A qualitative study of the barriers to using blinding in in vivo experiments and suggestions for improvement

Efficacy of mangiferin, kaempferol, and diosgenin on models of depression: A systematic review and network meta-analysis of rodent studies

BACKGROUND

Mangiferin (MGF), kaempferol (KMP), and diosgenin (DIO) are active compounds extracted from the dried rhizomes of Anemarrhena asphodeloides Bunge. that are proven to have antidepressant activity. However, no studies comprehensively compare and analyze the efficacy of MGF, KMP, and DIO.

METHODS

We searched electronic databases (e.g., Cochrane Library, Embase, Scopus, and PubMed) for studies of three compounds in rodents from inception to October 2024, performing a systematic review and network meta-analysis. We used animal behavioral tests as outcome indicators, including the forced swimming test, tail suspension test, and sucrose preference test.

RESULTS

A total of ten studies were included, involving 440 animals and six interventions. In the forced swimming test, the efficacy of fluoxetine was superior to KMP, MGF, and DIO. In the tail suspension test, DIO was more effective than fluoxetine, MGF, and KMP. In the sucrose preference test, the efficacy of fluoxetine was superior to MGF, DIO, and KMP. Specifically, MGF, KMP, and DIO significantly reduced the immobility time of the FST or TST and increased the sucrose preference index.

CONCLUSIONS

MGF, KMP, and DIO significantly improved depression-like behaviors of rodents, providing evidence for further development of new clinical antidepressants. Also, MGF, KMP, and DIO exert antidepressant effects primarily through anti-inflammatory, anti-oxidative stress, and regulation of neurotrophic factor and neurotransmitter levels.

Anxiety- and nociception-like behaviours in mature adult mice induced by audiovisual overstimulation during infancy

OBJECTIVES

To evaluate the behavioural effects in adult mice previously subjected to audiovisual overstimulation during infancy and adolescence.

METHODS

Mice aged 21, 26 and 36 days (p21, p26 and p36) underwent auditory (70 db) and visual (flashing lights) stimulation for 2 or 6 h per day until p64; naive animals were used as controls. At p200, tests assessed respectively motor activity (open field test), depression (forced swimming and splash tests), anxiety (hole board, plus maze and marble burying tests, aggression (resident-intruder test), and nociception (von Frey and hot plate tests).

RESULTS

There were no significant (ANOVA, p > 0.05) behavioural changes in forced swimming, splash, hole board, or marble burying tests between overstimulated and naive groups. However, the p21 group showed significantly (ANOVA, p < 0.05) increased anxiety-like behaviour (2 h) in the elevated plus maze test and altered nociceptive behaviour in the von Frey test (2 and 6 h). The p26 group (2 h) displayed significantly reduced rearing behaviours, fewer entries in the plus maze test, and faster reaction times to noxious thermal stimulation (2 h).

CONCLUSION

Audiovisual overstimulation during early development can promote anxiety-like behaviour and affect nociceptive behaviour in adult mice.

Testing the reproducibility of ecological studies on insect behavior in a multi-laboratory setting identifies opportunities for improving experimental rigor

The reproducibility of studies involving insect species is an underexplored area in the broader discussion about poor reproducibility in science. Our study addresses this gap by conducting a systematic multi-laboratory investigation into the reproducibility of ecological studies on insect behavior. We implemented a 3 × 3 experimental design, incorporating three study sites, and three independent experiments on three insect species from different orders: the turnip sawfly (Athalia rosae, Hymenoptera), the meadow grasshopper (Pseudochorthippus parallelus, Orthoptera), and the red flour beetle (Tribolium castaneum, Coleoptera). Using random-effect meta-analysis, we compared the consistency and accuracy of treatment effects on insect behavioral traits across replicate experiments. We successfully reproduced the overall statistical treatment effect in 83% of the replicate experiments, but overall effect size replication was achieved in only 66% of the replicates. Thus, though demonstrating sufficient reproducibility in some measures, this study also provides the first experimental evidence for cases of poor reproducibility in insect experiments. Our findings further show that reasons causing poor reproducibility established in rodent research also hold for other study organisms and research questions. We believe that a rethinking of current best practices is required to face reproducibility issues in insect studies but also across disciplines. Specifically, we advocate for adopting open research practices and the implementation of methodological strategies that reduce bias and problems arising from over-standardization. With respect to the latter, the introduction of systematic variation through multi-laboratory or heterogenized designs may contribute to improved reproducibility in studies involving any living organisms.

How Transparent and Reproducible Are Studies That Use Animal Models of Opioid Addiction?

The reproducibility crisis in psychology has caused various fields to consider the reliability of their own findings. Many of the unfortunate aspects of research design that undermine reproducibility also threaten translation potential. In preclinical addiction research, the rates of translation have been disappointing. We tallied indices of transparency and accurate and thorough reporting in animal models of opioid addiction from 2019 to 2023. By examining the prevalence of these practices, we aimed to understand whether efforts to improve reproducibility are relevant to this field. For 255 articles, we report the prevalence of transparency measures such as preregistration, registered reports, open data and open code, as well as compliance to the Animal Research: Reporting of In Vivo Experiments (ARRIVE) guidelines. We also report rates of bias minimization practices (randomization, masking and data exclusion), sample size calculations and multiple corrections adjustments. Lastly, we estimated the accuracy of test statistic reporting using a version of StatCheck. All the transparency measures and the ARRIVE guideline items had low prevalence, including no cases of study preregistration and no cases where authors shared their analysis code. Similarly, the levels of bias minimization practices and sample size calculations were unsatisfactory. In contrast, adjustments for multiple comparisons were implemented in most articles (76.5%). Lastly, p-value inconsistencies with test statistics were detected in about half of papers, and 11% contained statistical significance errors. We recommend that researchers, journal editors and others take steps to improve study reporting and to facilitate both replication and translation.

Preclinical extracellular matrix-based treatment strategies for myocardial infarction: a systematic review and meta-analysis

BACKGROUND

Administrating extracellular matrix (ECM) to restore cardiac function post-myocardial infarction (MI) shows promise, however study variability obscures its true impact. We therefore conducted a systematic review and meta-analysis of preclinical studies to assess the effects of ECM treatments on cardiac function and tissue homeostasis post-MI.

METHODS

We searched PubMed and SCOPUS from inception to June 28, 2024, for animal studies describing ECM treatment post-MI (pre-registered on PROSPERO, CRD42022368400). Random effects meta-analyses compared ECM treatment to controls regarding left ventricular ejection fraction (LVEF), fractional shortening, infarct size, stroke volume, and left ventricular wall thickness. Subgroup analyses examined the influence of sex, species, ECM source, and administration method. Funnel plots and Egger's regression assessed publication bias.

RESULTS

We identify 88 articles which meet our inclusion criteria. These studies describe the use of rats (51%), mice (38%), and pigs (11%). 44% of studies use males, 34% females, 5% both sexes, and 17% did not report sex. Most studies employ permanent MI models (85%) over ischemia reperfusion models (15%), and deliver ECM via intramyocardial injection (59%), cardiac patch (39%), cardiac sleeve (1%), or osmotic pump (1%). Our meta-analysis demonstrates that ECM treatment significantly improves LVEF (MD: 10.9%, 95% CI: [8.7%;13.0%]; p = 8.057e-24), fractional shortening (MD: 8.2%, 95% CI: [5.6%; 10.9%]; p = 1.751e-09), stroke volume (SMD 0.6, 95% CI: [0.2;1.0], p = 0.004), left ventricular wall thickening (SMD 1.2, 95% CI: [0.9; 1.5], p = 1.321e-17), while reducing infarct size (-11.7%, 95% CI: [-14.7%;-8.6%], p = 3.699e-14). We find no significant differences between the various subgroups and no indication of publication bias.

CONCLUSIONS

ECM-based treatments significantly enhance cardiac function and tissue homeostasis in preclinical post-MI models, supporting further research toward clinical translation.

CRIME-Q-a unifying tool for critical appraisal of methodological (technical) quality, quality of reporting and risk of bias in animal research

BACKGROUND

Systematic reviews within the field of animal research are becoming more common. However, in animal translational research, issues related to methodological quality and quality of reporting continue to arise, potentially leading to underestimation or overestimation of the effects of interventions or prevent studies from being replicated. The various tools and checklists available to ensure good-quality studies and proper reporting include both unique and/or overlapping items and/or simply lack necessary elements or are too situational to certain conditions or diseases. Currently, there is no tool available, which covers all aspects of animal models, from bench-top activities to animal facilities, hence a new tool is needed. This tool should be designed to be able to assess all kinds of animal studies such as old, new, low quality, high quality, interventional and noninterventional on. It should do this on multiple levels through items on quality of reporting, methodological (technical) quality, and risk of bias, for use in assessing the overall quality of studies involving animal research.

METHODS

During a systematic review of meningioma models in animals, we developed a novel unifying tool that can assess all types of animal studies from multiple perspectives. The tool was inspired by the Collaborative Approach to Meta Analysis and Review of Animal Data from Experimental Studies (CAMARADES) checklist, the ARRIVE 2.0 guidelines, and SYRCLE's risk of bias tool, while also incorporating unique items. We used the interrater agreement percentage and Cohen's kappa index to test the interrater agreement between two independent reviewers for the items in the tool.

RESULTS

There was high interrater agreement across all items (92.9%, 95% CI 91.0-94.8). Cohen's kappa index showed quality of reporting had the best mean index of 0.86 (95%-CI 0.78-0.94), methodological quality had a mean index of 0.83 (95%-CI 0.78-0.94) and finally the items from SYRCLE's risk of bias had a mean kappa index of 0.68 (95%-CI 0.57-0.79).

CONCLUSIONS

The Critical Appraisal of Methodological (technical) Quality, Quality of Reporting and Risk of Bias in Animal Research (CRIME-Q) tool unifies a broad spectrum of information (both unique items and items inspired by other methods) about the quality of reporting and methodological (technical) quality, and contains items from SYRCLE's risk of bias. The tool is intended for use in assessing overall study quality across multiple domains and items and is not, unlike other tools, restricted to any particular model or study design (whether interventional or noninterventional). It is also easy to apply when designing and conducting animal experiments to ensure proper reporting and design in terms of replicability, transparency, and validity.

Stop Fooling Yourself! (Diagnosing and Treating Confirmation Bias)

Confirmation bias (CB) is a cognitive bias that allows us to fool ourselves by selectively filtering data and distorting analyses to support favored beliefs or hypotheses. In this article, I will briefly review some classic experiments from cognitive psychology that illustrate what a powerful, pernicious, and insidious force CB is. I will then discuss how to recognize CB in our own thinking and behavior and describe specific elements of good experimental design that can mitigate its effects. These elements-such as randomization and blinding-are conceptually straightforward but often difficult in practice and therefore not as widely implemented as they should be.

Methods for applying blinding and randomisation in animal experiments

Blinding and randomisation are important methods for increasing the robustness of pre-clinical studies, as incomplete or improper implementation thereof is recognised as a source of bias. Randomisation ensures that any known and unknown covariates introducing bias are randomly distributed over the experimental groups. Thereby, differences between the experimental groups that might otherwise have contributed to false positive or -negative results are diminished. Methods for randomisation range from simple randomisation (e.g. rolling a dice) to advanced randomisation strategies involving the use of specialised software. Blinding on the other hand ensures that researchers are unaware of group allocation during the preparation, execution and acquisition and/or the analysis of the data. This minimises the risk of unintentional influences resulting in bias. Methods for blinding require strong protocols and a team approach. In this review, we outline methods for randomisation and blinding and give practical tips on how to implement them, with a focus on animal studies.

RNA interference-based strategies to control Botrytis cinerea infection in cultivated strawberry

KEY MESSAGE

Gene silencing of BcDCL genes improves gray mold disease control in the cultivated strawberry. Gene silencing technology offers new opportunities to develop new formulations or new pathogen-resistant plants for reducing impacts of agricultural systems. Recent studies offered the proof of concept that the symptoms of gray mold can be reduced by downregulating Dicer-like 1 (DCL1) and 2 (DCL2) genes of Botrytis cinerea. In this study, we demonstrate that both solutions based on dsRNA topical treatment and in planta expression targeting BcDCL1 and BcDCL2 genes can be used to control the strawberry gray mold, the most harmful disease for different fruit crops. 50, 70 and 100 ng μL-1 of naked BcDCL1/2 dsRNA, sprayed on plants of Fragaria x ananassa cultivar Romina in the greenhouse, displayed significant reduction of susceptibility, compared to the negative controls, but to a lesser extent than the chemical fungicide. Three independent lines of Romina cultivar were confirmed for their stable expression of the hairpin gene construct that targets the Bc-DCL1 and 2 sequences (hp-Bc-DCL1/2), and for the production of hp construct-derived siRNAs, by qRT-PCR and Northern blot analyses. In vitro and in vivo detached leaves, and fruits from the hp-Bc-DCL1/2 lines showed significantly enhanced tolerance to this fungal pathogen compared to the control. This decreased susceptibility was correlated to the reduced fungal biomass and the downregulation of the Bc-DCL1 and 2 genes in B. cinerea. These results confirm the potential of both RNAi-based products and plants for protecting the cultivated strawberry from B. cinerea infection, reducing the impact of chemical pesticides on the environment and the health of consumers.

Measuring the replicability of our own research

In the study of transgenic mouse models of neurodevelopmental and neurodegenerative disorders, we use batteries of tests to measure deficits in behaviour and from the results of these tests, we make inferences about the mental states of the mice that we interpret as deficits in "learning", "memory", "anxiety", "depression", etc. This paper discusses the problems of determining whether a particular transgenic mouse is a valid mouse model of disease X, the problem of background strains, and the question of whether our behavioural tests are measuring what we say they are. The problem of the reliability of results is then discussed: are they replicable between labs and can we replicate our results in our own lab? This involves the study of intra- and inter- experimenter reliability. The variables that influence replicability and the importance of conducting a complete behavioural phenotype: sensory, motor, cognitive and social emotional behaviour are discussed. Then the thorny question of failure to replicate is examined: Is it a curse or a blessing? Finally, the role of failure in research and what it tells us about our research paradigms is examined.

Advocating for Generalizability: Accepting Inherent Variability in Translation of Animal Research Outcomes

Advancing scientific discovery requires investigators to embrace research practices that increase transparency and disclosure about materials, methods, and outcomes. Several research advocacy and funding organizations have produced guidelines and recommended practices to enhance reproducibility through detailed and rigorous research approaches; however, confusion around vocabulary terms and a lack of adoption of suggested practices have stymied successful implementation. Although reproducibility of research findings cannot be guaranteed due to extensive inherent variables in attempts at experimental repetition, the scientific community can advocate for generalizability in the application of data outcomes to ensure a broad and effective impact on the comparison of animals to translation within human research. This report reviews suggestions, based upon work with National Institutes of Health advisory groups, for improving rigor and transparency in animal research through aspects of experimental design, statistical assessment, and reporting factors to advocate for generalizability in the application of comparative outcomes between animals and humans.

Behavioral Analysis of NMDAR Function in Rodents: Tests of Long-Term Spatial Memory

NMDAR-dependent forms of synaptic plasticity in brain regions like the hippocampus are widely believed to provide the neural substrate for long-term associative memory formation. However, the experimental data are equivocal at best and may suggest a more nuanced role for NMDARs and synaptic plasticity in memory. Much of the experimental data available comes from studies in genetically modified mice in which NMDAR subunits have been deleted or mutated in order to disrupt NMDAR function. Behavioral assessment of long-term memory in these mice has involved tests like the Morris watermaze and the radial arm maze. Here we describe these behavioral tests and some of the different testing protocols that can be used to assess memory performance. We discuss the importance of distinguishing selective effects on learning and memory processes from nonspecific effects on sensorimotor or motivational aspects of performance.

Antibiotic-induced gut dysbiosis and cognitive, emotional, and behavioral changes in rodents: a systematic review and meta-analysis

There are previous epidemiological studies reporting associations between antibiotic use and psychiatric symptoms. Antibiotic-induced gut dysbiosis and alteration of microbiota-gut-brain axis communication has been proposed to play a role in this association. In this systematic review and meta-analysis, we reviewed published articles that have presented results on changes in cognition, emotion, and behavior in rodents (rats and mice) after antibiotic-induced gut dysbiosis. We searched three databases-PubMed, Web of Science, and SCOPUS to identify such articles using dedicated search strings and extracted data from 48 articles. Increase in anxiety and depression-like behavior was reported in 32.7 and 40.7 percent of the study-populations, respectively. Decrease in sociability, social novelty preference, recognition memory and spatial cognition was found in 18.1, 35.3, 26.1, and 62.5 percent of the study-populations, respectively. Only one bacterial taxon (increase in gut Proteobacteria) showed statistically significant association with behavioral changes (increase in anxiety). There were no consistent findings with statistical significance for the potential biomarkers [Brain-derived neurotrophic factor (BDNF) expression in the hippocampus, serum corticosterone and circulating IL-6 and IL-1β levels]. Results of the meta-analysis revealed a significant association between symptoms of negative valence system (including anxiety and depression) and cognitive system (decreased spatial cognition) with antibiotic intake (p < 0.05). However, between-study heterogeneity and publication bias were statistically significant (p < 0.05). Risk of bias was evaluated to be high in the majority of the studies. We identified and discussed several reasons that could contribute to the heterogeneity between the results of the studies examined. The results of the meta-analysis provide promising evidence that there is indeed an association between antibiotic-induced gut dysbiosis and psychopathologies. However, inconsistencies in the implemented methodologies make generalizing these results difficult. Gut microbiota depletion using antibiotics may be a useful strategy to evaluate if and how gut microbes influence cognition, emotion, and behavior, but the heterogeneity in methodologies used precludes any definitive interpretations for a translational impact on clinical practice.

Macrophage/Microglia Sirt3 Contributes to the Anti-inflammatory Effects of Resveratrol Against Experimental Intracerebral Hemorrhage in Mice

Intracerebral hemorrhage (ICH) is a devastating stroke type with high mortality and disability. Inflammatory response induced by macrophages/microglia (M/Ms) activation is one of the leading causes of brain damage after ICH. The anti-inflammatory effects of resveratrol (RSV) have already been evaluated in several models of central nervous system disease. Therefore, we designed the current study to assess the role of RSV in ICH and explore its downstream mechanism related to Sirt3. The autologous artery blood injection was administrated to create an ICH mouse model. M/Ms-specific Sirt3 knockout Sirt3f/f; CX3CR1-Cre (Sirt3 cKO) mouse was used to evaluate the role of Sirt3 on RSV treatment. Neuronal function and hematoma volume were assessed to indicate brain damage. The pro-inflammatory marker (CD16) and cytokine (TNF) were measured to evaluate the inflammatory effects. Our results showed that RSV treatment alleviates neurological deficits, reduces cell death, and increases hematoma clearance on day 7 after ICH. In addition, RSV effectively suppressed CD16+ M/Ms activation and decreased TNF release. In Sirt3 cKO mice, the protective effects of RSV were abolished, indicating the potential mechanism of RSV was partially due to Sirt3 signaling activation. Therefore, RSV could be a promising candidate and therapeutic agent for ICH and Sirt3 could be a potential target to inhibit inflammation.

Universal Recommendations on Planning and Performing the Auditory Brainstem Responses (ABR) with a Focus on Mice and Rats

Translational audiology research aims to transfer basic research findings into practical clinical applications. While animal studies provide essential knowledge for translational research, there is an urgent need to improve the reproducibility of data derived from these studies. Sources of variability in animal research can be grouped into three areas: animal, equipment, and experimental. To increase standardization in animal research, we developed universal recommendations for designing and conducting studies using a standard audiological method: auditory brainstem response (ABR). The recommendations are domain-specific and are intended to guide the reader through the issues that are important when applying for ABR approval, preparing for, and conducting ABR experiments. Better experimental standardization, which is the goal of these guidelines, is expected to improve the understanding and interpretation of results, reduce the number of animals used in preclinical studies, and improve the translation of knowledge to the clinic.