimal time window for training in animal stroke models. METHODS: We searched the literature for studies analyzing the efficacy of training in animal models of ischemic stroke. Training was categorized into forced physical training, voluntary physical training, constraint-induced movement therapy, and skilled reaching training. Two reviewers independently extracted data on study quality, infarct size, and neurological outcome. Data were pooled by means of a meta-analysis. RESULTS: Thirty-five studies with >880 animals were included. A meta-analysis of all treatments showed that training reduced the infarct volume by 14% (95% confidence interval, 2%-25%) and improved the cognitive function by 33% (95% confidence interval, 8%-50%), the neuroscore by 13.4% (95% confidence interval, 1.5%-25.3%), and the running function by 6.6% (95% confidence interval, 1.4%-11.9%). Forced physical training reduced the infarct volume and enhanced the running function most effectively, whereas skilled reaching training improved the limb function most effectively. A meta-regression illustrated that training was particularly efficacious when initiated between 1 and 5 days after stroke onset. CONCLUSIONS: Our meta-analysis confirms that training reduces the infarct volume and improves the functional recovery in animal stroke models. Forced physical training and skilled reaching training were identified as particularly effective training strategies. The efficacy of training is time dependent.

Anti-LINGO-1 treatment restores myelination of corticospinal tract neurons and improves functional recovery after stroke.

Demyelination of corticospinal tract neurons contributes to long-term disability after cortical stroke. Nonetheless, poststroke myelin loss has not been addressed as a therapeutic target, so far. We hypothesized that an antibody-mediated inhibition of the Nogo receptor-interacting protein (LINGO-1, leucine-rich repeat and immunoglobulin domain-containing Nogo receptor-interacting protein) may counteract myelin loss, enhance remyelination and axonal growth, and thus promote functional recovery following stroke. To verify this hypothesis, mice were subjected to photothrombotic stroke and received either an antibody against LINGO-1 (n = 19) or a control treatment (n = 18). Behavioral tests were performed to assess the effects of anti-LINGO-1 treatment on the functional recovery. Seven weeks after stroke, immunohistochemical analyses were performed to analyze the effect of anti-LINGO-1 treatment on myelination and axonal loss of corticospinal tract neurons, proliferation of oligodendrocytes and neurogenesis. Anti-LINGO-1 treatment resulted in significantly improved functional recovery (p < 0.0001, repeated measures analysis of variance), and increased neurogenesis in the hippocampus and subventricular zone of the ipsilateral hemisphere (p = 0.0094 and p = 0.032, t-test). Notably, we observed a significant increase in myelin (p = 0.0295, t-test), platelet-derived growth factor receptor α-positive oligodendrocyte precursor cells (p = 0.0356, t-test) and myelinating adenomatous polyposis coli-positive cells within the ipsilateral internal capsule of anti-LINGO-1-treated mice (p = 0.0021, t-test). In conclusion, we identified anti-LINGO-1 as the first neuroregenerative treatment that counteracts poststroke demyelination of corticospinal tract neurons, presumably by increased proliferation of myelin precursor cells, and thereby improves functional recovery. Most importantly, our study presents myelin loss as a novel therapeutic target following stroke.

Rating enrichment items by female group-housed laboratory mice in multiple binary choice tests using an RFID-based tracking system.

Laboratory mice spend most of their lives in cages, not experiments, so improving housing conditions is a first-choice approach to improving their welfare. Despite the increasing popularity of enrichment, little is known about the benefits from an animal perspective. For a detailed analysis, we categorized enrichment items according to their prospective use into the categories 'structural', 'housing', and 'foraging'. In homecage-based multiple binary choice tests 12 female C57BL/6J mice chose between enrichment items within the respective categories over a 46-hour period. A new analyzing method combined the binary decisions and ranked the enrichment items within each category by calculating worth values and consensus errors. Although there was no unequivocal ranking that was true in its entire rank order for all individual mice, certain elements (e.g. lattice ball, second plane) were always among the top positions. Overall, a high consensus error in ranking positions reflects strong individual differences in preferences which could not be resolved due to the relatively small sample size. However, individual differences in the preference for enrichment items highlights the importance of a varied enrichment approach, as there does not seem to be one item that satisfies the wants and needs of all individuals to the same degree. An enrichment concept, in which the needs of the animals are central, contributes to a more specific refinement of housing conditions.

Effects of more natural housing conditions on the muscular and skeletal characteristics of female C57BL/6J mice.

BACKGROUND: Enrichment of home cages in laboratory experiments offers clear advantages, but has been criticized in some respects. First, there is a lack of definition, which makes methodological uniformity difficult. Second, there is concern that the enrichment of home cages may increase the variance of results in experiments. Here, the influence of more natural housing conditions on physiological parameters of female C57BL/6J mice was investigated from an animal welfare point of view. For this purpose, the animals were kept in three different housing conditions: conventional cage housing, enriched housing and the semi naturalistic environment. The focus was on musculoskeletal changes after long-term environmental enrichment. RESULTS: The housing conditions had a long-term effect on the body weight of the test animals. The more complex and natural the home cage, the heavier the animals. This was associated with increased adipose deposits in the animals. There were no significant changes in muscle and bone characteristics except for single clues (femur diameter, bone resorption marker CTX-1). Additionally, the animals in the semi naturalistic environment (SNE) were found to have the fewest bone anomalies. Housing in the SNE appears to have the least effect on stress hormone concentrations. The lowest oxygen uptake was observed in enriched cage housing. CONCLUSIONS: Despite increasing values, observed body weights were in the normal and strain-typical range. Overall, musculoskeletal parameters were slightly improved and age-related effects appear to have been attenuated. The variances in the results were not increased by more natural housing. This confirms the suitability of the applied housing conditions to ensure and increase animal welfare in laboratory experiments.

Challenges and advanced concepts for the assessment of learning and memory function in mice.

The mechanisms underlying the formation and retrieval of memories are still an active area of research and discussion. Manifold models have been proposed and refined over the years, with most assuming a dichotomy between memory processes involving non-conscious and conscious mechanisms. Despite our incomplete understanding of the underlying mechanisms, tests of memory and learning count among the most performed behavioral experiments. Here, we will discuss available protocols for testing learning and memory using the example of the most prevalent animal species in research, the laboratory mouse. A wide range of protocols has been developed in mice to test, e.g., object recognition, spatial learning, procedural memory, sequential problem solving, operant- and fear conditioning, and social recognition. Those assays are carried out with individual subjects in apparatuses such as arenas and mazes, which allow for a high degree of standardization across laboratories and straightforward data interpretation but are not without caveats and limitations. In animal research, there is growing concern about the translatability of study results and animal welfare, leading to novel approaches beyond established protocols. Here, we present some of the more recent developments and more advanced concepts in learning and memory testing, such as multi-step sequential lockboxes, assays involving groups of animals, as well as home cage-based assays supported by automated tracking solutions; and weight their potential and limitations against those of established paradigms. Shifting the focus of learning tests from the classical experimental chamber to settings which are more natural for rodents comes with a new set of challenges for behavioral researchers, but also offers the opportunity to understand memory formation and retrieval in a more conclusive way than has been attainable with conventional test protocols. We predict and embrace an increase in studies relying on methods involving a higher degree of automatization, more naturalistic- and home cage-based experimental setting as well as more integrated learning tasks in the future. We are confident these trends are suited to alleviate the burden on animal subjects and improve study designs in memory research.

Automatic classification of experimental models in biomedical literature to support searching for alternative methods to animal experiments.

Current animal protection laws require replacement of animal experiments with alternative methods, whenever such methods are suitable to reach the intended scientific objective. However, searching for alternative methods in the scientific literature is a time-consuming task that requires careful screening of an enormously large number of experimental biomedical publications. The identification of potentially relevant methods, e.g. organ or cell culture models, or computer simulations, can be supported with text mining tools specifically built for this purpose. Such tools are trained (or fine tuned) on relevant data sets labeled by human experts. We developed the GoldHamster corpus, composed of 1,600 PubMed (Medline) articles (titles and abstracts), in which we manually identified the used experimental model according to a set of eight labels, namely: "in vivo", "organs", "primary cells", "immortal cell lines", "invertebrates", "humans", "in silico" and "other" (models). We recruited 13 annotators with expertise in the biomedical domain and assigned each article to two individuals. Four additional rounds of annotation aimed at improving the quality of the annotations with disagreements in the first round. Furthermore, we conducted various machine learning experiments based on supervised learning to evaluate the corpus for our classification task. We obtained more than 7,000 document-level annotations for the above labels. After the first round of annotation, the inter-annotator agreement (kappa coefficient) varied among labels, and ranged from 0.42 (for "others") to 0.82 (for "invertebrates"), with an overall score of 0.62. All disagreements were resolved in the subsequent rounds of annotation. The best-performing machine learning experiment used the PubMedBERT pre-trained model with fine-tuning to our corpus, which gained an overall f-score of 0.83. We obtained a corpus with high agreement for all labels, and our evaluation demonstrated that our corpus is suitable for training reliable predictive models for automatic classification of biomedical literature according to the used experimental models. Our SMAFIRA - "Smart feature-based interactive" - search tool ( https://smafira.bf3r.de ) will employ this classifier for supporting the retrieval of alternative methods to animal experiments. The corpus is available for download ( https://doi.org/10.5281/zenodo.7152295 ), as well as the source code ( https://github.com/mariananeves/goldhamster ) and the model ( https://huggingface.co/SMAFIRA/goldhamster ).

Successful regeneration after experimental stroke by granulocyte-colony stimulating factor is not further enhanced by constraint-induced movement therapy either in concurrent or in sequential combination therapy.

BACKGROUND AND PURPOSE: Both application of granulocyte-colony stimulating factor (G-CSF) and constraint-induced movement therapy (CIMT) have been shown to improve outcome after experimental stroke. The aim of the present study was to determine whether concurrent or sequential combination of both therapies will further enhance therapeutic benefit and whether specific modifications in the abundance of various neurotransmitter receptors do occur. METHODS: Adult male Wistar rats were subjected to photothrombotic ischemia and assigned to the following treatment groups (n=20 each): (1) ischemic control (saline); (2) CIMT (CIMT between poststroke Days 2 and 11; (3) G-CSF (10 µg/kg G-CSF daily between poststroke Days 2 and 11; (4) combined concurrent group (CIMT plus 10 µg/kg G-CSF daily between poststroke Days 2 and 11; and (5) combined sequential group (CIMT between poststroke Days 2 and 11 and 10 µg/kg G-CSF daily between poststroke Days 12 and 21, respectively). Rats were functionally tested before and up to 4 weeks after ischemia. Quantitative receptor autography was performed for N-methyl-d-aspartate, AMPA, and GABA(A) receptors. RESULTS: Significant improvement of functional outcome was seen in all groups treated with G-CSF alone and in either combination with CIMT, whereas CIMT alone failed to enhance recovery. Infarct sizes and remaining cortical tissue did not differ in the various treatment groups. Failure of significant benefit in the CIMT group was associated with a shift toward inhibition in perilesional and remote cortical regions. CONCLUSIONS: Our findings disclose G-CSF as the major player for enhanced recovery after experimental stroke, preventing a shift toward inhibition as seen in the CIMT group.

Citicoline enhances neuroregenerative processes after experimental stroke in rats.

BACKGROUND AND PURPOSE: The neuroprotective potential of citicoline in acute ischemic stroke has been shown in many experimental studies and, although the exact mechanisms are still unknown, a clinical Phase III trial is currently underway. Our present study was designed to check whether citicoline also enhances neuroregeneration after experimental stroke. METHODS: Forty Wistar rats were subjected to photothrombotic stroke and treated either with daily injections of citicoline (100 mg/kg) or vehicle for 10 consecutive days starting 24 hours after ischemia induction. Sensorimotor tests were performed after an adequate training period at Days 1, 10, 21, and 28 after stroke. Then brains were removed and analyzed for infarct size, glial scar formation, neurogenesis, and ligand binding densities of excitatory and inhibitory neurotransmitter receptors. RESULTS: Animals treated with citicoline showed a significantly better neurological outcome at Days 10, 21, and 28 after ischemia, which could not be attributed to differences in infarct volumes or glial scar formation. However, neurogenesis in the dentate gyrus, subventricular zone, and peri-infarct area was significantly increased by citicoline. Furthermore, enhanced neurological outcome after citicoline treatment was associated with a shift toward excitation in the perilesional cortex. CONCLUSIONS: Our present data demonstrate that, apart from the well-known neuroprotective effects in acute ischemic stroke, citicoline also possesses a substantial neuroregenerative potential. Thanks to its multimodal effects, easy applicability, and history as a well-tolerated drug, promising possibilities of neurological treatment including chronic stroke open up.

Seeing old friends from a different angle: novel properties of hematopoietic growth factors in the healthy and diseased brain.

Hematopoietic growth factors are known for their bolstering effects on the growth, survival, and differentiation of blood progenitor cells. Several of these cytokines also influence the proliferation of neural stem/progenitor cells, paralleling cellular mechanisms in analogy to their function in the hematopoietic system. Erythropoietin (EPO), granulocyte-colony stimulating factor (G-CSF), thrombopoietin (TPO), and their respective receptors are all expressed in the hippocampus of the mammalian brain. Recent studies have confirmed EPO and G-CSF as vital neurotrophic and neuroprotective factors, and ascertained their role in neuroprotection and neuroregeneration as pertaining to the most prominent neurodegenerative diseases. The aims of this review are to discuss newly discovered properties of G-CSF, EPO, and TPO beyond their known functions in the hematopoietic system, to create an overview of the accumulating data on the role of these factors in hippocampal function, and to highlight any potential clinical implications.

Development of an IntelliCage-based cognitive bias test for mice.

The cognitive bias test is used to measure the emotional state of animals with regard to future expectations. Thus, the test offers a unique possibility to assess animal welfare with regard to housing and testing conditions of laboratory animals. So far, however, performing such a test is time-consuming and requires the presence of an experimenter. Therefore, we developed an automated and home-cage based cognitive bias test based on the IntelliCage system. We present several developmental steps to improve the experimental design leading to a successful measurement of cognitive bias in group-housed female C57BL/6J mice. The automated and home-cage based test design allows to obtain individual data from group-housed mice, to test the mice in their familiar environment, and during their active phase. By connecting the test-cage to the home-cage via a gating system, the mice participated in the test on a self-chosen schedule, indicating high motivation to actively participate in the experiment. We propose that this should have a positive effect on the animals themselves as well as on the data. Unexpectedly, the mice showed an optimistic cognitive bias after enrichment was removed and additional restraining. An optimistic expectation of the future as a consequence of worsening environmental conditions, however, can also be interpreted as an active coping strategy in which a potential profit is sought to be maximized through a higher willingness to take risks.

Bored at home?-A systematic review on the effect of environmental enrichment on the welfare of laboratory rats and mice.

Boredom is an emotional state that occurs when an individual has nothing to do, is not interested in the surrounding, and feels dreary and in a monotony. While this condition is usually defined for humans, it may very well describe the lives of many laboratory animals housed in small, barren cages. To make the cages less monotonous, environmental enrichment is often proposed. Although housing in a stimulating environment is still used predominantly as a luxury good and for treatment in preclinical research, enrichment is increasingly recognized to improve animal welfare. To gain insight into how stimulating environments influence the welfare of laboratory rodents, we conducted a systematic review of studies that analyzed the effect of enriched environment on behavioral parameters of animal well-being. Remarkably, a considerable number of these parameters can be associated with symptoms of boredom. Our findings show that a stimulating living environment is essential for the development of natural behavior and animal welfare of laboratory rats and mice alike, regardless of age and sex. Conversely, confinement and under-stimulation has potentially detrimental effects on the mental and physical health of laboratory rodents. We show that boredom in experimental animals is measurable and does not have to be accepted as inevitable.