Improving our understanding of the in vivo modelling of psychotic disorders: A protocol for a systematic review and meta-analysis.

Psychosis represents a set of symptoms against which current available treatments are not universally effective and are often accompanied by adverse side effects. Clinical management could potentially be improved with a greater understanding of the underlying biology and subsequently with the introduction of novel treatments. Since many clinical drug candidates are identified through in vivo modelling, a deeper understanding of the pre-clinical field, might help us understand why translation of results from animal models to inform mental health clinical practice has so far been weak. We set out to give a shallow, but broad unbiased overview of experiments looking at the in vivo modelling of psychotic disorders using a systematic review and meta-analysis. This protocol describes the exact methodology we propose to follow in order to quantitatively review both studies characterizing a model and those experiments that investigate the effects of novel therapeutic options. We are interested in assessing the prevalence of the reporting of measures to reduce risk of bias, and the internal and external validity of the animal models and outcome measures used to validate these models. This generation of strong empirical evidence has the potential to identify areas for improvement, make suggestions for future research avenues, and ultimately inform what we think we know to improve the current attrition rate between bench and bedside in psychosis research. A review like this will also support the reduction of animal numbers used in research and the refinement of experiments to maximize their value in informing the field.

Correction: Risk of Bias in Reports of In Vivo Research: A Focus for Improvement.

[This corrects the article DOI: 10.1371/journal.pbio.1002273.].

Risk of Bias in Reports of In Vivo Research: A Focus for Improvement.

The reliability of experimental findings depends on the rigour of experimental design. Here we show limited reporting of measures to reduce the risk of bias in a random sample of life sciences publications, significantly lower reporting of randomisation in work published in journals of high impact, and very limited reporting of measures to reduce the risk of bias in publications from leading United Kingdom institutions. Ascertainment of differences between institutions might serve both as a measure of research quality and as a tool for institutional efforts to improve research quality.

Integrin-mediated axoglial interactions initiate myelination in the central nervous system.

All but the smallest-diameter axons in the central nervous system are myelinated, but the signals that initiate myelination are unknown. Our prior work has shown that integrin signaling forms part of the cell-cell interactions that ensure only those oligodendrocytes contacting axons survive. Here, therefore, we have asked whether integrins regulate the interactions that lead to myelination. Using homologous recombination to insert a single-copy transgene into the hypoxanthine phosphoribosyl transferase (hprt) locus, we find that mice expressing a dominant-negative beta1 integrin in myelinating oligodendrocytes require a larger axon diameter to initiate timely myelination. Mice with a conditional deletion of focal adhesion kinase (a signaling molecule activated by integrins) exhibit a similar phenotype. Conversely, transgenic mice expressing dominant-negative beta3 integrin in oligodendrocytes display no myelination abnormalities. We conclude that beta1 integrin plays a key role in the axoglial interactions that sense axon size and initiate myelination, such that loss of integrin signaling leads to a delay in myelination of small-diameter axons.