Effect size, sample size and power of forced swim test assays in mice: Guidelines for investigators to optimize reproducibility

Mitigation and mechanism of low dose linoleic acid on depression caused by disorder of gut microbiome

OBJECTIVES

Depression is a widely prevalent mental disorder, and nutritional interventions play an increasingly important role in its treatment. In this paper, effects of linoleic acid (LA) on depressive behavior in mice induced by gut microbiome disorders were investigated.

METHODS

Fifty C57BL/6J male mice were randomly separated into five groups, control group (CK), ceftriaxone sodium group (CRO), low-dose linoleic acid group (LLA, 1 g/kg), medium-dose linoleic acid group (MLA, 2 g/kg), and high-dose linoleic acid group (HLA, 5 g/kg). In the LLA, MLA, and HLA groups, mice were treated with ceftriaxone sodium (CRO) to induce depressive behaviors, followed by LA administration. Behavioral tests were used to evaluate depressive behavior. High-throughput sequencing and Hematoxylin-eosin (H&E) staining in gut microenvironment were carried out. ELISA kits were used to measure brain inflammatory factors, and 5-hydroxy-tryptamine (5-HT). Gas chromatography and western blot were used to determine fatty acids compositions and the enzymes expression involved in lipid metabolism in brain respectively.

RESULTS

The results showed that 10 weeks CRO treatment contribute to depressive behavior, gut microbiome disturbance, and serotonin system disturbance. LLA and MLA improved the depressive-like behavior, and significantly increased the levels of 5-HT1A, 5-HTT and 5-HT in the hippocampus. LLA was found to improve the diversity of gut microbiome and alleviate colon tissue damage. Meantime, LLA increased the content of linoleic acid, improved the expression of FADS2 and COX-2, increased IL-10 levels, and decreased IL-6 levels in the brain.

DISCUSSION

LA alleviated depressive behavior in mice by improving the gut microenvironment, regulate fatty acid metabolism, and modulate inflammation.

Association between rare earth elements and depression: Evidence from pilot mice model of chronic unpredictable mild stress-induced depression and human studies of major depressive disorder

The etiology of Major Depressive Disorder (MDD) has been associated with levels of trace elements in the human body. The source of trace elements in the human body may be rare earth elements (REEs). Our study aimed to identify the potential relationship between t REEs in blood and brain samples and depression from two paths: animal experiments and population studies. In the animal experiments, 35 adult Sprague-Dawley rats were randomly allocated to the control group (n = 14) and treatment group (n = 21), which received the chronic unpredictable mild stress (CUMS) procedure for four weeks and further categorized into the sensitive group (n = 9) and resilient group (n = 12) by sucrose water preference test. Then, all rats were executed to obtain serum and brain tissue samples. We also recruited 197 participants and divided them into the major depressive disorder (MDD) group (n = 100) and the control group (n = 97) then serum samples were collected for REEs detection. Our finding reported that significant differences were found in the levels of La and Ce in blood samples from different groups in the CUMS rat model (sensitive group < resilient group < control group) (all p < 0.05), with similar patterns for other elements (Pr, Nd, and Y) (but p > 0.5). No significant inter-group difference was reported in rat brain tissue samples. After adjusting for demographic variables, we found that the concentrations of all five REEs (La, Ce, Pr, Nd, Y) were lower in depression group than in control group (all p < 0.01). The current conjoint animal and human data supported appropriate levels of REEs have a certain protective effect on body health. These results may be attributed to Hormesis effects. Whether the possible favorable effects of REEs on improving symptoms of depression or can be applied to drug development remains to be further investigated.

Preclinical trials in Alzheimer's disease: Sample size and effect size for behavioural and neuropathological outcomes in 5xFAD mice

5xFAD transgenic (TG) mice are used widely in AD preclinical trials; however, data on sample sizes are largely unaddressed. We therefore performed estimates of sample sizes and effect sizes for typical behavioural and neuropathological outcome measures in TG 5xFAD mice, based upon data from single-sex (female) groups. Group-size estimates to detect normalisation of TG body weight to WT littermate levels at 5.5m of age were N = 9-15 depending upon algorithm. However, by 1 year of age, group sizes were small (N = 1 -<6), likely reflecting the large difference between genotypes at this age. To detect normalisation of TG open-field hyperactivity to WT levels at 13-14m, group sizes were also small (N = 6-8). Cued learning in the Morris water maze (MWM) was normal in Young TG mice (5m of age). Mild deficits were noted during MWM spatial learning and memory. MWM reversal learning and memory revealed greater impairment, and groups of up to 22 TG mice were estimated to detect normalisation to WT performance. In contrast, Aged TG mice (tested between 13 and 14m) failed to complete the visual learning (non-spatial) phase of MWM learning, likely due to a failure to recognise the platform as an escape. Estimates of group size to detect normalisation of this severe impairment were small (N = 6-9, depending upon algorithm). Other cognitive tests including spontaneous and forced alternation and novel-object recognition either failed to reveal deficits in TG mice or deficits were negligible. For neuropathological outcomes, plaque load, astrocytosis and microgliosis in frontal cortex and hippocampus were quantified in TG mice aged 2m, 4m and 6m. Sample-size estimates were ≤9 to detect the equivalent of a reduction in plaque load to the level of 2m-old TG mice or the equivalent of normalisation of neuroinflammation outcomes. However, for a smaller effect size of 30%, larger groups of up to 21 mice were estimated. In light of published guidelines on preclinical trial design, these data may be used to provide provisional sample sizes and optimise preclinical trials in 5xFAD TG mice.

In Vivo Analysis of Extract of Leaves of Mistletoe as a Benalu Duku: Clinical Chemical Value Associated with Histopathology, Liver, Kidneys, and Lethal Dose Determinate

The active compounds from the leaves of Dendrophthoe pentandra L. Miq., also known as, Benalu Duku (in Indonesia), are known to contain progesterone-like compounds (PLCs). This study aims to determine the effect of giving a single dose of PLCs on liver and kidney function in rats and the dose limit that causes the death of experimental animals. The PLCs were analyzed for chemical and physical characterization and compared to a pure standard of progesterone using HPLC, IR spectrometry, thermogravimetry, and NMR. The research was carried out in two sections. In section one, thirty-five healthy adult male rats were divided into six experimental groups and a control group of five rats each. The groups received, respectively, 50 to 75 mg/kg of PLCs (i.p.). The control group was given a 0.5 mL Aqua Pro injection. Alanine aminotransferase, aspartate aminotransferase, creatinine, and blood urea nitrogen were assessed using the clinical chemistry of blood serum analysis. Cell disruptions were analyzed to determine the degeneration effects of PLCs on the liver and kidney in the experimental and control groups. In section two, thirty healthy adult male rats were divided into 6 groups, each group of 5 rats, and injected with PLCs at a dose of 0.9-2.1 g/kg BW, followed by a lethal dose test. The control groups were available for 5 individual rats at 0 g/kg BW of PLCs. Our findings indicated that PLCs have a similarity chemical and physical characterized each other compounds, then the following administration of 50 to 75 mg/kg of PLCs did not affect the parameters of clinical chemistry. Histopathology analysis of the liver and kidney revealed normal subcellular levels in the experimental group, with the nonlethal dose at 0.9 g/kg BW.

A systematic review of studies investigating the acute effects of N-methyl-D-aspartate receptor antagonists on behavioural despair in normal animals suggests poor predictive validity

The ability of the N-methyl-D-aspartate receptor antagonist ketamine to induce a rapid and sustained antidepressant effect has led to a surge in pre-clinical studies investigating underlying mechanisms and seeking novel treatments. Animal models are key to this research as they can provide a behavioural readout linking underlying mechanisms to clinical benefits. However, quantifying depression-related behaviours in rodents represents a major challenge with the validity of traditional methods such as models of behavioural despair (forced swim test and tail suspension test) a topic of debate. While there is good evidence to support the value of using these behavioural readouts to study the effects of stress, these approaches have largely failed to detect reliable phenotypic effects in other disease models. In this systematic review, we identified publications which had tested N-methyl-D-aspartate receptor antagonists in normal animals using either the forced swim test or tail suspension test. We compared findings for different doses and time points and also drugs with different clinical profiles to investigate how well the outcomes in the rodent model predicted their effects in the clinic. Despite clear evidence that N-methyl-D-aspartate receptor antagonists reduce immobility time and hence exhibit an antidepressant profile in these tasks, we found similar effects with both clinically effective drugs as well as those which have failed to show efficacy in clinical trials. These findings suggest that behavioural despair tests in normal animals do not provide a good method to predict clinical efficacy of N-methyl-D-aspartate receptor antagonists.

Faecal microbiota transplantation from patients with depression or healthy individuals into rats modulates mood-related behaviour

Differences in gut microbiota composition have been observed in patients with major depressive disorder (MDD) compared to healthy individuals. Here, we investigated if faecal microbiota transplantation (FMT) from patients with MDD into rats could induce a depressive-like phenotype. We performed FMT from patients with MDD (FMT-MDD) and healthy individuals (FMT-Healthy) into male Flinders Sensitive Line (FSL) and Flinders Resistant Line (FRL) rats and assessed depressive-like behaviour. No behavioural differences were observed in the FSL rats. In FRL rats, the FMT-Healthy group displayed significantly less depressive-like behaviour than the FMT-MDD group. However, there was no difference in behaviour between FMT-MDD FRL rats and negative controls, indicating that FMT-Healthy FRL rats received beneficial bacteria. We additionally found different taxa between the FMT-MDD and the FMT-Healthy FRL rats, which could be traced to the donors. Four taxa, three belonging to the family Ruminococcaceae and the genus Lachnospira, were significantly elevated in relative abundance in FMT-MDD rats, while the genus Coprococcus was depleted. In this study, the FMT-MDD group was different from the FMT-Healthy group based on behaviour and intestinal taxa.

DBscorer: An Open-Source Software for Automated Accurate Analysis of Rodent Behavior in Forced Swim Test and Tail Suspension Test

Forced swim test (FST) and tail suspension test (TST) are commonly used behavioral tests for screening antidepressant drugs with a high predictive validity. These tests have also proved useful to assess the non-motor symptoms in the animal models of movement disorders such as Parkinson's disease and Huntington's disease. Manual analysis of FST and TST is a time-consuming exercise and has large observer-to-observer variability. Automation of behavioral analysis alleviates these concerns, but there are no easy-to-use open-source tools for such analysis. Here, we describe the development of Depression Behavior Scorer (DBscorer), an open-source program installable on Windows, with an intuitive graphical user interface (GUI), that helps in accurate quantification of immobility behavior in FST and TST from video analysis. Several calibration options allow customization of various parameters to suit the experimental requirements. Apart from the readout of time spent immobile, DBscorer also provides additional data and graphics of immobility/mobility states across time revealing the evolution of behavioral despair over the duration of the test and allows the analysis of additional parameters. Such comprehensive analysis allows a more nuanced understanding of the expression of behavioral despair in FST and TST. We believe that DBscorer would make analysis of behavior in FST and TST unbiased, automated and rapid, and hence prove to be helpful to the wider neuroscience community.