Reporting in rodent models of 'chemobrain': a systematic review assessing compliance with the ARRIVE guidelines

Meta-analyses of executive function deficits in chemotherapy-treated rodent models

People diagnosed with cancer who undergo chemotherapy commonly encounter cognitive changes, particularly in executive functions (EFs). EFs support goal-directed behaviours, with EF deficits implicated in various neurocognitive impairments. We conducted five meta-analyses of the rodent models to investigate the impact of chemotherapy across five EF domains. A systematic search across PubMed, Web of Science, Scopus, and PsycINFO yielded 56 eligible papers. Our findings supported the clinical literature suggesting the selective impact of chemotherapy on different EF domains. Specifically, chemotherapy-treated animals performed significantly more poorly than controls in tasks assessing working memory, behavioural flexibility, and problem-solving, with no significant group differences in inhibition or attention. Subgroup analyses revealed that alkylating agents, antitumor antibiotics, and combination therapies were strongly associated with working memory deficits, whereas mitotic inhibitors were not. Rodent species, strain, age, sex, number of treatments, and time of behavioural assessment since the end of treatment did not moderate the drug effect on any assessed EF domains. To increase the generalisability and translational validity of the results, the overall reporting quality of animal studies needs to be improved with more details on randomisation, blinding, sample sizes, and criteria for animal exclusions.

Complications and comorbidities associated with antineoplastic chemotherapy: Rethinking drug design and delivery for anticancer therapy

Despite the considerable advancements in chemotherapy as a cornerstone modality in cancer treatment, the prevalence of complications and pre-existing diseases is on the rise among cancer patients along with prolonged survival and aging population. The relationships between these disorders and cancer are intricate, bearing significant influence on the survival and quality of life of individuals with cancer and presenting challenges for the prognosis and outcomes of malignancies. Herein, we review the prevailing complications and comorbidities that often accompany chemotherapy and summarize the lessons to learn from inadequate research and management of this scenario, with an emphasis on possible strategies for reducing potential complications and alleviating comorbidities, as well as an overview of current preclinical cancer models and practical advice for establishing bio-faithful preclinical models in such complex context.

Twelve years after the ARRIVE guidelines: Animal research has not yet arrived at high standards

The reproducibility crisis across animal studies jeopardizes the credibility of the main findings derived from animal research, even though these findings are critical for informing human studies. To clarify and improve transparency among animal studies, the ARRIVE reporting guidelines were first announced in 2010 and upgraded to version 2.0 in 2020. However, compliance with and awareness of those reporting guidelines has remained suboptimal. Journal editors should encourage the authors to adhere to those guidelines. Authors, editors, referees, and reviewers should be aware of the ARRIVE guideline 2.0 when assessing and evaluating the methodology and findings of animal studies. However, we should also question whether reporting guidelines alone can change a research culture and improve the reproducibility of animal investigations. Reported research may not reflect actual research. Large segments of animal research efforts are wasted because of poor design choices and because of non-publication rather than suboptimal reporting. Better training of the scientific workforce, interventions at improving animal research at the design stage, registration practices, and alignment of the reward system with the publication of rigorous animal research may achieve more than reporting guidelines alone.

Artificial and natural interventions for chemotherapy- and / or radiotherapy-induced cognitive impairment: A systematic review of animal studies

BACKGROUND

Cancer survivors frequently experience cognitive impairments. This systematic review assessed animal literature to identify artificial (pharmaceutical) or natural interventions (plant/endogenously-derived) to reduce treatment-related cognitive impairments.

METHODS

PubMed, EMBASE, PsycINFO, Web of Science, and Scopus were searched and SYRCLE's tool was used for risk of bias assessment of the 134 included articles.

RESULTS

High variability was observed and risk of bias analysis showed overall poor quality of reporting. Results generally showed positive effects in the intervention group versus cancer-therapy only group (67% of 156 cognitive measures), with only 15 (7%) measures reporting cognitive impairment despite intervention. Both artificial (61%) and natural (75%) interventions prevented cognitive impairment. Artificial interventions involving GSK3B inhibitors, PLX5622, and NMDA receptor antagonists, and natural interventions utilizing melatonin, curcumin, and N-acetylcysteine, showed most consistent outcomes.

CONCLUSIONS

Both artificial and natural interventions may prevent cognitive impairment in rodents, which merit consideration in future clinical trials. Greater consistency in design is needed to enhance the generalizability across studies, including timing of cognitive tests and description of treatments and interventions.

The effectiveness of anti-inflammatory agents in reducing chemotherapy-induced cognitive impairment in preclinical models - A systematic review

Chemotherapy-induced cognitive impairment (CICI) is a debilitating condition resulting from chemotherapy administration for cancer treatment. CICI is characterised by various cognitive impairments, including issues with learning, memory, and concentration, impacting quality of life. Several neural mechanisms are proposed to drive CICI, including inflammation, therefore, anti-inflammatory agents could ameliorate such impairments. Research is still in the preclinical stage; however, the efficacy of anti-inflammatories to reduce CICI in animal models is unknown. Therefore, a systematic review was conducted, with searches performed in PubMed, Scopus, Embase, PsycInfo and Cochrane Library. A total of 64 studies were included, and of the 50 agents identified, 41 (82%) reduced CICI. Interestingly, while non-traditional anti-inflammatory agents and natural compounds reduced impairment, the traditional agents were unsuccessful. Such results must be taken with caution due to the heterogeneity observed in terms of methods employed. Nevertheless, preliminary evidence suggests anti-inflammatory agents could be beneficial for treating CICI, although it may be critical to think beyond the use of traditional anti-inflammatories when considering which specific compounds to prioritise in development.

A systematic review of the biological mediators of fat taste and smell

Taste and smell play a key role in our ability to perceive foods. Overconsumption of highly palatable energy-dense foods can lead to increased caloric intake and obesity. Thus there is growing interest in the study of the biological mediators of fat taste and associated olfaction as potential targets for pharmacologic and nutritional interventions in the context of obesity and health. The number of studies examining mechanisms underlying fat taste and smell has grown rapidly in the last 5 years. Therefore, the purpose of this systematic review is to summarize emerging evidence examining the biological mechanisms of fat taste and smell. A literature search was conducted of studies published in English between 2014 and 2021 in adult humans and animal models. Database searches were conducted using PubMed, EMBASE, Scopus, and Web of Science for key terms including fat/lipid, taste, and olfaction. Initially, 4,062 articles were identified through database searches, and a total of 84 relevant articles met inclusion and exclusion criteria and are included in this review. Existing literature suggests that there are several proteins integral to fat chemosensation, including cluster of differentiation 36 (CD36) and G protein-coupled receptor 120 (GPR120). This systematic review will discuss these proteins and the signal transduction pathways involved in fat detection. We also review neural circuits, key brain regions, ingestive cues, postingestive signals, and genetic polymorphism that play a role in fat perception and consumption. Finally, we discuss the role of fat taste and smell in the context of eating behavior and obesity.